ANNEXES

Annex Number	Annex title	Page
I	Requirements for any other specified fuels, fuel mixtures or fuel emulsions
II	Arrangements with regard to conformity of production
III	Methodology for adapting the emission laboratory test results to include the deterioration factors
IV	Requirements with regard to emission control strategies, NOx control measures and particulate control measures
V	Measurements and tests with regard to the area associated with the non-road steady-state test cycle
VI	Conditions, methods, procedures and apparatus for the conduct of tests and for emission measurement and sampling
VII	Method for data evaluation and calculations
VIII	Performance requirements and test procedures for dual-fuel engines
IX	Technical characteristics of the reference fuels
X	Detailed technical specifications and conditions for delivering an engine separately from its exhaust after-treatment system
XI	Detailed technical specifications and conditions for the temporary placing on the market for the purposes of field testing
XII	Detailed technical specifications and conditions for special purpose engines
XIII	Acceptance of equivalent engine type-approvals
XIV	Details of the relevant information and instructions for OEMs
XV	Details of the relevant information and instructions for end-users
XVI	Performance standards and assessment of technical services
XVII	Characteristics of the steady-state and transient test cycles

ANNEX I

Requirements for any other specified fuels, fuel mixtures or fuel emulsions

1.   Requirements for engines fuelled with liquid fuels

1.1.   When applying for an EU type-approval, manufacturers may select one of the following options with regard to the engine's fuel range:

(a)	standard fuel range engine, in accordance with the requirements set out in point 1.2; or,

(b)	fuel-specific engine, in accordance with the requirements set out in point 1.3.

1.2.   Requirements for a standard fuel range (diesel, petrol) engine

A standard fuel range engine shall meet the requirements specified in points 1.2.1 to 1.2.4.

1.2.1.   The parent engine shall meet the applicable limit values set out in Annex II to Regulation (EU) 2016/1628 and the requirements set out in this Regulation when the engine is operated on the reference fuels specified in sections 1.1 or 2.1 of Annex IX.

1.2.2.   In the absence of either a standard from the European Committee for Standardization (‘CEN standard’) for non-road gas-oil or a table of fuel properties for non-road gas-oil in Directive 98/70/EC of the European Parliament and of the Council (1), the diesel (non-road gas-oil) reference fuel in Annex IX shall represent market non-road gas-oils with a sulphur content not greater than 10 mg/kg, cetane number not less than 45 and an Fatty-Acid Methyl Ester (‘FAME’) content not greater than 7,0 % v/v. Except where otherwise permitted in accordance with points 1.2.2.1, 1.2.3 and 1.2.4, the manufacturer shall make a corresponding declaration to the end-users in accordance with the requirements in Annex XV that operation of the engine on non-road gas-oil is limited to those fuels with a sulphur content not greater than 10 mg/kg (20 mg/kg at point of final distribution) cetane number not less than 45 and an FAME content not greater than 7,0 % v/v. The manufacturer may optionally specify other parameters (e.g. for lubricity).

1.2.2.1.   The engine manufacturer shall not indicate at the moment of EU type-approval that an engine type or engine family may be operated within the Union on market fuels other than those that comply with the requirements in this point unless the manufacturer additionally complies with the requirement in point 1.2.3.

(a)	In the case of petrol, Directive 98/70/EC or the CEN standard EN 228:2012. Lubricating oil may be added according to the specification of the manufacturer;

(b)	In the case of diesel (other than non-road gas-oil), Directive 98/70/EC of the European Parliament and of the Council or the CEN standard EN 590:2013;

(c)	In the case of diesel (non-road gas-oil), Directive 98/70/EC and also both a cetane number not less than 45 and FAME not greater than 7,0 % v/v.

1.2.3.   If the manufacturer permits engines to run on additional market fuels other than those identified in point 1.2.2, such as running on B100 (EN 14214:2012+A1:2014), B20 or B30 (EN16709:2015), or on specific fuels, fuel mixtures or fuel emulsions, all of the following actions shall be taken by the manufacturer in addition to the requirements of point 1.2.2.1:

(a)	declare, in the information document set out in Commission Implementing Regulation (EU) 2017/656 (2), the specification of the commercial fuels, fuel mixtures or emulsions on which the engine family is capable to run;

(b)	demonstrate the capability of the parent engine to meet the requirements of this Regulation on the fuels, fuel mixtures or emulsions declared;

(c)

be liable to meet the requirements of in-service monitoring specified in Commission Delegated Regulation (EU) 2017/655 (3) on the fuels, fuel mixtures or emulsions declared, including any blend between the declared fuels, fuel mixtures or emulsions, and the applicable market fuel identified in point 1.2.2.1.

1.2.4.   For SI engines, the fuel/oil mixture ratio must be the ratio which shall be recommended by the manufacturer. The percentage of oil in the fuel/lubricant mixture shall be recorded in the information document set out in Implementing Regulation (EU) 2017/656.

1.3.   Requirements for a fuel-specific (ED 95 or E 85) engine

A specific fuel (ED 95 or E 85) engine shall meet the requirements specified in points 1.3.1 and 1.3.2.

1.3.1.   For ED 95, the parent engine shall meet the applicable limit values set out in Annex II to Regulation (EU) 2016/1628 and the requirements set out in this Regulation when the engine is operated on the reference fuel specified in point 1.2 of Annex IX.

1.3.2.   For E 85, the parent engine shall meet the applicable limit values set out in Annex II to Regulation (EU) 2016/1628 and the requirements set out in this Regulation when the engine is operated on the reference fuel specified point 2.2 of Annex IX.

2.   Requirements for engines fuelled with natural gas/biomethane (NG) or liquefied petroleum gas (LPG), including dual-fuel engines

2.1.   When applying for an EU type-approval, manufacturers may select one of the following options with regard to the engine's fuel range:

(a)	universal fuel range engine, in accordance with the requirements set out in point 2.3;

(b)	restricted fuel range engine, in accordance with the requirements set out in point 2.4;

(c)	fuel-specific engine, in accordance with the requirements set out in point 2.5.

2.2.   Tables summarizing the requirements for EU type-approval of natural gas/biomethane fuelled engines, LPG-fuelled engines and dual-fuel engines are provided in Appendix 1.

2.3.   Requirements for a universal fuel range engine

2.3.1.   For engines fuelled with natural gas/biomethane, including dual-fuel engines, the manufacturer shall demonstrate the parent engine's capability to adapt to any natural gas/biomethane composition that may occur across the market. That demonstration shall be carried out in accordance with this section 2 and in case of dual-fuel engines, also in accordance with the additional provisions regarding the fuel adaptation procedure set out in point 6.4 of Annex VIII.

2.3.1.1.   For engines fuelled with compressed natural gas/biomethane (CNG) there are generally two types of fuel, high calorific fuel (H-gas) and low calorific fuel (L-gas), but with a significant spread within both ranges; they differ significantly in their energy content expressed by the Wobbe Index and in their λ-shift factor (Sλ). Natural gases with a λ-shift factor between 0,89 and 1,08 (0,89 ≤ Sλ ≤ 1,08) are considered to belong to H-range, while natural gases with a λ-shift factor between 1,08 and 1,19 (1,08 ≤ Sλ ≤ 1,19) are considered to belong to L-range. The composition of the reference fuels reflects the extreme variations of Sλ.

The parent engine shall meet the requirements of this Regulation on the reference fuels GR (fuel 1) and G25 (fuel 2), as specified in Annex IX, or on the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX, without any manual readjustment to the engine fuelling system between the two tests (self-adaptation is required). One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the non-road steady-state test cycles (‘NRSC’), where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.

2.3.1.1.1.   The manufacturer may test the engine on a third fuel (fuel 3) if the λ-shift factor (Sλ) lies between 0,89 (that is the lower range of GR) and 1,19 (that is the upper range of G25), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

2.3.1.2.   For engines fuelled with liquefied natural gas/liquefied biomethane (LNG), the parent engine shall meet the requirements of this Regulation on the reference fuels GR (fuel 1) and G20 (fuel 2), as specified in Annex IX, or on the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX, without any manual readjustment to the engine fuelling system between the two tests (self-adaptation is required). One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the NRSC, where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.

2.3.2.   For engines fuelled with compressed natural gas/biomethane (CNG) which are self-adaptive for the range of H-gases on the one hand and the range of L-gases on the other hand, and which switch between the H-range and the L-range by means of a switch, the parent engine shall be tested on the relevant reference fuel as specified in in Annex IX for each range, at each position of the switch. The fuels are GR (fuel 1) and G23 (fuel 3) for the H-range of gases and G25 (fuel 2) and G23 (fuel 3) for the L-range of gases, or the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX. The parent engine shall meet the requirements of this Regulation at both positions of the switch without any readjustment to the fuelling between the two tests at each position of the switch. One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the NRSC, where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.

2.3.2.1.   The manufacturers may test the engine on a third fuel instead of G23 (fuel 3) if the λ-shift factor (Sλ) lies between 0,89 (that is the lower range of GR) and 1,19 (that is the upper range of G25), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

2.3.3.   For engines fuelled with natural gas/biomethane, the ratio of the emission results ‘r’ shall be determined for each pollutant as follows:

or,

and

2.3.4.   For engines fuelled with LPG the manufacturer shall demonstrate the parent engine's capability to adapt to any fuel composition that may occur across the market.

For engines fuelled with LPG there are variations in C3/C4 composition. These variations are reflected in the reference fuels. The parent engine shall meet the emission requirements on the reference fuels A and B as specified in Annex IX without any readjustment to the fuelling between the two tests. One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the NRSC, where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.

2.3.4.1.   The ratio of emission results ‘r’ shall be determined for each pollutant as follows:

2.4.   Requirements for a restricted fuel range engine

A restricted fuel range engine shall meet the requirements specified in points 2.4.1 to 2.4.3.

2.4.1.   For engines fuelled with CNG and designed for operation on either the range of H-gases or on the range of L-gases

2.4.1.1.   The parent engine shall be tested on the relevant reference fuel, as specified in Annex IX, for the relevant range. The fuels are GR (fuel 1) and G23 (fuel 3) for the H-range of gases and G25 (fuel 2) and G23 (fuel 3) for the L-range of gases or the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX. The parent engine shall meet the requirements of this Regulation without any readjustment to the fuelling between the two tests. One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the NRSC, where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.

2.4.1.2.   The manufacturers may test the engine on a third fuel instead of G23 (fuel 3) if the λ-shift factor (Sλ) lies between 0,89 (that is the lower range of GR) and 1,19 (that is the upper range of G25), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

2.4.1.3.   The ratio of emission results ‘r’ shall be determined for each pollutant as follows:

or,

and

2.4.1.4.   On delivery to the customer the engine shall bear a label as specified in Annex III to Regulation (EU) 2016/1628 stating for which range of gases the engine is EU type-approved.

2.4.2.   For engines fuelled with natural gas or LPG and designed for operation on one specific fuel composition

2.4.2.1.   The parent engine shall meet the emission requirements on the reference fuels GR and G25 or on the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX in the case of CNG, on the reference fuels GR and G20 or on the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 2 of Annex VI in the case of LNG, or on the reference fuels A and B in the case of LPG, as specified in Annex IX. Fine-tuning of the fuelling system is allowed between the tests. This fine-tuning will consist of a recalibration of the fuelling database, without any alteration to either the basic control strategy or the basic structure of the database. If necessary the exchange of parts that are directly related to the amount of fuel flow such as injector nozzles is allowed.

2.4.2.2.   For engines fuelled with CNG, the manufacturer may test the engine on the reference fuels GR and G23, or on the reference fuels G25 and G23, or on the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX, in which case the EU type-approval is only valid for the H-range or the L-range of gases respectively.

2.4.2.3.   On delivery to the customer the engine shall bear a label as specified in Annex III to Implementing Regulation (EU) 2017/656 stating for which fuel range composition the engine has been calibrated.

2.5.   Requirements for a fuel-specific engine fuelled with liquefied natural gas/liquefied biomethane (LNG)

A fuel-specific engine fuelled with liquefied natural gas/liquefied biomethane shall meet the requirements specified in points 2.5.1 to 2.5.2.

2.5.1.   Fuel-specific engine fuelled with liquefied natural gas/liquefied biomethane (LNG)

2.5.1.1.   The engine shall be calibrated for a specific LNG gas composition resulting in a λ-shift factor not differing by more than 3 % from the λ -shift factor of the G20 fuel specified in Annex IX, and the ethane content of which does not exceed 1,5 %.

2.5.1.2.   If the requirements set out in point 2.5.1.1.are not fulfilled, the manufacturer shall apply for a universal fuel engine according to the specifications set out in point 2.1.3.2.

2.5.2.   Fuel-specific engine fuelled with Liquefied Natural Gas (LNG)

2.5.2.1.   For a dual-fuel engine family the engines shall be calibrated for a specific LNG gas composition resulting in a λ-shift factor not differing by more than 3 % from the λ-shift factor of the G20 fuel specified in Annex IX, and the ethane content of which does not exceed 1,5 %, the parent engine shall only be tested on the G20 reference gas fuel, or on the equivalent fuel created using an admixture of pipeline gas with other gases, as specified in Appendix 1 of Annex IX.

2.6.   EU type-approval of a member of a family

2.6.1.   With the exception of the case mentioned in point 2.6.2, the EU type-approval of a parent engine shall be extended to all family members, without further testing, for any fuel composition within the range for which the parent engine has been EU type-approved (in the case of engines described in point 2.5) or the same range of fuels (in the case of engines described in either point 2.3 or 2.4) for which the parent engine has been EU type-approved.

2.6.2.   Where the technical service determines that, with regard to the selected parent engine the submitted application does not fully represent the engine family defined in Annex IX to Implementing Regulation (EU) 2017/656, an alternative and if necessary an additional reference test engine may be selected by the technical service and tested.

2.7.   Additional requirements for dual-fuel engines

In order to receive an EU type-approval of a dual-fuel engine type or engine family, the manufacturer shall:

(a)	conduct the tests in accordance with Table 1.3 of Appendix 1;

(b)	in addition to the requirements set out in section 2, demonstrate that the dual-fuel engines are subject to the tests and comply with the requirements set out in Annex VIII.

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(1)  Directive 98/70/EC of the European Parliament and of the Council of 13 October 1998 relating to the quality of petrol and diesel fuels and amending Council Directive 93/12/EEC (OJ L 350, 28.12.1998, p. 58).

(2)  Commission Implementing Regulation (EU) 2017/656 of 19 December 2016 laying down the administrative requirements relating to emission limits and type-approval of internal combustion engines for non-road mobile machinery in accordance with Regulation (EU) 2016/1628 of the European Parliament and of the Council (See page 364 of this Official Journal).

(3)  Commission Delegated Regulation (EU) 2017/655 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to monitoring of gaseous pollutant emissions from in-service internal combustion engines installed in non-road mobile machinery (See page 334 of this Official Journal).

ANNEX II

Arrangements with regard to conformity of production

1.   Definitions

For the purposes of this Annex the following definitions shall apply:

1.1.	‘quality management system’ means a set of interrelated or interacting elements that organisations use to direct and control how quality policies are implemented and quality objectives are achieved;

1.2.	‘audit’ means an evidence-gathering process used to evaluate how well audit criteria are being applied; it should be objective, impartial and independent, and the audit process should be both systematic and documented;

1.3.	‘corrective actions’ means a problem-solving process with subsequent steps taken to remove the causes of a nonconformity or undesirable situation and designed to prevent their recurrence;

2.   Purpose

2.1.   The conformity of production arrangements aim to ensure that each engine is in conformity with the specification, performance and marking requirements of the approved engine type or engine family.

2.2.   Procedures include, inseparably, the assessment of quality management systems, referred as ‘initial assessment’ and set out in section 3 and verification and production-related controls, referred to as ‘product conformity arrangements’ and set out in section 4.

3.   Initial assessment

3.1.   Before granting EU type-approval, the approval authority shall verify the existence of satisfactory arrangements and procedures established by the manufacturer for ensuring effective control so that engines when in production conform to the approved engine type or engine family.

3.2.   Guidelines for quality and/or environmental management systems auditing set out in the EN ISO 19011:2011 standard shall apply to the initial assessment.

3.3.   The approval authority shall be satisfied with the initial assessment and the product conformity arrangements in section 4 taking account as necessary of one of the arrangements described in points 3.3.1 to 3.3.3 or a combination of those arrangements in full or in part as appropriate.

3.3.1.   The initial assessment and/or verification of product conformity arrangements shall be carried out by the approval authority granting the approval or an appointed body acting on behalf of the approval authority.

3.3.1.1.   When considering the extent of the initial assessment to be carried out, the approval authority may take account of available information relating to the manufacturer's certification which has not been accepted under point 3.3.3.

3.3.2.   The initial assessment and verification of product conformity arrangements may also be carried out by the approval authority of another Member State, or the appointed body designated for this purpose by the approval authority.

3.3.2.1.   In such a case, the approval authority of the other Member State shall prepare a statement of compliance outlining the areas and production facilities it has covered as relevant to the engines to be EU type-approved.

3.3.2.2.   On receiving an application for a compliance statement from the approval authority of a Member State granting EU type-approval, the approval authority of another Member State shall send forthwith the statement of compliance or advise that it is not in a position to provide such a statement.

3.3.2.3.   The statement of compliance shall include at least the following:

3.3.2.3.1.

group or company (e.g. XYZ manufacturing);

3.3.2.3.2.

particular organisation (e.g. European division);

3.3.2.3.3.

plants/sites (e.g. engine plant 1 (United Kingdom) — engine plant 2 (Germany));

3.3.2.3.4.

engine types/engine families included

3.3.2.3.5.

areas assessed (e.g. engine assembly, engine testing, after-treatment manufacture)

3.3.2.3.6.

documents examined (e.g. company and site quality manual and procedures);

3.3.2.3.7.

date of the assessment (e.g. audit conducted from 18 to 30.5.2013);

3.3.2.3.8.

planned monitoring visit (e.g. October 2014).

3.3.3.   The approval authority shall also accept the manufacturer's suitable certification to harmonised standard EN ISO 9001:2008 or an equivalent harmonised standard as satisfying the initial assessment requirements of point 3.3. The manufacturer shall provide details of the certification and undertake to inform the approval authority of any revisions to its validity or scope.

4.   Product conformity arrangements

4.1.   Every engine EU type-approved pursuant to Regulation (EU) 2016/1628, this Delegated Regulation, Delegated Regulation (EU) 2017/655 and Implementing Regulation (EU) 2017/656 shall be so manufactured as to conform to the approved engine type or engine family by meeting the requirements of this Annex, Regulation (EU) 2016/1628 and the abovementioned Delegated and Implementing Regulations.

4.2.   Before granting a EU type-approval pursuant to Regulation (EU) 2016/1628 and the delegated and implementing acts adopted pursuant to that Regulation, the approval authority shall verify the existence of adequate arrangements and documented control plans, to be agreed with the manufacturer for each approval, to carry out at specified intervals those tests or associated checks necessary to verify continued conformity with the approved engine type or engine family, including, where applicable, tests specified in Regulation (EU) 2016/1628 and the delegated and implementing acts adopted pursuant to that Regulation.

4.3.   The holder of the EU type-approval shall:

4.3.1.

ensure the existence and application of procedures for effective control of the conformity of engines to the approved engine type or engine family;

4.3.2.

have access to the testing or other appropriate equipment necessary for checking conformity to each approved engine type or engine family;

4.3.3.

ensure that test or check result data are recorded and that annexed documents remain available for a period of up to 10 years to be determined in agreement with the approval authority;

4.3.4.

for engine categories NRSh and NRS, except for NRS-v-2b and NRS-v-3, ensure that for each type of engine, at least the checks and the tests prescribed in Regulation (EU) 2016/1628 and the delegated and implementing acts adopted pursuant to that Regulation are carried out. For other categories tests at a component or assembly of components level with appropriate criterion may be agreed between the manufacturer and the approval authority.

4.3.5.

analyse the results of each type of test or check, in order to verify and ensure the stability of the product characteristics, making allowance for variation in industrial production;

4.3.6.

ensure that any set of samples or test pieces giving evidence of non-conformity in the type of test in question gives rise to a further sampling and test or check.

4.4.   If the further audit or check results referred to in point 4.3.6 are deemed not to be satisfactory in the opinion of the approval authority, the manufacturer shall ensure that conformity of production is restored as soon as possible by corrective actions to the satisfaction of the approval authority.

5.   Continued verification arrangements

5.1.   The authority which has granted EU type-approval may at any time verify the conformity of production control methods applied in each production facility by means of periodic audits. The manufacturer shall for that purpose allow access to the manufacture, inspection, testing, storage and distribution sites and shall provide all necessary information with regard to the quality management system documentation and records.

5.1.1.   The normal approach for such periodic audits shall be to monitor the continued effectiveness of the procedures laid down in sections 3 and 4 (initial assessment and product conformity arrangements).

5.1.1.1.   Surveillance activities carried out by the technical services (qualified or recognised as required in point 3.3.3) shall be accepted as satisfying the requirements of point 5.1.1 with regard to the procedures established at initial assessment.

5.1.1.2.   The minimum frequency of verifications (other than those referred to in point 5.1.1.1) to ensure that the relevant conformity of production controls applied in accordance with sections 3 and 4 are reviewed over a period consistent with the climate of trust established by the approval authority shall be at least once every two years. However, additional verifications shall be carried out by the approval authority depending on the yearly production, the results of previous evaluations, the need to monitor corrective actions and upon a reasoned request from another approval authority or any market surveillance authority.

5.2.   At every review, the records of tests, checks and production records, and in particular the records of those tests or checks documented as required in point 4.2, shall be available to the inspector.

5.3.   The inspector may select random samples to be tested in the manufacturer's laboratory or in the facilities of the technical service, in which case only physical tests shall be carried out. The minimum number of samples may be determined according to the results of the manufacturer's own verification.

5.4.   Where the level of control appears unsatisfactory, or when it seems necessary to verify the validity of the tests carried out in application of point 5.2, or upon a reasoned request from another approval authority or any market surveillance authority, the inspector shall select samples to be tested in the manufacturer's laboratory or sent to the technical service to perform physical tests in accordance with the requirements set out in section 6, in Regulation (EU) 2016/1628 and in the delegated and implementing acts adopted pursuant to that Regulation.

5.5.   Where unsatisfactory results are found by the approval authority during an inspection or a monitoring review, or by an approval authority in other Member State, in accordance with Article 39(3) of Regulation (EU) 2016/1628, the approval authority shall ensure that all necessary steps are taken to restore conformity of production as rapidly as possible.

6.   Conformity of production test requirements in cases of an unsatisfactory level of product conformity control as referred to in point 5.4.

6.1.   In case of an unsatisfactory level of product conformity control as referred to in point 5.4 or point 5.5, conformity of production shall be checked by emissions testing on the basis of the description in the EU type-approval certificates set out in Annex IV to Implementing Regulation (EU) 2017/656.

6.2.   Except otherwise provided in point 6.3, the following procedure shall apply:

6.2.1.   Three engines and, if applicable, three after-treatment systems shall randomly be taken for inspection from the series production of the engine type under consideration. Additional engines shall be taken as necessary to reach a pass or fail decision. For reaching a pass decision, a minimum of four engines needs to be tested.

6.2.2.   After the inspector's selection of the engines, the manufacturer shall not carry out any adjustment to the engines selected.

6.2.3.   Engines shall be subjected to emissions testing in accordance with the requirements of Annex VI, or, in the case of dual fuel engines, in accordance with Appendix 2 of Annex VIII, and shall be subject to the test cycles relevant for the engine type in accordance with Annex XVII.

6.2.4.   The limit values shall be those set out in Annex II to Regulation (EU) 2016/1628. Where an engine with after-treatment regenerates infrequently as referred to in point 6.6.2 of Annex VI, each gaseous or particulate pollutant emission result shall be adjusted by the factor applicable to the engine type. In all cases each gaseous or particulate pollutant emission result shall be adjusted by application of the appropriate deterioration factors (DFs) for that engine type, as determined in accordance with Annex III.

6.2.5.   The tests shall be carried out on newly manufactured engines.

6.2.5.1.   At the request of the manufacturer, the tests may be conducted on engines which have been run-in, up either 2 % of the emission durability period or, if this is a shorter period of time, 125 hours. Where the run-in procedure shall be conducted by the manufacturer who shall undertake not to make any adjustments to those engines. Where the manufacturer has specified a run-in procedure in point 3.3 of the information document, as set out in Annex I to Implementing Regulation (EU) 2017/656, the run-in shall be conducted using that procedure.

6.2.6.   On the basis of tests of the engine by sampling as set out in Appendix 1, the series production of the engines under consideration is regarded as conforming to the approved type where a pass decision is reached for all the pollutants and as non-conforming to the approved type where a fail decision is reached for one pollutant, in accordance with the test criteria applied in Appendix 1, and as shown in Figure 2.1.

6.2.7.   When a pass decision has been reached for one pollutant, this decision may not be changed as a consequence of a result from any additional tests made in order to reach a decision for the other pollutants.

If a pass decision is not reached for all the pollutants and no fail decision is reached for any of the pollutant, a test shall be carried out on another engine.

6.2.8.   If no decision is reached, the manufacturer may at any time decide to stop testing. In that case a fail decision shall be recorded.

6.3.   By derogation from point 6.2.1, the following procedure shall apply for engine types with a sales volume within the EU of less than 100 units per year:

6.3.1.

One engine and, if applicable, one after-treatment system shall be taken randomly for inspection from the series production of the engine type under consideration.

6.3.2.

If the engine meets the requirements outlined in point 6.2.4, a pass decision is reached and no further test is necessary.

6.3.3.

If the test does not satisfy the requirements outlined in point 6.2.4, the procedure outlined in points 6.2.6 to 6.2.9 shall be followed.

6.4.   All these tests may be conducted with the applicable market fuels. However, at the manufacturer's request, the reference fuels described in Annex IX shall be used. This implies tests, as described in Appendix 1 of Annex I, with at least two of the reference fuels for each gaseous-fuelled engine, except in the case of a gaseous-fuelled engine with a fuel-specific EU type-approval where only one reference fuel is required. Where more than one gaseous reference fuel is used the results shall demonstrate that the engine meets the limit values with each fuel.

6.5.   Non-compliance of gaseous-fuelled engines

In the case of dispute concerning compliance of gaseous-fuelled engines, including dual-fuel engines, when using a market fuel, the tests shall be performed with each reference fuel on which the parent engine has been tested, and, at the request of the manufacturer, with the possible additional third fuel, as referred to in points 2.3.1.1.1, 2.3.2.1 and 2.4.1.2 of Annex I, on which the parent engine may have been tested. When applicable, the result shall be converted by a calculation, applying the relevant factors ‘ r ’, ‘ r a ’ or ‘ r b ’ as described in points 2.3.3, 2.3.4.1 and 2.4.1.3 of Annex I. If r, r a or r b are less than 1, no correction shall take place. The measured results and, when applicable, the calculated results shall demonstrate that the engine meets the limit values with all relevant fuels (for example fuels 1, 2 and, if applicable, the third fuel in the case of natural gas/bio-methane engines, and fuels A and B in the case of LPG engines).

Figure 2.1

Schematic of production conformity testing

NO

YES

A pass decision is reached for one or more pollutants

NO

NO

YES

YES

Series accepted

Series rejected

Test of an additional engine

Is a pass decision reached for all pollutants?

According to the appropriate appendix does the test statistic result agree with the criteria for passing the series for at least one pollutant?

Computating of the test statistic result

According to the appropriate appendix does the test statistic result agree with the criteria for failing the series for at least one pollutant?

Test of three engines

ANNEX III

Methodology for adapting the emission laboratory test results to include the deterioration factors

1.   Definitions

For the purposes of this Annex, the following definitions apply:

1.1.	‘Ageing cycle’ means the non-road mobile machinery or engine operation (speed, load, power) to be executed during the service accumulation period.

1.2.	‘Critical emission-related components’ means the exhaust after- treatment system, the electronic engine control unit and its associated sensors and actuators, and the exhaust gas recirculation (EGR) including all related filters, coolers, control valves and tubing.

1.3.	‘Critical emission-related maintenance’ means the maintenance to be performed on critical emission-related components of the engine.

1.4.	‘Emission-related maintenance’ means the maintenance which substantially affects emissions or which is likely to affect emissions performance of the non-road mobile machinery or the engine during normal in-use operation.

1.5.	‘Engine-after-treatment system family’ means a manufacturer's grouping of engines that comply with the definition of engine family, but which are further grouped into a family of engine families utilising a similar exhaust after-treatment system.

1.6.	‘Non-emission-related maintenance’ means maintenance which does not substantially affect emissions and which does not have a lasting effect on the emissions performance deterioration of the non-road mobile machinery or the engine during normal in-use operation once the maintenance is performed.

1.7.	‘Service accumulation schedule’ means the ageing cycle and the service accumulation period for determining the deterioration factors for the engine-after-treatment system family.

2.   General

2.1.   This Annex details the procedures for selecting engines to be tested over a service accumulation schedule for the purpose of determining deterioration factors for engine type or engine family EU type-approval and conformity of production assessments. The deterioration factors shall be applied to the emissions measured in accordance with Annex VI and calculated in accordance with Annex VII in accordance with the procedure set out in point 3.2.7 or point 4.3, respectively.

2.2.   The service accumulation tests or the emissions tests performed to determine deterioration need not be witnessed by the approval authority.

2.3.   This Annex also details the emission-related and non-emission-related maintenance that should be or may be carried out on engines undergoing a service accumulation schedule. Such maintenance shall conform to the maintenance performed on in-service engines and communicated to the end-users of new engines.

3.   Engine categories NRE, NRG, IWP, IWA, RLL, RLR, SMB, ATS and sub-categories NRS-v-2b and NRS-v-3

3.1.   Selection of engines for establishing emission durability period deterioration factors

3.1.1.   Engines shall be selected from the engine family defined in section 2 of Annex IX to Implementing Regulation (EU) 2017/656 for emission testing to establish emission durability period deterioration factors.

3.1.2.   Engines from different engine families may be further combined into families based on the type of exhaust after-treatment system utilised. In order to place engines with a different cylinder configuration but having similar technical specifications and installation for the exhaust after-treatment systems into the same engine after-treatment system family, the manufacturer shall provide data to the approval authority that demonstrates that the emissions reduction performance of such engines is similar.

3.1.3.   The engine manufacturer shall select one engine representing the engine-after-treatment system family, as determined in accordance with point 3.1.2, for testing over the service accumulation schedule referred to in point 3.2.2, and shall be reported to the approval authority before any testing commences.

3.1.4.   If the approval authority decides that the worst case emissions of the engine-after-treatment system family can be better characterised by another test engine, the test engine to be used shall be selected jointly by the approval authority and the engine manufacturer.

3.2.   Determination of emission durability period deterioration factors

3.2.1.   General

Deterioration factors applicable to an engine-after-treatment system family shall be developed from the selected engines based on a service accumulation schedule that includes periodic testing for gaseous and particulate emissions over each test cycle applicable to the engine category, as given in Annex IV to Regulation (EU) 2016/1628. In the case of non-road transient test cycles for engines of category NRE (‘NRTC’), only the results of the hot-start run of the NRTC (‘hot-start NRTC’) shall be used.

3.2.1.1.   At the request of the manufacturer, the approval authority may allow the use of deterioration factors that have been established using alternative procedures to those specified in points 3.2.2 to 3.2.5. In that case, the manufacturer shall demonstrate to the satisfaction of the approval authority that the alternative procedures used are not less rigorous than those set out in points 3.2.2 to 3.2.5.

3.2.2.   Service accumulation schedule

Service accumulation schedules may be carried out at the choice of the manufacturer by running a non-road mobile machinery equipped with the selected engine over an ‘in-service’ accumulation schedule or by running the selected engine over a ‘dynamometer service’ accumulation schedule. The manufacturer shall not be required to use reference fuel for the service accumulation in-between emission measurement test points.

3.2.2.1.   In-service and dynamometer service accumulation

3.2.2.1.1.   The manufacturer shall determine the form and duration of the service accumulation and the ageing cycle for engines in a manner consistent with good engineering judgment.

3.2.2.1.2.   The manufacturer shall determine the test points where gaseous and particulate emissions will be measured over the applicable cycles, as follows:

3.2.2.1.2.1.

When running a service accumulation schedule shorter than the emission durability period in accordance with point 3.2.2.1.7, the minimum number of test points shall be three, one at the beginning, one approximately in the middle and one at the end of the service accumulation schedule.

3.2.2.1.2.2.

When completing the service accumulation up to the end of the emission durability period, the minimum number of test points shall be two, one at the beginning and one at the end of the service accumulation.

3.2.2.1.2.3.

The manufacturer may additionally test at evenly spaced intermediate points.

3.2.2.1.3.   The emission values at the start point and at the emission durability period endpoint either calculated in accordance with point 3.2.5.1 or measured directly in accordance with point 3.2.2.1.2.2, shall be within the limit values applicable to the engine family. However individual emission results from the intermediate test points may exceed those limit values.

3.2.2.1.4.   For engine categories or sub-categories to which a NRTC applies, or for engines category or sub-categories NRS to which a large spark-ignition engines non-road transient test cycles (‘LSI-NRTC’) applies, the manufacturer may request the agreement of the approval authority to run only one test cycle (either the hot-start NRTC or LSI-NRTC, as applicable, or NRSC) at each test point, and to run the other test cycle only at the beginning and at the end of the service accumulation schedule.

3.2.2.1.5.   In the case of engine categories or sub-categories for which there is no applicable non-road transient cycle given in Annex IV to Regulation (EU) 2016/1628, only the NRSC shall be run at each test point.

3.2.2.1.6.   Service accumulation schedules may be different for different engine-after-treatment system families.

3.2.2.1.7.   Service accumulation schedules may be shorter than the emission durability period, but shall not be shorter than the equivalent of at least one quarter of the relevant emission durability period specified in Annex V to Regulation (EU) 2016/1628.

3.2.2.1.8.   Accelerated ageing by adjusting the service accumulation schedule on a fuel consumption basis is permitted. The adjustment shall be based on the ratio between the typical in-use fuel consumption and the fuel consumption on the ageing cycle, but fuel consumption on the ageing cycle shall not exceed typical in-use fuel consumption by more than 30 %.

3.2.2.1.9.   The manufacturer may use, if agreed by the approval authority, alternative methods of accelerated ageing.

3.2.2.1.10.   The service accumulation schedule shall be fully described in the application for EU type-approval and reported to the approval authority before the start of any testing.

3.2.2.2.   If the approval authority decides that additional measurements need to be performed between the points selected by the manufacturer it shall notify the manufacturer. The revised service accumulation schedule shall be prepared by the manufacturer and agreed by the approval authority.

3.2.3.   Engine testing

3.2.3.1.   Engine stabilisation

3.2.3.1.1.   For each engine-after-treatment system family, the manufacturer shall determine the number of hours of non-road mobile machinery or engine running after which the operation of the engine-after-treatment system has stabilised. If requested by the approval authority the manufacturer shall make available the data and analysis used to make this determination. As an alternative, the manufacturer may run the engine or non-road mobile machinery between 60 and 125 hours or the equivalent time on the ageing cycle to stabilise the engine-after-treatment system.

3.2.3.1.2.   The end of the stabilisation period determined in point 3.2.3.1.1 shall be deemed to be the start of the service accumulation schedule.

3.2.3.2.   Service accumulation testing

3.2.3.2.1.   After stabilisation, the engine shall be run over the service accumulation schedule selected by the manufacturer, as described in point 3.2.2. At the periodic intervals in the service accumulation schedule determined by the manufacturer, and, where applicable, decided by the approval authority in accordance with point 3.2.2.2, the engine shall be tested for gaseous and particulate emissions over the hot-start NRTC and NRSC, or LSI-NRTC and NRSC applicable to the engine category, as set out in Annex IV to Regulation (EU) 2016/1628.

The manufacturer may select to measure the pollutant emissions before any exhaust after-treatment system separately from the pollutant emissions after any exhaust after-treatment system.

In accordance with point 3.2.2.1.4, if it has been agreed that only one test cycle (hot-start NRTC, LSI-NRTC or NRSC) be run at each test point, the other test cycle (hot-start NRTC, LSI-NRTC or NRSC) shall be run at the beginning and at the end of the service accumulation schedule.

In accordance with point 3.2.2.1.5, in the case of engine categories or sub-categories for which there is no applicable non-road transient cycle given in Annex IV to Regulation (EU) 2016/1628, only the NRSC shall be run at each test point.

3.2.3.2.2.   During the service accumulation schedule, maintenance shall be carried out on the engine in accordance with point 3.4.

3.2.3.2.3.   During the service accumulation schedule, unscheduled maintenance on the engine or non-road mobile machinery may be performed, for example if the manufacturer's normal diagnostic system has detected a problem that would have indicated to the non-road mobile machinery operator that a fault had arisen.

3.2.4.   Reporting

3.2.4.1.   The results of all emission tests (hot-start NRTC, LSI-NRTC and NRSC) conducted during the service accumulation schedule shall be made available to the approval authority. If an emission test is declared to be void, the manufacturer shall provide reasons why the test has been declared void. In such a case, another series of emission tests shall be carried out within the following 100 hours of service accumulation.

3.2.4.2.   The manufacturer shall retain records of all information concerning all the emission tests and maintenance carried out on the engine during the service accumulation schedule. This information shall be submitted to the approval authority along with the results of the emission tests conducted over the service accumulation schedule.

3.2.5.   Determination of deterioration factors

3.2.5.1.   When running a service accumulation schedule in accordance with point 3.2.2.1.2.1 or point 3.2.2.1.2.3, for each pollutant measured over the hot-start NRTC, LSI-NRTC and NRSC at each test point during the service accumulation schedule, a ‘best fit’ linear regression analysis shall be made on the basis of all test results. The results of each test for each pollutant shall be expressed to the same number of decimal places as the limit value for that pollutant, as applicable to the engine family, plus one additional decimal place.

Where in accordance with point 3.2.2.1.4 or point 3.2.2.1.5, only one test cycle (hot-start NRTC, LSI-NRTC or NRSC) has been run at each test point, the regression analysis shall be made only on the basis of the test results from the test cycle run at each test point.

The manufacturer may request the prior approval of the approval authority for a non-linear regression.

3.2.5.2.   The emission values for each pollutant at the start of the service accumulation schedule and at the emission durability period end point that is applicable for the engine under test shall be either:

(a)	determined by extrapolation of the regression equation in point 3.2.5.1, when running a service accumulation schedule in accordance with point 3.2.2.1.2.1 or point 3.2.2.1.2.3, or

(b)	measured directly, when running a service accumulation schedule in accordance with point 3.2.2.1.2.2.

Where emission values are used for engine families in the same engine-after-treatment family but with different emission durability periods, then the emission values at the emission durability period end point shall be recalculated for each emission durability period by extrapolation or interpolation of the regression equation as determined in point 3.2.5.1.

3.2.5.3.   The deterioration factor (DF) for each pollutant is defined as the ratio of the applied emission values at the emission durability period end point and at the start of the service accumulation schedule (multiplicative deterioration factor).

The manufacturer may request the prior approval of the approval authority for the application of an additive DF for each pollutant may be applied. The additive DF is defined as the difference between the calculated emission values at the emission durability period end point and at the start of the service accumulation schedule.

An example for determination of DFs by using linear regression is shown in Figure 3.1 for NOx emission.

Mixing of multiplicative and additive DFs within one set of pollutants is not permitted.

If the calculation results in a value of less than 1,00 for a multiplicative DF, or less than 0,00 for an additive DF, then the deterioration factor shall be 1,0 or 0,00, respectively.

In accordance with point 3.2.2.1.4, if it has been agreed that only one test cycle (hot-start NRTC, LSI-NRTC or NRSC) be run at each test point and the other test cycle (hot-start NRTC, LSI-NRTC or NRSC) run only at the beginning and end of the service accumulation schedule, the deterioration factor calculated for the test cycle that has been run at each test point shall be applicable also for the other test cycle.

Figure 3.1

Example of DF determination

NOx [g/kWh]

Multiplicative DF = 0,390 / 0,352 = 1,109

Additive DF = 0,390 - 0,352 = 0,038 g/kWh

EDP endpoint

25% of EDP

0,390 g/kWh

0,352 g/kWh

Limit value

Extrapolation

Minimum service accumulation

0,50

0,45

0,40

0,35

0,30

0,25

0,20

0 1 000 2 000 3 000 4 000 5 000 6 000 7 000 8 000

3.2.6.   Assigned deterioration factors

3.2.6.1.   As an alternative to using a service accumulation schedule to determine DFs, engine manufacturers may select to use assigned multiplicative DFs, as given in Table 3.1.

Table 3.1

Assigned deterioration factors

Test cycle	CO	HC	NOx	PM	PN
NRTC and LSI-NRTC	1,3	1,3	1,15	1,05	1,0
NRSC	1,3	1,3	1,15	1,05	1,0

Assigned additive DFs shall not be given. The assigned multiplicative DFs shall not be transformed into additive DFs.

For PN, either an additive DF of 0,0 or a multiplicative DF of 1,0 may be used, in conjunction with the results of previous DF testing that did not establish a value for PN if both of the following conditions are fulfilled:

(a)	the previous DF test was conducted on engine technology that would have qualified for inclusion in the same engine after-treatment system family, as set out in point 3.1.2, as the engine family to which it is intended to apply the DFs; and,

(b)	the test results were used in a previous type-approval granted before the applicable EU type-approval date given in Annex III to Regulation (EU) 2016/1628.

3.2.6.2.   Where assigned DFs are used, the manufacturer shall present to the approval authority robust evidence that the emission control components can reasonably be expected to have the emission durability associated with those assigned factors. This evidence may be based upon design analysis, or tests, or a combination of both.

3.2.7.   Application of deterioration factors

3.2.7.1.   The engines shall meet the respective emission limits for each pollutant, as applicable to the engine family, after application of the deterioration factors to the test result as measured in accordance with Annex VI (cycle-weighted specific emission for particulate and each individual gas). Depending on the type of DF, the following provisions apply:

(a)	Multiplicative: (cycle weighted specific emission) × DF ≤ emission limit

(b)	Additive: (cycle weighted specific emission) + DF ≤ emission limit

Cycle weighted specific emission may include the adjustment for infrequent regeneration, where applicable.

3.2.7.2.   For a multiplicative NOx + HC DF, separate HC and NOx DFs shall be determined and applied separately when calculating the deteriorated emission levels from an emissions test result before combining the resultant deteriorated NOx and HC values to establish compliance with the emission limit.

3.2.7.3.   The manufacturer may carry across the DFs determined for an engine-after-treatment system family to an engine that does not fall into the same engine-after-treatment system family. In such cases, the manufacturer shall demonstrate to the approval authority that the engine for which the engine-after-treatment system family was originally tested and the engine for which the DFs are being carried across have similar technical specifications and installation requirements on the non-road mobile machinery and that the emissions of such engine are similar.

Where DFs are carried across to an engine with a different emission durability period, the DFs shall be recalculated for the applicable emission durability period by extrapolation or interpolation of the regression equation as determined in point 3.2.5.1.

3.2.7.4.   The DF for each pollutant for each applicable test cycle shall be recorded in the test report set out in Appendix 1 of Annex VI to Implementing Regulation (EU) 2017/656.

3.3.   Checking of conformity of production

3.3.1.   Conformity of production for emissions compliance is checked on the basis of Section 6 of Annex II.

3.3.2.   The manufacturer may measure the pollutant emissions before any exhaust after-treatment system at the same time as the EU type-approval test is being performed. For that purpose, the manufacturer may develop informal DFs separately for the engine without after-treatment system and for the after-treatment system that may be used by the manufacturer as an aid to end of production line auditing.

3.3.3.   For the purposes of EU type-approval, only the DFs determined in accordance with point 3.2.5 or 3.2.6 shall be recorded in the test report set out in Appendix 1 of Annex VI to Implementing Regulation (EU) 2017/656.

3.4.   Maintenance

For the purpose of the service accumulation schedule, maintenance shall be performed in accordance with the manufacturer's manual for service and maintenance.

3.4.1.   Scheduled emission-related maintenance

3.4.1.1.   Scheduled emission-related maintenance during engine running, undertaken for the purpose of conducting a service accumulation schedule, shall occur at equivalent intervals to those that are specified in the manufacturer's maintenance instructions to the end-user of the non-road mobile machinery or engine. This schedule maintenance may be updated as necessary throughout the service accumulation schedule provided that no maintenance operation is deleted from the maintenance schedule after the operation has been performed on the test engine.

3.4.1.2.   Any adjustment, disassembly, cleaning or exchange of critical emission-related components which is performed on a periodic basis within the emission durability period to prevent malfunction of the engine, shall only be done to the extent that is technologically necessary to ensure proper functioning of the emission control system. The need for scheduled exchange, within the service accumulation schedule and after a certain running time of the engine, of critical emission-related components other than those qualifying as routine exchange items shall be avoided. In this context, consumable maintenance items for regular renewal or items that require cleaning after a certain running time of the engine, shall qualify as routine exchange items.

3.4.1.3.   Any scheduled maintenance requirements shall be subject to approval by the approval authority before an EU type-approval is granted and shall be included in the customer's manual. The approval authority shall not refuse to approve maintenance requirements that are reasonable and technically necessary, including but not limited to those identified in point 1.6.1.4.

3.4.1.4.   The engine manufacturer shall specify for the service accumulation schedules any adjustment, cleaning, maintenance (where necessary) and scheduled exchange of the following items:

—	filters and coolers in the exhaust gas recirculation (EGR)

—	positive crankcase ventilation valve, if applicable

—	fuel injector tips (only cleaning is permitted)

—	fuel injectors

—	turbocharger

—	electronic engine control unit and its associated sensors and actuators

—	particulate after-treatment system (including related components)

—	NOx after-treatment system (including related components)

—	exhaust gas recirculation (EGR), including all related control valves and tubing

—	any other exhaust after-treatment system.

3.4.1.5.   Scheduled critical emission-related maintenance shall only be performed if it is required to be performed in-use and that requirement is communicated to the end-user of the engine or non-road mobile machinery.

3.4.2.   Changes to scheduled maintenance

The manufacturer shall submit a request to the approval authority for approval of any new scheduled maintenance that it wishes to perform during the service accumulation schedule and subsequently to recommend to end-users of non-road mobile machinery and engines. The request shall be accompanied by data supporting the need for the new scheduled maintenance and the maintenance interval.

3.4.3.   Non-emission-related scheduled maintenance

Non-emission-related scheduled maintenance which is reasonable and technically necessary (for example oil change, oil filter change, fuel filter change, air filter change, cooling system maintenance, idle speed adjustment, governor, engine bolt torque, valve lash, injector lash, adjustment of the tension of any drive-belt, etc.) may be performed on engines or non-road mobile machinery selected for the service accumulation schedule at the least frequent intervals recommended by the manufacturer to the end-user (for example not at the intervals recommended for severe service).

3.5.   Repair

3.5.1.   Repairs to the components of an engine selected for testing over a service accumulation schedule shall be performed only as a result of component failure or engine malfunction. Repair of the engine itself, the emission control system or the fuel system is not permitted except to the extent defined in point 3.5.2.

3.5.2.   If the engine, its emission control system or its fuel system fails during the service accumulation schedule, the service accumulation shall be considered void, and a new service accumulation shall be started with a new engine.

The previous paragraph shall not apply when the failed components are replaced with equivalent components that have been subject to a similar number of hours of service accumulation.

4.   Engine categories and sub-categories NRSh and NRS, except for NRS-v-2b and NRS-v-3

4.1.   The applicable EDP category and corresponding deterioration factor (DF) shall be determined in accordance with this section 4.

4.2.   An engine family shall be considered as compliant with the limit values required for an engine sub-category when the emissions test results of all engines representing the engine family, once adjusted by multiplication by the DF laid down in section 2, are lower than or equal to the limit values required for that engine sub-category. However, where one or more emission test results of one or more engines representing the engine family, once adjusted by multiplication by the DF laid down in section 2, are higher than one or more single emission limit values required for that engine sub-category, the engine family shall be considered not compliant with the limit values required for that engine sub-category.

4.3.   DFs shall be determined as follows:

4.3.1.

On at least one test engine representing the configuration chosen to be the most likely to exceed HC + NOx emission limits, and constructed to be representative of production engines, the (full) test procedure emission testing shall be conducted as described in Annex VI after the number of hours representing stabilised emissions.

4.3.2.

If more than one engine is tested, the results shall be calculated as the average of the results for all the engines tested, rounded to the same number of decimal places as in the applicable limit, expressed to one additional significant figure.

4.3.3.

Such emission testing shall be conducted again following ageing of the engine. The ageing procedure should be designed to allow the manufacturer to appropriately predict the in-use emission deterioration expected over the EDP of the engine, taking into account the type of wear and other deterioration mechanisms expected under typical consumer use which could affect emissions performance. If more than one engine is tested, the results shall be calculated as the average of the results for all the engines tested, rounded to the same number of decimal places contained in the applicable limit, expressed to one additional significant figure.

4.3.4.

The emissions at the end of the EDP (average emissions, if applicable) for each regulated pollutant shall be divided by the stabilised emissions (average emissions, if applicable) and rounded to two significant figures. The resulting number shall be the DF, unless it is less than 1,00, in which case the DF shall be 1,00.

4.3.5.

The manufacturer may schedule additional emission test points between the stabilised emission test point and the end of the EDP. If intermediate tests are scheduled, the test points shall be evenly spaced over the EDP (plus or minus two hours) and one such test point shall be at one half of full EDP (plus or minus two hours).

4.3.6.

For each pollutant HC + NOx and CO, a straight line must be fitted to the data points treating the initial test as occurring at hour zero, and using the method of least-squares. The DF is the calculated emission at the end of the durability period divided by the calculated emission at zero hours. The DF for each pollutant for the applicable test cycle shall be recorded in the test report set out in Appendix 1 of Annex VII to Implementing Regulation (EU) 2017/656.

4.3.7.

Calculated deterioration factors may cover families in addition to the one on which they were generated if the manufacturer submits a justification acceptable to the approval authority in advance of EU type-approval that the affected engine families can be reasonably expected to have similar emission deterioration characteristic based on the design and technology used. A non-exclusive list of design and technology groupings is given below: — conventional two-stroke engines without after-treatment system, — conventional two-stroke engines with a catalyst of the same active material and loading, and the same number of cells per cm2, — stratified scavenging two-stroke engines, — stratified scavenging two-stroke engines with a catalyst of the same active material and loading, and the same number of cells per cm2, — four-stroke engines with catalyst with same valve technology and identical lubrication system, — four-stroke engines without catalyst with the same valve technology and identical lubrication system.

4.4.   EDP categories

4.4.1.   For those engine categories in Table V-3 or V-4 of Annex V to Regulation (EU) 2016/1628 that have alternative values for EDP, manufacturers shall declare the applicable EDP category for each engine family at the time of EU type-approval. Such category shall be the category from Table 3.2 which most closely approximates the expected useful lives of the equipment into which the engines are expected to be installed as determined by the engine manufacturer. Manufacturers shall retain data appropriate to support their choice of EDP category for each engine family. Such data shall be supplied to the approval authority upon request.

Table 3.2

EDP categories

EDP Category	Application of Engine
Cat 1	Consumer products
Cat 2	Semi-professional products
Cat 3	Professional products

4.4.2.   The manufacturer shall demonstrate to the satisfaction of the approval authority that the declared EDP category is appropriate. Data to support a manufacturer's choice of EDP category, for a given engine family, may include but are not limited to:

—	surveys of the life spans of the equipment in which the subject engines are installed,

—	engineering evaluations of field aged engines to ascertain when engine performance deteriorates to the point where usefulness and/or reliability is impacted to a degree sufficient to necessitate overhaul or replacement,

—	warranty statements and warranty periods,

—	marketing materials regarding engine life,

—	failure reports from engine customers, and

—	engineering evaluations of the durability, in hours, of specific engine technologies, engine materials or engine designs.

ANNEX IV

Requirements with regard to emission control strategies, NOx control measures and particulate control measures

1.   Definitions abbreviations and general requirements

1.1.   For the purposes of this Annex, the following definitions and abbreviations apply:

(1)	‘diagnostic trouble code (“DTC”)’ means a numeric or alphanumeric identifier which identifies or labels a NCM and/ PCM;

(2)	‘confirmed and active DTC’ means a DTC that is stored during the time the NCD and/or PCD system concludes that a malfunction exists;

(3)	‘NCD engine family’ means a manufacturer's grouping of engines having common methods of monitoring/diagnosing NCMs;

(4)

‘NOx Control Diagnostic system (NCD)’ means a system on-board the engine which has the capability of (a) detecting a NOx Control Malfunction, (b) identifying the likely cause of NOx control malfunctions by means of information stored in computer memory and/or communicating that information off-board;

(5)	‘NOx Control Malfunction (NCM)’ means an attempt to tamper with the NOx control system of an engine or a malfunction affecting that system that might be due to tampering, that is considered by this Regulation as requiring the activation of a warning or an inducement system once detected;

(6)

‘Particulate Control Diagnostic system (PCD)’ means a system on-board the engine which has a capability of: (a) detecting a Particulate Control Malfunction, (b) identifying the likely cause of particulate control malfunctions by means of information stored in computer memory and/or communicating that information off-board;

(7)

‘Particulate Control Malfunction (PCM)’ means an attempt to tamper with the particulate after-treatment system of an engine or a malfunction affecting the particulate after-treatment system that might be due to tampering, that is considered by this Regulation as requiring the activation of a warning once detected;

(8)	‘PCD engine family’ means a manufacturer's grouping of engines having common methods of monitoring/diagnosing PCMs;

(9)	‘Scan-tool’ means an external test equipment used for off-board communication with the NCD and/or PCD system.

1.2.   Ambient temperature

Notwithstanding Article 2(7), where reference is made to ambient temperature in relation to environments other than a laboratory environment, the following provisions shall apply:

1.2.1.

For an engine installed in a test-bed, ambient temperature shall be the temperature of the combustion air supplied to the engine, upstream of any part of the engine being tested.

1.2.2.

For an engine installed in non-road mobile machinery, ambient temperature shall be the air temperature immediately outside the perimeter of the non-road mobile machinery.

2.   Technical requirements relating to emission control strategies

2.1.   This section 2 shall apply for electronically controlled engines of categories NRE, NRG, IWP, IWA, RLL and RLR, complying with ‘Stage V’ emission limits set out in Annex II to Regulation (EU) 2016/1628 and using electronic control to determine both the quantity and timing of injecting fuel or using electronic control to activate, de-activate or modulate the emission control system used to reduce NOx.

2.2.   Requirements for base emission control strategy

2.2.1.   The base emission control strategy shall be designed as to enable the engine, in normal use, to comply with the provisions of this Regulation. Normal use is not restricted to the control conditions as specified in point 2.4.

2.2.2.   Base emission control strategies are, but not limited to, maps or algorithms for controlling:

(a)	timing of fuel injection or ignition (engine timing);

(b)	exhaust gas recirculation (EGR);

(c)	SCR catalyst reagent dosing.

2.2.3.   Any base emission control strategy that can distinguish engine operation between a standardised EU type-approval test and other operating conditions and subsequently reduce the level of emission control when not operating under conditions substantially included in the EU type-approval procedure is prohibited.

2.3.   Requirements for auxiliary emission control strategy

2.3.1.   An auxiliary emission control strategy may be activated by an engine or a non-road mobile non-road mobile machinery, provided that the auxiliary emission control strategy:

2.3.1.1.

does not permanently reduce the effectiveness of the emission control system;

2.3.1.2.

operates only outside the control conditions specified in points 2.4.1, 2.4.2 or 2.4.3 for the purposes defined in point 2.3.5 and only as long as is needed for those purposes, except as permitted by points 2.3.1.3, 2.3.2 and 2.3.4;

2.3.1.3.

is activated only exceptionally within the control conditions in points 2.4.1, 2.4.2 or 2.4.3, respectively, has been demonstrated to be necessary for the purposes identified in point 2.3.5 has been approved by the approval authority, and is not activated for longer than is needed for those purposes;

2.3.1.4.

ensures a level of performance of the emission control system that is as close as possible to that provided by the base emission control strategy.

2.3.2.   Where the auxiliary emission control strategy is activated during the EU type-approval test, activation shall not be limited to occur outside the control conditions set out in point 2.4, and the purpose shall not be limited to the criteria set out in point 2.3.5.

2.3.3.   Where the auxiliary emission control strategy is not activated during the EU type-approval test, it must be demonstrated that the auxiliary emission control strategy is active only for as long as required for the purposes set out in point 2.3.5.

2.3.4.   Cold temperature operation

An auxiliary emission control strategy may be activated on an engine equipped with exhaust gas recirculation (EGR) irrespective of the control conditions in point 2.4 if the ambient temperature is below 275 K (2 °C) and one of the two following criteria is met:

(a)	intake manifold temperature is less than or equal to the temperature defined by the following equation: IMTc = PIM/15,75 + 304,4, where: IMTc is the calculated intake manifold temperature, K and PIM is the absolute intake manifold pressure in kPa;

(b)	engine coolant temperature is less than or equal to the temperature defined by the following equation: ECTc = PIM/14,004 + 325,8, where: ECTc is the calculated engine coolant temperature, K and PIM is the absolute intake manifold pressure, kPa.

2.3.5.   Except as permitted by point 2.3.2, an auxiliary emission control strategy may solely be activated for the following purposes:

(a)	by on-board signals, for protecting the engine (including air-handling device protection) and/or non-road mobile machinery into which the engine is installed from damage;

(b)	for operational safety reasons;

(c)	for prevention of excessive emissions, during cold start or warming-up, during shut-down;

(d)

if used to trade-off the control of one regulated pollutant under specific ambient or operating conditions, for maintaining control of all other regulated pollutants, within the emission limit values that are appropriate for the engine concerned. The purpose is to compensate for naturally occurring phenomena in a manner that provides acceptable control of all emission constituents.

2.3.6.   The manufacturer shall demonstrate to the technical service at the time of the EU type-approval test that the operation of any auxiliary emission control strategy complies with the provisions of this section. The demonstration shall consist of an evaluation of the documentation referred to in point 2.6.

2.3.7.   Any operation of an auxiliary emission control strategy non-compliant with points 2.3.1 to 2.3.5 is prohibited.

2.4.   Control conditions

The control conditions specify an altitude, ambient temperature and engine coolant range that determines whether auxiliary emission control strategies may generally or only exceptionally be activated in accordance with point 2.3.

The control conditions specify an atmospheric pressure which is measured as absolute atmospheric static pressure (wet or dry) (‘Atmospheric pressure’)

2.4.1.   Control conditions for engines of categories IWP and IWA:

(a)	an altitude not exceeding 500 metres (or equivalent atmospheric pressure of 95,5 kPa);

(b)	an ambient temperature within the range 275 K to 303 K (2 °C to 30 °C);

(c)	the engine coolant temperature above 343 K (70 °C).

2.4.2.   Control conditions for engines of category RLL:

(a)	an altitude not exceeding 1 000 metres (or equivalent atmospheric pressure of 90 kPa);

(b)	an ambient temperature within the range 275 K to 303 K (2 °C to 30 °C);

(c)	the engine coolant temperature above 343 K (70 °C).

2.4.3.   Control conditions for engines of categories NRE, NRG and RLR:

(a)	the atmospheric pressure greater than or equal to 82,5 kPa;

(b)

the ambient temperature within the following range: — equal to or above 266 K (– 7 °C), — less than or equal to the temperature determined by the following equation at the specified atmospheric pressure: Tc = – 0,4514 × (101,3 – Pb) + 311, where: Tc is the calculated ambient air temperature, K and Pb is the atmospheric pressure, kPa;

(c)	the engine coolant temperature above 343 K (70 °C).

2.5.   Where the engine inlet air temperature sensor is being used to estimate ambient air temperature the nominal offset between the two measurement points shall be evaluated for an engine type or engine family. Where used, the measured intake air temperature shall be adjusted by an amount equal to the nominal offset to estimate ambient temperature for an installation using the specified engine type or engine family.

The evaluation of the offset shall be made using good engineering judgement based on technical elements (calculations, simulations, experimental results, data etc.) including:

(a)	the typical categories of non-road mobile machinery into which the engine type or engine family will be installed; and,

(b)	the installation instructions provided to the OEM by the manufacturer.

A copy of the evaluation shall be made available to the approval authority upon request.

2.6.   Documentation requirements

The manufacturer shall comply with the documentation requirements laid down in point 1.4 of Part A of Annex I to Implementing Regulation (EU) 2017/656 and Appendix 2 to that Annex.

3.   Technical requirements relating to NOx control measures

3.1.   This section 3 shall apply to electronically controlled engines of categories NRE, NRG, IWP, IWA, RLL and RLR, complying with ‘stage V’ emission limits set out in Annex II to Regulation (EU) 2016/1628 and using electronic control to determine both the quantity and timing of injecting fuel or using electronic control to activate, de-activate or modulate the emission control system used to reduce NOx.

3.2.   The manufacturer shall provide complete information on the functional operational characteristics of the NOx control measures using the documents set out in Annex I to Implementing Regulation (EU) 2017/656.

3.3.   The NOx control strategy shall be operational under all environmental conditions regularly occurring in the territory of the Union, especially at low ambient temperatures.

3.4.   The manufacturer shall demonstrate that the emission of ammonia during the applicable emission test cycle of the EU type-approval procedure, when a reagent is used, does not exceed a mean value of 25 ppm for engines of category RLL and 10 ppm for engines of all other applicable categories.

3.5.   If reagent containers are installed on or connected to a non-road mobile machinery, means for taking a sample of the reagent inside the containers must be included. The sampling point must be easily accessible without requiring the use of any specialised tool or device.

3.6.   In addition to the requirements set out in points 3.2 to 3.5, the following requirements shall apply:

(a)	For engines of category NRG the technical requirements set out in Appendix 1;

(b)

For engines of category NRE: (i) the requirements set out in Appendix 2, when the engine is exclusively intended for use in the place of Stage V engines of categories IWP and IWA, in accordance with Article 4(1), point (1)(b) of Regulation (EU) 2016/1628; or (ii) the requirements set out in Appendix 1 for engines not covered by subparagraph (i);

(c)	For engines of category IWP, IWA and RLR the technical requirements set out in Appendix 2;

(d)	For engines of category RLL the technical requirements set out in Appendix 3

4.   Technical requirements relating to particulate pollutant control measures

4.1.   This section shall apply to engines of sub-categories subject to a PN limit in accordance with the ‘stage V’ emission limits set out in Annex II to Regulation (EU) 2016/1628 fitted with a particulate after-treatment system In cases where the NOx control system and the particulate control system share the same physical components (e.g. same substrate (SCR on filter), same exhaust gas temperature sensor) the requirements of this section shall not apply to any component or malfunction where, after consideration of a reasoned assessment provided by the manufacturer, the approval authority concludes that a particulate control malfunction within the scope of this section would lead to a corresponding NOx control malfunction within the scope of section 3.

4.2.   The detailed technical requirements relating to particulate pollutant control measures are specified in Appendix 4.

ANNEX V

Measurements and tests with regard to the area associated with the non-road steady-state test cycle

1.   General requirements

This Annex shall apply for electronically controlled engines of categories NRE, NRG, IWP, IWA, and RLR, complying with ‘Stage V’ emission limits set out in Annex II to Regulation (EU) 2016/1628 and using electronic control to determine both the quantity and timing of injecting fuel or using electronic control to activate, de-activate or modulate the emission control system used to reduce NOx.

This Annex sets out the technical requirements relating to the area associated with the relevant NRSC, within which the amount by which that the emissions shall be permitted to exceed the emission limits set out in Annex II is controlled.

When an engine is tested in the manner set out in test requirements of section 4 the emissions sampled at any randomly selected point within the applicable control area set out in section 2 shall not exceed the applicable emission limit values in Annex II to Regulation (EU) 2016/1628 multiplied by a factor of 2,0.

Section 3 sets out the selection by the technical service of additional measurement points from within the control area during the emission bench test, in order to demonstrate that the requirements of this section 1 have been met.

The manufacturer may request that the Technical Service excludes operating points from any of the control areas set out in section 2 during the demonstration set out in section 3. The Technical Service may grant this exclusion if the manufacturer can demonstrate that the engine is never capable of operating at such points when used in any non-road mobile non-road mobile machinery combination.

The installation instructions provided by the manufacturer to the OEM in accordance with Annex XIV shall identify the upper and lower boundaries of the applicable control area and shall include a statement to clarify that the OEM shall not install the engine in such a way that it constrains the engine to operate permanently at only speed and load points outside of the control area for the torque curve corresponding to the approved engine type or engine family.

2.   Engine control area

The applicable control area for conducting the engine test shall be the area identified in this section 2 that corresponds to the applicable NRSC for the engine being tested.

2.1.   Control area for engines tested on NRSC cycle C1

These engines operate with variable-speed and load. Different control area exclusions apply depending upon the (sub-)category and operating speed of the engine.

2.1.1.   Variable-speed engines of category NRE with maximum net power ≥ 19 kW, variable-speed engines of category IWA with maximum net power ≥ 300 kW, variable-speed engines of category RLR and variable-speed engines of category NRG.

The control area (see Figure 5.1) is defined as follows:

upper torque limit: full load torque curve;

speed range: speed A to n hi;

where:

speed A = n lo + 0,15 × (n hi – n lo);

n hi	=	high speed [see Article 1(12)];
n lo	=	low speed [see Article 1(13)].

The following engine operating conditions shall be excluded from testing:

(a)	points below 30 % of maximum torque;

(b)	points below 30 % of maximum net power.

If the measured engine speed A is within ± 3 % of the engine speed declared by the manufacturer, the declared engine speeds shall be used. If the tolerance is exceeded for any of the test speeds, the measured engine speeds shall be used.

Intermediate test points within the control area shall be determined as follows:

%torque = % of maximum torque;

;

where: n100 % is the 100 % speed for the corresponding test cycle.

Figure 5.1

Control area for variable-speed engines of category NRE with maximum net power ≥ 19 kW, variable-speed engines of category IWA with maximum net power ≥ 300 kW and variable-speed engines of category NRG

Torque (% of maximum)

Speed (%)

30 % Torque

30 % Power

Control Area

Speed A

2.1.2.   Variable-speed engines of category NRE with maximum net power < 19 kW and variable-speed engines of category IWA with maximum net power < 300 kW

The control area specified in point 2.1.1 shall apply but with the additional exclusion of the engine operating conditions given in this point and illustrated in Figures 5.2 and 5.3.

(a)	for particulate matter only, if the C speed is below 2 400 r/min, points to the right of or below the line formed by connecting the points of 30 % of maximum torque or 30 % of maximum net power, whichever is greater, at the B speed and 70 % of maximum net power at the high speed;

(b)

for particulate matter only, if the C speed is at or above 2 400 r/min, points to the right of the line formed by connecting the points of 30 % of maximum torque or 30 % of maximum net power, whichever is greater, at the B speed, 50 % of maximum net power at 2 400 r/min, and 70 % of maximum net power at the high speed.

where:

speed B = n lo + 0,5 × (n hi – n lo);

speed C = n lo + 0,75 × (n hi – n lo).

n hi	=	high speed [see Article 1(12)],
n lo	=	low speed [see Article 1(13)],

If the measured engine speeds A, B and C are within ± 3 % of the engine speed declared by the manufacturer, the declared engine speeds shall be used. If the tolerance is exceeded for any of the test speeds, the measured engine speeds shall be used.

Figure 5.2

Control area for variable-speed engines of category NRE with maximum net power < 19 kW and variable-speed engines of category IWA with maximum net power < 300 kW, speed C < 2 400 rpm

30 % a

30 % b

70 % a

Torque (% of maximum)

Speed (%)

Key:

1	Engine Control Area
2	All Emissions Carve-Out
3	PM Carve-Out
a	% of maximum net power
b	% of maximum torque

Figure 5.3

Control area for variable-speed engines of category NRE with maximum net power < 19 kW and variable-speed engines of category IWA with maximum net power < 300 kW, speed C ≥ 2 400 rpm

50 % b

50 % a

30 % b

30 % a

70 % a

Torque (% of maximum)

Speed (%)

Key:

1	Engine Control Area
2	All Emissions Carve-Out
3	PM Carve-Out
a	Percent of maximum net power
b	Percent of maximum torque

2.2.   Control area for engines tested on NRSC cycles D2, E2 and G2

These engines are mainly operated very close to their designed operating speed, hence the control area is defined as:

speed	:	100 %
torque range	:	50 % to the torque corresponding to maximum power.

2.3.   Control area for engines tested on NRSC cycle E3

These engines are mainly operated slightly above and below a fixed pitch propeller curve. The control area is related to the propeller curve and has exponents of mathematical equations defining the boundaries of the control area. The control area is defined as follows:

Lower speed limit	:	0,7 × n 100 %
Upper boundary curve	:	%power = 100 × (%speed/90)3,5;
Lower boundary curve	:	%power = 70 × (%speed/100)2,5;
Upper power limit	:	Full load power curve
Upper speed limit	:	Maximum speed permitted by governor

where:

%power is % of maximum net power;

%speed is % of n 100 %

n 100 % is the 100 % speed for the corresponding test cycle.

Figure 5.4

Control area for engines tested on NRSC cycle E3

P = n3

Power (% of maximum)

Speed (%)

Key:

1	Lower speed limit
2	Upper boundary curve
3	Lower boundary curve
4	Full load power curve
5	Governor maximum speed curve
6	Engine Control Area

3.   Demonstration requirements

The technical service shall select random load and speed points within the control area for testing. For engines subject to point 2.1 up to three points shall be selected. For engines subject to point 2.2 one point shall be selected. For engines subject to points 2.3 or 2.4 up to two points shall be selected. The technical service shall also determine a random running order of the test points. The test shall be run in accordance with the principal requirements of the NRSC, but each test point shall be evaluated separately.

4.   Test requirements

The test shall be carried out immediately after the discrete mode NRSC as follows:

(a)

the test shall be carried out immediately after the discrete-mode NRSC as described in points (a) to (e) of point 7.8.1.2 of Annex VI but before the post test procedures (f) or after the ramped modal non-road steady-state test cycle (‘RMC’) test in points (a) to (d) of point 7.8.2.3 of Annex VI but before the post test procedures (e) as relevant;

(b)	the tests shall be carried out as required in points (b) to (e) of point 7.8.1.2 of Annex VI using the multiple filter method (one filter for each test point) for each of the test points chosen in accordance with section 3;

(c)	a specific emission value shall be calculated (in g/kWh or #/kWh as applicable) for each test point;

(d)	emissions values may be calculated on a mass basis using section 2 of Annex VII or on a molar basis using section 3 of Annex VII, but shall be consistent with the method used for the discrete-mode NRSC or RMC test;

(e)	for gaseous and PN, if applicable, summation calculations, Nmode in equation (7-63) shall be set to 1 and a weighting factor of 1 shall be used;

(f)	for particulate calculations the multiple filter method shall be used; for summation calculations, Nmode in equation (7-64) shall be set to 1 and a weighting factor of 1 shall be used.

ANNEX VI

Conduct of emission tests and requirements for measurement equipment

1.   Introduction

This Annex describes the method of determining emissions of gaseous and particulate pollutants from the engine to be tested and the specifications related to the measurement equipment. As from section 6, the numbering of this Annex is consistent with the numbering of the NRMM gtr 11 and UN R 96-03, Annex 4B. However, some points of the NRMM gtr 11 are not needed in this Annex, or are modified in accordance with the technical progress.

2.   General overview

This Annex contains the following technical provisions needed for conducting an emissions test. Additional provisions are listed in point 3.

—	Section 5: Performance requirements, including the determination of tests speeds

—	Section 6: Test conditions, including the method for accounting for emissions of crankcase gases, the method for determining and accounting for continuous and infrequent regeneration of exhaust after-treatment systems

—	Section 7: Test procedures, including the mapping of engines, the test cycle generation and the test cycle running procedure

—	Section 8: Measurement procedures, including the instrument calibration and performance checks and the instrument validation for the test

—	Section 9: Measurement equipment, including the measurement instruments, the dilution procedures, the sampling procedures and the analytical gases and mass standards

—	Appendix 1: PN measurement procedure

3.   Related annexes

—	Data evaluation and calculation	:	Annex VII
—	Test procedures for dual-fuel engines	:	Annex VIII
—	Reference fuels	:	Annex IX
—	Test cycles	:	Annex XVII

4.   General requirements

The engines to be tested shall meet the performance requirements set out in section 5 when tested in accordance with the test conditions set out in section 6 and the test procedures set out in section 7.

5.   Performance requirements

5.1.   Emissions of gaseous and particulate pollutants and of CO2 and NH3

The pollutants are represented by:

(a)	Oxides of nitrogen, NOx;

(b)	Hydrocarbons, expressed as total hydrocarbons, HC or THC;

(c)	Carbon monoxide, CO;

(d)	Particulate matter, PM;

(e)	Particle number, PN.

The measured values of gaseous and particulate pollutants and of CO2 exhausted by the engine refer to the brake-specific emissions in grams per kilowatt-hour (g/kWh).

The gaseous and particulate pollutants that shall be measured are those for which limit values are applicable to the engine sub-category being tested as set out in Annex II to Regulation (EU) 2016/1628. The results, inclusive of the deterioration factor determined according to Annex III, shall not exceed the applicable limit values.

The CO2 shall be measured and reported for all engine sub-categories as required by Article 41(4) of Regulation (EU) 2016/1628.

The mean emission of ammonia (NH3) shall additionally be measured, as required in accordance with section 3 of Annex IV, when the NOx control measures that are part of the engine emission control system include use of a reagent, and shall not exceed the values set out in that section.

The emissions shall be determined on the duty cycles (steady-state and/or transient test cycles), as described in section 7 and in Annex XVII. The measurement systems shall meet the calibration and performance checks set out in section 8 with the measurement equipment described in section 9.

Other systems or analysers may be approved by the approval authority if it is found that they yield equivalent results in accordance with point 5.1.1. The results shall be calculated according to the requirements of Annex VII.

5.1.1.   Equivalency

The determination of system equivalency shall be based on a seven-sample pair (or larger) correlation study between the system under consideration and one of the systems of this annex. ‘Results’ refer to the specific cycle weighted emissions value. The correlation testing is to be performed at the same laboratory, test cell and on the same engine, and is preferred to be run concurrently. The equivalency of the sample pair averages shall be determined by F-test and t-test statistics as described in Appendix 3 of Annex VII, obtained under the laboratory, test cell and the engine conditions described above. Outliers shall be determined in accordance with ISO 5725 and excluded from the database. The systems to be used for correlation testing shall be subject to the approval by the approval authority.

5.2.   General requirements on the test cycles

5.2.1.   The EU type-approval test shall be conducted using the appropriate NRSC and, where applicable, NRTC or LSI-NRTC, as specified in Article 24 and Annex IV to Regulation (EU) 2016/1628.

5.2.2.   The technical specifications and characteristics of the NRSC are set out in Annex XVII, Appendix 1 (discrete-mode NRSC) and Appendix 2 (ramped-modal NRSC). At the choice of the manufacturer, a NRSC test may be run as a discrete-mode NRSC or, where available, as a ramped-modal NRSC (‘RMC’) as set out in point 7.4.1.

5.2.3.   The technical specifications and characteristics of the NRTC and LSI-NRTC are set out in Appendix 3 of Annex XVII.

5.2.4.   The test cycles specified in point 7.4 and in Annex XVII are designed around percentages of maximum torque or power and test speeds that need to be determined for the correct performance of the test cycles:

(a)	100 % speed (maximum test speed (MTS) or rated speed)

(b)	Intermediate speed(s) as specified in point 5.2.5.4;

(c)	Idle speed, as specified in point 5.2.5.5.

The determination of the test speeds is set out in point 5.2.5, the use of torque and power in point 5.2.6.

5.2.5.   Test speeds

5.2.5.1.   Maximum test speed (MTS)

The MTS shall be calculated in accordance with point 5.2.5.1.1 or point 5.2.5.1.3.

5.2.5.1.1.   Calculation of MTS

In order to calculate the MTS the transient mapping procedure shall be performed in accordance with point 7.4. The MTS is then determined from the mapped values of engine speed versus power. MTS shall be calculated by means of equation (6-1), (6-2) or (6-3):

(a)	MTS = n lo + 0,95 × (n hi – n lo)	(6-1)
(b)	MTS = n i	(6-2)

with:

n i	is the average of the lowest and highest speeds at which (n 2 norm i + P 2 norm i ) is equal to 98 % of the maximum value of (n 2 norm i + P 2 norm i )

(c)

If there is only one speed at which the value of (n 2 norm i + P 2 norm i ) is equal to 98 % of the maximum value of (n 2 norm i + P 2 norm i ): MTS = n i (6-3) with: n i is the speed at which the maximum value of (n 2 norm i + P 2 norm i ) occurs. where: n = is the engine speed i = is an indexing variable that represents one recorded value of an engine map n hi = is the high speed as defined in Article 2(12), n lo = is the low speed as defined in Article 2(13), n norm i = is an engine speed normalized by dividing it by P norm i = is an engine power normalized by dividing it by Pmax = is the average of the lowest and highest speeds at which power is equal to 98 % of P max. Linear interpolation shall be used between the mapped values to determine: (a) the speeds where power is equal to 98 % of P max. If there is only one speed at which power is equal to 98 % of Pmax, shall be the speed at which Pmax occurs; (b) the speeds where (n 2 norm i + P 2 n orm i ) is equal to 98 % of the maximum value of (n 2 norm i + P 2 n orm i ).

5.2.5.1.2.   Use of a declared MTS

If the MTS calculated in accordance with point 5.2.5.1.1 or 5.2.5.1.3 is within ± 3 % of the MTS declared by the manufacturer, the declared MTS may be used for the emissions test. If the tolerance is exceeded, the measured MTS shall be used for the emissions test.

5.2.5.1.3.   Use of an adjusted MTS

If the falling part of the full load curve has a very steep edge, this may cause problems to drive the 105 % speeds of the NRTC correctly. In this case it is allowed, with prior agreement of the technical service, to use an alternative value of MTS determined using one of the following methods:

(a)	the MTS may be slightly reduced (maximum 3 %) in order to make correct driving of the NRTC possible.

(b)

Calculate an alternative MTS by means of equation (6-4): MTS = ((n max – n idle)/1,05) + n idle (6-4) where: n max = is the engine speed at which the engine governor function controls engine speed with operator demand at maximum and with zero load applied (‘maximum no-load speed’) n idle = is the idle speed

5.2.5.2.   Rated speed

The rated speed is defined in Article 3(29) of Regulation (EU) 2016/1628. Rated speed for variable-speed engines subject to an emission test shall be determined from the applicable mapping procedure set out in section 7.6. Rated speed for constant-speed engines shall be declared by the manufacturer according to the characteristics of the governor. Where an engine type equipped with alternative speeds as permitted by Article 3(21) of Regulation (EU) 2016/1628 is subject to an emission test, each alternative speed shall be declared and tested.

If the rated speed determined from the mapping procedure in section 7.6 is within ± 150 rpm of the value declared by the manufacturer for engines of category NRS provided with governor, or within ± 350 rpm or ± 4 % for engines of category NRS without governor, whichever is smaller, or within ± 100 rpm for all other engine categories, the declared value may be used. If the tolerance is exceeded, the rated speed determined from the mapping procedure shall be used.

For engines of category NRSh the 100 % test speed shall be within ± 350 rpm of the rated speed.

Optionally, MTS may be used instead of rated speed for any steady state test cycle.

5.2.5.3.   Maximum torque speed for variable-speed engines

The maximum torque speed determined from the maximum torque curve established from the applicable engine mapping procedure in point 7.6.1 or 7.6.2 shall be one of the following:

(a)	The speed at which the highest torque was recorded; or,

(b)	The average of the lowest and highest speeds at which the torque is equal to 98 % of the maximum torque. Where necessary, linear interpolation shall be used to determine the speeds at which the torque is equal to 98 % of the maximum torque.

If the maximum torque speed determined from the maximum torque curve is within ± 4 % of the maximum torque speed declared by the manufacturer for engines of category NRS or NRSh, or ± 2,5 % of the maximum torque speed declared by the manufacturer for all other engine categories, the declared value may be used for the purpose of this regulation. If the tolerance is exceeded, the maximum torque speed determined from the maximum torque curve shall be used.

5.2.5.4.   Intermediate speed

The intermediate speed shall meet one of the following requirements:

(a)	For engines that are designed to operate over a speed range on a full load torque curve, the intermediate speed shall be the maximum torque speed if it occurs between 60 % and 75 % of rated speed;

(b)	If the maximum torque speed is less than 60 % of rated speed, then the intermediate speed shall be 60 % of the rated speed;

(c)	If the maximum torque speed is greater than 75 % of the rated speed then the intermediate speed shall be 75 % of rated speed. Where the engine is only capable of operation at speeds higher than 75 % of rated speed the intermediate speed shall be the lowest speed at which the engine can be operated;

(d)	For engines that are not designed to operate over a speed range on a full-load torque curve at steady-state conditions, the intermediate speed shall be between 60 % and 70 % of the rated speed.

(e)	For engines to be tested on cycle G1, except for engines of category ATS, the intermediate speed shall be 85 % of the rated speed.

(f)	For engines of category ATS tested on cycle G1 the intermediate speed shall be 60 % or 85 % of rated speed based on which is closer to the actual maximum torque speed.

Where the MTS is used in place of rated speed for the 100 % test speed, MTS shall also replace rated speed when determining the intermediate speed.

5.2.5.5.   Idle speed

The idle speed is the lowest engine speed with minimum load (greater than or equal to zero load), where an engine governor function controls engine speed. For engines without a governor function that controls idle speed, idle speed means the manufacturer-declared value for lowest engine speed possible with minimum load. Note that warm idle speed is the idle speed of a warmed-up engine.

5.2.5.6.   Test speed for constant-speed engines

The governors of constant-speed engines may not always maintain speed exactly constant. Typically speed can decrease (0,1 to 10) % below the speed at zero load, such that the minimum speed occurs near the engine's point of maximum power. The test speed for constant-speed engines may be commanded by using the governor installed on the engine or using a test-bed speed demand where this represents the engine governor.

Where the governor installed on the engine is used the 100 % speed shall be the engine governed speed as defined in Article 2(24).

Where a test-bed speed demand signal is used to simulate the governor, the 100 % speed at zero load shall be the no-load speed specified by the manufacturer for that governor setting and the 100 % speed at full load shall be the rated speed for that governor setting. Interpolation shall be used to determine the speed for the other test modes.

Where the governor has an isochronous operation setting, or the rated speed and no-load speed declared by the manufacturer differ by no more than 3 %, a single value declared by the manufacturer may be used for the 100 % speed at all load points.

5.2.6.   Torque and Power

5.2.6.1   Torque

The torque figures given in the test cycles are percentage values that represent, for a given test mode, one of the following:

(a)	The ratio of the required torque to the maximum possible torque at the specified test speed (all cycles except D2 & E2);

(b)	The ratio of the required torque to the torque corresponding to the rated net power declared by the manufacturer (cycle D2 & E2).

5.2.6.2.   Power

The power figures given in the test cycles are percentage values that represent, for a given test mode, one of the following:

(a)	For the test cycle E3 the power figures are percentage values of the maximum net power at the 100 % speed as this cycle is based on a theoretical propeller characteristic curve for vessels driven by heavy-duty engines without limitation of length.

(b)	For the test cycle F the power figures are percentage values of the maximum net power at the given test speed, except for idle speed where it is a percentage of the maximum net power at the 100 % speed.

6.   Test Conditions

6.1.   Laboratory test conditions

The absolute temperature (T a) of the engine air at the inlet to the engine expressed in Kelvin, and the dry atmospheric pressure (p s), expressed in kPa shall be measured and the parameter f a shall be determined in accordance with the following provisions and by means of equation (6-5) or (6-6). If the atmospheric pressure is measured in a duct, negligible pressure losses shall be ensured between the atmosphere and the measurement location, and changes in the duct's static pressure resulting from the flow shall be accounted for. In multi-cylinder engines having distinct groups of intake manifolds, such as in a ‘V’ engine configuration, the average temperature of the distinct groups shall be taken. The parameter fa shall be reported with the test results.

Naturally aspirated and mechanically supercharged engines:

(6-5)

Turbocharged engines with or without cooling of the intake air:

(6-6)

6.1.1.   For the test to be considered valid both the following conditions must be met:

(a)	f a shall be within the range 0,93 ≤ f a ≤ 1,07 except as permitted by points 6.1.2 and 6.1.4;

(b)	The temperature of intake air shall be maintained to 298 ± 5 K (25 ± 5 °C), measured upstream of any engine component, except as permitted by points 6.1.3 and 6.1.4, and as required by points 6.1.5 and 6.1.6.

6.1.2.   Where the altitude of the laboratory in which the engine is being tested exceeds 600 m, with the agreement of the manufacturer f a may exceed 1,07 on the condition that p s shall not be less than 80 kPa.

6.1.3.   Where the power of the engine being tested is greater than 560 kW, with the agreement of the manufacturer the maximum value of intake air temperature may exceed 303 K (30 °C) on the condition that it shall not exceed 308 K (35 °C).

6.1.4.   Where the altitude of the laboratory in which the engine is being tested exceeds 300 m and the power of the engine being tested is greater than 560 kW, with the agreement of the manufacturer f a may exceed 1,07 on the condition that p s shall not be less than 80 kPa and the maximum value of intake air temperature may exceed 303 K (30 °C) on the condition that it shall not exceed 308 K (35 °C).

6.1.5.   In the case of an engine family of category NRS less than 19 kW exclusively consisting of engine types to be used in snow throwers, the temperature of the intake air shall be maintained between 273 K and 268 K (0 °C and – 5 °C).

6.1.6.   For engines of category SMB the temperature of the intake air shall be maintained to 263 ± 5 K (– 10 ± 5 °C), except as permitted by point 6.1.6.1.

6.1.6.1.   For engines of category SMB fitted with electronically controlled fuel injection that adjusts the fuel flow to the intake air temperature, at the choice of the manufacturer the temperature of the intake air may alternatively be maintained to 298 ± 5 K (25 ± 5 °C).

6.1.7.   It is allowed to use:

(a)

an atmospheric pressure meter whose output is used as the atmospheric pressure for an entire test facility that has more than one dynamometer test cell, as long as the equipment for handling intake air maintains ambient pressure, where the engine is tested, within ± 1 kPa of the shared atmospheric pressure;

(b)	A humidity measurement device to measure the humidity of intake air for an entire test facility that has more than one dynamometer test cell, as long as the equipment for handling intake air maintains dew point, where the engine is tested, within ± 0,5 K of the shared humidity measurement.

6.2.   Engines with charge-air cooling

(a)

A charge-air cooling system with a total intake-air capacity that represents production engines' in-use installation shall be used. Any laboratory charge-air cooling system to minimize accumulation of condensate shall be designed. Any accumulated condensate shall be drained and all drains shall be completely closed before emission testing. The drains shall be kept closed during the emission test. Coolant conditions shall be maintained as follows: (a) a coolant temperature of at least 20 °C shall be maintained at the inlet to the charge-air cooler throughout testing; (b) at the rated speed and full load, the coolant flow rate shall be set to achieve an air temperature within ± 5 °C of the value designed by the manufacturer after the charge-air cooler's outlet. The air-outlet temperature shall be measured at the location specified by the manufacturer. This coolant flow rate set point shall be used throughout testing; (c) if the engine manufacturer specifies pressure-drop limits across the charge-air cooling system, it shall be ensured that the pressure drop across the charge-air cooling system at engine conditions specified by the manufacturer is within the manufacturer's specified limit(s). The pressure drop shall be measured at the manufacturer's specified locations; When the MTS defined in point 5.2.5.1 is being used in place of rated speed to run the test cycle then this speed may be used in place of rated speed when setting the charge air temperature. The objective is to produce emission results that are representative of in-use operation. If good engineering judgment indicates that the specifications in this section would result in unrepresentative testing (such as overcooling of the intake air), more sophisticated set points and controls of charge-air pressure drop, coolant temperature, and flow rate may be used to achieve more representative results.

6.3.   Engine power

6.3.1.   Basis for emission measurement

The basis of specific emissions measurement is uncorrected net power as defined in Article 3(23) of Regulation (EU) 2016/1628.

6.3.2.   Auxiliaries to be fitted

During the test, the auxiliaries necessary for the engine operation shall be installed on the test bench according to the requirements of Appendix 2.

Where the necessary auxiliaries cannot be fitted for the test, the power they absorb shall be determined and subtracted from the measured engine power.

6.3.3.   Auxiliaries to be removed

Certain auxiliaries whose definition is linked with the operation of the non-road mobile machinery and which may be mounted on the engine shall be removed for the test.

Where auxiliaries cannot be removed, the power they absorb in the unloaded condition may be determined and added to the measured engine power (see note g in Appendix 2). If this value is greater than 3 % of the maximum power at the test speed it may be verified by the technical service. The power absorbed by auxiliaries shall be used to adjust the set values and to calculate the work produced by the engine over the test cycle in accordance with point 7.7.1.3 or point 7.7.2.3.1.

6.3.4.   Determination of auxiliary power

The power absorbed by the auxiliaries/equipment needs only be determined, if:

(a)	Auxiliaries/equipment required according to Appendix 2, are not fitted to the engine; and/or

(b)	Auxiliaries/equipment not required according to Appendix 2, are fitted to the engine.

The values of auxiliary power and the measurement/calculation method for determining auxiliary power shall be submitted by the engine manufacturer for the whole operating area of the applicable test cycles, and approved by the approval authority.

6.3.5.   Engine cycle work

The calculation of reference and actual cycle work (see point 7.8.3.4) shall be based upon engine power in accordance with point 6.3.1. In this case, P f and P r of equation (6-7) are zero, and P equals P m.

If auxiliaries/equipment are installed in accordance with points 6.3.2 and/or 6.3.3, the power absorbed by them shall be used to correct each instantaneous cycle power value P m,i, by means of equation (6-8):

P i = P m,i – P f,i + P r,i	(6-7)
P AUX = P r,i – P f,i	(6-8)

Where:

P m,i	is the measured engine power, kW
P f,i	is the power absorbed by auxiliaries/equipment to be fitted for the test but that were not installed, kW
P r,i	is the power absorbed by auxiliaries/equipment to be removed for the test but that were installed, kW.

6.4.   Engine intake air

6.4.1.   Introduction

The intake-air system installed on the engine or one that represents a typical in-use configuration shall be used. This includes the charge-air cooling and exhaust gas recirculation (EGR).

6.4.2.   Intake air pressure restriction

An engine air intake system or a test laboratory system shall be used presenting an intake air pressure restriction within ± 300 Pa of the maximum value specified by the manufacturer for a clean air cleaner at the rated speed and full load. Where this is not possible due to the design of the test laboratory air supply system a pressure restriction not exceeding the value specified by the manufacturer for a dirty filter shall be permitted subject to prior approval of the technical service. The static differential pressure of the pressure restriction shall be measured at the location and at the speed and torque set points specified by the manufacturer. If the manufacturer does not specify a location, this pressure shall be measured upstream of any turbocharger or exhaust gas recirculation (EGR) connection to the intake air system.

When the MTS defined in point 5.2.5.1 is being used in place of rated speed to run the test cycle then this speed may be used in place of rated speed when setting the intake air pressure restriction.

6.5.   Engine exhaust system

The exhaust system installed with the engine or one that represents a typical in-use configuration shall be used. The exhaust system shall conform to the requirements for exhaust emissions sampling, as set out in point 9.3. An engine exhaust system or a test laboratory system shall be used presenting a static exhaust gas back-pressure within 80 to 100 % of the maximum exhaust gas pressure restriction at the rated speed and full load. The exhaust gas pressure restriction may be set using a valve. If the maximum exhaust gas pressure restriction is 5 kPa or less, the set point shall not be more than 1,0 kPa from the maximum. When the MTS defined in point 5.2.5.1 is being used in place of rated speed to run the test cycle then this speed may be used in place of rated speed when setting the exhaust gas pressure restriction.

6.6.   Engine with exhaust after-treatment system

If the engine is equipped with an exhaust after-treatment system that is not mounted directly on the engine, the exhaust pipe shall have the same diameter as found in-use for at least four pipe diameters upstream of the expansion section containing the after-treatment device. The distance from the exhaust manifold flange or turbocharger outlet to the exhaust after-treatment system shall be the same as in the non-road mobile machinery configuration or within the distance specifications of the manufacturer. Where specified by the manufacturer the pipe shall be insulated to achieve an after-treatment inlet temperature within the specification of the manufacturer. Where other installation requirements are specified by the manufacturer these shall also be respected for the test configuration. The exhaust gas back-pressure or pressure restriction shall be set according to point 6.5. For exhaust after-treatment devices with variable exhaust gas pressure restriction, the maximum exhaust gas pressure restriction used in point 6.5 is defined at the after-treatment condition (degreening/ageing and regeneration/loading level) specified by the manufacturer. The after-treatment container may be removed during dummy tests and during engine mapping, and replaced with an equivalent container having an inactive catalyst support.

The emissions measured on the test cycle shall be representative of the emissions in the field. In the case of an engine equipped with an exhaust after-treatment system that requires the consumption of a reagent, the reagent used for all tests shall be declared by the manufacturer.

For engines of category NRE, NRG, IWP, IWA, RLR, NRS, NRSh, SMB, and ATS equipped with exhaust after-treatment systems that are regenerated on an infrequent (periodic) basis, as described in point 6.6.2, emission results shall be adjusted to account for regeneration events. In this case, the average emission depends on the frequency of the regeneration event in terms of fraction of tests during which the regeneration occurs. After-treatment systems with a regeneration process that occurs either in a sustained manner or at least once over the applicable transient (NRTC or LSI-NRTC) test cycle or RMC (‘continuous regeneration’) in accordance with point 6.6.1 do not require a special test procedure.

6.6.1.   Continuous regeneration

For an exhaust after-treatment system based on a continuous regeneration process the emissions shall be measured on an after-treatment system that has been stabilized so as to result in repeatable emissions behaviour. The regeneration process shall occur at least once during the hot-start NRTC, LSI-NRTC or NRSC test, and the manufacturer shall declare the normal conditions under which regeneration occurs (soot load, temperature, exhaust gas back-pressure, etc.). In order to demonstrate that the regeneration process is continuous, at least three hot-start runs of the NRTC, LSI-NRTC or NRSC shall be conducted. In case of hot-start NRTC, the engine shall be warmed up in accordance with point 7.8.2.1, the engine be soaked according to point 7.4.2.1(b) and the first hot-start NRTC.

The subsequent hot-start NRTC shall be started after soaking according with point 7.4.2.1(b). During the tests, exhaust gas temperatures and pressures shall be recorded (temperature before and after the exhaust after-treatment system, exhaust gas back-pressure, etc.). The exhaust after-treatment system is considered to be satisfactory if the conditions declared by the manufacturer occur during the test within a sufficient time and the emission results do not scatter by more than ± 25 % from the mean value or 0,005 g/kWh, whichever is greater.

6.6.2.   Infrequent regeneration

This provision only applies to engines equipped with an exhaust after-treatment system that is regenerated on an infrequent basis, typically occurring in less than 100 hours of normal engine operation. For those engines, either additive or multiplicative factors shall be determined for upward and downward adjustment as referred to in point 6.6.2.4 (‘adjustment factor’).

Testing and development of adjustment factors is only required for one applicable transient (NRTC or LSI-NRTC) test cycle or RMC. The factors that have been developed may be applied to results from the other applicable test cycles including discrete-mode NRSC.

In case that no suitable adjustment factors are available from testing using transient (NRTC or LSI-NRTC) test cycle or RMC then adjustment factors shall be established using an applicable discrete-mode NRSC test. Factors developed using a discrete-mode NRSC test shall only be applied to discrete-mode NRSC.

It shall not be required to conduct testing and develop adjustment factors on both RMC and discrete-mode NRSC.

6.6.2.1.   Requirement for establishing adjustment factors using NRTC, LSI-NRTC or RMC

The emissions shall be measured on at least three hot-start runs of the NRTC, LSI-NRTC or RMC, one with and two without a regeneration event on a stabilized exhaust after-treatment system. The regeneration process shall occur at least once during the NRTC, LSI-NRTC or RMC with a regeneration event. If regeneration takes longer than one NRTC, LSI-NRTC or RMC, consecutive NRTC, LSI-NRTC or RMC shall be run and emissions continued to be measured without shutting the engine off until regeneration is completed and the average of the tests shall be calculated. If regeneration is completed during any test, the test shall be continued over its entire length.

An appropriate adjustment factor shall be determined for the entire applicable cycle by means of equations (6-10) to (6-13).

6.6.2.2.   Requirement for establishing adjustment factors using discrete-mode NRSC testing

Starting with a stabilized exhaust after-treatment system the emissions shall be measured on at least three runs of each test mode of the applicable discrete-mode NRSC on which the conditions for regeneration can be met, one with and two without a regeneration event. The measurement of PM shall be conducted using the multiple filter method described in point 7.8.1.2(c). If regeneration has started but is not complete at the end of the sampling period for a specific test mode extend the sampling period shall be extended until regeneration is complete. Where there are multiple runs for the same mode an average result shall be calculated. The process shall be repeated for each test mode.

An appropriate adjustment factor shall be determined by means of equations (6-10) to (6-13) for those modes of the applicable cycle for which regeneration occurs.

6.6.2.3.   General procedure for developing infrequent regeneration adjustment factors (IRAFs)

The manufacturer shall declare the normal parameter conditions under which the regeneration process occurs (soot load, temperature, exhaust gas back-pressure, etc.). The manufacturer shall also provide the frequency of the regeneration event in terms of number of tests during which the regeneration occurs. The exact procedure to determine this frequency shall be agreed by the type approval or certification authority based upon good engineering judgement.

For a regeneration test, the manufacturer shall provide an exhaust after-treatment system that has been loaded. Regeneration shall not occur during this engine conditioning phase. As an option, the manufacturer may run consecutive tests of the applicable cycle until the exhaust after-treatment system is loaded. Emissions measurement is not required on all tests.

Average emissions between regeneration phases shall be determined from the arithmetic mean of several approximately equidistant tests of the applicable cycle. As a minimum, at least one applicable cycle as close as possible prior to a regeneration test and one applicable cycle immediately after a regeneration test shall be conducted.

During the regeneration test, all the data needed to detect regeneration shall be recorded (CO or NOx emissions, temperature before and after the exhaust after-treatment system, exhaust gas back-pressure, etc.). During the regeneration process, the applicable emission limits may be exceeded. The test procedure is schematically shown in Figure 6.1.

Figure 6.1

Scheme of infrequent (periodic) regeneration with n number of measurements and n r number of measurements during regeneration.

Mean emissions during sampling e1 … n

Emissions during regeneration er

Weighted emissions of sampling and regeneration ew

Number of cycles

nr

n

e1, 2, 3, … n

Emissions [g/kWh]

The average specific emission rate related to the test runs conducted according to points 6.6.2.1 or 6.6.2.2 [g/kWh or #/kWh] shall be weighted by means of equation (6-9) (see Figure 6.1):

(6-9)

Where:

n	is the number of tests in which regeneration does not occur,
n r	is the number of tests in which regeneration occurs (minimum one test),
	is the average specific emission from a test in which the regeneration does not occur [g/kWh or #/kWh]
	is the average specific emission from a test in which the regeneration occurs [g/kWh or #/kWh]

At the choice of the manufacturer and based on upon good engineering judgment, the regeneration adjustment factor k r, expressing the average emission rate, may be calculated either multiplicative or additive for all gaseous pollutants, and, where there is an applicable limit, for PM and PN, by means of equations (6-10) to (6-13):

Multiplicative (upward adjustment factor) (6-10) (downward adjustment factor) (6-11)

Additive k ru,a = e w – e (upward adjustment factor) (6-12) k rd,a = e w – e r (downward adjustment factor) (6-13)

6.6.2.4.   Application of adjustment factors

Upward adjustment factors are multiplied with or added to measured emission rates for all tests in which the regeneration does not occur. Downward adjustment factors are multiplied with or added to measured emission rates for all tests in which the regeneration occurs. The occurrence of the regeneration shall be identified in a manner that is readily apparent during all testing. Where no regeneration is identified, the upward adjustment factor shall be applied.

With reference to Annex VII and Appendix 5 of Annex VII on brake specific emission calculations, the regeneration adjustment factor:

(a)	When established for an entire weighted cycle, shall be applied to the results of the applicable weighted NRTC, LSI-NRTC and NRSC;

(b)

When established specifically for the individual modes of the applicable discrete-mode NRSC, shall be applied to the results of those modes of the applicable discrete-mode NRSC for which regeneration occurs prior to calculating the cycle weighted emission result. In this case the multiple filter method shall be used for PM measurement;

(c)	May be extended to other members of the same engine family;

(d)

May be extended to other engine families within the same engine after-treatment system family, as defined in Annex IX to Implementing Regulation (EU) 2017/656, with the prior approval of the approval authority based on technical evidence to be supplied by the manufacturer that the emissions are similar.

The following options shall apply:

(a)

A manufacturer may elect to omit adjustment factors for one or more of its engine families (or configurations) because the effect of the regeneration is small, or because it is not practical to identify when regenerations occur. In these cases, no adjustment factor shall be used, and the manufacturer is liable for compliance with the emission limits for all tests, without regard to whether a regeneration occurs;

(b)

Upon request by the manufacturer, the approval authority may account for regeneration events differently than is provided in paragraph (a). However, this option only applies to events that occur extremely infrequently, and which cannot be practically addressed using the adjustment factors described in paragraph (a).

6.7.   Cooling system

An engine cooling system with sufficient capacity to maintain the engine, with its intake-air, oil, coolant, block and head temperatures, at normal operating temperatures prescribed by the manufacturer shall be used. Laboratory auxiliary coolers and fans may be used.

6.8.   Lubricating oil

The lubricating oil shall be specified by the manufacturer and be representative of lubricating oil available in the market; the specifications of the lubricating oil used for the test shall be recorded and presented with the results of the test.

6.9.   Specification of the reference fuel

The reference fuels to be used for the test are specified in Annex IX.

The fuel temperature shall be in accordance with the manufacturer's recommendations. The fuel temperature shall be measured at the inlet to the fuel injection pump or as specified by the manufacturer, and the location of measurement recorded.

6.10.   Crankcase emissions

This section shall apply to engines of category NRE, NRG, IWP, IWA, RLR, NRS, NRSh, SMB, & ATS complying with Stage V emission limits set out in Annex II to Regulation (EU) 2016/1628.

Crankcase emissions that are discharged directly into the ambient atmosphere shall be added to the exhaust emissions (either physically or mathematically) during all emission testing.

Manufacturers taking advantage of this exception shall install the engines so that all crankcase emission can be routed into the emissions sampling system. For the purpose of this point, crankcase emissions that are routed into the exhaust gas upstream of exhaust after-treatment system during all operation are not considered to be discharged directly into the ambient atmosphere.

Open crankcase emissions shall be routed into the exhaust system for emission measurement, as follows:

(a)	The tubing materials shall be smooth-walled, electrically conductive, and not reactive with crankcase emissions. Tube lengths shall be minimized as far as possible;

(b)	The number of bends in the laboratory crankcase tubing shall be minimized, and the radius of any unavoidable bend shall be maximized;

(c)	The laboratory crankcase exhaust tubing shall meet the engine manufacturer's specifications for crankcase back-pressure;

(d)

The crankcase exhaust tubing shall connect into the raw exhaust gas downstream of any exhaust after-treatment system, downstream of any installed exhaust emissions restriction, and sufficiently upstream of any sample probes to ensure complete mixing with the engine's exhaust system before sampling. The crankcase exhaust tube shall extend into the free stream of exhaust system to avoid boundary-layer effects and to promote mixing. The crankcase exhaust tube's outlet may orient in any direction relative to the raw exhaust gas flow.

7.   Test procedures

7.1.   Introduction

This chapter describes the determination of brake specific emissions of gaseous and particulate pollutants on engines to be tested. The test engine shall be the parent engine configuration for the engine family as specified Annex IX to Implementing Regulation (EU) 2017/656.

A laboratory emission test consists of measuring emissions and other parameters for the test cycles specified in Annex XVII. The following aspects are treated:

(a)	The laboratory configurations for measuring the emissions (point 7.2);

(b)	The pre-test and post-test verification procedures (point 7.3);

(c)	The test cycles (point 7.4);

(d)	The general test sequence (point 7.5);

(e)	The engine mapping (point 7.6);

(f)	The test cycle generation (point 7.7);

(g)	The specific test cycle running procedure (point 7.8).

7.2.   Principle of emission measurement

To measure the brake-specific emissions, the engine shall be operated over the test cycles defined in point 7.4, as applicable. The measurement of brake-specific emissions requires the determination of the mass of pollutants in the exhaust emissions (i.e. HC, CO, NOx and PM), the number of particulates in the exhaust emissions (i.e. PN), the mass of CO2 in the exhaust emissions, and the corresponding engine work.

7.2.1.   Mass of constituent

The total mass of each constituent shall be determined over the applicable test cycle by using the following methods:

7.2.1.1.   Continuous sampling

In continuous sampling, the constituent's concentration is measured continuously from raw or diluted exhaust gas. This concentration is multiplied by the continuous (raw or diluted) exhaust gas flow rate at the emission sampling location to determine the constituent's flow rate. The constituent's emission is continuously summed over the test interval. This sum is the total mass of the emitted constituent.

7.2.1.2.   Batch sampling

In batch sampling, a sample of raw or diluted exhaust gas is continuously extracted and stored for later measurement. The extracted sample shall be proportional to the raw or diluted exhaust gas flow rate. Examples of batch sampling are collecting diluted gaseous emissions in a bag and collecting PM on a filter. In principal the method of emission calculation is done as follows: the batch sampled concentrations are multiplied by the total mass or mass flow (raw or dilute) from which it was extracted during the test cycle. This product is the total mass or mass flow of the emitted constituent. To calculate the PM concentration, the PM deposited onto a filter from proportionally extracted exhaust gas shall be divided by the amount of filtered exhaust gas.

7.2.1.3.   Combined sampling

Any combination of continuous and batch sampling is permitted (e.g. PM with batch sampling and gaseous emissions with continuous sampling).

Figure 6.2 illustrates the two aspects of the test procedures for measuring emissions: the equipment with the sampling lines in raw and diluted exhaust gas and the operations requested to calculate the pollutant emissions in steady-state and transient test cycles.

Figure 6.2

Test procedures for emission measurement

Note on Figure 6.2: The term ‘Partial flow PM sampling’ includes the partial flow dilution to extract only raw exhaust gas with constant or varying dilution ratio.

PM on filter divided by amount of filtered exhaust

Secondary dilution (Option)

Bag

Batch sampling

Multiplication of average concentration (from continuous or batch sampling) with average flow

Single PM filter per test

PM filter per mode

Multiplying modal emissions with weighting factors

Average flow

Continuous gas analysis

Constant dilution ratio

For each mode:

For whole test:

Steady-state discrete-mode cycle

Steady-state discrete-mode cycle

Transient cycle and steady-state RMC

Full flow dilution gaseous, PM or PN sampling

Partial flow PM or PN sampling

Raw gaseous sampling

PM filter

Exhaust

Varying dilution ratio

Calculation of average gaseous or PN concentration

Calculation of emission for each mode

PN per mode

PN per test

Varying dilution ratio

Transient cycle and steady-state RMC

Transient cycle, steady-state RMC and steady-state discrete-mode cycle

Multiplying modal emissions with weighting factors

Calculation of emission for whole test

Continuous gas analysis

Integration of instantaneous emissions

Calculation of average rate of emission

Calculation of instantaneous rate of emission

+ continuous flow measurement

Average gas analysis gas concentration

Exhaust

7.2.2.   Work determination

The work shall be determined over the test cycle by synchronously multiplying speed and brake torque to calculate instantaneous values for engine brake power. Engine brake power shall be integrated over the test cycle to determine total work.

7.3.   Verification and calibration

7.3.1.   Pre-test procedures

7.3.1.1.   Preconditioning

To achieve stable conditions, the sampling system and the engine shall be preconditioned before starting a test sequence as specified in this point.

The intent of engine preconditioning is to achieve the representativeness of emissions and emission controls over the duty cycle and to reduce bias in order to meet stable conditions for the following emission test.

Emissions may be measured during preconditioning cycles, as long as a predefined number of preconditioning cycles are performed and the measurement system has been started according to the requirements of point 7.3.1.4. The amount of preconditioning shall be identified by the engine manufacturer before starting to precondition. Preconditioning shall be performed as follows, noting that the specific cycles for preconditioning are the same ones that apply for emission testing.

7.3.1.1.1.   Preconditioning for cold-start run of NRTC

The engine shall be preconditioned by running at least one hot-start NRTC. Immediately after completing each preconditioning cycle, the engine shall be shut down and the engine-off hot-soak period shall be completed. Immediately after completing the last preconditioning cycle, the engine shall be shut down and the engine cool down described in point 7.3.1.2 shall be started.

7.3.1.1.2.   Preconditioning for hot-start run of NRTC or for LSI-NRTC

This point describes the pre-conditioning that shall be applied when it is intended to sample emissions from the hot-start NRTC without running the cold-start run of the NRTC (‘cold-start NRTC’), or for the LSI-NRTC. The engine shall be preconditioned by running at least one hot-start NRTC or LSI-NRTC as applicable. Immediately after completing each preconditioning cycle, the engine shall be shut down, and then the next cycle shall be started as soon as practical. It is recommended that the next preconditioning cycle shall be started within 60 seconds after completing the last preconditioning cycle. Where applicable, following the last pre-conditioning cycle the appropriate hot-soak (hot-start NRTC) or cool-down (LSI-NRTC) period shall apply before the engine is started for the emissions test. Where no hot-soak or cool down period applies it is recommended that the emissions test shall be started within 60 seconds after completing the last pre-conditioning cycle.

7.3.1.1.3.   Preconditioning for discrete-mode NRSC

For engine categories other than NRS and NRSh the engine shall be warmed-up and run until engine temperatures (cooling water and lube oil) have been stabilized on 50 % speed and 50 % torque for any discrete-mode NRSC test cycle other than type D2, E2, or G, or nominal engine speed and 50 % torque for any discrete-mode NRSC test cycle D2, E2 or G. The 50 % speed shall be calculated in accordance with point 5.2.5.1 in the case of an engine where MTS is used for the generation of test speeds, and calculated in accordance with point 7.7.1.3 in all other cases. 50 % torque is defined as 50 % of the maximum available torque at this speed. The emissions test shall be started without stopping the engine.

For engine categories NRS and NRSh the engine shall be warmed up according to the recommendation of the manufacturer and good engineering judgment. Before emission sampling can start, the engine shall be running on mode 1 of the appropriate test cycle until engine temperatures have been stabilized. The emissions test shall be started without stopping the engine.

7.3.1.1.4.   Preconditioning for RMC

The engine manufacturer shall select one of the following pre-conditioning sequences (a) or (b). The engine shall be pre-conditioned according to the chosen sequence.

(a)

The engine shall be preconditioned by running at least the second half of the RMC, based on the number of test modes. The engine shall not be shut down between cycles. Immediately after completing each preconditioning cycle, the next cycle (including the emission test) shall be started as soon as practical. Where possible, it is recommended that the next cycle be started within 60 seconds after completing the last preconditioning cycle.

(b)

The engine shall be warmed-up and run until engine temperatures (cooling water and lube oil) have been stabilized on 50 % speed and 50 % torque for any RMC test cycle other than type D2, E2, or G, or nominal engine speed and 50 % torque for any RMC test cycle D2, E2 or G. The 50 % speed shall be calculated in accordance with point 5.2.5.1 in the case of an engine where MTS is used for the generation of test speeds, and be calculated in accordance with point 7.7.1.3 in all other cases. 50 % torque is defined as 50 % of the maximum available torque at this speed.

7.3.1.1.5.   Engine cool-down (NRTC)

A natural or forced cool-down procedure may be applied. For forced cool-down, good engineering judgment shall be used to set up systems to send cooling air across the engine, to send cool oil through the engine lubrication system, to remove heat from the coolant through the engine cooling system, and to remove heat from an exhaust after-treatment system. In the case of a forced after-treatment cool down, cooling air shall not be applied until the exhaust after-treatment system has cooled below its catalytic activation temperature. Any cooling procedure that results in unrepresentative emissions is not permitted.

7.3.1.2.   Verification of HC contamination

If there is any presumption of an essential HC contamination of the exhaust gas measuring system, the contamination with HC may be checked with zero gas and the hang-up may then be corrected. If the amount of contamination of the measuring system and the background HC system has to be checked, it shall be conducted within 8 hours of starting each test-cycle. The values shall be recorded for later correction. Before this check, the leak check has to be performed and the FID analyzer has to be calibrated.

7.3.1.3.   Preparation of measurement equipment for sampling

The following steps shall be taken before emission sampling begins:

(a)	Leak checks shall be performed within 8 hours prior to emission sampling according to point 8.1.8.7;

(b)	For batch sampling, clean storage media shall be connected, such as evacuated bags or tare-weighed filters;

(c)	All measurement instruments shall be started according to the instrument manufacturer's instructions and good engineering judgment;

(d)	Dilution systems, sample pumps, cooling fans, and the data-collection system shall be started;

(e)	The sample flow rates shall be adjusted to desired levels, using bypass flow, if desired;

(f)	Heat exchangers in the sampling system shall be pre-heated or pre-cooled to within their operating temperature ranges for a test;

(g)	Heated or cooled components such as sample lines, filters, chillers, and pumps shall be allowed to stabilize at their operating temperatures;

(h)	Exhaust gas dilution system flow shall be switched on at least 10 minutes before a test sequence;

(i)	Calibration of gas analyzers and zeroing of continuous analyzers shall be carried out according to the procedure of the next point 7.3.1.4;

(j)	Any electronic integrating devices shall be zeroed or re-zeroed, before the start of any test interval.

7.3.1.4.   Calibration of gas analyzers

Appropriate gas analyzer ranges shall be selected. Emission analyzers with automatic or manual range switching are allowed. During a test using transient (NRTC or LSI-NRTC) test cycles or RMC and during a sampling period of a gaseous emission at the end of each mode for discrete-mode NRSC testing, the range of the emission analyzers may not be switched. Also the gains of an analyzer's analogue operational amplifier(s) may not be switched during a test cycle.

All continuous analyzers shall be zeroed and spanned using internationally-traceable gases that meet the specifications of point 9.5.1. FID analyzers shall be spanned on a carbon number basis of one (C1).

7.3.1.5.   PM filter preconditioning and tare weighing

The procedures for PM filter preconditioning and tare weighing shall be followed according to point 8.2.3.

7.3.2.   Post-test procedures

The following steps shall be taken after emission sampling is complete:

7.3.2.1.   Verification of proportional sampling

For any proportional batch sample, such as a bag sample or PM sample, it shall be verified that proportional sampling was maintained according to point 8.2.1. For the single filter method and the discrete steady-state test cycle, effective PM weighting factor shall be calculated. Any sample that does not fulfil the requirements of point 8.2.1 shall be voided.

7.3.2.2.   Post-test PM conditioning and weighing

Used PM sample filters shall be placed into covered or sealed containers or the filter holders shall be closed, in order to protect the sample filters against ambient contamination. Thus protected, the loaded filters have to be returned to the PM-filter conditioning chamber or room. Then the PM sample filters shall be conditioned and weighted accordingly to point 8.2.4 (PM filter post-conditioning and total weighing procedures).

7.3.2.3.   Analysis of gaseous batch sampling

As soon as practical, the following shall be performed:

(a)	All batch gas analyzers shall be zeroed and spanned no later than 30 minutes after the test cycle is complete or during the soak period if practical to check if gaseous analyzers are still stable;

(b)	Any conventional gaseous batch samples shall be analyzed no later than 30 minutes after the hot-start NRTC is complete or during the soak period;

(c)	The background samples shall be analyzed no later than 60 minutes after the hot-start NRTC is complete.

7.3.2.4.   Drift verification

After quantifying exhaust gas, drift shall be verified as follows:

(a)	For batch and continuous gas analyzers, the mean analyzer value shall be recorded after stabilizing a zero gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response;

(b)	The mean analyzer value shall be recorded after stabilizing the span gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response;

(c)	These data shall be used to validate and correct for drift as described in point 8.2.2.

7.4.   Test cycles

The EU type-approval test shall be conducted using the appropriate NRSC and, where applicable, NRTC or LSI-NRTC, specified in Article 23 and Annex IV to Regulation (EU) 2016/1628. The technical specifications and characteristics of the NRSC, NRTC and LSI-NRTC are laid down in Annex XVII and the method for determination of the load and speed settings for these test cycles set out in section 5.2.

7.4.1.   Steady-state test cycles

Non-road steady-state test cycles (NRSC) are specified in Appendices 1 and 2 of Annex XVII as a list of discrete-modes NRSC (operating points), where each operating point has one value of speed and one value of torque. A NRSC shall be measured with a warmed up and running engine according to manufacturer's specification. At the choice of the manufacturer, a NRSC may be run as a discrete-mode NRSC or a RMC, as explained in points 7.4.1.1 and 7.4.1.2. It shall not be required to conduct an emission test according to both points 7.4.1.1 and 7.4.1.2.

7.4.1.1.   Discrete-mode NRSC

The discrete-mode NRSC are hot running cycles where emissions shall be started to be measured after the engine is started, warmed up and running as specified in point 7.8.1.2. Each cycle consists of a number of speed and load modes (with the respective weighing factor for each mode) which cover the typical operating range of the specified engine category.

7.4.1.2.   Ramped modal NRSC

The RMC are hot running cycles where emissions shall be started to be measured after the engine is started, warmed up and running as specified in point 7.8.2.1. The engine shall be continuously controlled by the test bed control unit during the RMC. The gaseous and particulate emissions shall be measured and sampled continuously during the RMC in the same way as in a transient (NRTC or LSI-NRTC) test cycles.

An RMC is intended to provide a method for performing a steady-state test in a pseudo-transient manner. Each RMC consists of a series of steady state modes with a linear transition between them. The relative total time at each mode and its preceding transition match the weighting of the discrete-mode NRSC. The change in engine speed and load from one mode to the next one has to be linearly controlled in a time of 20 ± 1 seconds. The mode change time is part of the new mode (including the first mode). In some cases modes are not run in the same order as the discrete-mode NRSC or are split to prevent extreme changes in temperature.

7.4.2.   Transient (NRTC and LSI-NRTC) test cycles

The non-road transient cycle for engines of category NRE (NRTC) and the non-road transient cycle for large spark ignition engines of category NRS (LSI-NRTC) are each specified in Appendix 3 of Annex XVII as a second-by-second sequence of normalized speed and torque values. In order to perform the test in an engine test cell, the normalized values shall be converted to their equivalent reference values for the individual engine to be tested, based on specific speed and torque values identified in the engine-mapping curve. The conversion is referred to as denormalization, and the resulting test cycle is the reference NRTC or LSI-NRTC test cycle of the engine to be tested (see point 7.7.2).

7.4.2.1.   Test sequence for NRTC

A graphical display of the normalized NRTC dynamometer schedule is shown in Figure 6.3.

Figure 6.3

NRTC normalized dynamometer schedule

time [ s ]

NRTC dynamometer schedule

Speed [%]

Torque [%]

The NRTC shall be run twice after completion of pre-conditioning (see point 7.3.1.1.1) in accordance with the following procedure:

(a)

the cold start after the engine and exhaust after-treatment systems have cooled down to room temperature after natural engine cool down, or the cold start after forced cool down and the engine, coolant and oil temperatures, exhaust after-treatment systems and all engine control devices are stabilized between 293 K and 303 K (20 °C and 30 °C). The measurement of the cold start emissions shall be started with the start of the cold engine;

(b)	the hot soak period shall commence immediately upon completion of the cold start phase. The engine shall be shut-down and conditioned for the hot-start run by soaking it for 20 minutes ± 1 minute;

(c)

the hot-start run shall be started immediately after the soak period with the cranking of the engine. The gaseous analyzers shall be switched on at least 10 seconds before the end of the soak period to avoid switching signal peaks. The measurement of emissions shall be started in parallel with the start of the hot-start NRTC, including the cranking of the engine.

Brake specific emissions expressed in (g/kWh) shall be determined by using the procedures set out in this section for both the cold-start and hot-start NRTC. Composite weighted emissions shall be computed by weighting the cold-start run results by 10 % and the hot-start run results by 90 % as detailed in Annex VII.

7.4.2.2.   Test sequence for LSI-NRTC

The LSI-NRTC shall be run once as a hot-start run after completion of pre-conditioning (see point 7.3.1.1.2) in accordance with the following procedure:

(a)	the engine shall be started and operated for the first 180 seconds of the duty cycle, then operated at idle without load for 30 seconds. Emissions shall not be measured during this warm-up sequence.

(b)	At the end of the 30-second idling period, emissions measurement shall be started and the engine be operated over the entire duty cycle from the beginning (time 0 sec).

Brake specific emissions expressed in (g/kWh) shall be determined by using the procedures of Annex VII.

If the engine was already operating before the test, use good engineering judgment to let the engine cool down enough so measured emissions will accurately represent those from an engine starting at room temperature. For example, if an engine starting at room temperature warms up enough in three minutes to start closed-loop operation and achieve full catalyst activity, then minimal engine cooling is necessary before starting the next test.

With the prior agreement of the technical service, the engine warm-up procedure may include up to 15 minutes of operation over the duty cycle.

7.5.   General test sequence

To measure engine emissions the following steps have to be performed:

(a)	The engine test speeds and test loads have to be defined for the engine to be tested by measuring the max torque (for constant-speed engines) or max torque curve (for variable-speed engines) as function of the engine speed;

(b)	Normalized test cycles have to be denormalized with the torque (for constant-speed engines) or speeds and torques (for variable-speed engines) found in the previous point 7.5(a);

(c)	The engine, equipment, and measurement instruments shall be prepared for the following emission test or test series (cold-start run and hot-start run) in advance;

(d)	Pre-test procedures shall be performed to verify proper operation of certain equipment and analyzers. All analysers have to be calibrated. All pre-test data shall be recorded;

(e)	The engine shall be started (NRTC) or kept running (steady-state cycles and LSI-NRTC) at the beginning of the test cycle and the sampling systems shall be started at the same time;

(f)	Emissions and other required parameters shall be measured or recorded during sampling time (for NRTC, LSI-NRTC and RMC throughout the whole test cycle);

(g)	Post-test procedures shall be performed to verify proper operation of certain equipment and analyzers;

(h)	PM filter(s) shall be pre-conditioned, weighed (empty weight), loaded, re-conditioned, again weighed (loaded weight) and then samples shall be evaluated according to pre- (para. 7.3.1.5) and post-test (para. 7.3.2.2) procedures;

(i)	Emission test results shall be evaluated.

Figure 6.4 gives an overview about the procedures needed to conduct NRMM test cycles with measuring exhaust engine emissions.

Figure 6.4

Test sequence

Steady-state (discrete & RMC)

Generate engine map (maximum torque curve or constant speed operating line) if transient cycle not applied

Define steady-state test cycle

Generate reference transient test cycle

Run one or more practice cycle as necessary to check engine/test

Natural or forced cool down

Ready all systems for sampling (analyzer calibration included) & data collection

Pre-condition & warm-up engine

Exhaust emission test

Cold start exhaust emission test phase

Hot soak

Hot start exhaust emission test phase

1) Data collection 2) Post-test procedures 3) Evaluations

Emissions calculation

7.5.1.   Engine starting, and restarting

7.5.1.1.   Engine start

The engine shall be started:

(a)	As recommended in the end-users' instructions using a production starter motor or air-start system and either an adequately charged battery, a suitable power supply or a suitable compressed air source; or

(b)	By using the dynamometer to crank the engine until it starts. Typically operate the engine within ± 25 % of its typical in-use cranking speed or start the engine by linearly increasing the dynamometer speed from zero to 100 min– 1 below low idle speed but only until the engine starts.

Cranking shall be stopped within 1 s of starting the engine. If the engine does not start after 15 s of cranking, cranking shall be stopped and the reason for the failure to start determined, unless the end-users' instructions or the service-repair manual describes a longer cranking time as normal.

7.5.1.2.   Engine stalling

(a)	If the engine stalls anywhere during the cold-start NRTC, the test shall be voided;

(b)	If the engine stalls anywhere during the hot-start NRTC, the test shall be voided. The engine shall be soaked according to point 7.4.2.1(b), and the hot-start run repeated. In this case, the cold-start run does not need to be repeated;

(c)	If the engine stalls anywhere during the LSI-NRTC, the test shall be voided.

(d)

If the engine stalls anywhere during the NRSC (discrete or ramped), the test shall be voided and be repeated beginning with the engine warm-up procedure. In the case of PM measurement utilizing the multi-filter method (one sampling filter for each operating mode), the test shall be continued by stabilizing the engine at the previous mode for engine temperature conditioning and then initiating measurement with the mode where the engine stalled.

7.5.1.3   Engine operation

The ‘operator’ may be a person (i.e., manual), or a governor (i.e., automatic) that mechanically or electronically signals an input that demands engine output. Input may be from an accelerator pedal or signal, a throttle-control lever or signal, a fuel lever or signal, a speed lever or signal, or a governor set point or signal.

7.6.   Engine mapping

Before starting the engine mapping, the engine shall be warmed up and towards the end of the warm up it shall be operated for at least 10 minutes at maximum power or according to the recommendation of the manufacturer and good engineering judgement in order to stabilize the engine coolant and lube oil temperatures. When the engine is stabilized, the engine mapping shall be performed.

Where the manufacturer intends to use the torque signal broadcast by the electronic control unit, of engines so equipped, during the conduct of in-service monitoring tests according to Delegated Regulation (EU) 2017/655 on monitoring of emissions of in-service engines, the verification set out in Appendix 3 shall additionally be performed during the engine mapping.

Except constant-speed engines, engine mapping shall be performed with fully open fuel lever or governor using discrete speeds in ascending order. The minimum and maximum mapping speeds are defined as follows:

Minimum mapping speed	=	warm idle speed
Maximum mapping speed	=	n hi × 1,02 or speed where max torque drops off to zero, whichever is smaller.

Where:

n hi is the high speed, as defined in Article 2(12).

If the highest speed is unsafe or unrepresentative (e.g., for ungoverned engines), good engineering judgement shall be used to map up to the maximum safe speed or the maximum representative speed.

7.6.1.   Engine mapping for variable-speed NRSC

In the case of engine mapping for a variable-speed NRSC (only for engines which have not to run the NRTC or LSI-NRTC cycle), good engineering judgment shall be used to select a sufficient number of evenly spaced set-points. At each set-point, speed shall be stabilized and torque allowed to stabilize at least for 15 seconds. The mean speed and torque shall be recorded at each set-point. It is recommended that the mean speed and torque are calculated using the recorded data from the last 4 to 6 seconds. Linear interpolation shall be used to determine the NRSC test speeds and torques if needed. When engines are additionally required to run an NRTC or LSI-NRTC, the NRTC engine mapping curve shall be used to determine steady-state test speeds and torques.

At the choice of the manufacturer the engine mapping may alternatively be conducted according to the procedure in point 7.6.2.

7.6.2.   Engine mapping for NRTC and LSI-NRTC

The engine mapping shall be performed according to the following procedure:

(a)

The engine shall be unloaded and operated at idle speed; (i) For engines with a low-speed governor, the operator demand shall be set to the minimum, the dynamometer or another loading device shall be used to target a torque of zero on the engine's primary output shaft and the engine shall be allowed to govern the speed. This warm idle speed shall be measured; (ii) For engines without a low-speed governor, the dynamometer shall be set to target a torque of zero on the engine's primary output shaft, and the operator demand shall be set to control the speed to the manufacturer-declared lowest engine speed possible with minimum load (also known as manufacturer-declared warm idle speed); (iii) The manufacturer declared idle torque may be used for all variable-speed engines (with or without a low-speed governor), if a nonzero idle torque is representative of in-use operation;

(b)

Operator demand shall be set to maximum and engine speed shall be controlled to between warm idle and 95 % of its warm idle speed. For engines with reference duty cycles, which lowest speed is greater than warm idle speed, the mapping may be started at between the lowest reference speed and 95 % of the lowest reference speed;

(c)

The engine speed shall be increased at an average rate of 8 ± 1 min– 1/s or the engine shall be mapped by using a continuous sweep of speed at a constant rate such that it takes 4 to 6 min to sweep from minimum to maximum mapping speed. The mapping speed range shall be started between warm idle and 95 % of warm idle and ended at the highest speed above maximum power at which less than 70 % of maximum power occurs. If this highest speed is unsafe or unrepresentative (e.g., for ungoverned engines), good engineering judgment shall be used to map up to the maximum safe speed or the maximum representative speed. Engine speed and torque points shall be recorded at a sample rate of at least 1 Hz;

(d)

If a manufacturer believes that the above mapping techniques are unsafe or unrepresentative for any given engine, alternate mapping techniques may be used. These alternate techniques shall satisfy the intent of the specified mapping procedures to determine the maximum available torque at all engine speeds achieved during the test cycles. Deviations from the mapping techniques specified in this section for reasons of safety or representativeness shall be approved by the approval authority along with the justification for their use. In no case, however, the torque curve shall be run by descending engine speeds for governed or turbocharged engines;

(e)

An engine need not be mapped before each and every test cycle. An engine shall be remapped if: (i) an unreasonable amount of time has transpired since the last map, as determined by good engineering judgment; or (ii) physical changes or recalibrations have been made to the engine which potentially affect engine performance; or (iii) the atmospheric pressure near the engine's air inlet is not within ± 5 kPa of the value recorded at the time of the last engine map.

7.6.3.   Engine mapping for constant-speed NRSC

The engine may be operated with a production constant-speed governor or a constant-speed governor maybe simulated by controlling engine speed with an operator demand control system. Either isochronous or speed-droop governor operation shall be used, as appropriate.

7.6.3.1.   Rated power check for engines to be tested on cycles D2 or E2

The following check shall be conducted:

(a)	With the governor or simulated governor controlling speed using operator demand the engine shall be operated at the rated speed and the rated power for as long as required to achieve stable operation;

(b)

The torque shall be increased until the engine is unable to maintain the governed speed. The power at this point shall be recorded. Before this check is performed the method to safely determine when this point has been reached shall be agreed between the manufacturer and the technical service conducting the check, depending upon the characteristics of the governor. The power recorded at point (b) shall not exceed the rated power as defined in Article 3(25) of Regulation (EU) 2016/1628 by more than 12,5 %. If this value is exceeded the manufacturer shall revise the declared rated power.

If the specific engine being tested is unable to perform this check due to risk of damage to the engine or dynamometer the manufacturer shall present to the approval authority robust evidence that maximum power does not exceed the rated power by more than 12,5 %.

7.6.3.2.   Mapping procedure for constant-speed NRSC

(a)	With the governor or simulated governor controlling speed using operator demand, the engine shall be operated at no-load governed speed (at high speed, not low idle) for at least 15 seconds, unless the specific engine is unable to perform this task;

(b)

The dynamometer shall be used to increase torque at a constant rate. The map shall be conducted such that it takes no less than 2 min to sweep from no-load governed speed to the torque corresponding to rated power for engines to be tested on cycle D2 or E2 or to maximum torque in the case of other constant-speed test cycles. During the engine mapping actual speed and torque shall be recorded with at least 1 Hz;

(c)	In case of a constant-speed engine with a governor that can be reset to alternative speeds, the engine shall be tested at each applicable constant-speed.

For constant-speed engines good engineering judgment shall be used in agreement with the approval authority to apply other methods to record torque and power at the defined operating speed(s).

For engines tested on cycles other than D2 or E2, when both measured and declared values are available for the maximum torque, the declared value may be used instead of the measured value if it is between 95 and 100 % of the measured value.

7.7.   Test cycle generation

7.7.1.   Generation of NRSC

This point shall be used to generate the engine speeds and loads over which the engine shall be operated during steady-state tests with discrete-mode NRSC or RMC.

7.7.1.1.   Generation of NRSC test speeds for engines tested with both NRSC and either NRTC or LSI-NRTC.

For engines that are tested with either NRTC or LSI-NRTC in addition to a NRSC, the MTS specified in point 5.2.5.1 shall be used as the 100 % speed for both transient and steady state tests.

The MTS shall be used in place of rated speed when determining intermediate speed in accordance with point 5.2.5.4.

The idle speed shall be determined in accordance with point 5.2.5.5.

7.7.1.2.   Generation of NRSC test speeds for engines only tested with NRSC

For engines that are not tested with a transient (NRTC or LSI-NRTC) test cycle, the rated speed specified in point 5.2.5.3 shall be used as the 100 % speed.

The rated speed shall be used to determine the intermediate speed in accordance with point 5.2.5.4. If the NRSC specifies additional speeds as a percentage they shall be calculated as a percentage of the rated speed.

The idle speed shall be determined in accordance with point 5.2.5.5.

With prior approval of the technical service, MTS may be used instead of rated speed for the generation of test speeds in this point.

7.7.1.3.   Generation of NRSC load for each test mode

The per cent load for each test mode of the chosen test cycle shall be taken from the appropriate NRSC Table of Appendix 1 or 2 of Annex XVII. Depending upon the test cycle, the per cent load in these Tables is expressed as either power or torque in accordance with point 5.2.6 and in the footnotes for each Table.

The 100 % value at a given test speed shall be the measured or declared value taken from the mapping curve generated in accordance with point 7.6.1, point 7.6.2 or point 7.6.3 respectively, expressed as power (kW).

The engine setting for each test mode shall be calculated by means of equation (6-14):

(6-14)

Where:

S	is the dynamometer setting in kW
P max	is the maximum observed or declared power at the test speed under the test conditions (specified by the manufacturer) in kW
P AUX	is the declared total power absorbed by auxiliaries as defined in equation (6-8) (see point 6.3.5) at the specified test speed in kW
L	is per cent torque

A warm minimum torque that is representative of in-use operation may be declared and used for any load point that would otherwise fall below this value if the engine type will not normally operate below this minimum torque, for example because it will be connected to a non-road mobile machinery that does not operate below a certain minimum torque.

In the case of cycles E2 and D2 the manufacturer shall declare the rated power and these shall be used as 100 % power when generating the test cycle.

7.7.2.   Generation of NRTC & LSI-NRTC speed and load for each test point (denormalization)

This point shall be used to generate the corresponding engine speeds and loads over which the engine shall be operated during NRTC or LSI-NRTC tests. Appendix 3 of Annex XVII defines applicable test cycles in a normalized format. A normalized test cycle consists of a sequence of paired values for speed and torque %.

Normalized values of speed and torque shall be transformed using the following conventions:

(a)	The normalized speed shall be transformed into a sequence of reference speeds, n ref, in accordance with point 7.7.2.2;

(b)	The normalized torque is expressed as a percentage of the mapped torque from the curve generated according to point 7.6.2 at the corresponding reference speed. These normalized values shall be transformed into a sequence of reference torques, T ref, according to point 7.7.2.3;

(c)	The reference speed and reference torque values expressed in coherent units are multiplied to calculate the reference power values.

7.7.2.1.   Reserved

7.7.2.2.   Denormalization of engine speed

The engine speed shall be denormalized using by means of equation (6-15):

(6-15)

Where:

n ref	is the reference speed
MTS	is the maximum test speed
n idle	is the idle speed
%speed	is the value of NRTC or LSI-NRTC normalized speed taken from Appendix 3 of Annex XVII.

7.7.2.3   Denormalization of engine torque

The torque values in the engine dynamometer schedule of Appendix 3 of Annex XVII. are normalized to the maximum torque at the respective speed. The torque values of the reference cycle shall be denormalized, using the mapping curve determined according to point 7.6.2, by means of equation (6-16):

(6-16)

for the respective reference speed as determined in point 7.7.2.2

Where:

T ref	is the reference torque for the respective reference speed
max.torque	is the maximum torque for the respective test speed taken from the engine mapping performed in accordance with point 7.6.2 adjusted where necessary in accordance with point 7.7.2.3.1
%torque	is the value of NRTC or LSI-NRTC normalized torque taken from Appendix 3 of Annex XVII

(a)   Declared minimum torque

A minimum torque that is representative of in-use operation may be declared. For example, if the engine is typically connected to a non-road mobile machinery that does not operate below a certain minimum torque, this torque may be declared and used for any load point that would otherwise fall below this value.

(b)   Adjustment of engine torque due to auxiliaries fitted for the emissions test

Where auxiliaries are fitted in accordance with Appendix 2 there shall be no adjustment to the maximum torque for the respective test speed taken from the engine mapping performed according to point 7.6.2.

Where, according to points 6.3.2 or 6.3.3 necessary auxiliaries that should have been fitted for the test are not installed, or auxiliaries that should have been removed for the test are installed, the value of T max shall be adjusted by means of equation (6-17).

T max = T map – T AUX

(6-17)

with:

TAUX = Tr – Tf

(6-18)

where:

T map	is the unadjusted maximum torque for the respective test speed taken from the engine mapping performed in accordance with point 7.6.2
T f	is the torque required to drive auxiliaries that should have been fitted but were not installed for the test
Tr	is the torque required to drive auxiliaries that should have been removed for the test but were installed for the test

7.7.2.4.   Example of denormalization procedure

As an example, the following test point shall be denormalized:

% speed = 43 %

% torque = 82 %

Given the following values:

MTS = 2 200 min– 1

n idle = 600 min– 1

results in

With the maximum torque of 700 Nm observed from the mapping curve at 1 288 min– 1

7.8.   Specific test cycle running procedure

7.8.1.   Emission test sequence for discrete-mode NRSC

7.8.1.1.   Engine warming-up for steady state discrete-mode NRSC

Pre-test procedure according to point 7.3.1 shall be performed, including analyzer calibration. The engine shall be warmed-up using the pre-conditioning sequence in point 7.3.1.1.3. Immediately from this engine conditioning point, the test cycle measurement starts.

7.8.1.2.   Performing discrete-mode NRSC

(a)	The test shall be performed in ascending order of mode numbers as set out for the test cycle (see Appendix 1 of Annex XVII);

(b)

Each mode has a mode length of at least 10 minutes, except when testing spark ignition engines using cycles G1, G2 or G3 where each mode has a length of at least 3 minutes. In each mode the engine shall be stabilized for at least 5 minutes and emissions shall be sampled for 1-3 minutes for gaseous emissions and, where there is an applicable limit, PN at the end of each mode, except when testing spark ignition engines using cycles G1, G2 or G3 where emissions shall be sampled for at least the last 2 minutes of the respective test mode. Extended time of sampling is permitted to improve the accuracy of PM sampling; The mode length shall be recorded and reported.

(c)

The PM sampling may be done either with the single filter method or with the multiple filter method. Since the results of the methods may differ slightly, the method used shall be declared with the results; For the single filter method the modal weighting factors specified in the test cycle procedure and the actual exhaust gas flow shall be taken into account during sampling by adjusting sample flow rate and/or sampling time, accordingly. It is required that the effective weighing factor of the PM sampling is within ± 0,005 of the weighing factor of the given mode; Sampling shall be conducted as late as possible within each mode. For the single filter method, the completion of PM sampling shall be coincident within ± 5 s with the completion of the gaseous emission measurement. The sampling time per mode shall be at least 20 s for the single filter method and at least 60 s for the multi-filter method. For systems without bypass capability, the sampling time per mode shall be at least 60 s for single and multiple filter methods;

(d)	The engine speed and load, intake air temperature, fuel flow and where applicable air or exhaust gas flow shall be measured for each mode at the same time interval which is used for the measurement of the gaseous concentrations; Any additional data required for calculation shall be recorded.

(e)

If the engine stalls or the emission sampling is interrupted at any time after emission sampling begins for a discrete-mode NRSC and the single filter method, the test shall be voided and be repeated beginning with the engine warm-up procedure. In the case of PM measurement utilizing the multi-filter method (one sampling filter for each operating mode), the test shall be continued by stabilizing the engine at the previous mode for engine temperature conditioning and then initiating measurement with the mode where the engine stalled;

(f)	Post-test procedures according to point 7.3.2 shall be performed.

7.8.1.3.   Validation criteria

During each mode of the given steady-state test cycle after the initial transition period, the measured speed shall not deviate from the reference speed for more than ± 1 % of rated speed or ± 3 min– 1, whichever is greater except for idle which shall be within the tolerances declared by the manufacturer. The measured torque shall not deviate from the reference torque for more than ± 2 % of the maximum torque at the test speed.

7.8.2.   Emission test sequence for RMC

7.8.2.1.   Engine warming-up

Pre-test procedure according to point 7.3.1 shall be performed, including analyzer calibration. The engine shall be warmed-up using the pre-conditioning sequence in point 7.3.1.1.4. Immediately after this engine conditioning procedure, if the engine speed and torque are not already set for the first mode of the test they shall be changed in a linear ramp of 20 ± 1 s to the first mode of the test. In between 5 to 10 s after the end of the ramp, the test cycle measurement shall start.

7.8.2.2.   Performing an RMC

The test shall be performed in the order of mode numbers as set out for the test cycle (see Appendix 2 of Annex XVII) Where there is no RMC available for the specified NRSC the discrete-mode NRSC procedure set out in point 7.8.1 shall be followed.

The engine shall be operated for the prescribed time in each mode. The transition from one mode to the next shall be done linearly in 20 s ± 1 s following the tolerances prescribed in point 7.8.2.4.

For RMC, reference speed and torque values shall be generated at a minimum frequency of 1 Hz and this sequence of points shall be used to run the cycle. During the transition between modes, the denormalized reference speed and torque values shall be linearly ramped between modes to generate reference points. The normalized reference torque values shall not be linearly ramped between modes and then denormalized. If the speed and torque ramp runs through a point above the engine's torque curve, it shall be continued to command the reference torques and it shall be allowed for the operator demand to go to maximum.

Over the whole RMC (during each mode and including the ramps between the modes), the concentration of each gaseous pollutant shall be measured and where there is an applicable limit the PM and PN be sampled. The gaseous pollutants may be measured raw or diluted and be recorded continuously; if diluted, they can also be sampled into a sampling bag. The particulate sample shall be diluted with conditioned and clean air. One sample over the complete test procedure shall be taken, and, in the case of PM collected on a single PM sampling filter.

For calculation of the brake specific emissions, the actual cycle work shall be calculated by integrating actual engine power over the complete cycle.

7.8.2.3.   Emission test sequence

(a)	Execution of the RMC, sampling exhaust gas, recording data, and integrating measured values shall be started simultaneously;

(b)	Speed and torque shall be controlled to the first mode in the test cycle;

(c)	If the engine stalls anywhere during the RMC execution, the test shall be voided. The engine shall be pre-conditioned and the test repeated;

(d)

At the end of the RMC, sampling shall be continued, except for PM sampling, operating all systems to allow system response time to elapse. Then all sampling and recording shall be stopped, including the recording of background samples. Finally, any integrating devices shall be stopped and the end of the test cycle shall be indicated in the recorded data;

(e)	Post-test procedures according to point 7.3.2 shall be performed.

7.8.2.4.   Validation criteria

RMC tests shall be validated using the regression analysis as described in points 7.8.3.3 and 7.8.3.5. The allowed RMC tolerances are given in the following Table 6.1. Note that the RMC tolerances are different from the NRTC tolerances of Table 6.2. When conducting testing of engines of net power greater than 560 kW the regression line tolerances of Table 6.2 and the point deletion of Table 6.3 may be used.

Table 6.1

RMC Regression line tolerances

	Speed	Torque	Power
Standard error of estimate (SEE) of y on x	maximum 1 % of rated speed	maximum 2 % of maximum engine torque	maximum 2 % of maximum engine power
Slope of the regression line, a 1	0,99 to 1,01	0,98 - 1,02	0,98 - 1,02
Coefficient of determination, r 2	minimum 0,990	minimum 0,950	minimum 0,950
y intercept of the regression line, a 0	± 1 % of rated speed	± 20 Nm or 2 % of maximum torque whichever is greater	± 4 kW or 2 % of maximum power whichever is greater

In case of running the RMC test not on a transient test bed, where the second by second speed and torque values are not available, the following validation criteria shall be used.

At each mode the requirements for the speed and torque tolerances are given in point 7.8.1.3. For the 20 s linear speed and linear torque transitions between the RMC steady-state test modes (point 7.4.1.2) the following tolerances for speed and load shall be applied for the ramp:

(a)	the speed shall be held linear within ± 2 % of rated speed,

(b)	the torque shall be held linear within ± 5 % of the maximum torque at rated speed.

7.8.3.   Transient (NRTC and LSI-NRTC) test cycles

Reference speeds and torques commands shall be sequentially executed to perform the NRTC and LSI-NRTC. Speed and torque commands shall be issued at a frequency of at least 5 Hz. Because the reference test cycle is specified at 1 Hz, the in between speed and torque commands shall be linearly interpolated from the reference torque values generated from cycle generation.

Small denormalized speed values near warm idle speed may cause low-speed idle governors to activate and the engine torque to exceed the reference torque even though the operator demand is at a minimum. In such cases, it is recommended to control the dynamometer so it gives priority to follow the reference torque instead of the reference speed and let the engine govern the speed.

Under cold-start conditions engines may use an enhanced-idle device to quickly warm up the engine and the exhaust after-treatment system. Under these conditions, very low normalized speeds will generate reference speeds below this higher enhanced idle speed. In this case it is recommended controlling the dynamometer so it gives priority to follow the reference torque and let the engine govern the speed when the operator demand is at minimum.

During an emission test, reference speeds and torques and the feedback speeds and torques shall be recorded with a minimum frequency of 1 Hz, but preferably of 5 Hz or even 10 Hz. This larger recording frequency is important as it helps to minimize the biasing effect of the time lag between the reference and the measured feedback speed and torque values.

The reference and feedback speeds and torques maybe recorded at lower frequencies (as low as 1 Hz), if the average values over the time interval between recorded values are recorded. The average values shall be calculated based on feedback values updated at a frequency of at least 5 Hz. These recorded values shall be used to calculate cycle-validation statistics and total work.

7.8.3.1.   Performing an NRTC test

Pre-test procedures according to point 7.3.1 shall be performed, including pre-conditioning, cool-down and analyzer calibration.

Testing shall be started as follows:

The test sequence shall commence immediately after the engine has started from cooled down condition specified in point 7.3.1.2 in case of the cold-start NRTC or from hot soak condition in case of the hot-start NRTC. The sequence in point 7.4.2.1 shall be followed.

Data logging, sampling of exhaust gas and integrating measured values shall be initiated simultaneously at the start of the engine. The test cycle shall be initiated when the engine starts and shall be executed according to the schedule of Appendix 3 of Annex XVII.

At the end of the cycle, sampling shall be continued, operating all systems to allow system response time to elapse. Then all sampling and recording shall be stopped, including the recording of background samples. Finally, any integrating devices shall be stopped and the end of the test cycle shall be indicated in the recorded data.

Post-test procedures according to point 7.3.2 shall be performed.

7.8.3.2.   Performing an LSI-NRTC test

Pre-test procedures according to point 7.3.1 shall be performed, including pre-conditioning and analyzer calibration.

Testing shall be started as follows:

The test shall commence according to the sequence given in point 7.4.2.2.

Data logging, sampling of exhaust gas and integrating measured values shall be initiated simultaneously with the start of the LSI-NRTC at the end of the 30-second idle period specified in point 7.4.2.2(b). The test cycle shall be executed according to the schedule of Appendix 3 of Annex XVII.

At the end of the cycle, sampling shall be continued, operating all systems to allow system response time to elapse. Then all sampling and recording shall be stopped, including the recording of background samples. Finally, any integrating devices shall be stopped and the end of the test cycle shall be indicated in the recorded data.

Post-test procedures according to point 7.3.2 shall be performed.

7.8.3.3.   Cycle validation criteria for transient (NRTC and LSI-NRTC) test cycles

In order to check the validity of a test, the cycle-validation criteria in this point shall be applied to the reference and feedback values of speed, torque, power and overall work.

7.8.3.4.   Calculation of cycle work

Before calculating the cycle work, any speed and torque values recorded during engine starting shall be omitted. Points with negative torque values have to be accounted for as zero work. The actual cycle work W act (kWh) shall be calculated based on engine feedback speed and torque values. The reference cycle work W ref (kWh) shall be calculated based on engine reference speed and torque values. The actual cycle work W act is used for comparison to the reference cycle work W ref and for calculating the brake specific emissions (see point 7.2).

W act shall be between 85 % and 105 % of W ref.

7.8.3.5.   Validation statistics (see Appendix 2 of Annex VII)

Linear regression between the reference and the feedback values shall be calculated for speed, torque and power.

To minimize the biasing effect of the time lag between the reference and feedback cycle values, the entire engine speed and torque feedback signal sequence may be advanced or delayed in time with respect to the reference speed and torque sequence. If the feedback signals are shifted, both speed and torque shall be shifted by the same amount in the same direction.

The method of least squares shall be used, with the best-fit equation having the form set out in equation (6-19):

y= a 1 x + a 0

(6-19)

where:

y	is the feedback value of speed (min– 1), torque (Nm), or power (kW)
a 1	is the slope of the regression line
x	is the reference value of speed (min– 1), torque (Nm), or power (kW)
a 0	is the y intercept of the regression line.

The standard error of estimate (SEE) of y on x and the coefficient of determination (r 2) shall be calculated for each regression line in accordance with Appendix 3 of Annex VII.

It is recommended that this analysis be performed at 1 Hz. For a test to be considered valid, the criteria of Table 6.2 shall be met.

Table 6.2

Regression line tolerances

	Speed	Torque	Power
Standard error of estimate (SEE) of y on x	≤ 5,0 percent of maximum test speed	≤ 10,0 % of maximum mapped torque	≤ 10,0 % of maximum mapped power
Slope of the regression line, a 1	0,95 to 1,03	0,83 - 1,03	0,89 - 1,03
Coefficient of determination, r 2	minimum 0,970	minimum 0,850	minimum 0,910
y intercept of the regression line, a 0	≤ 10 % of idle	± 20 Nm or ± 2 % of maximum torque whichever is greater	± 4 kW or ± 2 % of maximum power whichever is greater

For regression purposes only, point deletions are permitted where noted in Table 6.3 before doing the regression calculation. However, those points shall not be deleted for the calculation of cycle work and emissions. An idle point is defined as a point having a normalized reference torque of 0 % and a normalized reference speed of 0 %. Point deletion may be applied to the whole or to any part of the cycle; points to which the point deletion is applied have to be specified.

Table 6.3

Permitted point deletions from regression analysis

Event	Conditions (n = engine speed, T = torque)	Permitted point deletions
Minimum operator demand (idle point)	n ref = n idle and T ref = 0 % and T act > (T ref – 0,02 T maxmappedtorque) and T act < (T ref + 0,02 T maxmappedtorque)	speed and power
Minimum operator demand	n act ≤ 1,02 n ref and T act > T ref or n act > n ref and T act ≤ T ref' or n act > 1,02 n ref and T ref < T act ≤ (T ref + 0,02 T maxmappedtorque)	power and either torque or speed
Maximum operator demand	n act < n ref and T act ≥ T ref or n act ≥ 0,98 n ref and T act < T ref or n act < 0,98 n ref and T ref > T act ≥ (T ref – 0,02 T maxmappedtorque)	power and either torque or speed

8.   Measurement procedures

8.1.   Calibration and performance checks

8.1.1.   Introduction

This point describes required calibrations and verifications of measurement systems. See point 9.4 for specifications that apply to individual instruments.

Calibrations or verifications shall be generally performed over the complete measurement chain.

If a calibration or verification for a portion of a measurement system is not specified, that portion of the system shall be calibrated and its performance verified at a frequency consistent with any recommendations from the measurement system manufacturer and consistent with good engineering judgment.

Internationally recognized-traceable standards shall be used to meet the tolerances specified for calibrations and verifications.

8.1.2.   Summary of calibration and verification

Table 6.4 summarizes the calibrations and verifications described in section 8 and indicates when these have to be performed.

Table 6.4

Summary of Calibration and Verifications

Type of calibration or verification	Minimum frequency (1)
8.1.3: accuracy, repeatability and noise	Accuracy: Not required, but recommended for initial installation. Repeatability: Not required, but recommended for initial installation. Noise: Not required, but recommended for initial installation.
8.1.4: linearity verification	Speed: Upon initial installation, within 370 days before testing and after major maintenance. Torque: Upon initial installation, within 370 days before testing and after major maintenance. Intake air, dilution air and diluted exhaust gas flows and batch sample flow rates: Upon initial installation, within 370 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance. Raw exhaust gas flow: Upon initial installation, within 185 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance. Gas dividers: Upon initial installation, within 370 days before testing and after major maintenance. Gas analyzers (unless otherwise noted): Upon initial installation, within 35 days before testing and after major maintenance. FTIR analyser: Upon installation, within 370 days before testing and after major maintenance. PM balance: Upon initial installation, within 370 days before testing and after major maintenance. Stand-alone pressure and temperature: Upon initial installation, within 370 days before testing and after major maintenance.
8.1.5: Continuous gas analyzer system response and updating-recording verification — for gas analyzers not continuously compensated for other gas species	Upon initial installation or after system modification that would affect response.
8.1.6: Continuous gas analyzer system response and updating-recording verification — for gas analyzers continuously compensated for other gas species	Upon initial installation or after system modification that would affect response.
8.1.7.1: torque	Upon initial installation and after major maintenance.
8.1.7.2: pressure, temperature, dew point	Upon initial installation and after major maintenance.
8.1.8.1: fuel flow	Upon initial installation and after major maintenance.
8.1.8.2: intake flow	Upon initial installation and after major maintenance.
8.1.8.3: exhaust gas flow	Upon initial installation and after major maintenance.
8.1.8.4: diluted exhaust gas flow (CVS and PFD)	Upon initial installation and after major maintenance.
8.1.8.5: CVS/PFD and batch sampler verification (2)	Upon initial installation, within 35 days before testing, and after major maintenance. (Propane check)
8.1.8.8: vacuum leak	Upon installation of the sampling system. Before each laboratory test according to point 7.1: within 8 hours before the start of the first test interval of each duty cycle sequence and after maintenance such as pre-filter changes.
8.1.9.1: CO2 NDIR H2O interference	Upon initial installation and after major maintenance.
8.1.9.2: CO NDIR CO2 and H2O interference	Upon initial installation and after major maintenance.
8.1.10.1: FID calibration HC FID optimization and HC FID verification	Calibrate, optimize, and determine CH4 response: upon initial installation and after major maintenance. Verify CH4 response: upon initial installation, within 185 days before testing, and after major maintenance.
8.1.10.2: raw exhaust gas FID O2 interference	For all FID analyzers: upon initial installation, and after major maintenance. For THC FID analyzers: upon initial installation, after major maintenance, and after FID optimization according to 8.1.10.1.
8.1.11.1: CLD CO2 and H2O quench	Upon initial installation and after major maintenance.
8.1.11.3: NDUV HC and H2O interference	Upon initial installation and after major maintenance.
8.1.11.4: cooling bath NO2 penetration (chiller)	Upon initial installation and after major maintenance.
8.1.11.5: NO2-to-NO converter conversion	Upon initial installation, within 35 days before testing, and after major maintenance.
8.1.12.1: Sample dryer verification	For thermal chillers: upon installation and after major maintenance. For osmotic membranes: upon installation, within 35 days of testing and after major maintenance
8.1.13.1: PM balance and weighing	Independent verification: upon initial installation, within 370 days before testing, and after major maintenance. Zero, span, and reference sample verifications: within 12 hours of weighing, and after major maintenance.

8.1.3.   Verifications for accuracy, repeatability, and noise

The performance values for individual instruments specified in Table 6.8 are the basis for the determination of the accuracy, repeatability, and noise of an instrument.

It is not required to verify instrument accuracy, repeatability, or noise. However, it may be useful to consider these verifications to define a specification for a new instrument, to verify the performance of a new instrument upon delivery, or to troubleshoot an existing instrument.

8.1.4.   Linearity verification

8.1.4.1.   Scope and frequency

A linearity verification shall be performed on each measurement system listed in Table 6.5 at least as frequently as indicated in the Table, consistent with measurement system manufacturer recommendations and good engineering judgment. The intent of a linearity verification is to determine that a measurement system responds proportionally over the measurement range of interest. A linearity verification shall consist of introducing a series of at least 10 reference values to a measurement system, unless otherwise specified. The measurement system quantifies each reference value. The measured values shall be collectively compared to the reference values by using a least squares linear regression and the linearity criteria specified in Table 6.5.

8.1.4.2.   Performance requirements

If a measurement system does not meet the applicable linearity criteria in Table 6.5, the deficiency shall be corrected by re-calibrating, servicing, or replacing components as needed. The linearity verification shall be repeated after correcting the deficiency to ensure that the measurement system meets the linearity criteria.

8.1.4.3.   Procedure

The following linearity verification protocol shall be used:

(a)	A measurement system shall be operated at its specified temperatures, pressures, and flows;

(b)	The instrument shall be zeroed as it would before an emission test by introducing a zero signal. For gas analyzers, a zero gas shall be used that meets the specifications of point 9.5.1 and it shall be introduced directly at the analyzer port;

(c)	The instrument shall be spanned as it would before an emission test by introducing a span signal. For gas analyzers, a span gas shall be used that meets the specifications of point 9.5.1 and it shall be introduced directly at the analyzer port;

(d)	After spanning the instrument, zero shall be checked with the same signal which has been used in paragraph (b) of this point. Based on the zero reading, good engineering judgment shall be used to determine whether or not to re-zero and or re-span the instrument before proceeding to the next step;

(e)

For all measured quantities manufacturer recommendations and good engineering judgment shall be used to select the reference values, y ref i , that cover the full range of values that are expected during emission testing, thus avoiding the need of extrapolation beyond these values. A zero reference signal shall be selected as one of the reference values of the linearity verification. For stand-alone pressure and temperature linearity verifications, at least three reference values shall be selected. For all other linearity verifications, at least ten reference values shall be selected;

(f)	Instrument manufacturer recommendations and good engineering judgment shall be used to select the order in which the series of reference values will be introduced;

(g)	Reference quantities shall be generated and introduced as described in point 8.1.4.4. For gas analyzers, gas concentrations known to be within the specifications of point 9.5.1 shall be used and they shall be introduced directly at the analyzer port;

(h)	Time for the instrument to stabilize while it measures the reference value shall be allowed;

(i)	At a recording frequency of at least the minimum frequency, as specified in Table 6.7, the reference value shall be measured for 30 s and the arithmetic mean of the recorded values, recorded;

(j)	Steps in paragraphs (g) to (i) of this point shall be repeated until all reference quantities are measured;

(k)	The arithmetic means , and reference values, y ref i , shall be used to calculate least-squares linear regression parameters and statistical values to compare to the minimum performance criteria specified in Table 6.5. The calculations described in Appendix 3 of Annex VII shall be used.

8.1.4.4.   Reference signals

This point describes recommended methods for generating reference values for the linearity-verification protocol in point 8.1.4.3. Reference values shall be used that simulate actual values, or an actual value shall be introduced and measured with a reference-measurement system. In the latter case, the reference value is the value reported by the reference-measurement system. Reference values and reference-measurement systems shall be internationally traceable.

For temperature measurement systems with sensors like thermocouples, RTDs, and thermistors, the linearity verification may be performed by removing the sensor from the system and using a simulator in its place. A simulator that is independently calibrated and cold junction compensated, as necessary shall be used. The internationally traceable simulator uncertainty scaled to temperature shall be less than 0,5 % of maximum operating temperature T max. If this option is used, it is necessary to use sensors that the supplier states are accurate to better than 0,5 % of T max compared to their standard calibration curve.

8.1.4.5.   Measurement systems that require linearity verification

Table 6.5 indicates measurement systems that require linearity verifications. For this Table the following provisions shall apply:

(a)	a linearity verification shall be performed more frequently if the instrument manufacturer recommends it or based on good engineering judgment;

(b)	‘min’ refers to the minimum reference value used during the linearity verification; Note that this value may be zero or a negative value depending on the signal;

(c)

‘max’ generally refers to the maximum reference value used during the linearity verification. For example for gas dividers, x max is the undivided, undiluted, span gas concentration. The following are special cases where ‘max’ refers to a different value: (i) For PM balance linearity verification, m max refers to the typical mass of a PM filter; (ii) For torque linearity verification, T max refers to the manufacturer's specified engine torque peak value of the highest torque engine to be tested;

(d)	the specified ranges are inclusive. For example, a specified range of 0,98-1,02 for the slope a 1 means 0,98 ≤ a 1 ≤ 1,02;

(e)

these linearity verifications are not required for systems that pass the flow-rate verification for diluted exhaust gas as described in point 8.1.8.5 for the propane check or for systems that agree within ± 2 % based on a chemical balance of carbon or oxygen of the intake air, fuel, and exhaust gas;

(f)	a 1 criteria for these quantities shall be met only if the absolute value of the quantity is required, as opposed to a signal that is only linearly proportional to the actual value;

(g)

stand-alone temperatures include engine temperatures and ambient conditions used to set or verify engine conditions; temperatures used to set or verify critical conditions in the test system; and temperatures used in emissions calculations: (i) these temperature linearity checks are required. Air intake; after-treatment bed(s) (for engines tested with exhaust after-treatment systems on cycles with cold start criteria); dilution air for PM sampling (CVS, double dilution, and partial flow systems); PM sample; and chiller sample (for gaseous sampling systems that use chillers to dry samples); (ii) these temperature linearity checks are only required if specified by the engine manufacturer. Fuel inlet; test cell charge air cooler air outlet (for engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler); test cell charge air cooler coolant inlet (for engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler); and oil in the sump/pan; coolant before the thermostat (for liquid cooled engines);

(h)

stand-alone pressures include engine pressures and ambient conditions used to set or verify engine conditions; pressures used to set or verify critical conditions in the test system; and pressures used in emissions calculations: (i) required pressure linearity checks are: intake air pressure restriction; exhaust gas back-pressure; barometer; CVS inlet gage pressure (if measurement using CVS); chiller sample (for gaseous sampling systems that use chillers to dry samples); (ii) pressure linearity checks that are required only if specified by the engine manufacturer: test cell charge air cooler and interconnecting pipe pressure drop (for turbo-charged engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler) fuel inlet; and fuel outlet.

Table 6.5

Measurement systems that require linearity verifications

Measurement System	Quantity	Minimum verification frequency	Linearity Criteria
				α	SEE	r 2
Engine speed	n	Within 370 days before testing	≤ 0,05 % n max	0,98-1,02	≤ 2 % n max	≥ 0,990
Engine torque	T	Within 370 days before testing	≤ 1 % T max	0,98-1,02	≤ 2 % T max	≥ 0,990
Fuel flow rate	qm	Within 370 days before testing	≤ 1 % qm , max	0,98-1,02	≤ 2 % qm , max	≥ 0,990
Intake-air flow rate (1)	qV	Within 370 days before testing	≤ 1 % qV , max	0,98-1,02	≤ 2 % qV , max	≥ 0,990
Dilution air flow rate (1)	qV	Within 370 days before testing	≤ 1 % qV , max	0,98-1,02	≤ 2 % qV , max	≥ 0,990
Diluted exhaust gas flow rate (1)	qV	Within 370 days before testing	≤ 1 % qV , max	0,98-1,02	≤ 2 % qV , max	≥ 0,990
Raw exhaust gas flow rate (1)	qV	Within 185 days before testing	≤ 1 % qV , max	0,98-1,02	≤ 2 % qV , max	≥ 0,990
Batch sampler flow rates (1)	qV	Within 370 days before testing	≤ 1 % qV , max	0,98-1,02	≤ 2 % qV , max	≥ 0,990
Gas dividers	x/x span	Within 370 days before testing	≤ 0,5 % x max	0,98-1,02	≤ 2 % x max	≥ 0,990
Gas analyzers	x	Within 35 days before testing	≤ 0,5 % x max	0,99-1,01	≤ 1 % x max	≥ 0,998
PM balance	m	Within 370 days before testing	≤ 1 % m max	0,99-1,01	≤ 1 % m max	≥ 0,998
Stand-alone pressures	p	Within 370 days before testing	≤ 1 % p max	0,99-1,01	≤ 1 % p max	≥ 0,998
Analog-to-digital conversion of stand-alone temperature signals	T	Within 370 days before testing	≤ 1 % T max	0,99-1,01	≤ 1 % T max	≥ 0,998

8.1.5.   Continuous gas analyser system-response and updating-recording verification

This section describes a general verification procedure for continuous gas analyzer system response and update recording. See point 8.1.6 for verification procedures for compensation type analysers.

8.1.5.1.   Scope and frequency

This verification shall be performed after installing or replacing a gas analyzer that is used for continuous sampling. Also this verification shall be performed if the system is reconfigured in a way that would change system response. This verification is needed for continuous gas analysers used for transient (NRTC and LSI-NRTC) test cycles or RMC but is not needed for batch gas analyzer systems or for continuous gas analyzer systems used only for testing with a discrete-mode NRSC.

8.1.5.2.   Measurement principles

This test verifies that the updating and recording frequencies match the overall system response to a rapid change in the value of concentrations at the sample probe. Gas analyzer systems shall be optimized such that their overall response to a rapid change in concentration is updated and recorded at an appropriate frequency to prevent loss of information. This test also verifies that continuous gas analyzer systems meet a minimum response time.

The system settings for the response time evaluation shall be exactly the same as during measurement of the test run (i.e. pressure, flow rates, filter settings on the analyzers and all other response time influences). The response time determination shall be done with gas switching directly at the inlet of the sample probe. The devices for gas switching shall have a specification to perform the switching in less than 0,1 s. The gases used for the test shall cause a concentration change of at least 60 % full scale (FS).

The concentration trace of each single gas component shall be recorded.

8.1.5.3.   System requirements

(a)	The system response time shall be ≤ 10 s with a rise time of ≤ 5 s for all measured components (CO, NOx, 2 and HC) and all ranges used. All data (concentration, fuel and air flows) have to be shifted by their measured response times before performing the emission calculations given in Annex VII.

(b)

To demonstrate acceptable updating and recording with respect to the system's overall response, the system shall meet one of the following criteria: (i) The product of the mean rise time and the frequency at which the system records an updated concentration shall be at least 5. In any case the mean rise time shall be no more than 10 s; (ii) The frequency at which the system records the concentration shall be at least 2 Hz (see also Table 6.7).

8.1.5.4.   Procedure

The following procedure shall be used to verify the response of each continuous gas analyzer system:

(a)

The analyzer system manufacturer's start-up and operating instructions for the instrument setup shall be followed. The measurement system shall be adjusted as needed to optimize performance. This verification shall be run with the analyzer operating in the same manner as used for emission testing. If the analyzer shares its sampling system with other analyzers, and if gas flow to the other analyzers will affect the system response time, then the other analyzers shall be started up and operated while running this verification test. This verification test may be run on multiple analyzers sharing the same sampling system at the same time. If analogue or real-time digital filters are used during emission testing, those filters shall be operated in the same manner during this verification;

(b)

For equipment used to validate system response time, minimal gas transfer line lengths between all connections are recommended to be used, a zero-air source shall be connected to one inlet of a fast-acting 3-way valve (2 inlets, 1 outlet) in order to control the flow of zero and blended span gases to the sample system's probe inlet or a tee near the outlet of the probe. Normally the gas flow rate is higher than the probe sample flow rate and the excess is overflowed out the inlet of the probe. If the gas flow rate is lower than the probe flow rate, the gas concentrations shall be adjusted to account for the dilution from ambient air drawn into the probe. Binary or multi-gas span gases may be used. A gas blending or mixing device may be used to blend span gases. A gas blending or mixing device is recommended when blending span gases diluted in N2 with span gases diluted in air; Using a gas divider, an NO–CO–CO2–C3H8–CH4 (balance N2) span gas shall be equally blended with a span gas of NO2, balance purified synthetic air. Standard binary span gases may be also be used, where applicable, in place of blended NO-CO-CO2-C3H8-CH4, balance N2 span gas; in this case separate response tests shall be run for each analyzer. The gas divider outlet shall be connected to the other inlet of the 3-way valve. The valve outlet shall be connected to an overflow at the gas analyzer system's probe or to an overflow fitting between the probe and transfer line to all the analyzers being verified. A setup that avoids pressure pulsations due to stopping the flow through the gas blending device shall be used. Any of these gas constituents if they are not relevant to the analyzers for this verification shall be omitted. Alternatively the use of gas bottles with single gases and a separate measurement of response times is allowed;

(c)

Data collection shall be done as follows: (i) The valve shall be switched to start the flow of zero gas; (ii) Stabilization shall be allowed for, accounting for transport delays and the slowest analyzer's full response; (iii) Data recording shall be started at the frequency used during emission testing. Each recorded value shall be a unique updated concentration measured by the analyzer; interpolation or filtering may not be used to alter recorded values; (iv) The valve shall be switched to allow the blended span gases to flow to the analyzers. This time shall be recorded as t 0; (v) Transport delays and the slowest analyzer's full response shall be allowed for; (vi) The flow shall be switched to allow zero gas to flow to the analyzer. This time shall be recorded as t 100; (vii) Transport delays and the slowest analyzer's full response shall be allowed for; (viii) The steps in paragraphs (c)(iv) to (vii) of this point shall be repeated to record seven full cycles, ending with zero gas flowing to the analyzers; (ix) Recording shall be stopped.

8.1.5.5.   Performance evaluation

The data from point 8.1.5.4(c) shall be used to calculate the mean rise time for each of the analyzers.

(a)

If it is chosen to demonstrate compliance with point 8.1.5.3(b)(i) the following procedure has to be applied: The rise times (in s) shall be multiplied by their respective recording frequencies in Hertz (1/s). The value for each result shall be at least 5. If the value is less than 5, the recording frequency shall be increased or the flows adjusted or the design of the sampling system shall be changed to increase the rise time as needed. Also digital filters may be configured to increase rise time;

(b)	If it is chosen to demonstrate compliance with point 8.1.5.3(b)(ii), the demonstration of compliance with the requirements of point 8.1.5.3(b)(ii) is sufficient.

8.1.6.   Response time verification for compensation type analysers

8.1.6.1.   Scope and frequency

This verification shall be performed to determine a continuous gas analyzer's response, where one analyzer's response is compensated by another's to quantify a gaseous emission. For this check water vapour shall be considered to be a gaseous constituent. This verification is required for continuous gas analyzers used for transient (NRTC and LSI-NRTC) test cycles or RMC. This verification is not needed for batch gas analyzers or for continuous gas analyzers that are used only for testing with a discrete-mode NRSC. This verification does not apply to correction for water removed from the sample done in post-processing. This verification shall be performed after initial installation (i.e. test cell commissioning). After major maintenance, point 8.1.5 may be used to verify uniform response provided that any replaced components have gone through a humidified uniform response verification at some point.

8.1.6.2.   Measurement principles

This procedure verifies the time-alignment and uniform response of continuously combined gas measurements. For this procedure, it is necessary to ensure that all compensation algorithms and humidity corrections are turned on.

8.1.6.3.   System requirements

The general response time and rise time requirement set out in point 8.1.5.3(a) is also valid for compensation type analysers. Additionally, if the recording frequency is different than the update frequency of the continuously combined/compensated signal, the lower of these two frequencies shall be used for the verification required by point 8.1.5.3(b)(i).

8.1.6.4.   Procedure

All procedures set out in point 8.1.5.4(a) to (c) shall be used. Additionally also the response and rise time of water vapour has to be measured, if a compensation algorithm based on measured water vapour is used. In this case at least one of the used calibration gases (but not NO2) has to be humidified as follows:

If the system does not use a sample dryer to remove water from the sample gas, the span gas shall be humidified by flowing the gas mixture through a sealed vessel that humidifies the gas to the highest sample dew point that is estimated during emission sampling by bubbling it through distilled water. If the system uses a sample dryer during testing that has passed the sample dryer verification check, the humidified gas mixture may be introduced downstream of the sample dryer by bubbling it through distilled water in a sealed vessel at 298 ± 10 K (25 ± 10 °C), or a temperature greater than the dew point. In all cases, downstream of the vessel, the humidified gas shall be maintained at a temperature of at least 5 K (5 °C) above its local dew point in the line. Note that it is possible to omit any of these gas constituents if they are not relevant to the analyzers for this verification. If any of the gas constituents are not susceptible to water compensation, the response check for these analyzers may be performed without humidification.

8.1.7.   Measurement of engine parameters and ambient conditions

The engine manufacturer shall apply internal quality procedures traceable to recognised national or international standards. Otherwise the following procedures apply.

8.1.7.1.   Torque calibration

8.1.7.1.1.   Scope and frequency

All torque-measurement systems including dynamometer torque measurement transducers and systems shall be calibrated upon initial installation and after major maintenance using, among others, reference force or lever-arm length coupled with dead weight. Good engineering judgment shall be used to repeat the calibration. The torque transducer manufacturer's instructions shall be followed for linearizing the torque sensor's output. Other calibration methods are permitted.

8.1.7.1.2.   Dead-weight calibration

This technique applies a known force by hanging known weights at a known distance along a lever arm. It shall be made sure that the weights' lever arm is perpendicular to gravity (i.e., horizontal) and perpendicular to the dynamometer's rotational axis. At least six calibration-weight combinations shall be applied for each applicable torque-measuring range, spacing the weight quantities about equally over the range. The dynamometer shall be oscillated or rotated during calibration to reduce frictional static hysteresis. Each weight's force shall be determined by multiplying its internationally-traceable mass by the local acceleration of Earth's gravity.

8.1.7.1.3.   Strain gage or proving ring calibration

This technique applies force either by hanging weights on a lever arm (these weights and their lever arm length are not used as part of the reference torque determination) or by operating the dynamometer at different torques. At least six force combinations shall be applied for each applicable torque-measuring range, spacing the force quantities about equally over the range. The dynamometer shall be oscillated or rotated during calibration to reduce frictional static hysteresis. In this case, the reference torque is determined by multiplying the force output from the reference meter (such as a strain gage or proving ring) by its effective lever-arm length, which is measured from the point where the force measurement is made to the dynamometer's rotational axis. It shall be made sure that this length is measured perpendicular to the reference meter's measurement axis and perpendicular to the dynamometer's rotational axis.

8.1.7.2.   Pressure, temperature, and dew point calibration

Instruments shall be calibrated for measuring pressure, temperature, and dew point upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.

For temperature measurement systems with thermocouple, RTD, or thermistor sensors, the calibration of the system shall be performed as described in point 8.1.4.4 for linearity verification.

8.1.8.   Flow-related measurements

8.1.8.1.   Fuel flow calibration

Fuel flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.

8.1.8.2.   Intake air flow calibration

Intake air flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.

8.1.8.3.   Exhaust gas flow calibration

Exhaust flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.

8.1.8.4.   Diluted exhaust gas flow (CVS) calibration

8.1.8.4.1.   Overview

(a)	This section describes how to calibrate flow meters for diluted exhaust gas constant-volume sampling (CVS) systems;

(b)

This calibration shall be performed while the flow meter is installed in its permanent position. This calibration shall be performed after any part of the flow configuration upstream or downstream of the flow meter has been changed that may affect the flow-meter calibration. This calibration shall be performed upon initial CVS installation and whenever corrective action does not resolve a failure to meet the diluted exhaust gas flow verification (i.e., propane check) in point 8.1.8.5;

(c)

A CVS flow meter shall be calibrated using a reference flow meter such as a subsonic venturi flow meter, a long-radius flow nozzle, a smooth approach orifice, a laminar flow element, a set of critical flow venturis, or an ultrasonic flow meter. A reference flow meter shall be used that reports quantities that are internationally-traceable within ± 1 % uncertainty. This reference flow meter's response to flow shall be used as the reference value for CVS flow-meter calibration;

(d)	An upstream screen or other pressure restriction that could affect the flow ahead of the reference flow meter may not be used, unless the flow meter has been calibrated with such a pressure restriction;

(e)	The calibration sequence described under this point 8.1.8.4 refers to the molar based approach. For the corresponding sequence used in the mass based approach, see point 2.5 of Annex VII.

(f)

By the choice of the manufacturer, CFV or SSV may alternatively be removed from its permanent position for calibration as long as the following requirements are met when installed in the CVS: (1) Upon installation of the CFV or SSV into the CVS, good engineering judgment shall be applied to verify that any leaks have not been introduced between the CVS inlet and the venturi. (2) After ex-situ venturi calibration, all venturi flow combinations must be verified for CFVs or at minimum of 10 flow points for an SSV using the propane check as described in point 8.1.8.5. The result of the propane check for each venturi flow point may not exceed the tolerance in point 8.1.8.5.6. (3) In order to verify the ex-situ calibration for a CVS with more than a single CFV, the following verification shall be conducted: (i) A constant flow device shall be used to deliver a constant flow of propane to the dilution tunnel. (ii) The hydrocarbon concentrations shall be measured at a minimum of 10 separate flow rates for an SSV flow meter, or at all possible flow combinations for a CFV flow meter, while keeping the flow of propane constant. (iii) The concentration of hydrocarbon background in the dilution air shall be measured at the beginning and end of this test. The average background concentration from each measurement at each flow point must be subtracted before performing the regression analysis in paragraph (iv). (iv) A power regression has to be performed using all the paired values of flow rate and corrected concentration to obtain a relationship in the form of y = a × xb, using the concentration as the independent variable and the flow rate as the dependent variable. For each data point, the calculation of the difference between the measured flow rate and the value represented by the curve fit is required. The difference at each point must be less than ± 1 % of the appropriate regression value. The value of b must be between – 1,005 and – 0,995. If the results do not meet these limits, corrective actions consistent with point 8.1.8.5.1(a) must be taken.

8.1.8.4.2.   PDP calibration

A positive-displacement pump (PDP) shall be calibrated to determine a flow-versus-PDP speed equation that accounts for flow leakage across sealing surfaces in the PDP as a function of PDP inlet pressure. Unique equation coefficients shall be determined for each speed at which the PDP is operated. A PDP flow meter shall be calibrated as follows:

(a)	The system shall be connected as shown in Figure 6.5;

(b)	Leaks between the calibration flow meter and the PDP shall be less than 0,3 % of the total flow at the lowest calibrated flow point; for example, at the highest pressure restriction and lowest PDP-speed point;

(c)	While the PDP operates, a constant temperature at the PDP inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;

(d)	The PDP speed is set to the first speed point at which it is intended to calibrate;

(e)	The variable restrictor is set to its wide-open position;

(f)

The PDP is operated for at least 3 minutes to stabilize the system. Then by continuously operating the PDP, the mean values of at least 30 s of sampled data of each of the following quantities are recorded: (i) The mean flow rate of the reference flow meter, ; (ii) The mean temperature at the PDP inlet, T in; (iii) The mean static absolute pressure at the PDP inlet, p in; (iv) The mean static absolute pressure at the PDP outlet, p out; (v) The mean PDP speed, n PDP;

(g)	The restrictor valve shall be incrementally closed to decrease the absolute pressure at the inlet to the PDP, p in;

(h)	The steps in paragraphs 8.1.8.4.2(f) and (g) shall be repeated to record data at a minimum of six restrictor positions reflecting the full range of possible in-use pressures at the PDP inlet;

(i)	The PDP shall be calibrated by using the collected data and the equations set out in Annex VII;

(j)	The steps in paragraphs (f) to (i) of this point shall be repeated for each speed at which the PDP is operated;

(k)	The equations in section 3 of Annex VII (molar based approach) or section 2 of Annex VII (mass based approach) shall be used to determine the PDP flow equation for emission testing;

(l)	The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.8.5;

(m)	The PDP may not be used below the lowest inlet pressure tested during calibration.

8.1.8.4.3.   CFV calibration

A critical-flow venturi (CFV) shall be calibrated to verify its discharge coefficient, C d, at the lowest expected static differential pressure between the CFV inlet and outlet. A CFV flow meter shall be calibrated as follows:

(a)	The system shall be connected as shown in Figure 6.5;

(b)	The blower shall be started downstream of the CFV;

(c)	While the CFV operates, a constant temperature at the CFV inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;

(d)	Leaks between the calibration flow meter and the CFV shall be less than 0,3 % of the total flow at the highest pressure restriction;

(e)	The variable restrictor shall be set to its wide-open position. In lieu of a variable restrictor the pressure downstream of the CFV may be varied by varying blower speed or by introducing a controlled leak. Note that some blowers have limitations on non-loaded conditions;

(f)

The CFV shall be operated for at least 3 minutes to stabilize the system. The CFV shall continue operating and the mean values of at least 30 s of sampled data of each of the following quantities shall be recorded: (i) The mean flow rate of the reference flow meter, ; (ii) Optionally, the mean dew point of the calibration air, T dew. See Annex VII for permissible assumptions during emission measurements; (iii) The mean temperature at the venturi inlet, T in; (iv) The mean static absolute pressure at the venturi inlet, p in; (v) The mean static differential pressure between the CFV inlet and the CFV outlet, Δp CFV;

(g)	The restrictor valve shall be incrementally closed to decrease the absolute pressure at the inlet to the CFV, p in;

(h)

The steps in paragraphs (f) and (g) of this point shall be repeated to record mean data at a minimum of ten restrictor positions, such that the fullest practical range of Δp CFV expected during testing is tested. It is not required to remove calibration components or CVS components to calibrate at the lowest possible pressure restrictions;

(i)	Cd and the highest allowable pressure ratio r shall be determined as described in Annex VII;

(j)	Cd shall be used to determine CFV flow during an emission test. The CFV shall not be used above the highest allowed r, as determined in Annex VII;

(k)	The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.z8.5;

(l)

If the CVS is configured to operate more than one CFV at a time in parallel, the CVS shall be calibrated by one of the following: (i) Every combination of CFVs shall be calibrated according to this section and with Annex VII. See Annex VII for instructions on calculating flow rates for this option; (ii) Each CFV shall be calibrated according to this point and Annex VII. See Annex VII for instructions on calculating flow rates for this option.

8.1.8.4.4.   SSV calibration

A subsonic venturi (SSV) shall be calibrated to determine its calibration coefficient, C d, for the expected range of inlet pressures. An SSV flow meter shall be calibrated as follows:

(a)	The system shall be connected as shown in Figure 6.5;

(b)	The blower shall be started downstream of the SSV;

(c)	Leaks between the calibration flow meter and the SSV shall be less than 0,3 % of the total flow at the highest pressure restriction;

(d)	While the SSV operates, a constant temperature at the SSV inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;

(e)

The variable restrictor or variable-speed blower shall be set to a flow rate greater than the greatest flow rate expected during testing. Flow rates may not be extrapolated beyond calibrated values, so it is recommended that it is made certain that a Reynolds number, Re, at the SSV throat at the greatest calibrated flow rate is greater than the maximum Re expected during testing;

(f)

The SSV shall be operated for at least 3 min to stabilize the system. The SSV shall continue operating and the mean of at least 30 s of sampled data of each of the following quantities shall be recorded: (i) The mean flow rate of the reference flow meter, ; (ii) Optionally, the mean dew point of the calibration air, T dew. See Annex VII for permissible assumptions; (iii) The mean temperature at the venturi inlet, T in; (iv) The mean static absolute pressure at the venturi inlet, p in; (v) Static differential pressure between the static pressure at the venturi inlet and the static pressure at the venturi throat, Δp SSV;

(g)	The restrictor valve shall be incrementally closed or the blower speed decreased to decrease the flow rate;

(h)	The steps in paragraphs (f) and (g) of this point shall be repeated to record data at a minimum of ten flow rates;

(i)	A functional form of C d versus Re shall be determined by using the collected data and the equations in Annex VII;

(j)	The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.8.5 using the new C d versus Re equation;

(k)	The SSV shall be used only between the minimum and maximum calibrated flow rates;

(l)	The equations in section 3 of Annex VII (molar based approach) or section 2 of Annex VII (mass based approach) shall be used to determine SSV flow during a test.

8.1.8.4.5.   Ultrasonic calibration (reserved)

Figure 6.5

Schematic diagrams for diluted exhaust gas flow CVS calibration

variable speed blower

reference flow meter

blower

downstream pressure control

variable restrictor

reference flow meter

variable restrictor

reference flow meter

8.1.8.5.   CVS and batch sampler verification (propane check)

8.1.8.5.1.   Introduction

(a)

A propane check serves as a CVS verification to determine if there is a discrepancy in measured values of diluted exhaust gas flow. A propane check also serves as a batch-sampler verification to determine if there is a discrepancy in a batch sampling system that extracts a sample from a CVS, as described in paragraph (f) of this point. Using good engineering judgment and safe practices, this check may be performed using a gas other than propane, such as CO2 or CO. A failed propane check might indicate one or more problems that may require corrective action, as follows: (i) Incorrect analyzer calibration. The FID analyzer shall be re-calibrated, repaired, or replaced; (ii) Leak checks shall be performed on CVS tunnel, connections, fasteners, and HC sampling system according to point 8.1.8.7; (iii) The verification for poor mixing shall be performed in accordance with point 9.2.2; (iv) The hydrocarbon contamination verification in the sample system shall be performed as described in point 7.3.1.2; (v) Change in CVS calibration. An in-situ calibration of the CVS flow meter shall be performed as described in point 8.1.8.4; (vi) Other problems with the CVS or sampling verification hardware or software. The CVS system, CVS verification hardware, and software shall be inspected for discrepancies;

(b)

A propane check uses either a reference mass or a reference flow rate of C3H8 as a tracer gas in a CVS. If a reference flow rate is used, any non-ideal gas behaviour of C3H8 in the reference flow meter shall be accounted for. See section 2 of Annex VII (mass based approach) or section 3 of Annex VII (molar based approach), which describe how to calibrate and use certain flow meters. No ideal gas assumption may be used in point 8.1.8.5 and Annex VII. The propane check compares the calculated mass of injected C3H8 using HC measurements and CVS flow rate measurements with the reference value.

8.1.8.5.2.   Method of introducing a known amount of propane into the CVS system

The total accuracy of the CVS sampling system and analytical system shall be determined by introducing a known mass of a pollutant gas into the system while it is being operated in the normal manner. The pollutant is analyzed, and the mass calculated in accordance with Annex VII. Either of the following two techniques shall be used:

(a)

Metering by means of a gravimetric technique shall be done as follows: A mass of a small cylinder filled with carbon monoxide or propane shall be determined with a precision of ± 0,01 g. For about 5 to 10 minutes, the CVS system shall be operated as in a normal exhaust emissions test, while carbon monoxide or propane is injected into the system. The quantity of pure gas discharged shall be determined by means of differential weighing. A gas sample shall be analyzed with the usual equipment (sampling bag or integrating method), and the mass of the gas calculated;

(b)

Metering with a critical flow orifice shall be done as follows: A known quantity of pure gas (carbon monoxide or propane) shall be fed into the CVS system through a calibrated critical orifice. If the inlet pressure is high enough, the flow rate, which is adjusted by means of the critical flow orifice, is independent of the orifice outlet pressure (critical flow). The CVS system shall be operated as in a normal exhaust emissions test for about 5 to 10 minutes. A gas sample shall be analyzed with the usual equipment (sampling bag or integrating method), and the mass of the gas calculated.

8.1.8.5.3.   Preparation of the propane check

The propane check shall be prepared as follows:

(a)	If a reference mass of C3H8 is used instead of a reference flow rate, a cylinder charged with C3H8 shall be obtained. The reference cylinder's mass of C3H8 shall be determined within ± 0,5 % of the amount of C3H8 that is expected to be used;

(b)	Appropriate flow rates shall be selected for the CVS and C3H8;

(c)	A C3H8 injection port shall be selected in the CVS. The port location shall be selected to be as close as practical to the location where engine exhaust system is introduced into the CVS. The C3H8 cylinder shall be connected to the injection system;

(d)	The CVS shall be operated and stabilized;

(e)	Any heat exchangers in the sampling system shall be pre-heated or pre-cooled;

(f)	Heated and cooled components such as sample lines, filters, chillers, and pumps shall be allowed to stabilize at operating temperature;

(g)	If applicable, a vacuum side leak verification of the HC sampling system shall be performed as described in point 8.1.8.7.

8.1.8.5.4.   Preparation of the HC sampling system for the propane check

Vacuum side leak check verification of the HC sampling system may be performed according to paragraph (g) of this point. If this procedure is used, the HC contamination procedure in point 7.3.1.2 may be used. If the vacuum side leak check is not performed according to paragraph (g), then the HC sampling system shall be zeroed, spanned, and verified for contamination, as follows:

(a)	The lowest HC analyzer range that can measure the C3H8 concentration expected for the CVS and C3H8 flow rates shall be selected;

(b)	The HC analyzer shall be zeroed using zero air introduced at the analyzer port;

(c)	The HC analyzer shall be spanned using C3H8 span gas introduced at the analyzer port;

(d)	Zero air shall be overflowed at the HC probe or into a fitting between the HC probe and the transfer line;

(e)	The stable HC concentration of the HC sampling system shall be measured as overflow zero air flows. For batch HC measurement, the batch container (such as a bag) shall be filled and the HC overflow concentration measured;

(f)	If the overflow HC concentration exceeds 2 μmol/mol, the procedure may not be advanced until contamination is eliminated. The source of the contamination shall be determined and corrective action taken, such as cleaning the system or replacing contaminated portions;

(g)	When the overflow HC concentration does not exceed 2 μmol/mol, this value shall be recorded as x HCinit and it shall be used to correct for HC contamination as described in section 2 of Annex VII (mass based approach) or section 3 of Annex VII (molar based approach).

8.1.8.5.5.   Propane check performance

(a)

The propane check shall be performed as follows: (i) For batch HC sampling, clean storage media, such as evacuated bags shall be connected; (ii) HC measurement instruments shall be operated according to the instrument manufacturer's instructions; (iii) If correction for dilution air background concentrations of HC is foreseen, background HC in the dilution air shall be measured and recorded; (iv) Any integrating devices shall be zeroed; (v) Sampling shall begin and any flow integrators shall be started; (vi) C3H8 shall be released at the rate selected. If a reference flow rate of C3H8 is used, the integration of this flow rate shall be started; (vii) C3H8 shall be continued to be released until at least enough C3H8 has been released to ensure accurate quantification of the reference C3H8 and the measured C3H8; (viii) The C3H8 cylinder shall be shut off and sampling shall continue until it has been accounted for time delays due to sample transport and analyzer response; (ix) Sampling shall be stopped and any integrators shall be stopped;

(b)

In case the metering with a critical flow orifice is used, the following procedure may be used for the propane check as the alternative method of point 8.1.8.5.5(a); (i) For batch HC sampling, clean storage media, such as evacuated bags shall be connected; (ii) HC measurement instruments shall be operated according to the instrument manufacturer's instructions; (iii) If correction for dilution air background concentrations of HC is foreseen, background HC in the dilution air shall be measured and recorded; (iv) Any integrating devices shall be zeroed; (v) The contents of the C3H8 reference cylinder shall be released at the rate selected; (vi) Sampling shall begin, and any flow integrators started after confirming that HC concentration is to be stable; (vii) The cylinder's contents shall be continued to be released until at least enough C3H8 has been released to ensure accurate quantification of the reference C3H8 and the measured C3H8; (viii) Any integrators shall be stopped; (ix) The C3H8 reference cylinder shall be shut off.

8.1.8.5.6.   Evaluation of the propane check

Post-test procedure shall be performed as follows:

(a)	If batch sampling has been used, batch samples shall be analyzed as soon as practical;

(b)	After analyzing HC, contamination and background shall be corrected for;

(c)	Total C3H8 mass based on the CVS and HC data shall be calculated as described in Annex VII, using the molar mass of C3H8, M C3H8, instead of the effective molar mass of HC, M HC;

(d)

If a reference mass (gravimetric technique) is used, the cylinder's propane mass shall be determined within ± 0,5 % and the C3H8 reference mass shall be determined by subtracting the empty cylinder propane mass from the full cylinder propane mass. If a critical flow orifice (metering with a critical flow orifice) is used, the propane mass shall be determined as flow rate multiplied by the test time;

(e)	The reference C3H8 mass shall be subtracted from the calculated mass. If this difference is within ± 3,0 % of the reference mass, the CVS passes this verification.

8.1.8.5.7.   PM secondary dilution system verification

When the propane check is to be repeated to verify the PM secondary dilution system, the following procedure from (a) to (d) shall be used for this verification:

(a)

The HC sampling system shall be configured to extract a sample near the location of the batch sampler's storage media (such as a PM filter). If the absolute pressure at this location is too low to extract an HC sample, HC may be sampled from the batch sampler pump's exhaust. Caution shall be used when sampling from pump's exhaust because an otherwise acceptable pump leak downstream of a batch sampler flow meter will cause a false failure of the propane check;

(b)	The propane check shall be repeated as described in this point, but HC shall be sampled from the batch sampler;

(c)	C3H8 mass shall be calculated, taking into account any secondary dilution from the batch sampler;

(d)	The reference C3H8 mass shall be subtracted from the calculated mass. If this difference is within ± 5 % of the reference mass, the batch sampler passes this verification. If not, corrective action shall be taken.

8.1.8.5.8.   Sample dryer verification

If a humidity sensor for continuous monitoring of dew point at the sample dryer outlet is used this check does not apply, as long as it is ensured that the dryer outlet humidity is below the minimum values used for quench, interference, and compensation checks.

(a)

If a sample dryer is used as allowed in point 9.3.2.3.1 to remove water from the sample gas, the performance shall be verified upon installation, after major maintenance, for thermal chillers. For osmotic membrane dryers, the performance shall be verified upon installation, after major maintenance, and within 35 days of testing;

(b)

Water can inhibit an analyzer's ability to properly measure the exhaust component of interest and thus is sometimes removed before the sample gas reaches the analyzer. For example water can negatively interfere with a CLD's NOx response through collisional quenching and can positively interfere with an NDIR analyzer by causing a response similar to CO;

(c)	The sample dryer shall meet the specifications as determined in point 9.3.2.3.1 for dew point, T dew, and absolute pressure, p total, downstream of the osmotic-membrane dryer or thermal chiller;

(d)

The following sample dryer verification procedure method shall be used to determine sample dryer performance, or good engineering judgment shall be used to develop a different protocol: (i) polytetrafluoroethylene (‘PTFE’) or stainless steel tubing shall be used to make necessary connections; (ii) N2 or purified air shall be humidified by bubbling it through distilled water in a sealed vessel that humidifies the gas to the highest sample dew point that is estimated during emission sampling; (iii) The humidified gas shall be introduced upstream of the sample dryer; (iv) The humidified gas temperature downstream of the vessel shall be maintained at least 5 °C above its dew point; (v) The humidified gas dew point, T dew, and pressure, p total, shall be measured as close as possible to the inlet of the sample dryer to verify that the dew point is the highest that was estimated during emission sampling; (vi) The humidified gas dew point, T dew, and pressure, p total, shall be measured as close as possible to the outlet of the sample dryer; (vii) The sample dryer meets the verification if the result of point (d)(vi) of this section is less than the dew point corresponding to the sample dryer specifications as determined in point 9.3.2.3.1 plus 2 °C or if the mol fraction from (d)(vi) is less than the corresponding sample dryer specifications plus 0,002 mol/mol or 0,2 volume %. Note for this verification, sample dew point is expressed in absolute temperature, Kelvin.

8.1.8.6.   Periodic calibration of the partial flow PM and associated raw exhaust gas measurement systems

8.1.8.6.1.   Specifications for differential flow measurement

For partial flow dilution systems to extract a proportional raw exhaust gas sample, the accuracy of the sample flow qm p is of special concern, if not measured directly, but determined by differential flow measurement as set out in equation (6-20):

qm p = qm dew – qm dw

(6-20)

Where:

qm p	is the sample mass flow rate of exhaust gas into partial flow dilution system
qm dw	is the dilution air mass flow rate (on wet basis)
qm dew	is the diluted exhaust gas mass flow rate on wet basis

In this case, the maximum error of the difference shall be such that the accuracy of qm p is within ± 5 % when the dilution ratio is less than 15. It can be calculated by taking root-mean-square of the errors of each instrument.

Acceptable accuracies of q mp can be obtained by either of the following methods:

(a)	The absolute accuracies of qm dew and qm dw are ± 0,2 % which guarantees an accuracy of qm p of ≤ 5 % at a dilution ratio of 15. However, greater errors will occur at higher dilution ratios;

(b)	Calibration of qm dw relative to qm dew is carried out such that the same accuracies for qm p as in (a) are obtained. For details see point 8.1.8.6.2;

(c)	The accuracy of q mp is determined indirectly from the accuracy of the dilution ratio as determined by a tracer gas, e.g. CO2. Accuracies equivalent to method (a) for q mp are required;

(d)	The absolute accuracy of qm dew and qm dw is within ± 2 % of full scale, the maximum error of the difference between qm dew and qm dw is within 0,2 % and the linearity error is within ± 0,2 % of the highest qm dew observed during the test.

8.1.8.6.2.   Calibration of differential flow measurement

The partial flow dilution system to extract a proportional raw exhaust gas sample shall be periodically calibrated with an accurate flow meter traceable to international and/or national standards. The flow meter or the flow measurement instrumentation shall be calibrated in one of the following procedures, such that the probe flow qm p into the tunnel shall fulfil the accuracy requirements of point 8.1.8.6.1.

(a)

The flow meter for qm dw shall be connected in series to the flow meter for qm dew, the difference between the two flow meters shall be calibrated for at least 5 set points with flow values equally spaced between the lowest qm dw value used during the test and the value of qm dew used during the test. The dilution tunnel may be bypassed;

(b)

A calibrated flow device shall be connected in series to the flowmeter for qm dew and the accuracy shall be checked for the value used for the test. The calibrated flow device shall be connected in series to the flow meter for qm dw, and the accuracy shall be checked for at least 5 settings corresponding to dilution ratio between 3 and 15, relative to qm dew used during the test;

(c)

The transfer line TL (see Figure 6.7) shall be disconnected from the exhaust system and a calibrated flow measuring device with a suitable range to measure qm p shall be connected to the transfer line. qm dew shall be set to the value used during the test, and qm dw shall be sequentially set to at least 5 values corresponding to dilution ratios between 3 and 15. Alternatively, a special calibration flow path may be provided, in which the tunnel is bypassed, but the total and dilution air flow is passed through the corresponding meters as in the actual test;

(d)

A tracer gas, shall be fed into the exhaust system transfer line TL. This tracer gas may be a component of the exhaust gas, like CO2 or NOx. After dilution in the tunnel the tracer gas component shall be measured. This shall be carried out for 5 dilution ratios between 3 and 15. The accuracy of the sample flow shall be determined from the dilution ratio r d by means of equation (6-21): qm p = qm dew / r d (6-21)

The accuracies of the gas analyzers shall be taken into account to guarantee the accuracy of qm p.

8.1.8.6.3.   Special requirements for differential flow measurement

A carbon flow check using actual exhaust gas is strongly recommended for detecting measurement and control problems and verifying the proper operation of the partial flow system. The carbon flow check should be run at least each time a new engine is installed, or something significant is changed in the test cell configuration.

The engine shall be operated at peak torque load and speed or any other steady state mode that produces 5 % or more of CO2. The partial flow sampling system shall be operated with a dilution factor of about 15 to 1.

If a carbon flow check is conducted, Appendix 2 of Annex VII shall be applied. The carbon flow rates shall be calculated according to equations of Appendix 2 of Annex VII. All carbon flow rates shall agree to within 5 %.

8.1.8.6.3.1.   Pre-test check

A pre-test check shall be performed within 2 hours before the test run in the following way.

The accuracy of the flow meters shall be checked by the same method as used for calibration (see point 8.1.8.6.2) for at least two points, including flow values of qm dw that correspond to dilution ratios between 5 and 15 for the qm dew value used during the test.

If it can be demonstrated by records of the calibration procedure under point 8.1.8.6.2 that the flow meter calibration is stable over a longer period of time, the pre-test check may be omitted.

8.1.8.6.3.2.   Determination of the transformation time

The system settings for the transformation time evaluation shall be the same as during measurement of the test run. The transformation time, as defined in point 2.4 of Appendix 5 to this Annex and in figure 6-11, shall be determined by the following method:

An independent reference flowmeter with a measurement range appropriate for the probe flow shall be put in series with and closely coupled to the probe. This flowmeter shall have a transformation time of less than 100 ms for the flow step size used in the response time measurement, with flow pressure restriction sufficiently low as to not affect the dynamic performance of the partial flow dilution system according to good engineering judgment. A step change shall be introduced to the exhaust gas flow (or air flow if exhaust gas flow is calculated) input of the partial flow dilution system, from a low flow to at least 90 % of full scale. The trigger for the step change shall be the same one used to start the look-ahead control in actual testing. The exhaust gas flow step stimulus and the flowmeter response shall be recorded at a sample rate of at least 10 Hz.

From this data, the transformation time shall be determined for the partial flow dilution system, which is the time from the initiation of the step stimulus to the 50 % point of the flowmeter response. In a similar manner, the transformation times of the qmp signal (i.e. sample flow of exhaust gas into partial flow dilution system) and of the qmew,i signal (i.e. the exhaust gas mass flow rate on wet basis supplied by the exhaust flow meter) shall be determined. These signals are used in the regression checks performed after each test (see point 8.2.1.2).

The calculation shall be repeated for at least 5 rise and fall stimuli, and the results shall be averaged. The internal transformation time (< 100 ms) of the reference flowmeter shall be subtracted from this value. Where look-ahead control is required, the look-ahead value of the partial flow dilution system shall be applied in accordance with point 8.2.1.2.

8.1.8.7.   Vacuum-side leak verification

8.1.8.7.1.   Scope and frequency

Upon initial sampling system installation, after major maintenance such as pre-filter changes, and within 8 hours prior to each duty-cycle sequence, it shall be verified that there are no significant vacuum-side leaks using one of the leak tests described in this section. This verification does not apply to any full-flow portion of a CVS dilution system.

8.1.8.7.2.   Measurement principles

A leak may be detected either by measuring a small amount of flow when there shall be zero flow, by detecting the dilution of a known concentration of span gas when it flows through the vacuum side of a sampling system or by measuring the pressure increase of an evacuated system.

8.1.8.7.3.   Low-flow leak test

A sampling system shall be tested for low-flow leaks as follows:

(a)

The probe end of the system shall be sealed by taking one of the following steps: (i) The end of the sample probe shall be capped or plugged; (ii) The transfer line shall be disconnected at the probe and the transfer line capped or plugged; (iii) A leak-tight valve in-line between a probe and transfer line shall be closed;

(b)

All vacuum pumps shall be operated. After stabilizing, it shall be verified that the flow through the vacuum-side of the sampling system is less than 0,5 % of the system's normal in-use flow rate. Typical analyzer and bypass flows may be estimated as an approximation of the system's normal in-use flow rate.

8.1.8.7.4.   Dilution-of-span-gas leak test

Any gas analyzer may be used for this test. If a FID is used for this test, any HC contamination in the sampling system shall be corrected in accordance with sections 2 or 3 of Annex VII on HC determination. Misleading results shall be avoided by using only analyzers that have a repeatability of 0,5 % or better at the span gas concentration used for this test. The vacuum side leak check shall be performed as follows:

(a)	A gas analyzer shall be prepared as it would be for emission testing;

(b)	Span gas shall be supplied to the analyzer port and it shall be verified that the span gas concentration is measured within its expected measurement accuracy and repeatability;

(c)

Overflow span gas shall be routed to one of the following locations in the sampling system: (i) The end of the sample probe; (ii) The transfer line shall be disconnected at the probe connection, and the span gas overflown at the open end of the transfer line; (iii) A three-way valve installed in-line between a probe and its transfer line;

(d)

It shall be verified that the measured overflow span gas concentration is within ± 0,5 % of the span gas concentration. A measured value lower than expected indicates a leak, but a value higher than expected may indicate a problem with the span gas or the analyzer itself. A measured value higher than expected does not indicate a leak.

8.1.8.7.5.   Vacuum-decay leak test

To perform this test a vacuum shall be applied to the vacuum-side volume of the sampling system and the leak rate of the system shall be observed as a decay in the applied vacuum. To perform this test the vacuum-side volume of the sampling system shall be known to within ± 10 % of its true volume. For this test measurement instruments that meet the specifications of points 8.1 and 9.4 shall also be used.

A vacuum-decay leak test shall be performed as follows:

(a)

The probe end of the system shall be sealed as close to the probe opening as possible by taking one of the following steps: (i) The end of the sample probe shall be capped or plugged; (ii) The transfer line at the probe shall be disconnected and the transfer line capped or plugged; (iii) A leak-tight valve in-line between a probe and transfer line shall be closed;

(b)	All vacuum pumps shall be operated. A vacuum shall be drawn that is representative of normal operating conditions. In the case of sample bags, it is recommend that the normal sample bag pump-down procedure be repeated twice to minimize any trapped volumes;

(c)

The sample pumps shall be turned off and the system sealed. The absolute pressure of the trapped gas and optionally the system absolute temperature shall be measured and recorded. Sufficient time shall be allowed for any transients to settle and long enough for a leak at 0,5 % to have caused a pressure change of at least 10 times the resolution of the pressure transducer. The pressure and optionally temperature shall be recorded once again;

(d)

The leak flow rate based on an assumed value of zero for pumped-down bag volumes and based on known values for the sample system volume, the initial and final pressures, optional temperatures, and elapsed time shall be calculated. It shall be verified that the vacuum-decay leak flow rate is less than 0,5 % of the system's normal in-use flow rate by means of equation (6-22): (6-22) Where: qV leak is the vacuum-decay leak rate, mol/s V vac is the geometric volume of the vacuum-side of the sampling system, m3 R is the molar gas constant, J/(mol · K) p 2 is the vacuum-side absolute pressure at time t 2, Pa T 2 is the vacuum-side absolute temperature at time t 2, K p 1 is the vacuum-side absolute pressure at time t 1, Pa T 1 is the vacuum-side absolute temperature at time t 1, K t 2 is the time at completion of vacuum-decay leak verification test, s t 1 is the time at start of vacuum-decay leak verification test, s

8.1.9.   CO and CO2 measurements

8.1.9.1.   H2O interference verification for CO2 NDIR analyzers

8.1.9.1.1.   Scope and frequency

If CO2 is measured using an NDIR analyzer, the amount of H2O interference shall be verified after initial analyzer installation and after major maintenance.

8.1.9.1.2.   Measurement principles

H2O can interfere with an NDIR analyzer's response to CO2. If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously these other measurements shall be conducted to test the compensation algorithms during the analyzer interference verification.

8.1.9.1.3.   System requirements

A CO2 NDIR analyzer shall have an H2O interference that is within (0,0 ± 0,4) mmol/mol (of the expected mean CO2 concentration).

8.1.9.1.4.   Procedure

The interference verification shall be performed as follows:

(a)	The CO2 NDIR analyzer shall be started, operated, zeroed, and spanned as it would be before an emission test;

(b)

A humidified test gas shall be created by bubbling zero air that meets the specifications in point 9.5.1 through distilled water in a sealed vessel. If the sample is not passed through a dryer, control the vessel temperature to generate an H2O level at least as high as the maximum expected during testing. If the sample is passed through a dryer during testing, control the vessel temperature to generate an H2O level at least as high as the level required in point 9.3.2.3.1;

(c)	The humidified test gas temperature shall be maintained at least 5 oK above its dew point downstream of the vessel;

(d)	The humidified test gas shall be introduced into the sampling system. The humidified test gas may be introduced downstream of any sample dryer, if one is used during testing;

(e)	The water mole fraction, x H2O, of the humidified test gas shall be measured, as close as possible to the inlet of the analyzer. For example, dew point, T dew, and absolute pressure p total, shall be measured to calculate x H2O;

(f)	Good engineering judgment shall be used to prevent condensation in the transfer lines, fittings, or valves from the point where x H2O is measured to the analyzer;

(g)	Time shall be allowed for the analyzer response to stabilize. Stabilization time shall include time to purge the transfer line and to account for analyzer response;

(h)	While the analyzer measures the sample's concentration, 30 s of sampled data shall be recorded. The arithmetic mean of this data shall be calculated. The analyzer meets the interference verification if this value is within (0,0 ± 0,4) mmol/mol.

8.1.9.2.   H2O and CO2 interference verification for CO NDIR analyzers

8.1.9.2.1.   Scope and frequency

If CO is measured using an NDIR analyzer, the amount of H2O and CO2 interference shall be verified after initial analyzer installation and after major maintenance.

8.1.9.2.2.   Measurement principles

H2O and CO2 can positively interfere with an NDIR analyzer by causing a response similar to CO. If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously these other measurements shall be conducted to test the compensation algorithms during the analyzer interference verification.

8.1.9.2.3.   System requirements

A CO NDIR analyzer shall have combined H2O and CO2 interference that is within ± 2 % of the expected mean concentration of CO.

8.1.9.2.4.   Procedure

The interference verification shall be performed as follows:

(a)	The CO NDIR analyzer shall be started, operated, zeroed, and spanned as it would be before an emission test;

(b)

A humidified CO2 test gas shall be created by bubbling a CO2 span gas through distilled water in a sealed vessel. If the sample is not passed through a dryer, the vessel temperature shall be controlled to generate an H2O level at least as high as the maximum expected during testing. If the sample is passed through a dryer during testing, the vessel temperature shall be controlled to generate an H2O level at least as high as the level required in point 9.3.2.3.1.1. A CO2 span gas concentration shall be used at least as high as the maximum expected during testing;

(c)	The humidified CO2 test gas shall be introduced into the sampling system. The humidified CO2 test gas may be introduced downstream of any sample dryer, if one is used during testing;

(d)	The water mole fraction, x H2O, of the humidified test gas shall be measured, as close as possible to the inlet of the analyzer. For example, dew point, T dew, and absolute pressure p total, shall be measured to calculate x H2O;

(e)	Good engineering judgment shall be used to prevent condensation in the transfer lines, fittings, or valves from the point where x H2O is measured to the analyzer;

(f)	Time shall be allowed for the analyzer response to stabilize;

(g)	While the analyzer measures the sample's concentration, its output shall be recorded for 30 s. The arithmetic mean of this data shall be calculated;

(h)	The analyzer meets the interference verification if the result of paragraph (g) of this point meets the tolerance in point 8.1.9.2.3;

(i)

Interference procedures for CO2 and H2O may be also run separately. If the CO2 and H2O levels used are higher than the maximum levels expected during testing, each observed interference value shall be scaled down by multiplying the observed interference by the ratio of the maximum expected concentration value to the actual value used during this procedure. Separate interference procedures concentrations of H2O (down to 0,025 mol/mol H2O content) that are lower than the maximum levels expected during testing may be run, but the observed H2O interference shall be scaled up by multiplying the observed interference by the ratio of the maximum expected H2O concentration value to the actual value used during this procedure. The sum of the two scaled interference values shall meet the tolerance in point 8.1.9.2.3.

8.1.10.   Hydrocarbon measurements

8.1.10.1.   FID optimization and verification

8.1.10.1.1.   Scope and frequency

For all FID analyzers, the FID shall be calibrated upon initial installation. The calibration shall be repeated as needed using good engineering judgment. The following steps shall be performed for a FID that measures HC:

(a)	A FID's response to various hydrocarbons shall be optimized after initial analyzer installation and after major maintenance. FID response to propylene and toluene shall be between 0,9 and 1,1 relative to propane;

(b)	A FID's methane (CH4) response factor shall be determined after initial analyzer installation and after major maintenance as described in point 8.1.10.1.4;

(c)	Methane (CH4) response shall be verified within 185 days before testing.

8.1.10.1.2.   Calibration

Good engineering judgment shall be used to develop a calibration procedure, such as one based on the FID-analyzer manufacturer's instructions and recommended frequency for calibrating the FID. The FID shall be calibrated using C3H8 calibration gases that meet the specifications of point 9.5.1. It shall be calibrated on a carbon number basis of one (C1).

8.1.10.1.3.   HC FID response optimization

This procedure is only for FID analyzers that measure HC.

(a)

Instrument manufacturer requirements and good engineering judgment shall be used for initial instrument start-up and basic operating adjustment using FID fuel and zero air. Heated FIDs shall be within their required operating temperature ranges. FID response shall be optimized to meet the requirement of the hydrocarbon response factors and the oxygen interference check according to points 8.1.10.1.1(a) and 8.1.10.2 at the most common analyzer range expected during emission testing. Higher analyzer range may be used according to the instrument manufacturer's recommendation and good engineering judgment in order to optimize FID accurately, if the common analyzer range is lower than the minimum range for the optimization specified by the instrument manufacturer;

(b)	Heated FIDs shall be within their required operating temperature ranges. FID response shall be optimized at the most common analyzer range expected during emission testing. With the fuel and airflow rates set at the manufacturer's recommendations, a span gas shall be introduced to the analyzer;

(c)

The following steps from (i) to (iv) or the procedure instructed by the instrument manufacturer shall be taken for optimization. The procedures outlined in SAE paper No 770141 may be optionally used for optimization; (i) The response at a given fuel flow shall be determined from the difference between the span gas response and the zero gas response; (ii) The fuel flow shall be incrementally adjusted above and below the manufacturer's specification. The span and zero response at these fuel flows shall be recorded; (iii) The difference between the span and zero response shall be plotted and the fuel flow adjusted to the rich side of the curve. This is the initial flow rate setting which may need further optimization depending on the results of the hydrocarbon response factors and the oxygen interference check according to points 8.1.10.1.1(a) and 8.1.10.2; (iv) If the oxygen interference or the hydrocarbon response factors do not meet the following specifications, the airflow shall be incrementally adjusted above and below the manufacturer's specifications, repeating points 8.1.10.1.1(a) and 8.1.10.2 for each flow;

(d)	The optimum flow rates and/or pressures for FID fuel and burner air shall be determined, and they shall be sampled and recorded for future reference.

8.1.10.1.4.   HC FID CH4 response factor determination

Since FID analyzers generally have a different response to CH4 versus C3H8, each HC FID analyzer's CH4 response factor, RF CH4[THC-FID] shall be determined, after FID optimization. The most recent RF CH4[THC-FID] measured in accordance with this section shall be used in the calculations for HC determination described in section 2 of Annex VII (mass based approach) or section 3 of Annex VII (molar based approach) to compensate for CH4 response. RF CH4[THC-FID] shall be determined as follows:

(a)	A C3H8 span gas concentration shall be selected to span the analyzer before emission testing. Only span gases that meet the specifications of point 9.5.1 shall be selected and the C3H8 concentration of the gas shall be recorded;

(b)	A CH4 span gas that meets the specifications of point 9.5.1 shall be selected and the CH4 concentration of the gas shall be recorded,

(c)	The FID analyzer shall be operated according to the manufacturer's instructions;

(d)	It shall be confirmed that the FID analyzer has been calibrated using C3H8. Calibration shall be performed on a carbon number basis of one (C1);

(e)	The FID shall be zeroed with a zero gas used for emission testing;

(f)	The FID shall be spanned with the selected C3H8 span gas;

(g)	The CH4 span gas selected in accordance with paragraph (b) shall be introduced at the sample port of the FID analyzer;

(h)	The analyzer response shall be stabilized. Stabilization time may include time to purge the analyzer and to account for its response;

(i)	While the analyzer measures the CH4 concentration, 30 s of sampled data shall be recorded and the arithmetic mean of these values shall be calculated;

(j)	The mean measured concentration shall be divided by the recorded span concentration of the CH4 calibration gas. The result is the FID analyzer's response factor for CH4, RF CH4[THC-FID].

8.1.10.1.5.   HC FID methane (CH4) response verification

If the value of RF CH4[THC-FID] obtained in accordance with point 8.1.10.1.4 is within ± 5,0 % of its most recent previously determined value, the HC FID passes the methane response verification.

(a)

It shall be first verified that the pressures and / or flow rates of FID fuel, burner air, and sample are each within ± 0,5 % of their most recent previously recorded values, as described in point 8.1.10.1.3. If these flow rates have to be adjusted, a new RF CH4[THC-FID] shall be determined as described in point 8.1.10.1.4. It should be verified that the value of RF CH4[THC-FID] determined is within the tolerance specified in this point 8.1.10.1.5;

(b)	If RF CH4[THC-FID] is not within the tolerance specified in this point 8.1.10.1.5, the FID response shall be re-optimized as described in point 8.1.10.1.3;

(c)	A new RF CH4[THC-FID] shall be determined as described in point 8.1.10.1.4. This new value of RF CH4[THC-FID] shall be used in the calculations for HC determination, in section 2 of Annex VII (mass based approach) or section 3 of Annex VII (molar based approach).

8.1.10.2.   Non-stoichiometric raw exhaust gas FID O2 interference verification

8.1.10.2.1.   Scope and frequency

If FID analyzers are used for raw exhaust gas measurements, the amount of FID O2 interference shall be verified upon initial installation and after major maintenance.

8.1.10.2.2.   Measurement principles

Changes in O2 concentration in raw exhaust gas can affect FID response by changing FID flame temperature. FID fuel, burner air, and sample flow shall be optimized to meet this verification. FID performance shall be verified with the compensation algorithms for FID O2 interference that is active during an emission test.

8.1.10.2.3.   System requirements

Any FID analyzer used during testing shall meet the FID O2 interference verification according to the procedure in this section.

8.1.10.2.4.   Procedure

FID O2 interference shall be determined as follows, noting that one or more gas dividers may be used to create reference gas concentrations that are required to perform this verification:

(a)

Three span reference gases that meet the specifications set out in point 9.5.1 and contain C3H8 concentration shall be selected to span the analyzers before emissions testing. CH4 span reference gases shall be selected for FIDs calibrated on CH4 with a non-methane cutter. The three balance gas concentrations shall be selected such that the concentrations of O2 and N2 represent the minimum and maximum and intermediate O2 concentrations expected during testing. The requirement for using the average O2 concentration can be removed if the FID is calibrated with span gas balanced with the average expected oxygen concentration;

(b)	It shall be confirmed that the FID analyzer meets all the specifications of point 8.1.10.1;

(c)	The FID analyzer shall be started and operated as it would be before an emission test. Regardless of the FID burner's air source during testing, zero air shall be used as the FID burner's air source for this verification;

(d)	The analyzer shall be set at zero;

(e)	The analyzer shall be spanned using a span gas that is used during emissions testing;

(f)

The zero response shall be checked by using the zero gas used during emission testing. It shall be proceeded to the next step if the mean zero response of 30 s of sampled data is within ± 0,5 % of the span reference value used in paragraph (e) of this point, otherwise the procedure shall be restarted at paragraph (d) of this point;

(g)	The analyzer response shall be checked using the span gas that has the minimum concentration of O2 expected during testing. The mean response of 30 s of stabilized sample data shall be recorded as x O2minHC;

(h)

The zero response of the FID analyzer shall be checked using the zero gas used during emission testing. The next step shall be performed if the mean zero response of 30 s of stabilized sample data is within ± 0,5 % of the span reference value used in paragraph (e) of this point, otherwise the procedure shall be restarted at paragraph (d) of this point;

(i)	The analyzer response shall be checked using the span gas that has the average concentration of O2 expected during testing. The mean response of 30 s of stabilized sample data shall be recorded as x O2avgHC;

(j)

The zero response of the FID analyzer shall be checked using the zero gas used during emission testing. The next step shall be performed if the mean zero response of 30 s of stabilized sample data is within ± 0,5 % of the span reference value used in paragraph (e) of this point, otherwise the procedure shall be restarted at paragraph (d) of this point;

(k)	The analyzer response shall be checked using the span gas that has the maximum concentration of O2 expected during testing. The mean response of 30 s of stabilized sample data shall be recorded as x O2maxHC;

(l)

The zero response of the FID analyzer shall be checked using the zero gas used during emission testing. The next step shall be performed if the mean zero response of 30 s of stabilized sample data is within ± 0,5 % of the span reference value used in paragraph (e) of this point, otherwise the procedure shall be restarted at paragraph (d) of this point;

(m)

The % difference between x O2maxHC and its reference gas concentration shall be calculated. The percent difference between x O2avgHC and its reference gas concentration shall be calculated. The % difference between x O2minHC and its reference gas concentration shall be calculated. The maximum % difference of the three shall be determined. This is the O2 interference;

(n)

If the O2 interference is within ± 3 %, the FID passes the O2 interference verification; otherwise one or more of the following need to be performed to address the deficiency: (i) The verification shall be repeated to determine if a mistake was made during the procedure; (ii) The zero and span gases for emission testing shall be selected that contain higher or lower O2 concentrations and the verification shall be repeated; (iii) The FID burner air, fuel, and sample flow rates shall be adjusted. Note that if these flow rates are adjusted on a THC FID to meet the O2 interference verification, the RF CH4 shall be reset for the next RF CH4 verification. The O2 interference verification shall be repeated after adjustment and RF CH4 shall be determined; (iv) The FID shall be repaired or replaced and the O2 interference verification shall be repeated.

8.1.10.3.   Non-methane cutter penetration fractions (Reserved)

8.1.11.   NOx measurements

8.1.11.1.   CLD CO2 and H2O quench verification

8.1.11.1.1.   Scope and frequency

If a CLD analyzer is used to measure NOx, the amount of H2O and CO2 quench shall be verified after installing the CLD analyzer and after major maintenance.

8.1.11.1.2.   Measurement principles

H2O and CO2 can negatively interfere with a CLD's NOx response by collisional quenching, which inhibits the chemiluminescent reaction that a CLD utilizes to detect NOx. This procedure and the calculations in point 8.1.11.2.3 determine quench and scale the quench results to the maximum mole fraction of H2O and the maximum CO2 concentration expected during emission testing. If the CLD analyzer uses quench compensation algorithms that utilize H2O and/or CO2 measurement instruments, quench shall be evaluated with these instruments active and with the compensation algorithms applied.

8.1.11.1.3.   System requirements

For dilute measurement a CLD analyzer shall not exceed a combined H2O and CO2 quench of ± 2 %. For raw measurement a CLD analyzer shall not exceed a combined H2O and CO2 quench of ± 2,5 %. Combined quench is the sum of the CO2 quench determined as described in point 8.1.11.1.4 and the H2O quench as determined in point 8.1.11.1.5. If these requirements are not met, corrective action shall be taken by repairing or replacing the analyzer. Before running emission tests, it shall be verified that the corrective action have successfully restored the analyzer to proper functioning.

8.1.11.1.4.   CO2 quench verification procedure

The following method or the method prescribed by the instrument manufacturer may be used to determine CO2 quench by using a gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in point 9.4.5.6, or good engineering judgment shall be used to develop a different protocol:

(a)	PTFE or stainless steel tubing shall be used to make necessary connections;

(b)	The gas divider shall be configured such that nearly equal amounts of the span and diluent gases are blended with each other;

(c)	If the CLD analyzer has an operating mode in which it detects NO-only, as opposed to total NOx, the CLD analyzer shall be operated in the NO-only operating mode;

(d)	A CO2 span gas that meets the specifications of point 9.5.1 and a concentration that is approximately twice the maximum CO2 concentration expected during emission testing shall be used;

(e)

An NO span gas that meets the specifications of point 9.5.1 and a concentration that is approximately twice the maximum NO concentration expected during emission testing shall be used. Higher concentration may be used according to the instrument manufacturer's recommendation and good engineering judgement in order to obtain accurate verification, if the expected NO concentration is lower than the minimum range for the verification specified by the instrument manufacturer;

(f)

The CLD analyzer shall be zeroed and spanned. The CLD analyzer shall be spanned with the NO span gas from paragraph (e) of this point through the gas divider. The NO span gas shall be connected to the span port of the gas divider; a zero gas shall be connected to the diluent port of the gas divider; the same nominal blend ratio shall be used as selected in paragraph (b) of this point; and the gas divider's output concentration of NO shall be used to span the CLD analyzer. Gas property corrections shall be applied as necessary to ensure accurate gas division;

(g)	The CO2 span gas shall be connected to the span port of the gas divider;

(h)	The NO span gas shall be connected to the diluents port of the gas divider;

(i)

While flowing NO and CO2 through the gas divider, the output of the gas divider shall be stabilized. The CO2 concentration from the gas divider output shall be determined, applying gas property correction as necessary to ensure accurate gas division. This concentration, x CO2act, shall be recorded and it shall be used in the quench verification calculations in point 8.1.11.2.3. As an alternative to using a gas divider, another simple gas blending device may be used. In this case an analyzer shall be used to determine CO2 concentration. If a NDIR is used together with a simple gas blending device, it shall meet the requirements of this section and it shall be spanned with the CO2 span gas from paragraph (d) of this point. The linearity of the NDIR analyzer has to be checked before over the whole range up to twice of the expected maximum CO2 concentration expected during testing;

(j)

The NO concentration shall be measured downstream of the gas divider with the CLD analyzer. Time shall be allowed for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response. While the analyzer measures the sample's concentration, the analyzer's output shall be recorded for 30 seconds. The arithmetic mean concentration shall be calculated from these data, x NOmeas. x NOmeas shall be recorded and it shall be used in the quench verification calculations in point 8.1.11.2.3;

(k)	The actual NO concentration shall be calculated at the gas divider's outlet, x NOact, based on the span gas concentrations and x CO2act by means of equation (6-24). The calculated value shall be used in the quench verification calculations by means of equation (6-23);

(l)	The values recorded according to this points 8.1.11.1.4 and 8.1.11.1.5 shall be used to calculate quench as described in point 8.1.11.2.3.

8.1.11.1.5.   H2O quench verification procedure

The following method or the method prescribed by the instrument manufacturer may be used to determine H2O quench, or good engineering judgment shall be used to develop a different protocol:

(a)	PTFE or stainless steel tubing shall be used to make necessary connections;

(b)	If the CLD analyzer has an operating mode in which it detects NO-only, as opposed to total NOx, the CLD analyzer shall be operated in the NO-only operating mode;

(c)

A NO span gas shall be used that meets the specifications of point 9.5.1 and a concentration that is near the maximum concentration expected during emission testing. Higher concentration may be used according to the instrument manufacturer's recommendation and good engineering judgement in order to obtain accurate verification, if the expected NO concentration is lower than the minimum range for the verification specified by the instrument manufacturer;

(d)	The CLD analyzer shall be zeroed and spanned. The CLD analyzer shall be spanned with the NO span gas from paragraph (c) of this point, the span gas concentration shall be recorded as x NOdry, and it shall be used in the quench verification calculations in point 8.1.11.2.3;

(e)

The NO span gas shall be humidified by bubbling it through distilled water in a sealed vessel. If the humidified NO span gas sample does not pass through a sample dryer for this verification test, the vessel temperature shall be controlled to generate an H2O level approximately equal to the maximum mole fraction of H2O expected during emission testing. If the humidified NO span gas sample does not pass through a sample dryer, the quench verification calculations in point 8.1.11.2.3 scale the measured H2O quench to the highest mole fraction of H2O expected during emission testing. If the humidified NO span gas sample passes through a dryer for this verification test, the vessel temperature shall be controlled to generate an H2O level at least as high as the level required in point 9.3.2.3.1. For this case, the quench verification calculations set out in point 8.1.11.2.3 do not scale the measured H2O quench;

(f)

The humidified NO test gas shall be introduced into the sample system. It may be introduced upstream or downstream of a sample dryer that is used during emission testing. Depending on the point of introduction, the respective calculation method of paragraph (e) of this point shall be selected. Note that the sample dryer shall meet the sample dryer verification check in point 8.1.8.5.8;

(g)

The mole fraction of H2O in the humidified NO span gas shall be measured. In case a sample dryer is used, the mole fraction of H2O in the humidified NO span gas shall be measured downstream of the sample dryer, x H2Omeas. It is recommended to measure x H2Omeas as close as possible to the CLD analyzer inlet. x H2Omeas may be calculated from measurements of dew point, T dew, and absolute pressure, p total;

(h)

Good engineering judgment shall be used to prevent condensation in the transfer lines, fittings, or valves from the point where x H2Omeas is measured to the analyzer. It is recommended that the system is designed so the wall temperatures in the transfer lines, fittings, and valves from the point where x H2Omeas is measured to the analyzer are at least 5 K above the local sample gas dew point;

(i)

The humidified NO span gas concentration shall be measured with the CLD analyzer. Time shall be allowed for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response. While the analyzer measures the sample's concentration, the analyzer's output shall be recorded for 30 seconds. The arithmetic mean shall be calculated of these data, x NOwet. x NOwet shall be recorded and used in the quench verification calculations in point 8.1.11.2.3.

8.1.11.2.   CLD quench verification calculations

CLD quench-check calculations shall be performed as described in this point.

8.1.11.2.1.   Amount of water expected during testing

The maximum expected mole fraction of water during emission testing, x H2Oexp shall be estimated. This estimate shall be made where the humidified NO span gas was introduced in point 8.1.11.1.5(f). When estimating the maximum expected mole fraction of water, the maximum expected water content in combustion air, fuel combustion products, and dilution air (if applicable) shall be considered. If the humidified NO span gas is introduced into the sample system upstream of a sample dryer during the verification test, it is not needed to estimate the maximum expected mole fraction of water and x H2Oexp shall be set equal to x H2Omeas.

8.1.11.2.2.   Amount of CO2 expected during testing

The maximum expected CO2 concentration during emission testing, x CO2exp shall be estimated. This estimate shall be made at the sample system location where the blended NO and CO2 span gases are introduced according to point 8.1.11.1.4(j). When estimating the maximum expected CO2 concentration, the maximum expected CO2 content in fuel combustion products and dilution air shall be considered.

8.1.11.2.3.   Combined H2O and CO2 quench calculations

Combined H2O and CO2 quench shall be calculated by means of equation (6-23):

(6-23)

Where:

quench =	amount of CLD quench
x NOdry	is the measured concentration of NO upstream of a bubbler, in accordance with point 8.1.11.1.5(d)
x NOwet	is the measured concentration of NO downstream of a bubbler, in accordance with point 8.1.11.1.5(i)
x H2Oexp	is the maximum expected mole fraction of water during emission testing in accordance with point 8.1.11.2.1.
x H2Omeas	is the measured mole fraction of water during the quench verification in accordance with point 8.1.11.1.5(g)
x NOmeas	is the measured concentration of NO when NO span gas is blended with CO2 span gas, in accordance with point 8.1.11.1.4(j)
x NOact	is the actual concentration of NO when NO span gas is blended with CO2 span gas, in accordance with point 8.1.11.1.4(k) and calculated by means of equation (6-24)
x CO2exp	is the maximum expected concentration of CO2 during emission testing, in accordance with point 8.1.11.2.2.
x CO2act	is the actual concentration of CO2 when NO span gas is blended with CO2 span gas, in accordance with point 8.1.11.1.4(i)

(6-24)

Where:

x NOspan	is the NO span gas concentration input to the gas divider, in accordance with point 8.1.11.1.4(e)
x CO2span	is the CO2 span gas concentration input to the gas divider, in accordance with point 8.1.11.1.4(d)

8.1.11.3.   NDUV analyzer HC and H2O interference verification

8.1.11.3.1.   Scope and frequency

If NOx is measured using an NDUV analyzer, the amount of H2O and hydrocarbon interference shall be verified after initial analyzer installation and after major maintenance.

8.1.11.3.2.   Measurement principles

Hydrocarbons and H2O can positively interfere with a NDUV analyzer by causing a response similar to NOx. If the NDUV analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously such measurements shall be conducted to test the algorithms during the analyzer interference verification.

8.1.11.3.3.   System requirements

A NOx NDUV analyzer shall have combined H2O and HC interference within ± 2 % of the mean concentration of NOx.

8.1.11.3.4.   Procedure

The interference verification shall be performed as follows:

(a)	The NOx NDUV analyzer shall be started, operated, zeroed, and spanned according to the instrument manufacturer's instructions;

(b)

It is recommended to extract engine exhaust gas to perform this verification. A CLD shall be used that meets the specifications of point 9.4 to quantify NOx in the exhaust gas. The CLD response shall be used as the reference value. Also HC shall be measured in the exhaust gas with a FID analyzer that meets the specifications of point 9.4. The FID response shall be used as the reference hydrocarbon value;

(c)	Upstream of any sample dryer, if one is used during testing, the engine exhaust gas shall be introduced into the NDUV analyzer;

(d)	Time shall be allowed for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response;

(e)	While all analyzers measure the sample's concentration, 30 s of sampled data shall be recorded, and the arithmetic means for the three analyzers calculated;

(f)	The CLD mean shall be subtracted from the NDUV mean;

(g)

This difference shall be multiplied by the ratio of the expected mean HC concentration to the HC concentration measured during the verification. The analyzer meets the interference verification of this point if this result is within ± 2 % of the NOx concentration expected at the standard, as set out in equation (6-25):

(6-25)

Where:

	is the mean concentration of NOx measured by CLD [μmol/mol] or [ppm]
	is the mean concentration of NOx measured by NDUV [μmol/mol] or [ppm]
	is the mean concentration of HC measured [μmol/mol] or [ppm]
	is the mean concentration of HC expected at the standard [μmol/mol] or [ppm]
	is the mean concentration of NOx expected at the standard [μmol/mol] or [ppm]

8.1.11.4   Sample dryer NO2 penetration

8.1.11.4.1.   Scope and frequency

If a sample dryer is used to dry a sample upstream of a NOx measurement instrument, but no NO2-to-NO converter is used upstream of the sample dryer, this verification shall be performed for sample dryer NO2 penetration. This verification shall be performed after initial installation and after major maintenance.

8.1.11.4.2.   Measurement principles

A sample dryer removes water, which can otherwise interfere with a NOx measurement. However, liquid water remaining in an improperly designed cooling bath can remove NO2 from the sample. If a sample dryer is used without an NO2-to-NO converter upstream, it could therefore remove NO2 from the sample prior NOx measurement.

8.1.11.4.3.   System requirements

The sample dryer shall allow for measuring at least 95 % of the total NO2 at the maximum expected concentration of NO2.

8.1.11.4.4.   Procedure

The following procedure shall be used to verify sample dryer performance:

(a)	Instrument setup. The analyzer and sample dryer manufacturers' start-up and operating instructions shall be followed. The analyzer and sample dryer shall be adjusted as needed to optimize performance;

(b)

Equipment setup and data collection. (i) The total NOx gas analyzer(s) shall be zeroed and spanned as it would be before emission testing; (ii) NO2 calibration gas (balance gas of dry air) that has an NO2 concentration that is near the maximum expected during testing shall be selected. Higher concentration may be used in accordance with the instrument manufacturer's recommendation and good engineering judgement in order to obtain accurate verification, if the expected NO2 concentration is lower than the minimum range for the verification specified by the instrument manufacturer; (iii) This calibration gas shall be overflowed at the gas sampling system's probe or overflow fitting. Time shall be allowed for stabilization of the total NOx response, accounting only for transport delays and instrument response; (iv) The mean of 30 s of recorded total NOx data shall be calculated and this value recorded as x NOxref; (v) The flowing the NO2 calibration gas shall be stopped; (vi) Next the sampling system shall be saturated by overflowing a dew point generator's output, set at a dew point of 323 K (50 °C), to the gas sampling system's probe or overflow fitting. The dew point generator's output shall be sampled through the sampling system and sample dryer for at least 10 minutes until the sample dryer is expected to be removing a constant rate of water; (vii) It shall be immediately switched back to overflowing the NO2 calibration gas used to establish x NOxref. It shall be allowed for stabilization of the total NOx response, accounting only for transport delays and instrument response. The mean of 30 s of recorded total NOx data shall be calculated and this value recorded as x NOxmeas; (viii) x NOxmeas shall be corrected to x NOxdry based upon the residual water vapour that passed through the sample dryer at the sample dryer's outlet temperature and pressure;

(c)	Performance evaluation. If xNOxdry is less than 95 % of xNOxref, the sample dryer shall be repaired or replaced.

8.1.11.5.   NO2-to-NO converter conversion verification

8.1.11.5.1.   Scope and frequency

If an analyzer is used that measures only NO to determine NOx, an NO2-to-NO converter shall be used upstream of the analyzer. This verification shall be performed after installing the converter, after major maintenance and within 35 days before an emission test. This verification shall be repeated at this frequency to verify that the catalytic activity of the NO2-to-NO converter has not deteriorated.

8.1.11.5.2.   Measurement principles

An NO2-to-NO converter allows an analyzer that measures only NO to determine total NOx by converting the NO2 in exhaust gas to NO.

8.1.11.5.3.   System requirements

An NO2-to-NO converter shall allow for measuring at least 95 % of the total NO2 at the maximum expected concentration of NO2.

8.1.11.5.4   Procedure

The following procedure shall be used to verify the performance of a NO2-to-NO converter:

(a)	For the instrument setup the analyzer and NO2-to-NO converter manufacturers' start-up and operating instructions shall be followed. The analyzer and converter shall be adjusted as needed to optimize performance;

(b)	An ozonator's inlet shall be connected to a zero-air or oxygen source and its outlet shall be connected to one port of a 3-way tee fitting. An NO span gas shall be connected to another port and the NO2-to-NO converter inlet shall be connected to the last port;

(c)

The following steps shall be taken when performing this check: (i) The ozonator air shall be set off and the ozonator power shall be turned off and the NO2-to-NO converter shall be set to the bypass mode (i.e., NO mode). Stabilization shall be allowed for, accounting only for transport delays and instrument response; (ii) The NO and zero-gas flows shall be adjusted so the NO concentration at the analyzer is near the peak total NOx concentration expected during testing. The NO2 content of the gas mixture shall be less than 5 % of the NO concentration. The concentration of NO shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value shall be recorded as x NOref. Higher concentration may be used according to the instrument manufacturer's recommendation and good engineering judgement in order to obtain accurate verification, if the expected NO concentration is lower than the minimum range for the verification specified by the instrument manufacturer; (iii) The ozonator O2 supply shall be turned on and the O2 flow rate adjusted so that the NO indicated by the analyzer is about 10 percent less than x NOref. The concentration of NO shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value recorded as x NO+O2mix; (iv) The ozonator shall be switched on and the ozone generation rate adjusted so that the NO measured by the analyzer is approximately 20 percent of x NOref, while maintaining at least 10 % unreacted NO. The concentration of NO shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value shall be recorded as x NOmeas; (v) The NOx analyzer shall be switched to NOx mode and total NOx measured. The concentration of NOx shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value shall be recorded as x NOxmeas; (vi) The ozonator shall be switched off but gas flow through the system shall be maintained. The NOx analyzer will indicate the NOx in the NO + O2 mixture. The concentration of NOx shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value shall be recorded as x NOx+O2mix; (vii) O2 supply shall be turned off. The NOx analyzer will indicate the NOx in the original NO-in-N2 mixture. The concentration of NOx shall be recorded by calculating the mean of 30 s of sampled data from the analyzer and this value shall be recorded as x NOxref. This value shall be no more than 5 % above the x NOref value;

(d)	Performance evaluation. The efficiency of the NOx converter shall be calculated by substituting the concentrations obtained into equation (6-26): (6-26)

(e)	If the result is less than 95 %, the NO2-to-NO converter shall be repaired or replaced.

8.1.12.   PM measurements

8.1.12.1.   PM balance verifications and weighing process verification

8.1.12.1.1.   Scope and frequency

This section describes three verifications.

(a)	Independent verification of PM balance performance within 370 days prior to weighing any filter;

(b)	Zero and span of the balance within 12 h prior to weighing any filter;

(c)	Verification that the mass determination of reference filters before and after a filter weighing session be less than a specified tolerance.

8.1.12.1.2.   Independent verification

The balance manufacturer (or a representative approved by the balance manufacturer) shall verify the balance performance within 370 days of testing in accordance with internal audit procedures.

8.1.12.1.3.   Zeroing and spanning

Balance performance shall be verified by zeroing and spanning it with at least one calibration weight, and any weights that are used shall meet the specifications in point 9.5.2 to perform this verification. A manual or automated procedure shall be used:

(a)

A manual procedure requires that the balance shall be used in which the balance shall be zeroed and spanned with at least one calibration weight. If normally mean values are obtained by repeating the weighing process to improve the accuracy and precision of PM measurements, the same process shall be used to verify balance performance;

(b)	An automated procedure is carried out with internal calibration weights that are used automatically to verify balance performance. These internal calibration weights shall meet the specifications in point 9.5.2 to perform this verification.

8.1.12.1.4.   Reference sample weighing

All mass readings during a weighing session shall be verified by weighing reference PM sample media (e.g. filters) before and after a weighing session. A weighing session may be as short as desired, but no longer than 80 hours, and may include both pre- and post-test mass readings. Successive mass determinations of each reference PM sample media shall return the same value within ± 10 μg or ± 10 % of the expected total PM mass, whichever is higher. Should successive PM sample filter weighing events fail this criterion, all individual test filter mass readings mass readings occurring between the successive reference filter mass determinations shall be invalidated. These filters may be re-weighed in another weighing session. Should a post-test filter be invalidated then the test interval is void. This verification shall be performed as follows:

(a)	At least two samples of unused PM sample media shall be kept in the PM-stabilization environment. These shall be used as references. Unused filters of the same material and size shall be selected for use as references;

(b)

References shall be stabilized in the PM stabilization environment. References shall be considered stabilized if they have been in the PM-stabilization environment for a minimum of 30 min, and the PM-stabilization environment has been within the specifications of point 9.3.4.4 for at least the preceding 60 min;

(c)	The balance shall be exercised several times with a reference sample without recording the values;

(d)	The balance shall be zeroed and spanned. A test mass shall be placed on the balance (e.g. calibration weight) and then removed ensuring that the balance returns to an acceptable zero reading within the normal stabilization time;

(e)

Each of the reference media (e.g. filters) shall be weighed and their masses recorded. If normally mean values are obtained by repeating the weighing process to improve the accuracy and precision of reference media (e.g. filters) masses, the same process shall be used to measure mean values of sample media (e.g. filters) masses;

(f)	The balance environment dew point, ambient temperature, and atmospheric pressure shall be recorded;

(g)	The recorded ambient conditions shall be used to correct results for buoyancy as described in point 8.1.13.2. The buoyancy-corrected mass of each of the references shall be recorded;

(h)	Each of the reference media's (e.g. filter's) buoyancy-corrected reference mass shall be subtracted from its previously measured and recorded buoyancy-corrected mass;

(i)

If any of the reference filters' observed mass changes by more than that allowed under this section, all PM mass determinations made since the last successful reference media (e.g. filter) mass validation shall be invalidated. Reference PM filters may be discarded if only one of the filters mass has changed by more than the allowable amount and a special cause for that filter's mass change can be positively identified which would not have affected other in-process filters. Thus the validation can be considered a success. In this case, the contaminated reference media shall not be included when determining compliance with paragraph (j) of this point, but the affected reference filter shall be discarded and replaced;

(j)

If any of the reference masses change by more than that allowed under this point 8.1.13.1.4, all PM results that were determined between the two times that the reference masses were determined shall be invalidated. If reference PM sample media is discarded in accordance with paragraph (i) of this point, at least one reference mass difference that meets the criteria set out in point 8.1.13.1.4 shall be available. Otherwise, all PM results that were determined between the two times that the reference media (e.g. filters) masses were determined shall be invalidated.

8.1.12.2.   PM sample filter buoyancy correction

8.1.12.2.1.   General

PM sample filter shall be corrected for their buoyancy in air. The buoyancy correction depends on the sample media density, the density of air, and the density of the calibration weight used to calibrate the balance. The buoyancy correction does not account for the buoyancy of the PM itself, because the mass of PM typically accounts for only (0,01 to 0,10) % of the total weight. A correction to this small fraction of mass would be at the most 0,010 %. The buoyancy-corrected values are the tare masses of the PM samples. These buoyancy-corrected values of the pre-test filter weighing are subsequently subtracted from the buoyancy-corrected values of the post-test weighing of the corresponding filter to determine the mass of PM emitted during the test.

8.1.12.2.2.   PM sample filter density

Different PM sample filter have different densities. The known density of the sample media shall be used, or one of the densities for some common sampling media shall be used, as follows:

(a)	For PTFE-coated borosilicate glass, a sample media density of 2 300 kg/m3 shall be used;

(b)	For PTFE membrane (film) media with an integral support ring of polymethylpentene that accounts for 95 % of the media mass, a sample media density of 920 kg/m3 shall be used;

(c)	For PTFE membrane (film) media with an integral support ring of PTFE, a sample media density of 2 144 kg/m3 shall be used.

8.1.12.2.3.   Air density

Because a PM balance environment shall be tightly controlled to an ambient temperature of 295 ± 1 K (22 ± 1 °C) and a dew point of 282,5 ± 1 K (9,5 ± 1 °C), air density is primarily function of atmospheric pressure. Therefore a buoyancy correction is specified that is only a function of atmospheric pressure.

8.1.12.2.4.   Calibration weight density

The stated density of the material of the metal calibration weight shall be used.

8.1.12.2.5.   Correction calculation

The PM sample filter shall be corrected for buoyancy by means of equation (6-27):

(6-27)

Where:

m cor	is the PM sample filter mass corrected for buoyancy
m uncor	is the PM sample filter mass uncorrected for buoyancy
ρ air	is the density of air in balance environment
ρ weight	is the density of calibration weight used to span balance
ρ media	is the density of PM sample filter

with

(6-28)

Where:

p abs	is the absolute pressure in balance environment
M mix	is the molar mass of air in balance environment
R	is the molar gas constant.
T amb	is the absolute ambient temperature of balance environment

8.2.   Instrument validation for test

8.2.1.   Validation of proportional flow control for batch sampling and minimum dilution ratio for PM batch sampling

8.2.1.1.   Proportionality criteria for CVS

8.2.1.1.1.   Proportional flows

For any pair of flow meters, the recorded sample and total flow rates or their 1 Hz means shall be used with the statistical calculations in Appendix 3 of Annex VII. The standard error of the estimate, SEE, of the sample flow rate versus the total flow rate shall be determined. For each test interval, it shall be demonstrated that SEE was less than or equal to 3,5 % of the mean sample flow rate.

8.2.1.1.2.   Constant flows

For any pair of flow meters, the recorded sample and total flow rates or their 1 Hz means shall be used to demonstrate that each flow rate was constant within ± 2,5 % of its respective mean or target flow rate. The following options may be used instead of recording the respective flow rate of each type of meter:

(a)

Critical-flow venturi option. For critical-flow venturis, the recorded venturi-inlet conditions or their 1 Hz means shall be used. It shall be demonstrated that the flow density at the venturi inlet was constant within ± 2,5 % of the mean or target density over each test interval. For a CVS critical-flow venturi, this may be demonstrated by showing that the absolute temperature at the venturi inlet was constant within ± 4 % of the mean or target absolute temperature over each test interval;

(b)

Positive-displacement pump option. The recorded pump-inlet conditions or their 1 Hz means shall be used. It shall be demonstrated that the flow density at the pump inlet was constant within ± 2,5 % of the mean or target density over each test interval. For a CVS pump, this may be demonstrated by showing that the absolute temperature at the pump inlet was constant within ± 2 % of the mean or target absolute temperature over each test interval.

8.2.1.1.3.   Demonstration of proportional sampling

For any proportional batch sample such as a bag or PM filter, it shall be demonstrated that proportional sampling was maintained using one of the following, noting that up to 5 % of the total number of data points may be omitted as outliers.

Using good engineering judgment, it shall be demonstrated with an engineering analysis that the proportional-flow control system inherently ensures proportional sampling under all circumstances expected during testing. For example, CFVs may be used for both sample flow and total flow if it is demonstrated that they always have the same inlet pressures and temperatures and that they always operate under critical-flow conditions.

Measured or calculated flows and/or tracer gas concentrations (e.g. CO2) shall be used to determine the minimum dilution ratio for PM batch sampling over the test interval.

8.2.1.2.   Partial flow dilution system validation

For the control of a partial flow dilution system to extract a proportional raw exhaust gas sample, a fast system response is required; this is identified by the promptness of the partial flow dilution system. The transformation time for the system shall be determined in accordance with the procedure set out in point 8.1.8.6.3.2. The actual control of the partial flow dilution system shall be based on the current measured conditions. If the combined transformation time of the exhaust gas flow measurement and the partial flow system is ≤ 0,3 s, online control shall be used. If the transformation time exceeds 0,3 s, look-ahead control based on a pre-recorded test run shall be used. In this case, the combined rise time shall be ≤ 1 s and the combined delay time ≤ 10 s. The total system response shall be designed as to ensure a representative sample of the particulates, qm p,i (sample flow of exhaust gas into partial flow dilution system), proportional to the exhaust gas mass flow. To determine the proportionality, a regression analysis of qm p,i versus qm ew,i (exhaust gas mass flow rate on wet basis) shall be conducted on a minimum 5 Hz data acquisition rate, and the following criteria shall be met:

(a)	The correlation coefficient r 2 of the linear regression between qm p,i and qm ew,i shall not be less than 0,95;

(b)	The standard error of estimate of qm p,i on qm ew,i shall not exceed 5 % of qm p maximum;

(c)	qm p intercept of the regression line shall not exceed ± 2 % of qm p maximum.

Look-ahead control is required if the combined transformation times of the particulate system, t 50,P and of the exhaust gas mass flow signal, t 50,F are > 0,3 s. In this case, a pre-test shall be run and the exhaust gas mass flow signal of the pre-test be used for controlling the sample flow into the particulate system. A correct control of the partial dilution system is obtained, if the time trace of qm ew,pre of the pre-test, which controls qm p, is shifted by a ‘look-ahead’ time of t 50,P + t 50,F.

For establishing the correlation between qm p,i and qm ew,i the data taken during the actual test shall be used, with qm ew,i time aligned by t 50,F relative to qm p,i (no contribution from t 50,P to the time alignment). The time shift between qm ew and qm p is the difference between their transformation times that were determined in point 8.1.8.6.3.2.

8.2.2.   Gas analyzer range validation, drift validation and drift correction

8.2.2.1.   Range validation

If an analyzer operated above 100 % of its range at any time during the test, the following steps shall be performed:

8.2.2.1.1.   Batch sampling

For batch sampling, the sample shall be re-analyzed using the lowest analyzer range that results in a maximum instrument response below 100 %. The result shall be reported from the lowest range from which the analyzer operates below 100 % of its range for the entire test.

8.2.2.1.2.   Continuous sampling

For continuous sampling, the entire test shall be repeated using the next higher analyzer range. If the analyzer again operates above 100 % of its range, the test shall be repeated using the next higher range. The test shall be continued to be repeated until the analyzer always operates at less than 100 % of its range for the entire test.

8.2.2.2.   Drift validation and drift correction

If the drift is within ±1 %, the data can be either accepted without any correction or accepted after correction. If the drift is greater than ± 1 %, two sets of brake specific emission results shall be calculated for each pollutant with a brake-specific limit value and for CO2, or the test shall be voided. One set shall be calculated using data before drift correction and another set of data calculated after correcting all the data for drift in accordance with point 2.6 of Annex VII and Appendix 1 of Annex VII. The comparison shall be made as a percentage of the uncorrected results. The difference between the uncorrected and the corrected brake-specific emission values shall be within ± 4 % of either the uncorrected brake-specific emission values or the emission limit value, whichever is greater. If not, the entire test is void.

8.2.3.   PM sampling media (e.g. filters) preconditioning and tare weighing

Before an emission test, the following steps shall be taken to prepare PM sample filter media and equipment for PM measurements:

8.2.3.1.   Periodic verifications

It shall be made sure that the balance and PM-stabilization environments meet the periodic verifications in point 8.1.12. The reference filter shall be weighed just before weighing test filters to establish an appropriate reference point (see section details of the procedure in point 8.1.12.1). The verification of the stability of the reference filters shall occur after the post-test stabilisation period, immediately before the post-test weighing.

8.2.3.2.   Visual Inspection

The unused sample filter media shall be visually inspected for defects, defective filters shall be discarded.

8.2.3.3.   Grounding

Electrically grounded tweezers or a grounding strap shall be used to handle PM filters as described in point 9.3.4.

8.2.3.4.   Unused sample media

Unused sample media shall be placed in one or more containers that are open to the PM-stabilization environment. If filters are used, they may be placed in the bottom half of a filter cassette.

8.2.3.5.   Stabilization

Sample media shall be stabilized in the PM-stabilization environment. An unused sample medium can be considered stabilized as long as it has been in the PM-stabilization environment for a minimum of 30 min, during which the PM-stabilization environment has been within the specifications of point 9.3.4. However, if a mass of 400 μg or more is expected, then the sample media shall be stabilised for at least 60 min.

8.2.3.6.   Weighing

The sample media shall be weighed automatically or manually, as follows:

(a)	For automatic weighing, the automation system manufacturer's instructions shall be followed to prepare samples for weighing; this may include placing the samples in a special container;

(b)	For manual weighing, good engineering judgment shall be used;

(c)	Optionally, substitution weighing is permitted (see point 8.2.3.10);

(d)	Once a filter is weighed it shall be returned to the Petri dish and covered.

8.2.3.7.   Buoyancy correction

The measured weight shall be corrected for buoyancy as described in point 8.1.13.2.

8.2.3.8.   Repetition

The filter mass measurements may be repeated to determine the average mass of the filter using good engineering judgement and to exclude outliers from the calculation of the average.

8.2.3.9.   Tare-weighing

Unused filters that have been tare-weighed shall be loaded into clean filter cassettes and the loaded cassettes shall be placed in a covered or sealed container before they are taken to the test cell for sampling.

8.2.3.10.   Substitution weighing

Substitution weighing is an option and, if used, involves measurement of a reference weight before and after each weighing of a PM sampling medium (e.g. filter). While substitution weighing requires more measurements, it corrects for a balance's zero-drift and it relies on balance linearity only over a small range. This is most appropriate when quantifying total PM masses that are less than 0,1 % of the sample medium's mass. However, it may not be appropriate when total PM masses exceed 1 % of the sample medium's mass. If substitution weighing is used, it shall be used for both pre-test and post-test weighing. The same substitution weight shall be used for both pre-test and post-test weighing. The mass of the substitution weight shall be corrected for buoyancy if the density of the substitution weight is less than 2,0 g/cm3. The following steps are an example of substitution weighing:

(a)	Electrically grounded tweezers or a grounding strap shall be used, as described in point 9.3.4.6;

(b)	A static neutralizer shall be used as described in point 9.3.4.6 to minimize static electric charge on any object before it is placed on the balance pan;

(c)

A substitution weight shall be selected that meets the specifications for calibration weights in point 9.5.2. The substitution weight shall also have the same density as the weight that is used to span the microbalance, and shall be similar in mass to an unused sample medium (e.g. filter). If filters are used, the weight's mass should be about (80 to 100) mg for typical 47 mm diameter filters;

(d)	The stable balance reading shall be recorded and then the calibration weight shall be removed;

(e)	An unused sampling medium (e.g. a new filter) shall be weighed, the stable balance reading recorded and the balance environment's dew point, ambient temperature, and atmospheric pressure recorded;

(f)	The calibration weight shall be reweighed and the stable balance reading recorded;

(g)

The arithmetic mean of the two calibration-weight readings that were recorded immediately before and after weighing the unused sample shall be calculated. That mean value shall be subtracted from the unused sample reading, then the true mass of the calibration weight as stated on the calibration-weight certificate shall be added. This result shall be recorded. This is the unused sample's tare weight without correcting for buoyancy;

(h)	These substitution-weighing steps shall be repeated for the remainder of the unused sample media;

(i)	The instructions given in points 8.2.3.7 to 8.2.3.9 shall be followed once weighing is completed.

8.2.4.   Post-test PM sample conditioning and weighing

Used PM sample filters shall be placed into covered or sealed containers or the filter holders shall be closed, in order to protect the sample filters against ambient contamination. Thus protected, the loaded filters have to be returned to the PM-filter conditioning chamber or room. Then the PM sample filters shall be conditioned and weighted accordingly.

8.2.4.1.   Periodic verification

It shall be assured that the weighing and PM-stabilization environments have met the periodic verifications in point 8.1.13.1. After testing is complete, the filters shall be returned to the weighing and PM-stabilisation environment. The weighing and PM-stabilisation environment shall meet the ambient conditions requirements in point 9.3.4.4, otherwise the test filters shall be left covered until proper conditions have been met.

8.2.4.2.   Removal from sealed containers

In the PM-stabilization environment, the PM samples shall be removed from the sealed containers. Filters may be removed from their cassettes before or after stabilization. When a filter is removed from a cassette, the top half of the cassette shall be separated from the bottom half using a cassette separator designed for this purpose.

8.2.4.3.   Electrical grounding

To handle PM samples, electrically grounded tweezers or a grounding strap shall be used, as described in point 9.3.4.5.

8.2.4.4.   Visual inspection

The collected PM samples and the associated filter media shall be inspected visually. If the conditions of either the filter or the collected PM sample appear to have been compromised, or if the particulate matter contacts any surface other than the filter, the sample may not be used to determine particulate emissions. In the case of contact with another surface; the affected surface shall be cleaned before proceeding.

8.2.4.5.   Stabilisation of PM samples

To stabilise PM samples, they shall be placed in one or more containers that are open to the PM-stabilization environment, which is described in point 9.3.4.3.A PM sample is stabilized as long as it has been in the PM-stabilization environment for one of the following durations, during which the stabilization environment has been within the specifications of point 9.3.4.3:

(a)	If it is expected that a filter's total surface concentration of PM will be greater than 0,353 μg/mm2, assuming a 400 μg loading on a 38 mm diameter filter stain area, the filter shall be exposed to the stabilization environment for at least 60 minutes before weighing;

(b)	If it is expected that a filter's total surface concentration of PM will be less than 0,353 μg/mm2, the filter shall be exposed to the stabilization environment for at least 30 minutes before weighing;

(c)	If a filter's total surface concentration of PM to be expected during the test is unknown, the filter shall be exposed to the stabilization environment for at least 60 minutes before weighing.

8.2.4.6.   Determination of post-test filter mass

The procedures in point 8.2.3 shall be repeated (points 8.2.3.6 through 8.2.3.9) to determine the post-test filter mass.

8.2.4.7.   Total mass

Each buoyancy-corrected filter tare mass shall be subtracted from its respective buoyancy-corrected post-test filter mass. The result is the total mass, m total, which shall be used in emission calculations in Annex VII.

9.   Measurement equipment

9.1.   Engine dynamometer specification

9.1.1.   Shaft work

An engine dynamometer shall be used that has adequate characteristics to perform the applicable duty cycle including the ability to meet appropriate cycle validation criteria. The following dynamometers may be used:

(a)	Eddy-current or water-brake dynamometers;

(b)	Alternating-current or direct-current motoring dynamometers;

(c)	One or more dynamometers.

9.1.2.   Transient (NRTC and LSI-NRTC) test cycles

Load cell or in-line torque meter may be used for torque measurements.

When using a load cell, the torque signal shall be transferred to the engine axis and the inertia of the dynamometer shall be considered. The actual engine torque is the torque read on the load cell plus the moment of inertia of the brake multiplied by the angular acceleration. The control system has to perform such a calculation in real time.

9.1.3.   Engine accessories

The work of engine accessories required to fuel, lubricate, or heat the engine, circulate liquid coolant to the engine, or to operate exhaust after-treatment systems shall be accounted for and they shall be installed in accordance with point 6.3.

9.1.4.   Engine fixture and power transmission shaft system (category NRSh)

Where necessary for the proper testing of an engine of category NRSh, the engine fixture for the test bench and power transmission shaft system for connection to the dynamometer rotating system specified by the manufacturer shall be used.

9.2.   Dilution procedure (if applicable)

9.2.1.   Diluent conditions and background concentrations

Gaseous constituents may be measured raw or dilute whereas PM measurement generally requires dilution. Dilution may be accomplished by a full flow or partial flow dilution system. When dilution is applied then the exhaust gas may be diluted with ambient air, synthetic air, or nitrogen. For gaseous emissions measurement the diluent shall be at least 288 K (15 °C). For PM sampling the temperature of the diluent is specified in points 9.2.2 for CVS and 9.2.3 for PFD with varying dilution ratio. The flow capacity of the dilution system shall be large enough to completely eliminate water condensation in the dilution and sampling systems. De-humidifying the dilution air before entering the dilution system is permitted, if the air humidity is high. The dilution tunnel walls may be heated or insulated as well as the bulk stream tubing downstream of the tunnel to prevent the precipitation of water-containing constituents from a gas phase to a liquid phase (‘aqueous condensation’).

Before a diluent is mixed with exhaust gas, it may be preconditioned by increasing or decreasing its temperature or humidity. Constituents may be removed from the diluent to reduce their background concentrations. The following provisions apply to removing constituents or accounting for background concentrations:

(a)	Constituent concentrations in the diluent may be measured and compensated for background effects on test results. See Annex VII for calculations that compensate for background concentrations;

(b)

The following changes to the requirements of sections 7.2, 9.3 and 9.4 are permitted for measuring background gaseous or particulate pollutants: (i) It shall not be required to use proportional sampling; (ii) Unheated sampling systems may be used; (iii) Continuous sampling may be used irrespective of the use of batch sampling for diluted emissions; (iv) Batch sampling may be used irrespective of the use of continuous sampling for diluted emissions.

(c)

To account for background PM the following options are available: (i) For removing background PM, the diluent shall be filtered with high-efficiency particulate air (HEPA) filters that have an initial minimum collection efficiency specification of 99,97 % (see Article 2(19) for procedures related to HEPA-filtration efficiencies); (ii) For correcting for background PM without HEPA filtration, the background PM shall not contribute more than 50 % of the net PM collected on the sample filter; (iii) Background correction of net PM with HEPA filtration is permitted without pressure restriction.

9.2.2.   Full flow system

Full-flow dilution; constant-volume sampling (CVS). The full flow of raw exhaust gas is diluted in a dilution tunnel. Constant flow may be maintained by maintaining the temperature and pressure at the flow meter within the limits. For non-constant flow the flow shall be measured directly to allow for proportional sampling. The system shall be designed as follows (see Figure 6.6):

(a)	A tunnel with inside surfaces of stainless steel shall be used. The entire dilution tunnel shall be electrically grounded. Alternatively non-conductive materials may be used for engine categories neither subject to PM nor PN limits;

(b)	The exhaust gas back-pressure shall not be artificially lowered by the dilution air inlet system. The static pressure at the location where raw exhaust gas is introduced into the tunnel shall be maintained within ± 1,2 kPa of atmospheric pressure;

(c)	To support mixing the raw exhaust gas shall be introduced into the tunnel by directing it downstream along the centreline of the tunnel. A fraction of dilution air maybe introduced radially from the tunnel's inner surface to minimize exhaust gas interaction with the tunnel walls;

(d)	Diluent. For PM sampling the temperature of the diluents (ambient air, synthetic air, or nitrogen as quoted in point 9.2.1) shall be maintained between 293 and 325 K (20 to 52 °C) in close proximity to the entrance into the dilution tunnel;

(e)

The Reynolds number, Re, shall be at least 4 000 for the diluted exhaust gas flow, where Re is based on the inside diameter of the dilution tunnel. Re is defined in Annex VII. Verification of adequate mixing shall be performed while traversing a sampling probe across the tunnel's diameter, vertically and horizontally. If the analyzer response indicates any deviation exceeding ± 2 % of the mean measured concentration, the CVS shall be operated at a higher flow rate or a mixing plate or orifice shall be installed to improve mixing;

(f)

Flow measurement preconditioning. The diluted exhaust gas may be conditioned before measuring its flow rate, as long as this conditioning takes place downstream of heated HC or PM sample probes, as follows: (i) Flow straighteners, pulsation dampeners, or both of these may be used; (ii) A filter may be used; (iii) A heat exchanger may be used to control the temperature upstream of any flow meter but steps shall be taken to prevent aqueous condensation;

(g)

Aqueous condensation. Aqueous condensation is a function of humidity, pressure, temperature, and concentrations of other constituents such as sulphuric acid. These parameters vary as a function of engine intake-air humidity, dilution-air humidity, engine air-to-fuel ratio, and fuel composition — including the amount of hydrogen and sulphur in the fuel. To ensure that a flow is measured that corresponds to a measured concentration, either aqueous condensation shall be prevented between the sample probe location and the flow meter inlet in the dilution tunnel or aqueous condensation shall be allowed to occur and humidity at the flow meter inlet measured. The dilution tunnel walls or bulk stream tubing downstream of the tunnel may be heated or insulated to prevent aqueous condensation. Aqueous condensation shall be prevented throughout the dilution tunnel. Certain exhaust gas components can be diluted or eliminated by the presence of moisture; For PM sampling, the already proportional flow coming from CVS goes through secondary dilution (one or more) to achieve the requested overall dilution ratio as shown in Figure 9.2 and set out in point 9.2.3.2;

(h)	The minimum overall dilution ratio shall be within the range of 5:1 to 7:1 and at least 2:1 for the primary dilution stage based on the maximum engine exhaust gas flow rate during the test cycle or test interval;

(i)	The overall residence time in the system shall be between 0,5 and 5 seconds, as measured from the point of diluent introduction to the filter holder(s);

(j)	The residence time in the secondary dilution system, if present, shall be at least 0,5 seconds, as measured from the point of secondary diluent introduction to the filter holder(s).

To determine the mass of the particulates, a particulate sampling system, a particulate sampling filter, a gravimetric balance, and a temperature and humidity controlled weighing chamber, are required.

Figure 6.6

Examples of full-flow dilution sampling configurations

9.2.3.   Partial flow dilution (PFD) system

9.2.3.1.   Description of partial flow system

A schematic of a PFD system is shown in Figure 6.7. It is a general schematic showing principles of sample extraction, dilution and PM sampling. It is not meant to indicate that all the components described in the Figure are necessary for other possible sampling systems that satisfy the intent of sample collection. Other configurations which do not match these schematics are allowed under the condition that they serve the same purpose of sample collection, dilution, and PM sampling. These need to satisfy other criteria such as in points 8.1.8.6 (periodic calibration) and 8.2.1.2 (validation) for varying dilution PFD, and point 8.1.4.5 as well as Table 8.2 (linearity verification) and point 8.1.8.5.7 (verification) for constant dilution PFD.

As shown in Figure 6.7, the raw exhaust gas or the primary diluted flow is transferred from the exhaust pipe EP or from CVS respectively to the dilution tunnel DT through the sampling probe SP and the transfer line TL. The total flow through the tunnel is adjusted with a flow controller and the sampling pump P of the particulate sampling system (PSS). For proportional raw exhaust gas sampling, the dilution air flow is controlled by the flow controller FC1, which may use qm ew (exhaust gas mass flow rate on wet basis) or qm aw (intake air mass flow rate on wet basis) and qm f (fuel mass flow rate) as command signals, for the desired exhaust gas split. The sample flow into the dilution tunnel DT is the difference of the total flow and the dilution air flow. The dilution air flow rate is measured with the flow measurement device FM1, the total flow rate with the flow measurement device of the particulate sampling system. The dilution ratio is calculated from these two flow rates. For sampling with a constant dilution ratio of raw or diluted exhaust gas versus exhaust gas flow (e.g.: secondary dilution for PM sampling), the dilution air flow rate is usually constant and controlled by the flow controller FC1 or dilution air pump.

The dilution air (ambient air, synthetic air, or nitrogen) shall be filtered with a high-efficiency PM air (HEPA) filter.

Figure 6.7

Schematic of partial flow dilution system (total sampling type).

a	=	engine exhaust gas or primary diluted flow
b	=	optional
c	=	PM sampling

Components of Figure 6.7:

DAF	:	Dilution air filter
DT	:	Dilution tunnel or secondary dilution system
EP	:	Exhaust pipe or primary dilution system
FC1	:	Flow controller
FH	:	Filter holder
FM1	:	Flow measurement device measuring the dilution air flow rate
P	:	Sampling pump
PSS	:	PM sampling system
PTL	:	PM transfer line
SP	:	Raw or diluted exhaust gas sampling probe
TL	:	Transfer line

Mass flow rates applicable only for proportional raw exhaust gas sampling PFD:

qm ew	is the exhaust gas mass gas flow rate on wet basis
qm aw	is the intake air mass flow rate on wet basis
qm f	is the fuel mass flow rate

9.2.3.2.   Dilution

The temperature of the diluents (ambient air, synthetic air, or nitrogen as quoted in point 9.2.1) shall be maintained between 293 and 325 K (20 to 52 °C) in close proximity to the entrance into the dilution tunnel.

De-humidifying the dilution air before entering the dilution system is permitted. The partial flow dilution system has to be designed to extract a proportional raw exhaust gas sample from the engine exhaust gas stream, thus responding to excursions in the exhaust gas stream flow rate, and introduce dilution air to this sample to achieve a temperature at the test filter as prescribed by point 9.3.3.4.3. For this it is essential that the dilution ratio be determined such that the accuracy requirements of point 8.1.8.6.1 are fulfilled.

To ensure that a flow is measured that corresponds to a measured concentration, either aqueous condensation shall be prevented between the sample probe location and the flow meter inlet in the dilution tunnel or aqueous condensation shall be allowed to occur and humidity at the flow meter inlet measured. The PFD system may be heated or insulated to prevent aqueous condensation. Aqueous condensation shall be prevented throughout the dilution tunnel.

The minimum dilution ratio shall be within the range of 5:1 to 7:1 based on the maximum engine exhaust gas flow rate during the test cycle or test interval.

The residence time in the system shall be between 0,5 and 5 s, as measured from the point of diluent introduction to the filter holder(s).

To determine the mass of the particulates, a particulate sampling system, a particulate sampling filter, a gravimetric balance, and a temperature and humidity controlled weighing chamber, are required.

9.2.3.3.   Applicability

PFD may be used to extract a proportional raw exhaust gas sample for any batch or continuous PM and gaseous emission sampling over any transient (NRTC and LSI-NRTC) duty cycle, any discrete-mode NRSC or any RMC duty cycle.

The system may be used also for a previously diluted exhaust gas where, via a constant dilution-ratio, an already proportional flow is diluted (see Figure 9.2). This is the way of performing secondary dilution from a CVS tunnel to achieve the necessary overall dilution ratio for PM sampling.

9.2.3.4.   Calibration

The calibration of the PFD to extract a proportional raw exhaust gas sample is considered in point 8.1.8.6.

9.3.   Sampling procedures

9.3.1.   General sampling requirements

9.3.1.1.   Probe design and construction

A probe is the first fitting in a sampling system. It protrudes into a raw or diluted exhaust gas stream to extract a sample, such that it's inside and outside surfaces are in contact with the exhaust gas. A sample is transported out of a probe into a transfer line.

Sample probes shall be made with inside surfaces of stainless steel or, for raw exhaust gas sampling, with any non-reactive material capable of withstanding raw exhaust gas temperatures. Sample probes shall be located where constituents are mixed to their mean sample concentration and where interference with other probes is minimised. It is recommended that all probes remain free from influences of boundary layers, wakes, and eddies — especially near the outlet of a raw-exhaust meter tailpipe where unintended dilution might occur. Purging or back-flushing of a probe shall not influence another probe during testing. A single probe to extract a sample of more than one constituent may be used as long as the probe meets all the specifications for each constituent.

9.3.1.1.1.   Mixing chamber (category NRSh)

Where permitted by the manufacturer, a mixing chamber may be used when testing engines of category NRSh. The mixing chamber is an optional component of a raw gas sampling system and is located in the exhaust system between the silencer and the sample probe. The shape and dimensions of the mixing chamber and tubing before and after shall be such that it provides a well-mixed, homogenous sample at the sample probe location and so that strong pulsations or resonances of the chamber influencing the emissions results are avoided.

9.3.1.2.   Transfer lines

Transfer lines that transport an extracted sample from a probe to an analyzer, storage medium, or dilution system shall be minimized in length by locating analyzers, storage media, and dilution systems as close to the probes as practical. The number of bends in transfer lines shall be minimized and that the radius of any unavoidable bend shall be maximized.

9.3.1.3.   Sampling methods

For continuous and batch sampling, introduced in point 7.2, the following conditions apply:

(a)	When extracting from a constant flow rate, the sample shall also be carried out at a constant flow rate;

(b)	When extracting from a varying flow rate, the sample flow rate shall be varied in proportion to the varying flow rate;

(c)	Proportional sampling shall be validated as described in point 8.2.1.

9.3.2.   Gas sampling

9.3.2.1.   Sampling probes

Either single-port or multi-port probes are used for sampling gaseous emissions. The probes may be oriented in any direction relative to the raw or diluted exhaust gas flow. For some probes, the sample temperatures shall be controlled, as follows:

(a)	For probes that extract NOx from diluted exhaust gas, the probe's wall temperature shall be controlled to prevent aqueous condensation;

(b)	For probes that extract hydrocarbons from the diluted exhaust gas, a probe wall temperature is recommended to be controlled approximately 191 °C to minimise contamination.

9.3.2.1.1.   Mixing chamber (Category NRSh)

When used in accordance with point 9.3.1.1.1, the internal volume of the mixing chamber shall not be less than ten times the cylinder displacement of the engine under test. The mixing chamber shall be coupled as closely as possible to the engine silencer and shall have a minimum inner surface temperature of 452 K (179 °C). The manufacturer may specify the design of the mixing chamber.

9.3.2.2.   Transfer lines

Transfer lines with inside surfaces of stainless steel, PTFE, VitonTM, or any other material that has better properties for emission sampling shall be used. A non-reactive material capable of withstanding exhaust gas temperatures shall be used. In-line filters may be used if the filter and its housing meet the same temperature requirements as the transfer lines, as follows:

(a)	For NOx transfer lines upstream of either an NO2-to-NO converter that meets the specifications set out in point 8.1.11.5 or a chiller that meets the specifications set out in point 8.1.11.4 a sample temperature that prevents aqueous condensation shall be maintained;

(b)

For THC transfer lines a wall temperature tolerance throughout the entire line of (191 ± 11) °C shall be maintained. If sampled from raw exhaust gas, an unheated, insulated transfer line may be connected directly to a probe. The length and insulation of the transfer line shall be designed to cool the highest expected raw exhaust gas temperature to no lower than 191 °C, as measured at the transfer line outlet. For dilute sampling a transition zone between the probe and transfer line of up to 0,92 m in length is allowed to transition the wall temperature to (191 ± 11) °C.

9.3.2.3.   Sample-conditioning components

9.3.2.3.1.   Sample dryers

9.3.2.3.1.1.   Requirements

Sample dryers may be used for removing moisture from the sample in order to decrease the effect of water on gaseous emissions measurement. Sample dryers shall meet the requirements set out in point 9.3.2.3.1.1 and in point 9.3.2.3.1.2. The moisture content 0,8 volume % is used in equation (7-13).

For the highest expected water vapour concentration H m, the water removal technique shall maintain humidity at ≤ 5 g water/kg dry air (or about 0,8 volume % H2O), which is 100 % relative humidity at 277,1 K (3,9 °C) and 101,3 kPa. This humidity specification is equivalent to about 25 % relative humidity at 298 K (25 °C) and 101,3 kPa. This may be demonstrated by

(a)	measuring the temperature at the outlet of the sample dryer;

(b)	measuring humidity at a point just upstream of the CLD;

performing the verification procedure in point 8.1.8.5.8.

9.3.2.3.1.2.   Type of sample dryers allowed and procedure to estimate moisture content after the dryer

Either type of sample dryer described in this point may be used.

(a)

If an osmotic-membrane dryer upstream of any gaseous analyzer or storage medium is used, it shall meet the temperature specifications set out in point 9.3.2.2. The dew point, T dew, and absolute pressure, p total, downstream of an osmotic-membrane dryer shall be monitored. The amount of water shall be calculated as specified in Annex VII by using continuously recorded values of T dew and p total or their peak values observed during a test or their alarm set points. Lacking a direct measurement, the nominal p total is given by the dryer's lowest absolute pressure expected during testing.

(b)

A thermal chiller upstream of a THC measurement system for compression-ignition engines may not be used. If a thermal chiller upstream of an NO2-to-NO converter or in a sampling system without an NO2-to-NO converter is used, the chiller shall meet the NO2 loss-performance check specified in point 8.1.11.4. The dew point, T dew, and absolute pressure, p total, downstream of a thermal chiller shall be monitored. The amount of water shall be calculated as specified in Annex VII by using continuously recorded values of T dew and p total or their peak values observed during a test or their alarm set points. Lacking a direct measurement, the nominal p total is given by the thermal chiller's lowest absolute pressure expected during testing. If it is valid to assume the degree of saturation in the thermal chiller, T dew based on the known chiller efficiency and continuous monitoring of chiller temperature, T chiller may be calculated. If values of T chiller are not continuously recorded, its peak value observed during a test, or its alarm set point, may be used as a constant value to determine a constant amount of water in accordance with Annex VII. If it is valid to assume that T chiller is equal to T dew, T chiller may be used in lieu of T dew in accordance with Annex VII. If it is valid to assume a constant temperature offset between T chiller and T dew, due to a known and fixed amount of sample reheat between the chiller outlet and the temperature measurement location, this assumed temperature offset value may be factored in into emission calculations. The validity of any assumptions allowed by this point shall be shown by engineering analysis or by data.

9.3.2.3.2.   Sample pumps

Sample pumps upstream of an analyzer or storage medium for any gas shall be used. Sample pumps with inside surfaces of stainless steel, PTFE, or any other material having better properties for emission sampling shall be used. For some sample pumps, temperatures shall be controlled, as follows:

(a)	If a NOx sample pump upstream of either an NO2-to-NO converter that meets the requirements set out in point 8.1.11.5 or a chiller that meets the requirements set out in point 8.1.11.4 is used, it shall be heated to prevent aqueous condensation;

(b)	If a THC sample pump upstream of a THC analyzer or storage medium is used, its inner surfaces shall be heated to a tolerance of 464 ± 11 K (191 ± 11) °C.

9.3.2.3.3.   Ammonia scrubbers

Ammonia scrubbers may be used for any or all gaseous sampling systems to prevent NH3 interference, poisoning of NO2-to-NO converter, and deposits in the sampling system or analysers. Installation of the ammonia scrubber shall follow the manufacturer's recommendations.

9.3.2.4.   Sample storage media

In the case of bag sampling, gas volumes shall be stored in sufficiently clean containers that minimally off-gas or allow permeation of gases. Good engineering judgment shall be used to determine acceptable thresholds of storage media cleanliness and permeation. To clean a container, it may be repeatedly purged and evacuated and may be heated. A flexible container (such as a bag) within a temperature-controlled environment, or a temperature controlled rigid container that is initially evacuated or has a volume that can be displaced, such as a piston and cylinder arrangement, shall be used. Containers meeting the specifications in the following Table 6.6 shall be used.

Table 6.6

Gaseous Batch Sampling Container Materials

CO, CO2, O2, CH4, C2H6, C3H8, NO, NO2  (2)	polyvinyl fluoride (PVF) (3) for example TedlarTM, polyvinylidene fluoride (3) for example KynarTM, polytetrafluoroethylene (4) for example TeflonTM, or stainless steel (4)
HC	polytetrafluoroethylene (5) or stainless steel (5)

9.3.3.   PM sampling

9.3.3.1.   Sampling probes

PM probes with a single opening at the end shall be used. PM probes shall be oriented to face directly upstream.

The PM probe may be shielded with a hat that conforms with the requirements in Figure 6.8. In this case the pre-classifier described in point 9.3.3.3 shall not be used.

Figure 6.8

Scheme of a sampling probe with a hat-shaped pre-classifier

Cross-section

9.3.3.2.   Transfer lines

Insulated or heated transfer lines or a heated enclosure are recommended to minimize temperature differences between transfer lines and exhaust gas constituents. Transfer lines that are inert with respect to PM and are electrically conductive on the inside surfaces shall be used. It is recommended using PM transfer lines made of stainless steel; any material other than stainless steel will be required to meet the same sampling performance as stainless steel. The inside surface of PM transfer lines shall be electrically grounded.

9.3.3.3.   Pre-classifier

The use of a PM pre-classifier to remove large-diameter particles is permitted that is installed in the dilution system directly before the filter holder. Only one pre-classifier is permitted. If a hat shaped probe is used (see Figure 6.8), the use of a pre-classifier is prohibited.

The PM pre-classifier may be either an inertial impactor or a cyclonic separator. It shall be constructed of stainless steel. The pre-classifier shall be rated to remove at least 50 % of PM at an aerodynamic diameter of 10 μm and no more than 1 % of PM at an aerodynamic diameter of 1 μm over the range of flow rates for which it is used. The pre-classifier outlet shall be configured with a means of bypassing any PM sample filter so that the pre-classifier flow can be stabilized before starting a test. PM sample filter shall be located within 75 cm downstream of the pre-classifier's exit.

9.3.3.4.   Sample filter

The diluted exhaust gas shall be sampled by a filter that meets the requirements set out in points 9.3.3.4.1 to 9.3.3.4.4 during the test sequence.

9.3.3.4.1.   Filter specification

All filter types shall have a collection efficiency of at least 99,7 %. The sample filter manufacturer's measurements reflected in their product ratings may be used to show this requirement. The filter material shall be either:

(a)	Fluorocarbon (PTFE) coated glass fibre; or

(b)	Fluorocarbon (PTFE) membrane.

If the expected net PM mass on the filter exceeds 400 μg, a filter with a minimum initial collection efficiency of 98 % may be used.

9.3.3.4.2.   Filter size

The nominal filter size shall be 46,50 mm ± 0,6 mm diameter (at least 37 mm stain diameter). Larger diameter filters may be used with prior agreement of the approval authority. Proportionality between filter and stain area is recommended.

9.3.3.4.3.   Dilution and temperature control of PM samples

PM samples shall be diluted at least once upstream of transfer lines in case of a CVS system and downstream in case of PFD system (see point 9.3.3.2 relating to transfer lines). Sample temperature shall be controlled to a 320 ± 5 K (47 ± 5 °C) tolerance, as measured anywhere within 200 mm upstream or 200 mm downstream of the PM storage media. The PM sample is intended to be heated or cooled primarily by dilution conditions as specified in point 9.2.1(a).

9.3.3.4.4.   Filter face velocity

A filter face velocity shall be between 0,90 and 1,00 m/s with less than 5 % of the recorded flow values exceeding this range. If the total PM mass exceeds 400 μg, the filter face velocity may be reduced. The face velocity shall be measured as the volumetric flow rate of the sample at the pressure upstream of the filter and temperature of the filter face, divided by the filter's exposed area. The exhaust system stack or CVS tunnel pressure shall be used for the upstream pressure if the pressure drop through the PM sampler up to the filter is less than 2 kPa.

9.3.3.4.5.   Filter holder

To minimize turbulent deposition and to deposit PM evenly on a filter, a 12,5° (from centre) divergent cone angle to transition from the transfer-line inside diameter to the exposed diameter of the filter face shall be used. Stainless steel for this transition shall be used.

9.3.4.   PM-stabilization and weighing environments for gravimetric analysis

9.3.4.1.   Environment for gravimetric analysis

This section describes the two environments required to stabilize and weigh PM for gravimetric analysis: the PM stabilization environment, where filters are stored before weighing; and the weighing environment, where the balance is located. The two environments may share a common space.

Both the stabilization and the weighing environments shall be kept free of ambient contaminants, such as dust, aerosols, or semi-volatile material that could contaminate PM samples.

9.3.4.2.   Cleanliness

The cleanliness of the PM-stabilization environment using reference filters shall be verified, as described in point 8.1.12.1.4.

9.3.4.3.   Temperature of the chamber

The temperature of the chamber (or room) in which the particulate filters are conditioned and weighed shall be maintained to within 295 ± 1 K (22 °C ± 1 °C) during all filter conditioning and weighing. The humidity shall be maintained to a dew point of 282,5 ± 1 K (9,5 °C ± 1 °C) and a relative humidity of 45 % ± 8 %. If the stabilization and weighing environments are separate, the stabilization environment shall be maintained at a tolerance of 295 ± 3 K (22 °C ± 3 °C).

9.3.4.4.   Verification of ambient conditions

When using measurement instruments that meet the specifications in point 9.4 the following ambient conditions shall be verified:

(a)	Dew point and ambient temperature shall be recorded. These values shall be used to determine if the stabilization and weighing environments have remained within the tolerances specified in point 9.3.4.3 for at least 60 min before weighing filters;

(b)

Atmospheric pressure shall be continuously recorded within the weighing environment. An acceptable alternative is to use a barometer that measures atmospheric pressure outside the weighing environment, as long as it can be ensured that the atmospheric pressure at the balance is always at the balance within ± 100 Pa of the shared atmospheric pressure. A means to record the most recent atmospheric pressure shall be provided when each PM sample is weighed. This value shall be used to calculate the PM buoyancy correction in point 8.1.12.2.

9.3.4.5.   Installation of balance

The balance shall be installed as follows:

(a)	Installed on a vibration-isolation platform to isolate it from external noise and vibration;

(b)	Shielded from convective airflow with a static-dissipating draft shield that is electrically grounded.

9.3.4.6.   Static electric charge

Static electric charge shall be minimized in the balance environment, as follows:

(a)	The balance is electrically grounded;

(b)	Stainless steel tweezers shall be used if PM samples shall be handled manually;

(c)	Tweezers shall be grounded with a grounding strap, or a grounding strap shall be provided for the operator such that the grounding strap shares a common ground with the balance;

(d)	A static-electricity neutralizer shall be provided that is electrically grounded in common with the balance to remove static charge from PM samples.

9.4.   Measurement instruments

9.4.1.   Introduction

9.4.1.1.   Scope

This point specifies measurement instruments and associated system requirements related to emission testing. This includes laboratory instruments for measuring engine parameters, ambient conditions, flow-related parameters, and emission concentrations (raw or diluted).

9.4.1.2.   Instrument types

Any instrument mentioned in this Regulation shall be used as described in the Regulation itself (see Table 6.5 for measurement quantities provided by these instruments). Whenever an instrument mentioned in this Regulation is used in a way that is not specified, or another instrument is used in its place, the requirements for equivalency provisions shall apply as specified in point 5.1.1. Where more than one instrument for a particular measurement is specified, one of them will be identified by the type approval or certifying authority upon application as the reference for showing that an alternative procedure is equivalent to the specified procedure.

9.4.1.3.   Redundant systems

Data from multiple instruments to calculate test results for a single test may be used for all measurement instruments described in this point, with prior approval of the type approval or certification authority. Results from all measurements shall be recorded and the raw data shall be retained. This requirement applies whether or not the measurements are actually used in the calculations.

9.4.2.   Data recording and control

The test system shall be able to update data, record data and control systems related to operator demand, the dynamometer, sampling equipment, and measurement instruments. Data acquisition and control systems shall be used that can record at the specified minimum frequencies, as shown in Table 6.7 (this Table does not apply to discrete-mode NRSC testing).

Table 6.7

Data recording and control minimum frequencies

Applicable Test Protocol Section	Measured Values	Minimum Command and Control Frequency	Minimum Recording Frequency
7.6	Speed and torque during an engine step-map	1 Hz	1 mean value per step
7.6	Speed and torque during an engine sweep-map	5 Hz	1 Hz means
7.8.3	Transient (NRTC and LSI-NRTC) duty cycle reference and feedback speeds and torques	5 Hz	1 Hz means
7.8.2	Discrete-mode NRSC and RMC duty cycle reference and feedback speeds and torques	1 Hz	1 Hz
7.3	Continuous concentrations of raw analyzers	N/A	1 Hz
7.3	Continuous concentrations of dilute analyzers	N/A	1 Hz
7.3	Batch concentrations of raw or dilute analyzers	N/A	1 mean value per test interval
7.6 8.2.1	Diluted exhaust gas flow rate from a CVS with a heat exchanger upstream of the flow measurement	N/A	1 Hz
7.6 8.2.1	Diluted exhaust gas flow rate from a CVS without a heat exchanger upstream of the flow measurement	5 Hz	1 Hz means
7.6 8.2.1	Intake-air or exhaust gas flow rate (for raw transient measurement)	N/A	1 Hz means
7.6 8.2.1	Dilution air if actively controlled	5 Hz	1 Hz means
7.6 8.2.1	Sample flow from a CVS with a heat exchanger	1 Hz	1 Hz
7.6 8.2.1	Sample flow from a CVS without a heat exchanger	5 Hz	1 Hz mean

9.4.3.   Performance specifications for measurement instruments

9.4.3.1.   Overview

The test system as a whole shall meet all the applicable calibrations, verifications, and test-validation criteria specified in point 8.1, including the requirements of the linearity check of points 8.1.4 and 8.2. Instruments shall meet the specifications in Table 6.7 for all ranges to be used for testing. Furthermore, any documentation received from instrument manufacturers showing that instruments meet the specifications in Table 6.7 shall be kept.

9.4.3.2.   Component requirements

Table 6.8 shows the specifications of transducers of torque, speed, and pressure, sensors of temperature and dew point, and other instruments. The overall system for measuring the given physical and/or chemical quantity shall meet the linearity verification in point 8.1.4. For gaseous emissions measurements, analyzers may be used, that have compensation algorithms that are functions of other measured gaseous components, and of the fuel properties for the specific engine test. Any compensation algorithm shall only provide offset compensation without affecting any gain (that is no bias).

Table 6.8

Recommended performance specifications for measurement instruments

Measurement Instrument	Measured quantity symbol	Complete System Rise time	Recording update frequency	Accuracy (3)	Repeatability (3)
Engine speed transducer	n	1 s	1 Hz means	2,0 % of pt. or 0,5 % of max	1,0 % of pt. or 0,25 % of max
Engine torque transducer	T	1 s	1 Hz means	2,0 % of pt. or 1,0 % of max	1,0 % of pt. or 0,5 % of max
Fuel flow meter (Fuel totalizer)		5 s (N/A)	1 Hz (N/A)	2,0 % of pt. or 1,5 % of max	1,0 % of pt. or 0,75 % of max
Total diluted exhaust gas meter (CVS) (With heat exchanger before meter)		1 s (5 s)	1 Hz means (1 Hz)	2,0 % of pt. or 1,5 % of max	1,0 % of pt. or 0,75 % of max
Dilution air, inlet air, exhaust gas, and sample flow meters		1 s	1 Hz means of 5 Hz samples	2,5 % of pt. or 1,5 % of max	1,25 % of pt. or 0,75 % of max
Continuous gas analyzer raw	x	5 s	2 Hz	2,0 % of pt. or 2,0 % of meas.	1,0 % of pt. or 1,0 % of meas.
Continuous gas analyzer dilute	x	5 s	1 Hz	2,0 % of pt. or 2,0 % of meas.	1,0 % of pt. or 1,0 % of meas.
Continuous gas analyzer	x	5 s	1 Hz	2,0 % of pt. or 2,0 % of meas.	1,0 % of pt. or 1,0 % of meas.
Batch gas analyzer	x	N/A	N/A	2,0 % of pt. or 2,0 % of meas.	1,0 % of pt. or 1,0 % of meas.
Gravimetric PM balance	m PM	N/A	N/A	See 9.4.11	0,5 μg
Inertial PM balance	m PM	5 s	1 Hz	2,0 % of pt. or 2,0 % of meas.	1,0 % of pt. or 1,0 % of meas.

9.4.4.   Measurement of engine parameters & ambient conditions

9.4.4.1.   Speed and torque sensors

9.4.4.1.1.   Application

Measurement instruments for work inputs and outputs during engine operation shall meet the specifications in this point. Sensors, transducers, and meters meeting the specifications in Table 6.8 are recommended. Overall systems for measuring work inputs and outputs shall meet the linearity verifications in point 8.1.4.

9.4.4.1.2.   Shaft work

Work and power shall be calculated from outputs of speed and torque transducers according to point 9.4.4.1. Overall systems for measuring speed and torque shall meet the calibration and verifications in points 8.1.7 and 8.1.4.

Torque induced by the inertia of accelerating and decelerating components connected to the flywheel, such as the drive shaft and dynamometer rotor, shall be compensated for as needed, based on good engineering judgment.

9.4.4.2.   Pressure transducers, temperature sensors, and dew point sensors

Overall systems for measuring pressure, temperature, and dew point shall meet the calibration in point 8.1.7.

Pressure transducers shall be located in a temperature-controlled environment, or they shall compensate for temperature changes over their expected operating range. Transducer materials shall be compatible with the fluid being measured.

9.4.5.   Flow-related measurements

For any type of flow meter (of fuel, intake-air, raw exhaust gas, diluted exhaust gas, sample), the flow shall be conditioned as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. For some meters, this may be accomplished by using a sufficient length of straight tubing (such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, straightening fins, orifice plates (or pneumatic pulsation dampeners for the fuel flow meter) to establish a steady and predictable velocity profile upstream of the meter.

9.4.5.1.   Fuel flow meter

Overall system for measuring fuel flow shall meet the calibration in point 8.1.8.1. In any fuel flow measurement it shall be accounted for any fuel that bypasses the engine or returns from the engine to the fuel storage tank.

9.4.5.2.   Intake-air flow meter

Overall system for measuring intake-air flow shall meet the calibration in point 8.1.8.2.

9.4.5.3.   Raw exhaust flow meter

9.4.5.3.1.   Component requirements

The overall system for measuring raw exhaust gas flow shall meet the linearity requirements in point 8.1.4. Any raw-exhaust meter shall be designed to appropriately compensate for changes in the raw exhaust gas' thermodynamic, fluid, and compositional states.

9.4.5.3.2.   Flow meter response time

For the purpose of controlling of a partial flow dilution system to extract a proportional raw exhaust gas sample, a flow meter response time faster than indicated in Table 9.3 is required. For partial flow dilution systems with online control, the flow meter response time shall meet the specifications of point 8.2.1.2.

9.4.5.3.3.   Exhaust gas cooling

This point does not apply to cooling of the exhaust gas due to the design of the engine, including, but not limited to, water-cooled exhaust manifolds or turbochargers.

Exhaust gas cooling upstream of the flow meter is permitted with the following restrictions:

(a)	PM shall not be sampled downstream of the cooling;

(b)	If cooling causes exhaust gas temperatures above 475 K (202 °C) to decrease to below 453 K (180 °C), HC shall not be sampled downstream of the cooling;

(c)	If cooling causes aqueous condensation, NOx shall not be sampled downstream of the cooling unless the cooler meets the performance verification in point 8.1.11.4;

(d)	If cooling causes aqueous condensation before the flow reaches a flow meter, dew point T dew and pressure p total shall be measured at the flow meter inlet. These values shall be used in emission calculations in accordance with Annex VII.

9.4.5.4.   Dilution air and diluted exhaust flow meters

9.4.5.4.1.   Application

Instantaneous diluted exhaust gas flow rates or total diluted exhaust gas flow over a test interval shall be determined by using a diluted exhaust flow meter. Raw exhaust gas flow rates or total raw exhaust gas flow over a test interval may be calculated from the difference between a diluted exhaust flow meter and a dilution air meter.

9.4.5.4.2.   Component requirements

The overall system for measuring diluted exhaust gas flow shall meet the calibration and verifications in points 8.1.8.4 and 8.1.8.5. The following meters may be used:

(a)

For constant-volume sampling (CVS) of the total flow of diluted exhaust gas, a critical-flow venturi (CFV) or multiple critical-flow venturis arranged in parallel, a positive-displacement pump (PDP), a subsonic venturi (SSV), or an ultrasonic flow meter (UFM) may be used. Combined with an upstream heat exchanger, either a CFV or a PDP will also function as a passive flow controller by keeping the diluted exhaust gas temperature constant in a CVS system;

(b)

For the Partial Flow Dilution (PFD) system the combination of any flow meter with any active flow control system to maintain proportional sampling of exhaust gas constituents may be used. The total flow of diluted exhaust gas, or one or more sample flows, or a combination of these flow controls may be controlled to maintain proportional sampling.

For any other dilution system, a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a critical-flow venturi or multiple critical-flow venturis arranged in parallel, a positive-displacement meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer may be used.

9.4.5.4.3.   Exhaust gas cooling

Diluted exhaust gas upstream of a dilute flow meter may be cooled, as long as all the following provisions are observed:

(a)	PM shall not be sampled downstream of the cooling;

(b)	If cooling causes exhaust gas temperatures above 475 K (202 °C) to decrease to below 453 K (180 °C), HC shall not be sampled downstream of the cooling;

(c)	If cooling causes aqueous condensation, NOx shall not be sampled downstream of the cooling unless the cooler meets the performance verification in point 8.1.11.4;

(d)	If cooling causes aqueous condensation before the flow reaches a flow meter, dew point, T dew and pressure p total shall be measured at the flow meter inlet. These values shall be used in emission calculations in accordance with Annex VII.

9.4.5.5.   Sample flow meter for batch sampling

A sample flow meter shall be used to determine sample flow rates or total flow sampled into a batch sampling system over a test interval. The difference between two flow meters may be used to calculate sample flow into a dilution tunnel e.g. for partial flow dilution PM measurement and secondary dilution flow PM measurement. Specifications for differential flow measurement to extract a proportional raw exhaust gas sample is set out in point 8.1.8.6.1 and the calibration of differential flow measurement is given in point 8.1.8.6.2.

Overall system for the sample flow meter shall meet the calibration requirements set out in point 8.1.8.

9.4.5.6.   Gas divider

A gas divider may be used to blend calibration gases.

A gas divider shall be used that blends gases to the specifications of point 9.5.1 and to the concentrations expected during testing. Critical-flow gas dividers, capillary-tube gas dividers, or thermal-mass-meter gas dividers may be used. Viscosity corrections shall be applied as necessary (if not done by gas divider internal software) to appropriately ensure correct gas division. The gas-divider system shall meet the linearity verification set out in point 8.1.4.5. Optionally, the blending device may be checked with an instrument which by nature is linear, e.g. using NO gas with a CLD. The span value of the instrument shall be adjusted with the span gas directly connected to the instrument. The gas divider shall be checked at the settings used and the nominal value shall be compared to the measured concentration of the instrument.

9.4.6.   CO and CO2 measurements

A Non-dispersive infrared (NDIR) analyzer shall be used to measure CO and CO2 concentrations in raw or diluted exhaust gas for either batch or continuous sampling.

The NDIR-based system shall meet the calibration and verifications set out in point 8.1.8.1.

9.4.7.   Hydrocarbon measurements

9.4.7.1.   Flame-ionization detector

9.4.7.1.1.   Application

A heated flame-ionization detector (HFID) analyzer shall be used to measure hydrocarbon concentrations in raw or diluted exhaust gas for either batch or continuous sampling. Hydrocarbon concentrations shall be determined on a carbon number basis of one, C1. Heated FID analyzers shall maintain all surfaces that are exposed to emissions at a temperature of 464 ± 11 K (191 ± 11 °C). Optionally, for NG and LPG fuelled and SI engines, the hydrocarbon analyzer may be of the non-heated flame ionization detector (FID) type.

9.4.7.1.2.   Component requirements

The FID-based system for measuring THC shall meet all of the verifications for hydrocarbon measurement in point 8.1.10.

9.4.7.1.3.   FID fuel and burner air

FID fuel and burner air shall meet the specifications of point 9.5.1. The FID fuel and burner air shall not mix before entering the FID analyzer to ensure that the FID analyzer operates with a diffusion flame and not a premixed flame.

9.4.7.1.4.   Reserved

9.4.7.1.5.   Reserved

9.4.7.2.   Reserved

9.4.8.   NOx measurements

Two measurement instruments are specified for NOx measurement and either instrument may be used provided it meets the criteria specified in point 9.4.8.1 or 9.4.8.2, respectively. The chemiluminescent detector shall be used as the reference procedure for comparison with any proposed alternate measurement procedure under point 5.1.1.

9.4.8.1.   Chemiluminescent detector

9.4.8.1.1.   Application

A chemiluminescent detector (CLD) coupled with an NO2-to-NO converter is used to measure NOx concentration in raw or diluted exhaust gas for batch or continuous sampling.

9.4.8.1.2.   Component requirements

The CLD-based system shall meet the quench verification set out in point 8.1.11.1. A heated or unheated CLD may be used, and a CLD that operates at atmospheric pressure or under a vacuum may be used.

9.4.8.1.3.   NO2-to-NO converter

An internal or external NO2-to-NO converter that meets the verification in point 8.1.11.5 shall be placed upstream of the CLD, while the converter shall be configured with a bypass to facilitate this verification.

9.4.8.1.4.   Humidity effects

All CLD temperatures shall be maintained to prevent aqueous condensation. To remove humidity from a sample upstream of a CLD, one of the following configurations shall be used:

(a)	A CLD connected downstream of any dryer or chiller that is downstream of an NO2-to-NO converter that meets the verification set out in point 8.1.11.5;

(b)	A CLD connected downstream of any dryer or thermal chiller that meets the verification set out in point 8.1.11.4.

9.4.8.1.5.   Response time

A heated CLD may be used to improve CLD response time.

9.4.8.2.   Non-dispersive ultraviolet analyzer

9.4.8.2.1.   Application

A non-dispersive ultraviolet (NDUV) analyzer is used to measure NOx concentration in raw or diluted exhaust gas for batch or continuous sampling.

9.4.8.2.2.   Component requirements

The NDUV-based system shall meet the verifications set out in point 8.1.11.3.

9.4.8.2.3.   NO2-to-NO converter

If the NDUV analyzer measures only NO, an internal or external NO2-to-NO converter that meets the verification set out in point 8.1.11.5 shall be placed upstream of the NDUV analyzer. The converter shall be configured with a bypass to facilitate this verification.

9.4.8.2.4.   Humidity effects

The NDUV temperature shall be maintained to prevent aqueous condensation, unless one of the following configurations is used:

(a)	An NDUV shall be connected downstream of any dryer or chiller that is downstream of an NO2-to-NO converter that meets the verification in point 8.1.11.5;

(b)	An NDUV shall be connected downstream of any dryer or thermal chiller that meets the verification in point 8.1.11.4.

9.4.9.   O2 measurements

A paramagnetic detection (PMD) or magneto pneumatic detection (MPD) analyzer shall be used to measure O2 concentration in raw or diluted exhaust gas for batch or continuous sampling.

9.4.10.   Air-to-fuel ratio measurements

A Zirconia (ZrO2) analyser may be used to measure air-to-fuel ratio in raw exhaust gas for continuous sampling. O2 measurements with intake air or fuel flow measurements may be used to calculate exhaust gas flow rate in accordance with Annex VII.

9.4.11.   PM measurements with gravimetric balance

A balance shall be used to weigh net PM collected on sample filter media.

The minimum requirement on the balance resolution shall be equal or lower than the repeatability of 0,5 microgram recommended in Table 6.8. If the balance uses internal calibration weights for routine spanning and linearity verifications, the calibration weights shall meet the specifications in point 9.5.2.

The balance shall be configured for optimum settling time and stability at its location.

9.4.12.   Ammonia (NH3) measurements

A FTIR (Fourier transform infrared) analyser, NDUV or laser infrared analyser may be used in accordance with the instrument supplier's instructions.

9.5.   Analytical gases and mass standards

9.5.1.   Analytical gases

Analytical gases shall meet the accuracy and purity specifications of this section.

9.5.1.1.   Gas specifications

The following gas specifications shall be considered:

(a)

Purified gases shall be used to blend with calibration gases and to adjust measurement instruments so as to obtain a zero response to a zero calibration standard. Gases with contamination no higher than the highest of the following values in the gas cylinder or at the outlet of a zero-gas generator shall be used: (i) 2 % contamination, measured relative to the mean concentration expected at the standard. For example, if a CO concentration of 100,0 μmol/mol is expected, then it would be allowed to use a zero gas with CO contamination less than or equal to 2 000 μmol/mol; (ii) Contamination as specified in Table 6.9, applicable for raw or dilute measurements; (iii) Contamination as specified in Table 6.10, applicable for raw measurements. Table 6.9 Contamination limits, applicable for raw or dilute measurements [μmol/mol = ppm] Constituent Purified Synthetic Air (4) Purified N2  (4) THC (C1 equivalent) ≤ 0,05 μmol/mol ≤ 0,05 μmol/mol CO ≤ 1 μmol/mol ≤ 1 μmol/mol CO2 ≤ 1, μmol/mol ≤ 10 μmol/mol O2 0,205 to 0,215 mol/mol ≤ 2 μmol/mol NOx ≤ 0,02 μmol/mol ≤ 0,02 μmol/mol Table 6.10 Contamination limits applicable for raw measurements [μmol/mol = ppm] Constituent Purified Synthetic Air (5) Purified N2  (5) THC (C1 equivalent) ≤ 1 μmol/mol ≤ 1 μmol/mol CO ≤ 1 μmol/mol ≤ 1 μmol/mol CO2 ≤ 400 μmol/mol ≤ 400 μmol/mol O2 0,18 to 0,21 mol/mol — NOx ≤ 0,1 μmol/mol ≤ 0,1 μmol/mol

(b)

The following gases shall be used with a FID analyzer: (i) FID fuel shall be used with an H2 concentration of (0,39 to 0,41) mol/mol, balance He or N2. The mixture shall not contain more than 0,05 μmol/mol THC; (ii) FID burner air shall be used that meets the specifications of purified air in paragraph (a) of this point; (iii) FID zero gas. Flame-ionization detectors shall be zeroed with purified gas that meets the specifications in paragraph (a) of this point, except that the purified gas O2 concentration may be any value; (iv) FID propane span gas. The THC FID shall be spanned and calibrated with span concentrations of propane, C3H8. It shall be calibrated on a carbon number basis of one (C1); (v) Reserved;

(c)

The following gas mixtures shall be used, with gases traceable within ±1,0 % of the international and/or national recognized standards true value or of other gas standards that are approved: (i) Reserved; (ii) Reserved; (iii) C3H8, balance purified synthetic air and/or N2 (as applicable); (iv) CO, balance purified N2; (v) CO2, balance purified N2; (vi) NO, balance purified N2; (vii) NO2, balance purified synthetic air; (viii) O2, balance purified N2; (ix) C3H8, CO, CO2, NO, balance purified N2; (x) C3H8, CH4, CO, CO2, NO, balance purified N2.

(d)

Gases for species other than those listed in paragraph (c) of this point may be used (such as methanol in air, which may be used to determine response factors), as long as they are traceable to within ± 3,0 % of the international and/or national recognized standards true value, and meet the stability requirements of point 9.5.1.2;

(e)

Own calibration gases may be generated using a precision blending device, such as a gas divider, to dilute gases with purified N2 or purified synthetic air. If the gas dividers meet the specifications in point 9.4.5.6, and the gases being blended meet the requirements of paragraphs (a) and (c) of this point, the resulting blends are considered to meet the requirements of this point 9.5.1.1.

9.5.1.2.   Concentration and expiration date

The concentration of any calibration gas standard and its expiration date specified by the gas supplier shall be recorded.

(a)	No calibration gas standard may be used after its expiration date, except as allowed by paragraph (b) of this point.

(b)	Calibration gases may be relabelled and used after their expiration date if it is approved in advance by type approval or certification authority.

9.5.1.3.   Gas transfer

Gases shall be transferred from their source to analyzers using components that are dedicated to controlling and transferring only those gases.

The shelf life of all calibration gases shall be respected. The expiration date of the calibration gases stated by the manufacturer shall be recorded.

9.5.2.   Mass standards

PM balance calibration weights that are certified as international and/or national recognized standards-traceable within 0,1 % uncertainty shall be used. Calibration weights may be certified by any calibration lab that maintains international and/or national recognized standards-traceability. It shall be made sure that the lowest calibration weight has no greater than ten times the mass of an unused PM-sample medium. The calibration report shall also state the density of the weights.

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(1)  Perform calibrations and verifications more frequently, according to measurement system manufacturer instructions and good engineering judgment.

(2)  The CVS verification is not required for systems that agree within ± 2 % based on a chemical balance of carbon or oxygen of the intake air, fuel, and diluted exhaust gas.

(1)  Molar flow rate may be used instead of standard volumetric flow rate as the term representing ‘quantity’. In this case maximum molar flow rate may be used instead of the maximum standard volumetric flow rate in the corresponding linearity criteria.

(2)  As long as aqueous condensation in storage container is prevented.

(3)  Up to 313 K (40 °C).

(4)  Up to 475 K (202 °C).

(5)  At 464 ± 11 K (191 ± 11 °C).

(3)  Accuracy and repeatability are all determined with the same collected data, as described in point 9.4.3, and based on absolute values. ‘pt.’ refers to the overall mean value expected at the emission limit; ‘max.’ refers to the peak value expected at the emission limit over the duty cycle, not the maximum of the instrument's range; ‘meas.’ refers to the actual mean measured over the duty cycle.

(4)  It is not required that these levels of purity are internationally and/or nationally recognized standards traceable.

(5)  It is not required that these levels of purity are internationally and/or nationally recognized standards traceable.