Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery

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 emission limit value. 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 [^E0014] Purified N2 [^E0014] THC (C1 equivalent) ≤ 0,05 μmol/mol ≤ 0,05 μmol/mol CO ≤ 1 μmol/mol ≤ 1 μmol/mol

CO2 ≤ 10 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 (¹) It is not required that these levels of purity are internationally and/or nationally recognized standards traceable. Table 6.10 Contamination limits applicable for raw measurements [μmol/mol = ppm] Constituent Purified Synthetic Air [^E0015] Purified N2 [^E0015] 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 (¹) It is not required that these levels of purity are internationally and/or nationally recognized standards traceable.

• (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) CH4, balance purified synthetic air and/or N2 (as applicable);
• (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 approval 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.

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.

Appendix 1

Particle number emissions measurement equipment

1. Measurement test procedure

1.1.   Sampling

Particle number emissions shall be measured by continuous sampling from either a partial flow dilution system, as described in point 9.2.3 of this Annex or a full flow dilution system as described in point 9.2.2 of this Annex.

1.1.1.   Diluent filtration

Diluent used for both the primary and, where applicable, secondary dilution of the exhaust gas in the dilution system shall be passed through filters meeting the High-Efficiency Particulate Air (HEPA) filter requirements defined in Article 1(19). The diluent may optionally be charcoal scrubbed before being passed to the HEPA filter to reduce and stabilize the hydrocarbon concentrations in the diluent. It is recommended that an additional coarse particle filter is situated before the HEPA filter and after the charcoal scrubber, if used.

1.2.   Compensating for particle number sample flow — full flow dilution systems

To compensate for the mass flow extracted from the dilution system for particle number sampling the extracted mass flow (filtered) shall be returned to the dilution system. Alternatively, the total mass flow in the dilution system may be mathematically corrected for the particle number sample flow extracted. Where the total mass flow extracted from the dilution system for the sum of particle number sampling and particulate mass sampling is less than 0,5 % of the total diluted exhaust gas flow in the dilution tunnel (med) this correction, or flow return, may be neglected.

1.3.   Compensating for particle number sample flow — partial flow dilution systems

• 1.3.1. For partial flow dilution systems the mass flow extracted from the dilution system for particle number sampling shall be accounted for in controlling the proportionality of sampling. This shall be achieved either by feeding the particle number sample flow back into the dilution system upstream of the flow measuring device or by mathematical correction as outlined in point 1.3.2. In the case of total sampling type partial flow dilution systems, the mass flow extracted for particle number sampling shall also be corrected for in the particulate mass calculation as outlined in point 1.3.3.

• 1.3.2. The instantaneous exhaust gas flow rate into the dilution system (qmp), used for controlling the proportionality of sampling, shall be corrected according to one of the following methods:

• (a) In the case where the extracted particle number sample flow is discarded, equation (6-20) in point 8.1.8.6.1 of this Annex shall be replaced by equation (6-29): qmp = qmdew – qmdw + qex (6-29) Where: qmdew is the diluted exhaust gas mass flow rate, kg/s, qmdw is the dilution air mass flow rate, kg/s, qex is the particle number sample mass flow rate, kg/s. The qex signal sent to the partial flow system controller shall be accurate to within ± 0,1 % of qmdew at all times and should be sent with frequency of at least 1 Hz.

• (b) In the case where the extracted particle number sample flow is fully or partially discarded, but an equivalent flow is fed back to the dilution system upstream of the flow measurement device, equation (6-20) in point 8.1.8.6.1 of this Annex shall be replaced by equation (6-30): qmp = qmdew – qmdw + qex – qsw (6-30) Where: qmdew is the diluted exhaust gas mass flow rate, kg/s, qmdw is the dilution air mass flow rate, kg/s, qex is the particle number sample mass flow rate, kg/s, qsw is the mass flow rate fed back into dilution tunnel to compensate for particle number sample extraction, kg/s. The difference between qex and qsw sent to the partial flow system controller shall be accurate to within ± 0,1 % of qmdew at all times. The signal (or signals) should be sent with frequency of at least 1 Hz.

• 1.3.3. Correction of PM measurement

When a particle number sample flow is extracted from a total sampling partial flow dilution system, the mass of particulates (mPM) calculated in point 2.3.1.1 of Annex VII shall be corrected as follows to account for the flow extracted. This correction is required even where filtered extracted flow is fed back into the partial flow dilution systems, as set out in equation (6-31):

Image omitted; see official source	(6-31)

Where:

• mPM is the mass of particulates determined in accordance with point 2.3.1.1 of Annex VII, g/test,

• msed is the total mass of diluted exhaust gas passing through the dilution tunnel, kg,

- mex is the total mass of diluted exhaust gas extracted from the dilution tunnel for particle number sampling, kg.

- 1.3.4. Proportionality of partial flow dilution sampling

For particle number measurement, exhaust gas mass flow rate, determined according to any of the methods described in points 2.1.6.1 to 2.1.6.4 of Annex VII, is used for controlling the partial flow dilution system to take a sample proportional to the exhaust gas mass flow rate. The quality of proportionality shall be checked by applying a regression analysis between sample and exhaust gas flow in accordance with point 8.2.1.2 of this Annex.

• 1.3.5. Particle number calculation

Determination and calculation of PN are laid down in Appendix 5 of Annex VII.

2. Measurement equipment

2.1.   Specification

2.1.1.   System overview

• 2.1.1.1. The particle sampling system shall consist of a probe or sampling point extracting a sample from a homogenously mixed flow in a dilution system as described in point 9.2.2 or 9.2.3 of this Annex, a volatile particle remover (VPR) upstream of a particle number counter (PNC) and suitable transfer tubing.

• 2.1.1.2. It is recommended that a particle size pre-classifier (e.g. cyclone, impactor, etc.) be located prior to the inlet of the VPR. However, a sample probe acting as an appropriate size-classification device, such as shown in Figure 6.8, is an acceptable alternative to the use of a particle size pre-classifier. In the case of partial flow dilution systems it is acceptable to use the same pre-classifier for particulate mass and particle number sampling, extracting the particle number sample from the dilution system downstream of the pre-classifier. Alternatively separate pre-classifiers may be used, extracting the particle number sample from the dilution system upstream of the particulate mass pre-classifier.

2.1.2.   General requirements

• 2.1.2.1. The particle sampling point shall be located within a dilution system.

The sampling probe tip or particle sampling point and particle transfer tube (PTT) together comprise the particle transfer system (PTS). The PTS conducts the sample from the dilution tunnel to the entrance of the VPR. The PTS shall meet the following conditions:

In the case of full flow dilution systems and partial flow dilution systems of the fractional sampling type (as described in point 9.2.3 of this Annex) the sampling probe shall be installed near the tunnel centre line, 10 to 20 tunnel diameters downstream of the gas inlet, facing upstream into the tunnel gas flow with its axis at the tip parallel to that of the dilution tunnel. The sampling probe shall be positioned within the dilution tract so that the sample is taken from a homogeneous diluent/exhaust gas mixture.

In the case of partial flow dilution systems of the total sampling type (as described in point 9.2.3.of this Annex) the particle sampling point or sampling probe shall be located in the particulate transfer tube, upstream of the particulate filter holder, flow measurement device and any sample/bypass bifurcation point. The sampling point or sampling probe shall be positioned so that the sample is taken from a homogeneous diluent/exhaust gas mixture. The dimensions of the particle sampling probe should be sized not to interfere with the operation of the partial flow dilution system.

Sample gas drawn through the PTS shall meet the following conditions:

• (a) In the case of full flow dilution systems, it shall have a flow Reynolds number (Re) of < 1 700 ;

• (b) In the case of partial flow dilution systems, it shall have a flow Reynolds number (Re) of < 1 700 in the PTT i.e. downstream of the sampling probe or point;

• (c) It shall have a residence time in the PTS of ≤ 3 seconds.

• (d) Any other sampling configuration for the PTS for which equivalent particle penetration at 30 nm can be demonstrated will be considered acceptable.

• (e) The outlet tube (OT) conducting the diluted sample from the VPR to the inlet of the PNC shall have the following properties:

• (f) It shall have an internal diameter of ≥ 4 mm;

- (g) Sample Gas flow through the OT shall have a residence time of ≤ 0,8 second.

• (h) Any other sampling configuration for the OT for which equivalent particle penetration at 30 nm can be demonstrated will be considered acceptable.

• 2.1.2.2. The VPR shall include devices for sample dilution and for volatile particle removal.

• 2.1.2.3. All parts of the dilution system and the sampling system from the exhaust pipe up to the PNC, which are in contact with raw and diluted exhaust gas, shall be designed to minimize deposition of the particles. All parts shall be made of electrically conductive materials that do not react with exhaust gas components, and shall be electrically grounded to prevent electrostatic effects.

• 2.1.2.4. The particle sampling system shall incorporate good aerosol sampling practice that includes the avoidance of sharp bends and abrupt changes in cross-section, the use of smooth internal surfaces and the minimisation of the length of the sampling line. Gradual changes in the cross-section are permissible.

2.1.3.   Specific requirements

• 2.1.3.1. The particle sample shall not pass through a pump before passing through the PNC.

• 2.1.3.2. A sample pre-classifier is recommended.

• 2.1.3.3. The sample preconditioning unit shall:

• 2.1.3.3.1. Be capable of diluting the sample in one or more stages to achieve a particle number concentration below the upper threshold of the single particle count mode of the PNC and a gas temperature below 308 K (35 °C) at the inlet to the PNC;

• 2.1.3.3.2. Include an initial heated dilution stage which outputs a sample at a temperature of ≥ 423 K (150 °C) and ≤ 673 K (400 °C), and dilutes by a factor of at least 10;

• 2.1.3.3.3. Control heated stages to constant nominal operating temperatures, within the range specified in point 2.1.3.3.2, to a tolerance of ± 10 K (± 10 °C). Provide an indication of whether or not heated stages are at their correct operating temperatures;

• 2.1.3.3.4. Achieve a particle concentration reduction factor (ƒr(di)), as defined in point 2.2.2.2, for particles of 30 nm and 50 nm electrical mobility diameters, that is no more than 30 % and 20 % respectively higher, and no more than 5 % lower than that for particles of 100 nm electrical mobility diameter for the VPR as a whole;

• 2.1.3.3.5. Also achieve > 99,0 % vaporisation of 30 nm tetracontane (CH3(CH2)38CH3) particles, with an inlet concentration of ≥ 10 000 cm^–3, by means of heating and reduction of partial pressures of the tetracontane.

• 2.1.3.4. The PNC shall:

• 2.1.3.4.1. Operate under full flow operating conditions;

• 2.1.3.4.2. Have a counting accuracy of ± 10 % across the range 1 cm^–3 to the upper threshold of the single particle count mode of the PNC against a traceable standard. At concentrations below 100 cm^–3 measurements averaged over extended sampling periods may be required to demonstrate the accuracy of the PNC with a high degree of statistical confidence;

• 2.1.3.4.3. Have a readability of at least 0,1 particle cm^–3 at concentrations below 100 cm^–3;

• 2.1.3.4.4. Have a linear response to particle concentrations over the full measurement range in single particle count mode;

• 2.1.3.4.5. Have a data reporting frequency equal to or greater than 0,5 Hz;

• 2.1.3.4.6. Have a response time over the measured concentration range of less than 5 s;

• 2.1.3.4.7. Incorporate a coincidence correction function up to a maximum 10 % correction, and may make use of an internal calibration factor as determined in point 2.2.1.3, but shall not make use of any other algorithm to correct for or define the counting efficiency;

• 2.1.3.4.8. Have counting efficiencies at particle sizes of 23 nm (± 1 nm) and 41 nm (± 1 nm) electrical mobility diameter of 50 % (± 12 %) and > 90 % respectively. These counting efficiencies may be achieved by internal (for example; control of instrument design) or external (for example; size pre-classification) means;

- 2.1.3.4.9. If the PNC makes use of a working liquid, it shall be replaced at the frequency specified by the instrument manufacturer.

• 2.1.3.5. Where they are not held at a known constant level at the point at which PNC flow rate is controlled, the pressure and/or temperature at inlet to the PNC shall be measured and reported for the purposes of correcting particle concentration measurements to standard conditions.

• 2.1.3.6. The sum of the residence time of the PTS, VPR and OT plus the response time of the PNC shall be no greater than 20 s.

• 2.1.3.7. The transformation time of the entire particle number sampling system (PTS, VPR, OT and PNC) shall be determined by aerosol switching directly at the inlet of the PTS. The aerosol switching shall be done in less than 0,1 s. The aerosol used for the test shall cause a concentration change of at least 60 % full scale (FS).

The concentration trace shall be recorded. For time alignment of the particle number concentration and exhaust gas flow signals, the transformation time is defined as the time from the change (t0) until the response is 50 % of the final reading (t50).

2.1.4.   Recommended system description

This point contains the recommended practice for measurement of particle number. However, any system meeting the performance specifications in points 2.1.2 and 2.1.3 is acceptable.

Figures 6.9 and 6.10 are schematic drawings of the recommended particle sampling system configures for partial and full flow dilution systems respectively.

Figure 6.9

Schematic of recommended particle sampling system — Partial flow sampling

Image omitted; see official source

Figure 6.10

Schematic of recommended particle sampling system – Full flow sampling

Image omitted; see official source

2.1.4.1.   Sampling system description

The particle sampling system shall consist of a sampling probe tip or particle sampling point in the dilution system, a particle transfer tube (PTT), a particle pre-classifier (PCF) and a volatile particle remover (VPR) upstream of the particle number concentration measurement (PNC) unit. The VPR shall include devices for sample dilution (particle number diluters: PND1 and PND2) and particle evaporation (Evaporation tube, ET). The sampling probe or sampling point for the test gas flow shall be so arranged within the dilution tract that a representative sample gas flow is taken from a homogeneous diluent/exhaust gas mixture. The sum of the residence time of the system plus the response time of the PNC shall be no greater than 20 s.

2.1.4.2.   Particle transfer system

The sampling probe tip or particle sampling point and Particle Transfer Tube (PTT) together comprise the Particle Transfer System (PTS). The PTS conducts the sample from the dilution tunnel to the entrance to the first particle number diluter. The PTS shall meet the following conditions:

In the case of full flow dilution systems and partial flow dilution systems of the fractional sampling type (as described in point 9.2.3 of this Annex) the sampling probe shall be installed near the tunnel centre line, 10 to 20 tunnel diameters downstream of the gas inlet, facing upstream into the tunnel gas flow with its axis at the tip parallel to that of the dilution tunnel. The sampling probe shall be positioned within the dilution tract so that the sample is taken from a homogeneous diluent/exhaust gas mixture.

In the case of partial flow dilution systems of the total sampling type (as described in point 9.2.3 of this Annex) the particle sampling point shall be located in the particulate transfer tube, upstream of the particulate filter holder, flow measurement device and any sample/bypass bifurcation point. The sampling point or sampling probe shall be positioned so that the sample is taken from a homogeneous diluent/exhaust gas mixture.

Sample gas drawn through the PTS shall meet the following conditions:

It shall have a flow Reynolds number (Re) of < 1 700 ;

It shall have a residence time in the PTS of ≤ 3 seconds.

Any other sampling configuration for the PTS for which equivalent particle penetration for particles of 30 nm electrical mobility diameter can be demonstrated will be considered acceptable.

The outlet tube (OT) conducting the diluted sample from the VPR to the inlet of the PNC shall have the following properties:

It shall have an internal diameter of ≥ 4 mm;

Sample gas flow through the POT shall have a residence time of ≤ 0,8 second.

Any other sampling configuration for the OT for which equivalent particle penetration for particles of 30 nm electrical mobility diameter can be demonstrated will be considered acceptable.

2.1.4.3.   Particle pre-classifier

The recommended particle pre-classifier shall be located upstream of the VPR. The pre-classifier 50 % cut point particle diameter shall be between 2,5 μm and 10 μm at the volumetric flow rate selected for sampling particle number emissions. The pre-classifier shall allow at least 99 % of the mass concentration of 1 μm particles entering the pre-classifier to pass through the exit of the pre-classifier at the volumetric flow rate selected for sampling particle number emissions. In the case of partial flow dilution systems, it is acceptable to use the same pre-classifier for particulate mass and particle number sampling, extracting the particle number sample from the dilution system downstream of the pre-classifier. Alternatively separate pre-classifiers may be used, extracting the particle number sample from the dilution system upstream of the particulate mass pre-classifier.

2.1.4.4.   Volatile particle remover (VPR)

The VPR shall comprise one particle number diluter (PND1), an evaporation tube and a second diluter (PND2) in series. This dilution function is to reduce the number concentration of the sample entering the particle concentration measurement unit to less than the upper threshold of the single particle count mode of the PNC and to suppress nucleation within the sample. The VPR shall provide an indication of whether or not PND1 and the evaporation tube are at their correct operating temperatures.

The VPR shall achieve > 99,0 % vaporisation of 30 nm tetracontane (CH3(CH2)38CH3) particles, with an inlet concentration of ≥ 10 000 cm^{– 3}, by means of heating and reduction of partial pressures of the tetracontane. It shall also achieve a particle concentration reduction factor (fr) for particles of 30 nm and 50 nm electrical mobility diameters, that is no more than 30 % and 20 % respectively higher, and no more than 5 % lower than that for particles of 100 nm electrical mobility diameter for the VPR as a whole.

2.1.4.4.1.   First particle number dilution device (PND1)

The first particle number dilution device shall be specifically designed to dilute particle number concentration and operate at a (wall) temperature of 423 K to 673 K (150 °C to 400 °C). The wall temperature set point should be held at a constant nominal operating temperature, within this range, to a tolerance of ± 10 °C and not exceed the wall temperature of the ET (point 2.1.4.4.2). The diluter should be supplied with HEPA filtered dilution air and be capable of a dilution factor of 10 to 200 times.

2.1.4.4.2.   Evaporation Tube (ET)

The entire length of the ET shall be controlled to a wall temperature greater than or equal to that of the first particle number dilution device and the wall temperature held at a fixed nominal operating temperature between 300 °C and 400 °C, to a tolerance of ± 10 °C.

2.1.4.4.3.   Second particle number dilution device (PND2)

PND2 shall be specifically designed to dilute particle number concentration. The diluter shall be supplied with HEPA filtered dilution air and be capable of maintaining a single dilution factor within a range of 10 to 30 times. The dilution factor of PND2 shall be selected in the range between 10 and 15 such that particle number concentration downstream of the second diluter is less than the upper threshold of the single particle count mode of the PNC and the gas temperature prior to entry to the PNC is < 35 °C.

2.1.4.5.   Particle number counter (PNC)

The PNC shall meet the requirements of point 2.1.3.4.

2.2.   Calibration/Validation of the particle sampling system ([^E0016])

2.2.1.   Calibration of the particle number counter

• 2.2.1.1 The Technical Service shall ensure the existence of a calibration certificate for the PNC demonstrating compliance with a traceable standard within a 12-month period prior to the emissions test.

• 2.2.1.2. The PNC shall also be recalibrated and a new calibration certificate issued following any major maintenance.

• 2.2.1.3. Calibration shall be traceable to a standard calibration method:

- (a) By comparison of the response of the PNC under calibration with that of a calibrated aerosol electrometer when simultaneously sampling electrostatically classified calibration particles; or

• (b) By comparison of the response of the PNC under calibration with that of a second PNC which has been directly calibrated by the above method.

In the electrometer case, calibration shall be undertaken using at least six standard concentrations spaced as uniformly as possible across the PNC's measurement range. These points will include a nominal zero concentration point produced by attaching HEPA filters of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of each instrument. With no calibration factor applied to the PNC under calibration, measured concentrations shall be within ± 10 % of the standard concentration for each concentration used, with the exception of the zero point, otherwise the PNC under calibration shall be rejected. The gradient from a linear regression of the two data sets shall be calculated and recorded. A calibration factor equal to the reciprocal of the gradient shall be applied to the PNC under calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R²) of the two data sets and shall be equal to or greater than 0,97. In calculating both the gradient and R² the linear regression shall be forced through the origin (zero concentration on both instruments).

In the reference PNC case, calibration shall be undertaken using at least six standard concentrations across the PNC's measurement range. At least 3 points shall be at concentrations below 1 000 cm^{– 3}, the remaining concentrations shall be linearly spaced between 1 000 cm^{– 3} and the maximum of the PNC's range in single particle count mode. These points will include a nominal zero concentration point produced by attaching HEPA filters of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of each instrument. With no calibration factor applied to the PNC under calibration, measured concentrations shall be within ± 10 % of the standard concentration for each concentration, with the exception of the zero point, otherwise the PNC under calibration shall be rejected. The gradient from a linear regression of the two data sets shall be calculated and recorded. A calibration factor equal to the reciprocal of the gradient shall be applied to the PNC under calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R²) of the two data sets and shall be equal to or greater than 0,97. In calculating both the gradient and R² the linear regression shall be forced through the origin (zero concentration on both instruments).

• 2.2.1.4. Calibration shall also include a check, against the requirements in point 2.1.3.4.8, on the PNC's detection efficiency with particles of 23 nm electrical mobility diameter. A check of the counting efficiency with 41 nm particles is not required.

2.2.2.   Calibration/Validation of the volatile particle remover

• 2.2.2.1. Calibration of the VPR's particle concentration reduction factors across its full range of dilution settings, at the instrument's fixed nominal operating temperatures, shall be required when the unit is new and following any major maintenance. The periodic validation requirement for the VPR's particle concentration reduction factor is limited to a check at a single setting, typical of that used for measurement on diesel particulate filter equipped non-road mobile machinery. The Technical Service shall ensure the existence of a calibration or validation certificate for the volatile particle remover within a 6-month period prior to the emissions test. If the volatile particle remover incorporates temperature monitoring alarms a 12 month validation interval shall be permissible.

The VPR shall be characterised for particle concentration reduction factor with solid particles of 30 nm, 50 nm and 100 nm electrical mobility diameter. Particle concentration reduction factors (ƒr(d)) for particles of 30 nm and 50 nm electrical mobility diameters shall be no more than 30 % and 20 % higher respectively, and no more than 5 % lower than that for particles of 100 nm electrical mobility diameter. For the purposes of validation, the mean particle concentration reduction factor shall be within ± 10 % of the mean particle concentration reduction factor (

Image omitted; see official source ) determined during the primary calibration of the VPR.

• 2.2.2.2. The test aerosol for these measurements shall be solid particles of 30, 50 and 100 nm electrical mobility diameter and a minimum concentration of 5 000 particles cm^{– 3} at the VPR inlet. Particle concentrations shall be measured upstream and downstream of the components.

The particle concentration reduction factor at each particle size (ƒr(di)) shall be calculated by means of equation (6-32):

Image omitted; see official source	(6-32)

Where:

• Nin(di) is the upstream particle number concentration for particles of diameter di

• Nout(di) is the downstream particle number concentration for particles of diameter di

• di is the particle electrical mobility diameter (30, 50 or 100 nm)

Nin(di) and Nout(di) shall be corrected to the same conditions.

The mean particle concentration reduction (

Image omitted; see official source

) at a given dilution setting shall be calculated by means of equation (6-33):

Image omitted; see official source	(6-33)

It is recommended that the VPR is calibrated and validated as a complete unit.

• 2.2.2.3. The Technical Service shall ensure the existence of a validation certificate for the VPR demonstrating effective volatile particle removal efficiency within a 6 month period prior to the emissions test. If the volatile particle remover incorporates temperature monitoring alarms a 12 month validation interval shall be permissible. The VPR shall demonstrate greater than 99,0 % removal of tetracontane (CH3(CH2)38CH3) particles of at least 30 nm electrical mobility diameter with an inlet concentration of ≥ 10 000 cm^{– 3} when operated at its minimum dilution setting and manufacturers recommended operating temperature.

2.2.3.   Particle number system check procedures

- 2.2.3.1. Prior to each test, the particle counter shall report a measured concentration of less than 0,5 particles cm^{– 3} when a HEPA filter of at least class H13 of EN 1822:2008, or equivalent performance, is attached to the inlet of the entire particle sampling system (VPR and PNC).

- 2.2.3.2. On a monthly basis, the flow into the particle counter shall report a measured value within 5 % of the particle counter nominal flow rate when checked with a calibrated flow meter.

• 2.2.3.3. Each day, following the application of a HEPA filter of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of the particle counter, the particle counter shall report a concentration of ≤ 0,2 cm^{– 3}. Upon removal of this filter, the particle counter shall show an increase in measured concentration to at least 100 particles cm^{– 3} when challenged with ambient air and a return to ≤ 0,2 cm^{– 3} on replacement of the HEPA filter.

• 2.2.3.4. Prior to the start of each test it shall be confirmed that the measurement system indicates that the evaporation tube, where featured in the system, has reached its correct operating temperature.

• 2.2.3.5. Prior to the start of each test it shall be confirmed that the measurement system indicates that the diluter PND1 has reached its correct operating temperature.

Appendix 2

Installation requirements for equipment and auxiliaries

Number	Equipment and auxiliaries	Fitted for emission test
1	Inlet system
	Inlet manifold	Yes
	Crankcase emission control system	Yes
	Air flow meter	Yes
	Air filter	Yes [^E0017]
	Inlet silencer	Yes [^E0017]
2	Exhaust system
	Exhaust after-treatment system	Yes
	Exhaust manifold	Yes
	Connecting pipes	Yes [^E0018]
	Silencer	Yes [^E0018]
	Tail pipe	Yes [^E0018]
	Exhaust brake	No [^E0019]
	Pressure charging device	Yes
3	Fuel supply pump	Yes [^E0020]
4	Fuel injection equipment
	Prefilter	Yes
	Filter	Yes
	Pump	Yes
5	High-pressure pipe	Yes
	Injector	Yes
	Electronic control unit, sensors, etc.	Yes
	Governor/control system	Yes
	Automatic full-load stop for the control rack depending on atmospheric conditions	Yes
6	Liquid-cooling equipment
	Radiator	No
	Fan	No
	Fan cowl	No
	Water pump	Yes [^E0021]
	Thermostat	Yes [^E0022]
7	Air cooling
	Cowl	No [^E0023]
	Fan or Blower	No [^E0023]
	Temperature-regulating device	No
8	Pressure charging equipment
	Compressor driven either directly by the engine and/or by the exhaust system	Yes
	Charge air cooler	Yes [^E0023] [^E0024]
	Coolant pump or fan (engine-driven)	No [^E0023]
	Coolant flow control device	Yes
9	Auxiliary test-bed fan	Yes, if necessary
10	Anti-pollution device	Yes
11	Starting equipment	Yes or test bed equipment [^E0025]
12	Lubricating oil pump	Yes
13	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. The following non-exhaustive list is given as an example: (i) air compressor for brakes (ii) power steering compressor (iii) suspension compressor (iv) air-conditioning system.	No

The complete inlet system shall be fitted as provided for the intended application: (i) where there is a risk of an appreciable effect on the engine power; (ii) when the manufacturer requests that this should be done.

In other cases, an equivalent system may be used and a check should be made to ascertain that the intake pressure does not differ by more than 100 Pa from the upper limit specified by the manufacturer for a clean air filter.

The complete exhaust system shall be fitted as provided for the intended application: (i) where there is a risk of an appreciable effect on the engine power; (ii) when the manufacturer requests that this should be done.

In other cases, an equivalent system may be installed provided the pressure measured does not differ by more than 1 000 Pa from the upper limit specified by the manufacturer.

[^E0019]: (³)

If an exhaust system brake is incorporated in the engine, the throttle valve shall be fixed in the fully open position.

[^E0020]: (⁴)

The fuel feed pressure may be adjusted, if necessary, to reproduce the pressure existing in the particular engine application (particularly when a ‘fuel return’ system is used).

[^E0021]: (⁵)

The cooling-liquid circulation shall be operated by the engine water pump only. Cooling of the liquid may be produced by an external circuit, such that the pressure loss of this circuit and the pressure at the pump inlet remain substantially the same as those of the engine cooling system.

The thermostat may be fixed in the fully open position.

When the cooling fan or blower is fitted for the test, the power absorbed shall be added to the results, except for cooling fans of air cooled engines directly fitted on the crankshaft. The fan or blower power shall be determined at the speeds used for the test either by calculation from standard characteristics or by practical tests.

[^E0024]: (⁸)

Charge air-cooled engines shall be tested with charge air cooling, whether liquid — or air-cooled, but if the manufacturer prefers, a test bench system may replace the air cooler. In either case, the measurement of power at each speed shall be made with the maximum pressure drop and the minimum temperature drop of the engine air across the charge air cooler on the test bench system as those specified by the manufacturer.

The power for electrical or other starting systems shall be provided from the test bed.

Appendix 3

Verification of torque signal broadcast by electronic control unit

The purpose of this Appendix is to set out the requirements for verification in the case that the manufacturer intends to use the torque signal broadcast by the electronic control unit (ECU), of engines so equipped, during the conduct of in-service monitoring tests according to Delegated Regulation (EU) 2017/655.

The basis for the net torque shall be uncorrected net torque delivered by the engine inclusive of the equipment and auxiliaries to be included for an emissions test according to Appendix 2.

With the engine installed on the test bench for conducting the mapping procedure, means shall be provided to read the torque signal broadcast by the ECU according to the requirements of Appendix 6 of Annex I to Delegated Regulation (EU) 2017/655.

When conducting the mapping procedure according to section 7.6.2 of this Annex readings of the torque measured by the dynamometer and torque broadcast by the ECU shall be taken simultaneously at a minimum of three points on the torque curve. At least one of the readings shall be taken at a point on the curve where the torque is no less than 98 % of the maximum value.

The torque broadcast by the ECU shall be accepted without correction if, at each point where measurements were taken, the factor calculated from dividing the torque value from the dynamometer by the torque value from the ECU is not less than 0,93 (i.e. a maximum difference of 7 %). In this case it shall be recorded in the type approval certificate that the torque broadcast by the ECU has been verified without correction. Where the factor at one or more test points is less than 0,93 the average correction factor shall be determined from all the points where readings were taken and recorded in the type approval certificate. Where a factor is recorded in the type approval certificate it shall be applied to the torque broadcast by the ECU when conducting in-service monitoring tests according to Delegated Regulation (EU) 2017/655.

Appendix 4

Procedure for the measurement of ammonia

• 1. This appendix describes the procedure for measurement of ammonia (NH3). For non-linear analysers, the use of linearising circuits shall be permitted.

• 1. Three measurement principles are specified for NH3 measurement and either principle may be used provided it meets the criteria specified in points 2.1, 2.2 or 2.3, respectively. Gas dryers shall not be permitted for NH3 measurement.

2.1.   Fourier Transform Infrared (hereinafter ‘FTIR’) analyser

2.1.1.   Measurement principle

The FTIR employs the broad waveband infrared spectroscopy principle. It allows simultaneous measurement of exhaust gas components whose standardized spectra are available in the instrument. The absorption spectrum (intensity/wavelength) is calculated from the measured interferogram (intensity/time) by means of the Fourier transform method.

2.1.2.   Installation and sampling

The FTIR shall be installed in accordance with the instrument manufacturer's instructions. The NH3 wavelength shall be selected for evaluation. The sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C) in order to minimize NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible.

2.1.3.   Cross interference

The spectral resolution of the NH3 wavelength shall be within 0,5 cm^{– 1} in order to minimize cross interference from other gases present in the exhaust gas.

2.2.   Non Dispersive Ultra Violet Resonance Absorption analyser (hereinafter ‘NDUV’)

2.2.1.   Measurement Principle

The NDUV is based on a purely physical principle, no auxiliary gases or equipment is necessary. The main element of the photometer is an electrode-less discharge lamp. It produces a sharply structured radiation in the ultraviolet range, enabling the measurement of several components such as NH3.

The photometric system has a dual beam in time design set up to produce a measuring and a reference beam by filter correlation technique.

In order to achieve a high stability of the measuring signal the dual beam in time design is combined with a dual beam in space design. The detector signals processing fosters an almost negligible amount of zero point drift rate.

In the calibration mode of the analyser a sealed-off quartz cell is tilted into the beam path to obtain an exact calibration value, since any reflection and absorption losses of the cell windows are compensated. Since the gas filling of the cell is very stable, this calibration method leads to a very high long term stability of the photometer.

2.2.2.   Installation

The analyser shall be installed within an analyser cabinet using extractive sampling in accordance with the instrument manufacturer's instructions. The analyzer location shall be capable of supporting the weight specified by the manufacturer.

The sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C).

In addition, the sampling line shall be as short as possible. Influence from exhaust gas temperature and pressure, installation environment and vibrations on the measurement shall be minimized.

The gas analyzer shall be protected from cold, heat, temperature variations, and strong air currents, accumulation of dust, corrosive atmosphere and vibrations. Adequate air circulation shall be provided to avoid heat build-up. The complete surface shall be used to dissipate the heat losses.

2.2.3.   Cross Sensitivity

An appropriate spectral range shall be chosen in order to minimize cross interferences of accompanying gases. Typical components causing cross sensitivities on the NH3 measurement are SO2, NO2 and NO.

Additionally, further methods can be applied to reduce the cross sensitivities.

• (a) Usage of interference filters;

• (b) Cross sensitivity compensation by measuring cross sensitivity components and using the measurement signal for compensation.

2.3.   Laser Infrared analyser

2.3.1.   Measurement principle

An infrared laser such as a tunable diode laser (TDL) or a quantum cascade laser (QCL) can emit coherent light in the near-infrared region or in mid-infrared region respectively where nitrogen compounds including NH3 have strong absorption. This laser optics can give a pulsed-mode high resolution narrow band near-infrared or mid-infrared spectrum. Therefore, laser infrared analyzers can reduce interference caused by the spectral overlap of co-existing components in engine exhaust gas.

2.3.2.   Installation

The analyser shall be installed either directly in the exhaust pipe (in-situ) or within an analyser cabinet using extractive sampling in accordance with the instrument manufacturer's instructions. If installed in an analyser cabinet, the sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C) in order to minimize NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible.

Influence from exhaust gas temperature and pressure, installation environment and vibrations on the measurement shall be minimized, or compensation techniques be used.

If applicable, sheath air used in conjunction with in-situ measurement for protection of the instrument, shall not affect the concentration of any exhaust gas component measured downstream of the device, or sampling of other exhaust gas components shall be made upstream of the device.

2.3.3.   Interference verification for NH3 laser infrared analyzers (cross interference)

2.3.3.1.   Scope and frequency

If NH3 is measured using laser infrared analyser, the amount of interference shall be verified after initial analyser installation and after major maintenance.

2.3.3.2.   Measurement principles for interference verification

Interference gasses can positively interfere with certain laser infrared analyzer by causing a response similar to NH3. If the analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, these other measurements shall be simultaneously conducted to test the compensation algorithms during the analyzer interference verification.

Good engineering judgment shall be used to determine interference gases for laser infrared analyzer. Note that interference species, with the exception of H2O, are dependent on the NH3 infrared absorption band chosen by the instrument manufacturer. For each analyzer the NH3 infrared absorption band shall be determined. For each NH3 infrared absorption band, good engineering judgment shall be used to determine interference gases to use in the verification.

• 1. Emissions test procedure

3.1.   Checking the analysers

Prior to the emissions test, the analyser range shall be selected. Emission analysers with automatic or manual range switching shall be permitted. During the test cycle, the range of the analysers shall not be switched.

Zero and span response shall be determined, if the provisions set out in point 3.4.2 do not apply for the instrument. For the span response, a NH3 gas that meets the specifications set out in point 4.2.7, shall be used. The use of reference cells that contain NH3 span gas is permitted.

3.2.   Collection of emission relevant data

At the start of the test sequence, the NH3 data collection shall be started, simultaneously. The NH3 concentration shall be measured continuously and stored with at least 1 Hz on a computer system.

3.3.   Operations after test

At the completion of the test, sampling shall continue until system response times have elapsed. Determination of analyser's drift in accordance with point 3.4.1 shall only be required if the information required in point 3.4.2 is not available.

3.4.   Analyser drift

• 3.4.1. As soon as practical but no later than 30 minutes after the test cycle is complete or during the soak period, the zero and span responses of the analyser shall be determined.  The difference between the pre-test and post-test results shall be less than 2 % of full scale.

• 3.4.2. Determination of analyser drift is not required in the following situations:

• (a) If the zero and span drift specified by the instrument manufacturer in points 4.2.3 and 4.2.4 meets the requirements of point 3.4.1;

• (b) The time interval for zero and span drift specified by the instrument manufacturer in points 4.2.3 and 4.2.4 exceeds the duration of the test.

• 1. Analyser specification and verification

4.1.   Linearity requirements

The analyser shall comply with the linearity requirements specified in Table 6.5 of this Annex. The linearity verification in accordance with point 8.1.4 of this Annex shall be performed at least at the minimum frequency set out in Table 6.4 of this Annex. With the prior approval of the approval authority, less than 10 reference points are permitted, if an equivalent accuracy can be demonstrated.

For the linearity verification, a NH3 gas that meets the specifications set out in point 4.2.7 shall be used. The use of reference cells that contain NH3 span gas shall be permitted.

Instruments, whose signals are used for compensation algorithms, shall meet the linearity requirements specified in Table 6.5 of this Annex. Linearity verification shall be done as required by internal audit procedures, by the instrument manufacturer or in accordance with ISO 9000 requirements.

4.2.   Analyser specifications

The analyser shall have a measuring range and response time appropriate for the accuracy required to measure the concentration of NH3 under transient and steady state conditions.

4.2.1.   Minimum detection limit

The analyser shall have a minimum detection limit of < 2 ppm under all conditions of testing.

4.2.2.   Accuracy

The accuracy, defined as the deviation of the analyser reading from the reference value, shall not exceed ± 3 % of the reading or ± 2 ppm, whichever is larger.

4.2.3.   Zero drift

The drift of the zero response and the related time interval shall be specified by the instrument manufacturer.

4.2.4.   Span drift

The drift of the span response and the related time interval shall be specified by the instrument manufacturer.

4.2.5.   System response time

The system response time shall be ≤ 20 s.

4.2.6.   Rise time

The rise time of the analyser shall be ≤ 5 s.

4.2.7.   NH3 calibration gas

A gas mixture with the following chemical composition shall be available.

NH3 and purified nitrogen.

The true concentration of the calibration gas shall be within ± 3 % of the nominal value. The concentration of NH3 shall be given on a volume basis (volume per cent or volume ppm).

The expiration date of the calibration gases shall be recorded.

4.2.8.   Interference verification procedure

The interference verification shall be performed as follows:

• (a) The NH3 analyzer shall be started, operated, zeroed, and spanned as it would be before an emission test;

• (b) A humidified interference test gas shall be created by bubbling a multi component span gas through distilled H2O in a sealed vessel. If the sample is not passed through a sample dryer, the vessel temperature shall be controlled to generate an H2O level at least as high as the maximum expected during emission testing. Interference span gas concentrations shall be used at least as high as the maximum expected during testing;

• (c) The humidified interference test gas shall be introduced into the sample system.

• (d) The water mole fraction, x H2O, of the humidified interference 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 analyser response to stabilize;

- (g) While the analyser 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 this section.

• (i) Interference procedures for individual interference gases may also run separately. If the interference gas levels used are higher than the maximum levels expected during testing, each observed interference value may 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 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 scaled interference values must meet the tolerance for combined interference as specified in paragraph (j) of this point.

• (j) Analyser shall have combined interference within ± 2 % of the applicable mean value of ammonia (NH3) specified in point 3.4 of Annex IV.

• 1. Alternative systems

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 of this Annex. In this case, ‘Results’ in that point shall refer to mean NH3 concentration calculated for the applicable cycle.

Appendix 5

Description of system responses

• 1. This appendix describes the times used to express the response of analytical systems and other measurement systems to an input signal.

• 1. The following times apply, as shown in figure 6-11:

• 2.1. Delay time is the difference in time between the change of the component to be measured at the reference point and a system response of 10 % of the final reading (t 10) with the sampling probe being defined as the reference point.

- 2.2. Response time is the difference in time between the change of the component to be measured at the reference point and a system response of 90 % of the final reading (t

90) with the sampling probe being defined as the reference point.

- 2.3. Rise time is the difference in time the 10 % and 90 % response of the final reading (t

90 – t 10)

- 2.4. Transformation time is the difference in time between the change of the component to be measured at the reference point and a system response of 50 % of the final reading (t

50) with the sampling probe being defined as the reference point

• 2.5. Step input time is the time at which there is a change in the parameter being measured.

Figure 6-11

Illustration of system responses

Image omitted; see official source

ANNEX VII

Method for data evaluation and calculation

Calculation of emissions shall be performed according to either section 2 (mass based calculations) or section 3 (molar based calculations). Mixture between the two methods is not permitted. It shall not be required to perform the calculations according to both section 2 and section 3.

The specific requirements for particle number (PN) measurement, where applicable, are laid down in Appendix 5.

1.1.   General symbols

| Section 2 | Section 3 | Unit | Quantity |

| --- | --- | --- | --- | | | A | m² | Area | | | At | m² | Venturi throat cross-sectional area | | b, D 0 | a 0 | t.b.d. [^E0028] | y intercept of the regression line | | A/F st | | — | Stoichiometric air to fuel ratio | | | C | — | Coefficient | | C d | C d | — | Discharge coefficient | | | C f | — | Flow coefficient | | c | x | ppm, % vol | Concentration/mole fraction (μmol/mol = ppm) | | c d | [^E0026] | ppm, % vol | Concentration on dry basis | | c w | [^E0026] | ppm, % vol | Concentration on wet basis | | cb | [^E0026] | ppm, % vol | Background concentration | | D | x dil | — | Dilution factor [^E0027] | | D 0 | | m³/rev | PDP calibration intercept | | d | d | m | Diameter | | d V | | m | Throat diameter of venturi | | e | e | g/kWh | Brake specific basis | | e gas | e gas | g/kWh | Specific emission of gaseous components | | e PM | e PM | g/kWh | Specific emission of particulates | | E | 1 – PF | % | Conversion efficiency (PF = Penetration fraction) | | F s | | — | Stoichiometric factor | | | f | Hz | Frequency | | f c | | — | Carbon factor | | | γ | — | Ratio of specific heats | | H | | g/kg | Absolute humidity | | | K | — | Correction factor | | K V | | Image omitted; see official source | CFV calibration function | | k f | | m³/kg fuel | Fuel specific factor | | k h | | — | Humidity correction factor for NOx, diesel engines | | k Dr | k Dr | — | Downward adjustment factor | | k r | k r | — | Multiplicative regeneration factor | | k Ur | k Ur | — | Upward adjustment factor | | k w,a | | — | Dry to wet correction factor for the intake air | | k w,d | | — | Dry to wet correction factor for the dilution air | | k w,e | | — | Dry to wet correction factor for the diluted exhaust gas | | k w,r | | — | Dry to wet correction factor for the raw exhaust gas | | μ | μ | kg/(m·s) | Dynamic viscosity | | M | M | g/mol | Molar mass [^E0028] | | M a | [^E0026] | g/mol | Molar mass of the intake air | | M e | ^v | g/mol | Molar mass of the exhaust gas | | M gas | M gas | g/mol | Molar mass of gaseous components | | m | m | kg | Mass | | m | a 1 | t.b.d. [^E0028] | Slope of the regression line | | | ν | m²/s | Kinematic viscosity | | m d | ^v | kg | Mass of the dilution air sample passed through the particulate sampling filters | | m ed | [^E0026] | kg | Total diluted exhaust gas mass over the cycle | | m edf | [^E0026] | kg | Mass of equivalent diluted exhaust gas over the test cycle | | m ew | [^E0026] | kg | Total exhaust gas mass over the cycle | | m f | [^E0026] | mg | Particulate sample mass collected | | m f,d | [^E0026] | mg | Particulate sample mass of the dilution air collected | | m gas | m gas | g | Mass of gaseous emissions over the test cycle | | m PM | m PM | g | Mass of particulate emissions over the test cycle | | m se | [^E0026] | kg | Exhaust gas sample mass over the test cycle | | m sed | [^E0026] | kg | Mass of diluted exhaust gas passing the dilution tunnel | | m sep | [^E0026] | kg | Mass of diluted exhaust gas passing the particulate collection filters | | m ssd | | kg | Mass of secondary dilution air | | | N | — | Total number of a series | | | n | mol | Amount of substance | | | ṅ | mol/s | Amount of substance rate | | n | f n | min^{– 1} | Engine rotational speed | | n p | | r/s | PDP pump speed | | P | P | kW | Power | | p | p | kPa | Pressure | | p a | | kPa | Dry atmospheric pressure | | p b | | kPa | Total atmospheric pressure | | p d | | kPa | Saturation vapour pressure of the dilution air | | p p | p abs | kPa | Absolute pressure | | p r | p H2O | kPa | Water vapour pressure | | p s | | kPa | Dry atmospheric pressure | | 1 — E | PF | % | Penetration fraction | | qm | ṁ | kg/s | Mass rate | | qm ad | ṁ [^E0026] | kg/s | Intake air mass flow rate on dry basis | | qm aw | [^E0026] | kg/s | Intake air mass flow rate on wet basis | | qm Ce | [^E0026] | kg/s | Carbon mass flow rate in the raw exhaust gas | | qm Cf | [^E0026] | kg/s | Carbon mass flow rate into the engine | | qm Cp | [^E0026] | kg/s | Carbon mass flow rate in the partial flow dilution system | | qm dew | [^E0026] | kg/s | Diluted exhaust gas mass flow rate on wet basis | | qm dw | [^E0026] | kg/s | Dilution air mass flow rate on wet basis | | qm edf | [^E0026] | kg/s | Equivalent diluted exhaust gas mass flow rate on wet basis | | qm ew | [^E0026] | kg/s | Exhaust gas mass flow rate on wet basis | | qm ex | [^E0026] | kg/s | Sample mass flow rate extracted from dilution tunnel | | qm f | [^E0026] | kg/s | Fuel mass flow rate | | qm p | [^E0026] | kg/s | Sample flow of exhaust gas into partial flow dilution system | | qV | V̇ | m³/s | Volume flow rate | | qV CVS | [^E0026] | m³/s | CVS volume rate | | qV s | [^E0026] | dm³/min | System flow rate of exhaust gas analyzer system | | qV t | [^E0026] | cm³/min | Tracer gas flow rate | | ρ | ρ | kg/m³ | Mass density | | ρ e | | kg/m³ | Exhaust gas density | | | r | — | Ratio of pressures | | r d | DR | — | Dilution ratio [^E0027] | | | Ra | μm | Average surface roughness | | RH | | % | Relative humidity | | r D | β | m/m | Ratio of diameters (CVS systems) | | r p | | — | Pressure ratio of SSV | | Re | Re^# | — | Reynolds number | | | S | K | Sutherland constant | | σ | σ | — | Standard deviation | | T | T | °C | Temperature | | | T | Nm | Engine torque | | T a | | K | Absolute temperature | | t | t | s | Time | | Δt | Δt | s | Time interval | | u | | — | Ratio between densities of gas component and exhaust gas | | V | V | m³ | Volume | | qV | V̇ | m³/s | Volume rate | | V 0 | | m³/r | PDP gas volume pumped per revolution | | W | W | kWh | Work | | W act | W act | kWh | Actual cycle work of the test cycle | | WF | WF | — | Weighting factor | | w | w | g/g | Mass fraction | | | Image omitted; see official source | mol/mol | Flow-weighted mean concentration | | X 0 | K s | s/rev | PDP calibration function | | | y | — | Generic variable | | Image omitted; see official source | Image omitted; see official source | | Arithmetic mean | | | Z | — | Compressibility factor |

See subscripts; e.g.: ṁ air for mass rate of dry air, ṁ fuel for fuel mass rate, etc.

[^E0027]: (²)

Dilution ratio r d in section 2 and DR in section 3: different symbols but same meaning and same equations. Dilution factor D in section 2 and x dil in section 3: different symbols but same physical meaning; equation (7-124) shows the relationship between x dil and DR.

t.b.d.= to be defined.

1.2.   Subscripts

Section 2 [^E0029]	Section 3	Quantity
act	act	Actual quantity
i		Instantaneous measurement (e.g.: 1 Hz)
	i	An individual of a series

In section 2 the meaning of subscript is determined by the associated quantity; for example, the subscript ‘d’ can indicate a dry basis as in ‘c d = concentration on dry basis’, dilution air as in ‘p d = saturation vapour pressure of the dilution air’ or ‘k w,d = dry to wet correction factor for the dilution air’, dilution ratio as in ‘r d’.

1.3.   Symbols and abbreviations for the chemical components (used also as a subscript)

| Section 2 | Section 3 | Quantity |

| --- | --- | --- | | Ar | Ar | Argon | | C1 | C1 | Carbon 1 equivalent hydrocarbon | | CH4 | CH4 | Methane | | C2H6 | C2H6 | Ethane | | C3H8 | C3H8 | Propane | | CO | CO | Carbon monoxide | | CO2 | CO2 | Carbon dioxide | | | H | Atomic hydrogen | | | H2 | Molecular hydrogen | | HC | HC | Hydrocarbon | | H2O | H2O | Water | | | He | Helium | | | N | Atomic nitrogen | | | N2 | Molecular nitrogen | | NOx | NOx | Oxides of nitrogen | | NO | NO | Nitric oxide | | NO2 | NO2 | Nitrogen dioxide | | | O | Atomic oxygen | | PM | PM | Particulate matter | | S | S | Sulphur |

1.4.   Symbols and abbreviations for the fuel composition

| Section 2 [^E0030] | Section 3 [^E0031] | Quantity |

| --- | --- | --- | | w C [^E0033] | w C [^E0033] | Carbon content of fuel, mass fraction [g/g] or [% mass] | | w H | w H | Hydrogen content of fuel, mass fraction [g/g] or [% mass] | | w N | w N | Nitrogen content of fuel, mass fraction [g/g] or [% mass] | | w O | w O | Oxygen content of fuel, mass fraction [g/g] or [% mass] | | w S | w S | Sulphur content of fuel, mass fraction [g/g] or [% mass] | | α | α | Atomic hydrogen-to-carbon ratio (H/C) | | ε | β | Atomic oxygen-to-carbon ratio (O/C) [^E0032] | | γ | γ | Atomic sulphur-to-carbon ratio (S/C) | | δ | δ | Atomic nitrogen-to-carbon ratio (N/C) |

Referred to a fuel with chemical formula CHαOεNδSγ.

Referred to a fuel with chemical formula CHαOβSγNδ.

Attention should be paid to the different meaning of symbol β in the two emissions calculation sections: in section 2 it refers to a fuel having the chemical formula CHαSγNδOε (i.e. the formula CβHαSγNδOε where β = 1, assuming one carbon atom per molecule), while in section 3 it refers to the oxygen-to-carbon ratio with CHαOβSγNδ. Then β of section 3 corresponds to ε of section 2.

Mass fraction w accompanied by the symbol of the chemical component as a subscript.

2.1.   Measurement of gaseous emissions in raw exhaust gas

2.1.1.   Discrete-mode NRSC tests

The emission rate of a gaseous emission qm gas, i [g/h] for each mode i of the steady state test shall be calculated by multiplying the concentration of the gaseous emission with its respective flow, as follows:

| | |

| --- | --- | | Image omitted; see official source | (7-1) |

where:

k	=	1 for cgasr,w,i in [ppm] and k = 10 000 for cgasr,w,i in [% vol]
---	---	---
k h	=	NOx correction factor [-], for NOx emission calculation (see point 2.1.4)
---	---	---
u gas	=	component specific factor or ratio between densities of gas component and exhaust gas [-]
---	---	---
qm ew, i	=	exhaust gas mass flow rate in mode i on a wet basis [kg/s]
---	---	---
c gas, i	=	emission concentration in the raw exhaust gas in mode i, on a wet basis [ppm] or [% vol]

2.1.2.   Transient (NRTC and LSI-NRTC) test cycles and RMC tests

The total mass per test of a gaseous emission m gas [g/test] shall be calculated by multiplication of the time aligned instantaneous concentrations and exhaust gas flows and integration over the test cycle by means of equation (7-2):

Image omitted; see official source	(7-2)

where:

| | | |

| --- | --- | --- | | ƒ | = | data sampling rate [Hz] | | | | | | --- | --- | --- | | k h | = | NOx correction factor [-], only to be applied for the NOx emission calculation | | | | | | --- | --- | --- | | k | = | 1 for cgasr,w,i in [ppm] and k = 10 000 for cgasr,w, i in [% vol] | | | | | | --- | --- | --- | | u gas | = | component specific factor [-] (see point 2.1.5) | | | | | | --- | --- | --- | | N | = | number of measurements [-] | | | | | | --- | --- | --- | | qm ew, i | = | instantaneous exhaust gas mass flow rate on a wet basis [kg/s] | | | | | | --- | --- | --- | | c gas, i | = | instantaneous emission concentration in the raw exhaust gas, on a wet basis [ppm] or [% vol] |

2.1.3.   Dry-to-wet concentration conversion