ANNEX VISupplementary provisions
ANNEX VI Annex VI to Delegated Regulation (EU) 2017/654 is amended as follows: (1) point 1 is replaced by the following: ‘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 Global technical regulation No 11 ( *1 ) (GTR No 11) and UNECE Regulation No 96.04 series of amendments ( *2 ) , Annex 4B. However, some points of the GTR No 11 are not needed in this Annex, or are modified in accordance with the technical progress. ( *1 ) Global technical regulation No 11 on Engine Emissions from agricultural and forestry tractors and from non-road mobile machinery under the Global Registry created on 18 November 2004, pursuant to Article 6 of the Agreement concerning the establishing of global technical regulations for wheeled vehicles, equipment and parts which can be fitted and/or be used on wheeled vehicles." ( *2 ) Regulation No 96 of the Economic Commission for Europe of the United Nations (UN/ECE) — Uniform provisions concerning the approval of compression ignition (C.I.) engines to be installed in agricultural and forestry tractors and in non-road mobile machinery with regard to the emissions of pollutants by the engine.’;" (2) in point 5.1, the second, third and fourth paragraphs are replaced by the following: ‘The measured values of gaseous and particulate pollutants and of CO 2 exhausted by the engine refer to the brake-specific emissions in grams per kilowatt-hour (g/kWh), or number per kilowatt-hour (#/kWh) for PN. 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: (a) the crankcase emissions determined in accordance with section 6.10, if relevant, (b) the adjustment factors for infrequent regeneration of the after-treatment system determined in accordance with section 6.6, if relevant, and (c) as the final step of the calculation, the deterioration factor determined in accordance with Annex III, shall not exceed the applicable limit values. The CO 2 shall be measured and reported for all engine sub-categories as required by Article 43(4) of Regulation (EU) 2016/1628.’; (3) point 5.2.5.1.1 is replaced by the following: ‘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 one of the following options: (a) Calculation based upon low speed and high speed values MTS = n lo + 0,95 · ( n hi – n lo ) (6-1) where: n hi is the high speed as defined in Article 1(12), n lo is the low speed as defined in Article 1(13). (b) Calculation based upon the longest vector method MTS = n i (6-2) where: 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 ) 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) where: 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 norm i is an engine speed normalized by dividing it by P norm i is an engine power normalized by dividing it by P max 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: (i) 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 P max , shall be the speed at which P max occurs; (ii) the speeds where ( 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 ).’; (4) point 5.2.5.2 is amended as follows: (a) the first paragraph is replaced by the following: ‘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 other than those tested on a constant-speed NRSC defined in Article 1(31) of this Regulation shall be determined from the applicable mapping procedure set out in point 7.6 of this Annex. Rated speed for variable-speed engines tested on a constant-speed NRSC shall be declared by the manufacturer according to the characteristics of the engine. 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.’; (b) the third paragraph is replaced by the following: ‘For engines of category NRSh the 100 % test speed shall be within ± 350 rpm of the rated speed declared by the manufacturer.’; (5) point 5.2.5.3 is amended as follows: (a) the introductory wording of the first paragraph is replaced by the following: ‘Where required, the maximum torque speed determined from the maximum torque curve established by the applicable engine mapping procedure in point 7.6.1 or 7.6.2 shall be one of the following:’; (b) in the last paragraph, the words ‘engines of category NRS or NRSh’ are replaced by the words ‘engines of category NRS’; (6) in point 6.2, the first paragraph is replaced by the following: ‘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 shall be designed to minimize accumulation of condensate. 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 293 K (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 K (± 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;’; (7) point 6.3.4 is replaced by the following: ‘6.3.4. Determination of auxiliary power Where applicable as per point 6.3.2 and 6.3.3, 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.’; (8) point 6.6.2.3 is amended as follows: (a) the last sentence of the first paragraph is replaced by the following: ‘The exact procedure to determine this frequency shall be agreed by the approval authority based upon good engineering judgement.’; (b) the title of Figure 6.1 is replaced by the following: ‘ Figure 6.1 Scheme of infrequent regeneration with n number of measurements and n r number of measurements during regeneration ’; (c) equation (6-9) and the legend thereof are replaced by the following: ‘ (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]’; (d) equations (6-10) and (6-11) are replaced by the following: ‘ (upward adjustment factor) (6-10) (downward adjustment factor) (6-11)’; (a) equations (6-12) and (6-13) are replaced by the following: ‘ (upward adjustment factor) (6-12) (downward adjustment factor) (6-13)’; (9) in point 6.6.2.4, in the third paragraph, point (b) is replaced by the following: ‘(b) Upon request by the manufacturer, the approval authority may account for regeneration events differently than pursuant to point (a). However, this option only applies to events that occur extremely infrequently, and which cannot be practically addressed using the adjustment factors described in point 6.6.2.3.’; (10) point 7.3.1.1 is amended as follows: (a) the heading is replaced by the following: ‘7.3.1.1. General requirements for preconditioning the sampling system and the engine’; (b) the following paragraph is added: ‘Engines fitted with an after-treatment system may be operated prior to cycle-specific preconditioning set out in points 7.3.1.1.1 to 7.3.1.1.4, so that the after-treatment system is regenerated and, where applicable, the soot load in the particulate after-treatment system is re-established.’; (11) point 7.3.1.1.5 is deleted; (12) points 7.3.1.2 to 7.3.1.5 are replaced by the following: ‘7.3.1.2. 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. 7.3.1.3. 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. 7.3.1.4. 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 in accordance with 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 in accordance with 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 in accordance with the procedure of point 7.3.1.5; (j) Any electronic integrating devices shall be zeroed or re-zeroed, before the start of any test interval. 7.3.1.5. 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 shall not be switched. Also the gains of an analyzer's analogue operational amplifier(s) shall 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 (C 1 ).’; (13) the following point 7.3.1.6 is inserted: ‘7.3.1.6. PM filter preconditioning and tare weighing The procedures for PM filter preconditioning and tare weighing shall be performed in accordance with point 8.2.3.’; (14) point 7.4 is replaced by the following: ‘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 18 of Regulation (EU) 2016/1628 and Annex IV thereto. The technical specifications and characteristics of the NRSC, NRTC and LSI-NRTC are laid down in Annex XVII of this Regulation and the method for determination of the torque, power and speed settings for these test cycles set out in section 5.2.’; (15) point 7.5 is amended as follows: (a) in the first paragraph, point (h) is replaced by the following: ‘(h) PM filter(s) shall be pre-conditioned, weighed (empty weight), loaded, re-conditioned, again weighed (loaded weight) and then samples shall be evaluated in accordance with the pre-test (point 7.3.1.6) and post-test (point 7.3.2.2) procedures;’; (b) Figure 6.4 is replaced by the following: ‘ Figure 6.4 Test sequence Emissions calculation 1) Data collection 2) Post-test procedures 3) Evaluations Hot start exhaust emission test phase Exhaust emission test Pre-condition & warm-up engine Pre-condition engine If transient cycle and steady state cycle are applied Run one or more practice cycle as necessary to check engine/test Define steady-state test cycle Generate engine map (maximum torque curve) Transient (NRTC & LSI-NRTC) Steady-state (discrete & RMC) NRTC LSI-NRTC Hot soak Cold start exhaust emission test phase Ready all systems for sampling (analyzer, calibration included) & data collection Natural or forced cool down Generate reference transient test cycle Generate engine map maximum torque curve or constant speed operating line) if transient cycle not applied ’ (16) in point 7.5.1.2, points (a) and (b) are replaced by the following: ‘(a) If the engine stalls anywhere during the cold start run of the NRTC, the entire test shall be voided; (b) If the engine stalls anywhere during the hot-start run of the NRTC, only this run shall be voided. The engine shall be soaked in accordance with point 7.8.3, and the hot-start run repeated. In this case, the cold-start run does not need to be repeated;’; (17) point 7.8.1.2 is amended as follows: (a) point (b) is replaced by the following: ‘(b) Each mode has a mode length of at least 10 minutes. In each mode the engine shall be stabilised for at least 5 minutes. Gaseous emissions, and, where applicable, PN, shall be sampled for 1 to 3 minutes at the end of each mode and PM emissions shall be sampled in accordance with point (c). Notwithstanding the previous paragraph, when either testing spark ignition engines using cycles G1, G2 or G3 or when conducting measurements in accordance with Annex V of this Regulation each mode has a mode length of at least 3 minutes. In this case gaseous emissions, and, where applicable, PN, shall be sampled for at least the last 2 minutes of each mode and PM emissions shall be sampled in accordance with point (c). The mode length and sampling time may be extended to improve accuracy. The mode length shall be recorded and reported.’; (b) in point (c), the first paragraph is replaced by the following: ‘For PM emissions, 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.’; (18) in point 7.8.2.4, the last sentence of the first paragraph is replaced by the following: ‘When conducting testing of engines of reference power greater than 560 kW the regression line tolerances of Table 6.2 and the point deletion of Table 6.3 may be used.’; (19) in point 7.8.3.5, Table 6.3 is replaced by the following: ‘ 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 Where: n ref is the reference speed (see section 7.7.2.), n idle is the idle speed, n act is the actual (measured) speed, T ref is the reference torque (see section 7.7.2.), T act is the actual (measured) torque, T maxmappedtorque is the highest value of torque on the full-load torque curve mapped in accordance with section 7.6.’; (20) in point 8.1.2, Table 6.4 is amended as follows: (a) the row referring to point 8.1.11.4 is replaced by the following: ‘8.1.11.4.: Sample dryer NO 2 penetration (chiller) Upon initial installation and after major maintenance.’; (b) the row referring to point 8.1.12.1 is replaced by the following: ‘8.1.12.: 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.’; (21) point 8.1.7 is replaced by the following: ‘8.1.7. Measurement of engine parameters and ambient conditions Internal quality procedures traceable to recognised national or international standards shall be applied. Otherwise the following procedures apply.’; (22) in point 8.1.8.4.1(f), the first paragraph is replaced by the following: ‘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:’; (23) in point 8.1.8.5.1(a), point (iv) is replaced by the following: ‘(iv) The hydrocarbon contamination verification in the sample system shall be performed as described in point 7.3.1.3;’; (24) in point 8.1.8.5.4, the first and second sentence below the heading are replaced by the following: ‘Vacuum side leak check verification of the HC sampling system may be performed in accordance with point (g). If this procedure is used, the HC contamination procedure set out in point 7.3.1.3 may be used.’; (25) point 8.1.8.5.8 is deleted; (26) point 8.1.9.1.2 is replaced by the following: ‘8.1.9.1.2. Measurement principles H 2 O can interfere with an NDIR analyzer's response to CO 2 . If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, these other measurements shall be conducted simultaneously to test the compensation algorithms during the analyzer interference verification.’; (27) in point 8.1.9.1.4, point (b) is replaced by the following: ‘(b) A humidified test gas shall be created by bubbling zero air that meets the specifications set out 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 H 2 O content in the test gas 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 H 2 O content in the test gas at least as high as the maximum expected at the outlet of the dryer, in accordance with point 9.3.2.3.1.1;’; (28) point 8.1.9.2.4(b) is replaced by the following: ‘(b) A humidified CO 2 test gas shall be created by bubbling a CO 2 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 H 2 O content in the test gas 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 H 2 O content in the test gas at least as high as the maximum expected at the outlet of the dryer, in accordance with point 9.3.2.3.1.1. A CO 2 span gas concentration shall be used at least as high as the maximum expected during testing;’; (29) point 8.1.10.1.3 is amended as follows: (a) in point (b), the last sentence is replaced by the following: ‘With the FID fuel and airflow rates set at the manufacturer's recommendations, a span gas shall be introduced to the analyzer;’; (b) point (c) is amended as follows: (i) point (i) is replaced by the following: ‘(i) The response at a given FID fuel flow shall be determined from the difference between the span gas response and the zero gas response;’; (ii) in point (ii), the last sentence is replaced by the following: ‘The span and zero response at these FID fuel flows shall be recorded;’; (30) in point 8.1.10.2.4(a), the second sentence is deleted; (31) point 8.1.11.1.5 is amended as follows: (a) point (e) is replaced by the following: ‘(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 H 2 O content in the span gas approximately equal to the maximum mole fraction of H 2 O 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 H 2 O quench to the highest mole fraction of H 2 O 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 H 2 O content in the span gas at least as high as the maximum expected at the outlet of the dryer in accordance with point 9.3.2.3.1.1. In this case, the quench verification calculations set out in point 8.1.11.2.3 do not scale the measured H 2 O quench;’; (b) the last sentence of point (f) is replaced by the following: ‘Note that the sample dryer shall meet the sample dryer verification check in point 8.1.12;’; (32) in point 8.1.11.3.4(g), the introductory wording is replaced by the following: ‘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 NO x concentration expected at the emission limit value, as set out in equation (6-25):’; (33) in point 8.1.11.4.2, the words ‘cooling bath’ are replaced by the words ‘sample dryer’. (34) point 8.1.12 is replaced by the following: ‘8.1.12. 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. 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. 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 NO x response through collisional quenching and can positively interfere with an NDIR analyzer by causing a response similar to CO. 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. 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) N 2 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 K (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 K (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.’; (35) points 8.1.12.1 to 8.1.12.2.5 are deleted; (36) the following points 8.1.13 to 8.1.13.2.5 are inserted: ‘8.1.13. PM measurements 8.1.13.1. PM balance verifications and weighing process verification 8.1.13.1.1. 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. 8.1.13.1.2. 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. 8.1.13.1.3. 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 that 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 that verification. 8.1.13.1.4. 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 that 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. That 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 that 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 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 point (i), 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. 8.1.13.2. PM sample filter buoyancy correction 8.1.13.2.1. 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. 8.1.13.2.2. 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/m 3 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/m 3 shall be used; (c) For PTFE membrane (film) media with an integral support ring of PTFE, a sample media density of 2 144 kg/m 3 shall be used. 8.1.13.2.3. 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. 8.1.13.2.4. Calibration weight density The stated density of the material of the metal calibration weight shall be used. 8.1.13.2.5. 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’; (37) in point 9.3.2.1.1, the first sentence is replaced by the following: ‘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 individual cylinder swept volume of the engine under test.’; (38) in point 9.3.2.2, point (b) is replaced by the following: ‘(b) For THC transfer lines a wall temperature tolerance throughout the entire line of (464 ± 11) K [(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 (464 ± 11) K [(191 ± 11) °C].’; (39) in point 9.3.2.3.1.1, the last paragraph is replaced by the following: ‘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 % H 2 O), 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 either: (a) measuring the temperature at the outlet of the sample dryer; or (b) measuring humidity at a point just upstream of the CLD; or (c) performing the verification procedure in point 8.1.12.’; (40) in point 9.3.3.4.3, the second sentence is replaced by the following: ‘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 filter media.’; (41) in point 9.3.4.4, in point (b), the last sentence is replaced by the following: ‘This value shall be used to calculate the PM sample filter buoyancy correction in point 8.1.13.2.’; (42) in point 9.4.1.2, the last sentence is replaced by the following: ‘Where more than one instrument for a particular measurement is specified, one of them will be identified by the approval authority upon application as the reference for showing that an alternative procedure is equivalent to the specified procedure.’; (43) in point 9.4.1.3, the first sentence is replaced by the following: ‘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 approval authority.’; (44) in point 9.4.5.3.2, the first sentence is replaced by the following: ‘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 6.8 is required.’; (45) in point 9.4.6, the last sentence is replaced by the following: ‘The NDIR-based system shall meet the calibration and verifications set out in point 8.1.9.1 or 8.1.9.2, as applicable.’; (46) in point 9.4.12, the paragraph below the heading is replaced by the following: ‘A FTIR (Fourier transform infrared) analyser, NDUV or laser infrared analyser may be used in accordance with Appendix 4.’; (47) point 9.5.1.1(a) is amended as follows, (a) point (i) is replaced by the following: ‘(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;’; (b) in point (iii), in Table 6.9, the third row is replaced by the following: ‘CO 2 ≤ 10 μmol/mol ≤ 10 μmol/mol’; (48) in point 9.5.1.1(c), point (i) is replaced by the following: ‘(i) CH 4 , balance purified synthetic air and/or N 2 (as applicable);’; (49) in point 9.5.1.2, point (b) is replaced by the following: ‘(b) Calibration gases may be relabelled and used after their expiration date if it is approved in advance by approval authority.’; (50) in point 9.5.1.3, the second paragraph below the heading is deleted; (51) Appendix 1 is amended as follows: (a) in point 1.3.4, the first sentence is replaced by the following: ‘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.’; (b) in point 2.1.3.3.3, the first sentence is replaced by the following: ‘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).’; (c) in point 2.1.4, figure 6.10 is replaced by the following ‘ Figure 6.10 Schematic of recommended particle sampling system – Full flow sampling Text of image from engine exhaust LEPA HEPA act. carbon Flow direction cyclone filled air excess air ’; (52) in Appendix 3, in point 3, in the second paragraph, the first sentence is replaced by the following: ‘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 %).’; (53) Appendix 4 is amended as follows: (a) in point 4.2.7, the last sentence is replaced by the following: ‘The expiration date of the calibration gases shall be recorded.’; (b) in point 4.2.8, point (j) is replaced by the following: ‘(j) Analyser shall have combined interference within ± 2 % of the applicable mean value of ammonia (NH 3 ) specified in point 3.4 of Annex IV.’; (54) Appendix 5 is amended as follows: (a) in point 2.4, figure 6-11 is replaced by the following: ‘ Figure 6-11 Illustration of system responses Response Time rise time delay time transformation time response time Step input time ’. (b) the following point 2.5 is added: ‘2.5. Step input time is the time at which there is a change in the parameter being measured.’. ( *1 ) Global technical regulation No 11 on Engine Emissions from agricultural and forestry tractors and from non-road mobile machinery under the Global Registry created on 18 November 2004, pursuant to Article 6 of the Agreement concerning the establishing of global technical regulations for wheeled vehicles, equipment and parts which can be fitted and/or be used on wheeled vehicles. ( *2 ) Regulation No 96 of the Economic Commission for Europe of the United Nations (UN/ECE) — Uniform provisions concerning the approval of compression ignition (C.I.) engines to be installed in agricultural and forestry tractors and in non-road mobile machinery with regard to the emissions of pollutants by the engine.’;’