{
  "url": "https://openlegislation.uk/eu-regulation-2008-692/annex-IIIA/appendix-2",
  "json_url": "https://openlegislation.uk/eu-regulation-2008-692/annex-IIIA/appendix-2.json",
  "legislation": "eur/2008/692",
  "legislation_title": "Commission Regulation (EC) No 692/2008 of 18 July 2008 implementing and amending Regulation (EC) No 715/2007 of the European Parliament and of the Council on type-approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information (Text with EEA relevance)",
  "legislation_url": "https://openlegislation.uk/eu-regulation-2008-692",
  "path": "annex/IIIA/appendix/2",
  "kind": "appendix",
  "number": "2",
  "heading": null,
  "text": "Specifications and calibration of PEMS components and signals\n1.\nINTRODUCTION\nThis appendix sets out the specifications and calibration of PEMS components and signals.\n2.\nSYMBOLS\n> larger than\n≥ larger than or equal to\n% per cent\n≤ smaller than or equal to\nA undiluted CO 2 concentration [%]\na 0 y-axis intercept of the linear regression line\na 1 slope of the linear regression line\nB diluted CO 2 concentration [%]\nC diluted NO concentration [ppm]\nc analyser response in the oxygen interference test\nc FS,b full scale HC concentration in step (b) [ppmC 1 ]\nc FS,d full scale HC concentration in step (d) [ppmC 1 ]\nc HC(w/NMC) HC concentration with CH 4 or C 2 H 6 flowing through the NMC [ppmC 1 ]\nc HC(w/o NMC) HC concentration with CH 4 or C 2 H 6 bypassing the NMC [ppmC 1 ]\nc m,b measured HC concentration in step (b) [ppmC 1 ]\nc m,d measured HC concentration in step (d) [ppmC 1 ]\nc ref,b reference HC concentration in step (b) [ppmC 1 ]\nc ref,d reference HC concentration in step (d) [ppmC 1 ]\n°C degree centigrade\nD undiluted NO concentration [ppm]\nD e expected diluted NO concentration [ppm]\nE absolute operating pressure [kPa]\nE CO2 per cent CO 2 quench\nE E ethane efficiency\nE H2O per cent water quench\nE M methane efficiency\nE O2 oxygen interference\nF water temperature [K]\nG saturation vapour pressure [kPa]\ng gramme\ngH 2 O/kg gramme water per kilogram\nh hour\nH water vapour concentration [%]\nH m maximum water vapour concentration [%]\nHz hertz\nK kelvin\nkg kilogramme\nkm/h kilometre per hour\nkPa kilopascal\nmax maximum value\nNO X,dry moisture-corrected mean concentration of the stabilised NO X recordings\nNO X,m mean concentration of the stabilised NO X recordings\nNO X,ref reference mean concentration of the stabilised NO X recordings\nppm parts per million\nppmC 1 parts per million carbon equivalents\nr 2 coefficient of determination\ns second\nt 0 time point of gas flow switching [s]\nt 10 time point of 10 % response of the final reading\nt 50 time point of 50 % response of the final reading\nt 90 time point of 90 % response of the final reading\nx independent variable or reference value\nχ min minimum value\ny dependent variable or measured value\n3.\nLINEARITY VERIFICATION\n3.1.\nGeneral\nThe linearity of analysers, flow-measuring instruments, sensors and signals, shall be traceable to international or national standards. Any sensors or signals that are not directly traceable, e.g. simplified flow-measuring instruments shall be calibrated alternatively against chassis dynamometer laboratory equipment that has been calibrated against international or national standards.\n3.2.\nLinearity requirements\nAll analysers, flow-measuring instruments, sensors and signals shall comply with the linearity requirements given in Table 1. If air flow, fuel flow, the air-to-fuel ratio or the exhaust mass flow rate is obtained from the ECU, the calculated exhaust mass flow rate shall meet the linearity requirements specified in Table 1.\nTable 1\nLinearity requirements of measurement parameters and systems\nOptional to determine exhaust mass flow.\nOptional parameter.\nTo be decided once equipment becomes available.\nMeasurement parameter/instrument\nχ min × a 1 − 1 + a 0\nSlope a 1\nStandard error SEE\nCoefficient of determination r 2\nFuel flow rate\n≤ 1 % max\n0,98 - 1,02\n≤ 2 % max\n≥ 0,990\nAir flow rate\n≤ 1 % max\n0,98 - 1,02\n≤ 2 % max\n≥ 0,990\nExhaust mass flow rate\n≤ 2 % max\n0,97 - 1,03\n≤ 2 % max\n≥ 0,990\nGas analysers\n≤ 0,5 % max\n0,99 - 1,01\n≤ 1 % max\n≥ 0,998\nTorque\n≤ 1 % max\n0,98 - 1,02\n≤ 2 % max\n≥ 0,990\nPN analysers\ntbd\ntbd\ntbd\ntbd\n3.3.\nFrequency of linearity verification\nThe linearity requirements according to point 3.2 shall be verified:\n(a) for each analyser at least every three months or whenever a system repair or change is made that could influence the calibration;\n(b) for other relevant instruments, such as exhaust mass flow meters and traceably calibrated sensors, whenever damage is observed, as required by internal audit procedures, by the instrument manufacturer or by ISO 9000 but no longer than one year before the actual test.\nThe linearity requirements according to point 3.2 for sensors or ECU signals that are not directly traceable shall be performed once for each PEMS set-up with a traceably calibrated measurement device on the chassis dynamometer.\n3.4.\nProcedure of linearity verification\n3.4.1.\nGeneral requirements\nThe relevant analysers, instruments and sensors shall be brought to their normal operating condition according to the recommendations of their manufacturer. The analysers, instruments and sensors shall be operated at their specified temperatures, pressures and flows.\n3.4.2.\nGeneral procedure\nThe linearity shall be verified for each normal operating range by executing the following steps:\n(a) The analyser, flow-measuring instrument or sensor shall be set at zero by introducing a zero signal. For gas analysers, purified synthetic air or nitrogen shall be introduced to the analyser port via a gas path that is as direct and short as possible.\n(b) The analyser, flow-measuring instrument or sensor shall be spanned by introducing a span signal. For gas analysers, an appropriate span gas shall be introduced to the analyser port via a gas path that is as direct and short as possible.\n(c) The zero procedure of (a) shall be repeated.\n(d) The verification shall be established by introducing at least 10, approximately equally spaced and valid, reference values (including zero). The reference values with respect to the concentration of components, the exhaust mass flow rate or any other relevant parameter shall be chosen to match the range of values expected during the emissions test. For measurements of exhaust mass flow, reference points below 5 % of the maximum calibration value can be excluded from the linearity verification.\n(e) For gas analysers, known gas concentrations in accordance with point 5 shall be introduced to the analyser port. Sufficient time for signal stabilisation shall be given.\n(f) The values under evaluation and, if needed, the reference values shall be recorded at a constant frequency of at least 1,0 Hz over a period of 30 seconds.\n(g) The arithmetic mean values over the 30-second period shall be used to calculate the least squares linear regression parameters, with the best-fit equation having the form:\ny = a 1 x + a 0\nwhere:\ny is the actual value of the measurement system\na 1 is the slope of the regression line\nx is the reference value\na 0 is the y intercept of the regression line\nThe standard error of estimate (SEE) of y on x and the coefficient of determination (r 2 ) shall be calculated for each measurement parameter and system.\n(h) The linear regression parameters shall meet the requirements specified in Table 1.\n3.4.3.\nRequirements for linearity verification on a chassis dynamometer\nNon-traceable flow-measuring instruments, sensors or ECU signals that cannot directly be calibrated according to traceable standards, shall be calibrated on the chassis dynamometer. The procedure shall follow as far as applicable, the requirements of Annex 4a to UN/ECE Regulation No 83. If necessary, the instrument or sensor to be calibrated shall be installed on the test vehicle and operated according to the requirements of Appendix 1. The calibration procedure shall follow whenever possible the requirements of point 3.4.2; at least 10 appropriate reference values shall be selected as to ensure that at least 90 % of the maximum value expected to occur during the emissions test is covered.\nIf a not directly traceable flow-measuring instrument, sensor or ECU signal for determining exhaust flow is to be calibrated, a traceably calibrated reference exhaust mass flow meter or the CVS shall be attached to the vehicle's tailpipe. It shall be ensured that the vehicle exhaust is accurately measured by the exhaust mass flow meter according to point 3.4.3 of Appendix 1. The vehicle shall be operated by applying constant throttle at a constant gear selection and chassis dynamometer load.\n4.\nANALYSERS FOR MEASURING GASEOUS COMPONENTS\n4.1.\nPermissible types of analysers\n4.1.1.\nStandard analysers\nThe gaseous components shall be measured with analysers specified in points 1.3.1 to 1.3.5 of Appendix 3, Annex 4A to UN/ECE Regulation No 83, 07 series of amendments. If an NDUV analyser measures both NO and NO 2 , a NO 2 /NO converter is not required.\n4.1.2.\nAlternative analysers\nAny analyser not meeting the design specifications of point 4.1.1 is permissible provided that it fulfils the requirements of point 4.2. The manufacturer shall ensure that the alternative analyser achieves an equivalent or higher measurement performance compared to a standard analyser over the range of pollutant concentrations and co-existing gases that can be expected from vehicles operated with permissible fuels under moderate and extended conditions of valid on-road testing as specified in points 5, 6 and 7. Upon request, the manufacturer of the analyser shall submit in writing supplemental information, demonstrating that the measurement performance of the alternative analyser is consistently and reliably in line with the measurement performance of standard analysers. Supplemental information shall contain:\n(a) a description of the theoretical basis and the technical components of the alternative analyser;\n(b) a demonstration of equivalency with the respective standard analyser specified in point 4.1.1 over the expected range of pollutant concentrations and ambient conditions of the type-approval test defined in Annex 4a to UN/ECE Regulation No 83, 07 series of amendments as well as a validation test as described in point 3 of Appendix 3 for a vehicle equipped with a spark-ignition and compression-ignition engine; the manufacturer of the analyser shall demonstrate the significance of equivalency within the permissible tolerances given in point 3.3 of Appendix 3;\n(c) a demonstration of equivalency with the respective standard analyser specified in point 4.1.1 with respect to the influence of atmospheric pressure on the measurement performance of the analyser; the demonstration test shall determine the response to span gas having a concentration within the analyser range to check the influence of atmospheric pressure under moderate and extended altitude conditions defined in point 5.2. Such a test can be performed in an altitude environmental test chamber;\n(d) a demonstration of equivalency with the respective standard analyser specified in point 4.1.1 over at least three on-road tests that fulfil the requirements of this Annex;\n(e) a demonstration that the influence of vibrations, accelerations and ambient temperature on the analyser reading does not exceed the noise requirements for analysers set out in point 4.2.4.\nApproval authorities may request additional information to substantiate equivalency or refuse approval if measurements demonstrate that an alternative analyser is not equivalent to a standard analyser.\n4.2.\nAnalyser specifications\n4.2.1.\nGeneral\nIn addition to the linearity requirements defined for each analyser in point 3, the compliance of analyser types with the specifications laid down in points 4.2.2 to 4.2.8 shall be demonstrated by the analyser manufacturer. Analysers shall have a measuring range and response time appropriate to measure with adequate accuracy the concentrations of the exhaust gas components at the applicable emissions standard under transient and steady state conditions. The sensitivity of the analysers to shocks, vibration, aging, variability in temperature and air pressure as well as electromagnetic interferences and other impacts related to vehicle and analyser operation shall be limited as far as possible.\n4.2.2.\nAccuracy\nThe accuracy, defined as the deviation of the analyser reading from the reference value, shall not exceed 2 % of reading or 0,3 % of full scale, whichever is larger.\n4.2.3.\nPrecision\nThe precision, defined as 2,5 times the standard deviation of 10 repetitive responses to a given calibration or span gas, shall be no greater than 1 % of the full scale concentration for a measurement range equal or above 155 ppm (or ppmC 1 ) and 2 % of the full scale concentration for a measurement range of below 155 ppm (or ppmC 1 ).\n4.2.4.\nNoise\nThe noise, defined as two times the root mean square of ten standard deviations, each calculated from the zero responses measured at a constant recording frequency of at least 1,0 Hz during a period of 30 seconds, shall not exceed 2 % of full scale. Each of the 10 measurement periods shall be interspersed with an interval of 30 seconds in which the analyser is exposed to an appropriate span gas. Before each sampling period and before each span period, sufficient time shall be given to purge the analyser and the sampling lines.\n4.2.5.\nZero response drift\nThe drift of the zero response, defined as the mean response to a zero gas during a time interval of at least 30 seconds, shall comply with the specifications given in Table 2.\n4.2.6.\nSpan response drift\nThe drift of the span response, defined as the mean response to a span gas during a time interval of at least 30 seconds, shall comply with the specifications given in Table 2.\nTable 2\nPermissible zero and span response drift of analysers for measuring gaseous components under laboratory conditions\nPollutant\nZero response drift\nSpan response drift\nCO 2\n≤ 1 000 ppm over 4 h\n≤ 2 % of reading or ≤ 1 000 ppm over 4 h, whichever is larger\nCO\n≤ 50 ppm over 4 h\n≤ 2 % of reading or ≤ 50 ppm over 4 h, whichever is larger\nNO 2\n≤ 5 ppm over 4 h\n≤ 2 % of reading or ≤ 5 ppm over 4 h, whichever is larger\nNO/NO X\n≤ 5 ppm over 4 h\n≤ 2 % of reading or 5 ppm over 4h, whichever is larger\nCH 4\n≤ 10 ppmC 1\n≤ 2 % of reading or ≤ 10 ppmC 1 over 4 h, whichever is larger\nTHC\n≤ 10 ppmC 1\n≤ 2 % of reading or ≤ 10 ppmC 1 over 4 h, whichever is larger\n4.2.7.\nRise time\nRise time is defined as the time between the 10 per cent and 90 per cent response of the final reading ( t 90 – t 10 ; see point 4.4). The rise time of PEMS analysers shall not exceed 3 seconds.\n4.2.8.\nGas drying\nExhaust gases may be measured wet or dry. A gas-drying device, if used, shall have a minimal effect on the composition of the measured gases. Chemical dryers are not permitted.\n4.3.\nAdditional requirements\n4.3.1.\nGeneral\nThe provisions in points 4.3.2 to 4.3.5 define additional performance requirements for specific analyser types and apply only to cases, in which the analyser under consideration is used for PEMS emission measurements.\n4.3.2.\nEfficiency test for NO X converters\nIf a NO X converter is applied, for example to convert NO 2 into NO for analysis with a chemiluminescence analyser, its efficiency shall be tested by following the requirements of point 2.4 of Appendix 3 of Annex 4a to UN/ECE Regulation No 83, 07 series of amendments. The efficiency of the NO X converter shall be verified no longer than one month before the emissions test.\n4.3.3.\nAdjustment of the Flame Ionisation Detector\n(a)\nOptimisation of the detector response\nIf hydrocarbons are measured, the FID shall be adjusted at intervals specified by the analyser manufacturer by following point 2.3.1 of Appendix 3 of Annex 4a to UN/ECE Regulation No 83, 07 series of amendments. A propane-in-air or propane-in-nitrogen span gas shall be used to optimise the response in the most common operating range.\n(b)\nHydrocarbon response factors\nIf hydrocarbons are measured, the hydrocarbon response factor of the FID shall be verified by following the provisions of point 2.3.3 of Appendix 3 of Annex 4a to UN/ECE Regulation No 83, 07 series of amendments, using propane-in-air or propane-in-nitrogen as span gases and purified synthetic air or nitrogen as zero gases, respectively.\n(c)\nOxygen interference check\nThe oxygen interference check shall be performed when introducing an analyser into service and after major maintenance intervals. A measuring range shall be chosen in which the oxygen interference check gases fall in the upper 50 per cent. The test shall be conducted with the oven temperature set as required. The specifications of the oxygen interference check gases are described in point 5.3.\nThe following procedure applies:\n(i) The analyser shall be set at zero.\n(ii) The analyser shall be spanned with a 0 per cent oxygen blend for positive ignition engines and a 21 per cent oxygen blend for compression ignition engines.\n(iii) The zero response shall be rechecked. If it has changed by more than 0,5 per cent of full scale, steps (i) and (ii) shall be repeated.\n(iv) The 5 per cent and 10 per cent oxygen interference check gases shall be introduced.\n(v) The zero response shall be rechecked. If it has changed by more than ± 1 per cent of full scale, the test shall be repeated.\n(vi) The oxygen interference E O2 shall be calculated for each oxygen interference check gas in step (d) as follows:\nE O 2 = c ref,d − c c ref,d × 100\nwhere the analyser response is:\nc = c ref,d × c FS,b c m,b × c m,b c FS,d\nwhere:\nc ref,b is the reference HC concentration in step (b) [ppmC 1 ]\nc ref,d is the reference HC concentration in step (d) [ppmC 1 ]\nc FS,b is the full scale HC concentration in step (b) [ppmC 1 ]\nc FS,d is the full scale HC concentration in step (d) [ppmC 1 ]\nc m,b is the measured HC concentration in step (b) [ppmC 1 ]\nc m,d is the measured HC concentration in step (d) [ppmC 1 ].\n(vii) The oxygen interference E O2 shall be less than ± 1,5 per cent for all required oxygen interference check gases.\n(viii) If the oxygen interference E O2 is greater than ± 1,5 per cent, corrective action may be taken by incrementally adjusting the air flow (above and below the manufacturer's specifications), the fuel flow and the sample flow.\n(ix) The oxygen interference check shall be repeated for each new setting.\n4.3.4.\nConversion efficiency of the non-methane cutter (NMC)\nIf hydrocarbons are analysed, a NMC can be used to remove non-methane hydrocarbons from the gas sample by oxidising all hydrocarbons except methane. Ideally, the conversion for methane is 0 per cent and for the other hydrocarbons represented by ethane is 100 per cent. For the accurate measurement of NMHC, the two efficiencies shall be determined and used for the calculation of the NMHC emissions (see point 9.2 of Appendix 4). It is not necessary to determine the methane conversion efficiency in case the NMC-FID is calibrated according to method (b) in point 9.2 of Appendix 4 by passing the methane/air calibration gas through the NMC.\n(a) Methane conversion efficiency\nMethane calibration gas shall be flown through the FID with and without bypassing the NMC; the two concentrations shall be recorded. The methane efficiency shall be determined as:\nE M = 1 − c HC w ∕ NMC c HC w ∕ oNMC\nwhere:\nc HC(w/NMC) is the HC concentration with CH 4 flowing through the NMC [ppmC 1 ]\nc HC(w/o NMC) is the HC concentration with CH 4 bypassing the NMC [ppmC 1 ]\n(b) Ethane conversion efficiency\nEthane calibration gas shall be flown through the FID with and without bypassing the NMC; the two concentrations shall be recorded. The ethane efficiency shall be determined as:\nE E = 1 − c HC w ∕ NMC c HC w ∕ oNMC\nwhere:\nc HC(w/NMC) is the HC concentration with C 2 H 6 flowing through the NMC [ppmC 1 ]\nc HC(w/o NMC) is the HC concentration with C 2 H 6 bypassing the NMC [ppmC 1 ]\n4.3.5.\nInterference effects\n(a)\nGeneral\nOther gases than the ones being analysed can affect the analyser reading. A check for interference effects and the correct functionality of analysers shall be performed by the analyser manufacturer prior to market introduction at least once for each type of analyser or device addressed in points (b) to (f).\n(b)\nCO analyser interference check\nWater and CO 2 can interfere with the measurements of the CO analyser. Therefore, a CO 2 span gas having a concentration of 80 to 100 per cent of full scale of the maximum operating range of the CO analyser used during the test shall be bubbled through water at room temperature and the analyser response recorded. The analyser response shall not be more than 2 per cent of the mean CO concentration expected during normal on-road testing or ± 50 ppm, whichever is larger. The interference check for H 2 O and CO 2 may be run as separate procedures. If the H 2 O and CO 2 levels used for the interference check are higher than the maximum levels expected during the test, each observed interference value shall be scaled down by multiplying the observed interference with the ratio of the maximum expected concentration value during the test and the actual concentration value used during this check. Separate interference checks with concentrations of H 2 O that are lower than the maximum concentration expected during the test may be run and the observed H 2 O interference shall be scaled up by multiplying the observed interference with the ratio of the maximum H 2 O concentration value expected during the test and the actual concentration value used during this check. The sum of the two scaled interference values shall meet the tolerance specified in this point.\n(c)\nNO X analyser quench check\nThe two gases of concern for CLD and HCLD analysers are CO 2 and water vapour. The quench response to these gases is proportional to the gas concentrations. A test shall determine the quench at the highest concentrations expected during the test. If the CLD and HCLD analysers use quench compensation algorithms that utilise H 2 O or CO 2 measurement analysers or both, quench shall be evaluated with these analysers active and with the compensation algorithms applied.\n(i)\nCO 2 quench check\nA CO 2 span gas having a concentration of 80 to 100 per cent of the maximum operating range shall be passed through the NDIR analyser; the CO 2 value shall be recorded as A. The CO 2 span gas shall then be diluted by approximately 50 per cent with NO span gas and passed through the NDIR and CLD or HCLD; the CO 2 and NO values shall be recorded as B and C, respectively. The CO 2 gas flow shall then be shut off and only the NO span gas shall be passed through the CLD or HCLD; the NO value shall be recorded as D. The per cent quench shall be calculated as:\nE CO 2 = 1 − C × A D × A − D × B × 100\nwhere:\nA is the undiluted CO 2 concentration measured with NDIR [%]\nB is the diluted CO 2 concentration measured with NDIR [%]\nC is the diluted NO concentration measured with the CLD or HCLD [ppm]\nD is the undiluted NO concentration measured with the CLD or HCLD [ppm].\nAlternative methods of diluting and quantifying of CO 2 and NO span gas values such as dynamic mixing/blending are permitted upon approval of the approval authority.\n(ii)\nWater quench check\nThis check applies to measurements of wet gas concentrations only. The calculation of water quench shall consider dilution of the NO span gas with water vapour and the scaling of the water vapour concentration in the gas mixture to concentration levels that are expected to occur during an emissions test. A NO span gas having a concentration of 80 per cent to 100 per cent of full scale of the normal operating range shall be passed through the CLD or HCLD; the NO value shall be recorded as D . The NO span gas shall then be bubbled through water at room temperature and passed through the CLD or HCLD; the NO value shall be recorded as C . The analyser's absolute operating pressure and the water temperature shall be determined and recorded as E and F, respectively. The mixture's saturation vapour pressure that corresponds to the water temperature of the bubbler F shall be determined and recorded as G . The water vapour concentration H [%] of the gas mixture shall be calculated as:\nH = G E × 100\nThe expected concentration of the diluted NO-water vapour span gas shall be recorded as D e after being calculated as:\nD e = D × 1 − H 100\nFor diesel exhaust, the maximum concentration of water vapour in the exhaust gas (in per cent) expected during the test shall be recorded as H m after being estimated, under the assumption of a fuel H/C ratio of 1,8/1, from the maximum CO 2 concentration in the exhaust gas A as follows:\nH m = 0,9 × A\nThe per cent water quench shall be calculated as:\nE H 2 O = D e − C D e × H m H × 100\nwhere:\nD e is the expected diluted NO concentration [ppm]\nC is the measured diluted NO concentration [ppm]\nH m is the maximum water vapour concentration [%]\nH is the actual water vapour concentration [%].\n(iii)\nMaximum allowable quench\nThe combined CO 2 and water quench shall not exceed 2 per cent of full scale.\n(d)\nQuench check for NDUV analysers\nHydrocarbons and water can positively interfere with NDUV analysers by causing a response similar to that of NO X . The manufacturer of the NDUV analyser shall use the following procedure to verify that quench effects are limited:\n(i) The analyser and chiller shall be set up by following the operating instructions of the manufacturer; adjustments should be made as to optimise the analyser and chiller performance.\n(ii) A zero calibration and span calibration at concentration values expected during emissions testing shall be performed for the analyser.\n(iii) A NO 2 calibration gas shall be selected that matches as far as possible the maximum NO 2 concentration expected during emissions testing.\n(iv) The NO 2 calibration gas shall overflow at the gas sampling system's probe until the NO X response of the analyser has stabilised.\n(v) The mean concentration of the stabilised NO X recordings over a period of 30 s shall be calculated and recorded as NO X,ref .\n(vi) The flow of the NO 2 calibration gas shall be stopped and the sampling system saturated by overflowing with a dew point generator's output, set at a dew point of 50 °C. The dew point generator's output shall be sampled through the sampling system and chiller for at least 10 minutes until the chiller is expected to be removing a constant rate of water.\n(vii) Upon completion of (iv), the sampling system shall again be overflown by the NO 2 calibration gas used to establish NO X,ref until the total NO X response has stabilised.\n(viii) The mean concentration of the stabilised NO X recordings over a period of 30 s shall be calculated and recorded as NO X,m .\n(ix) NO X,m shall be corrected to NO X,dry based upon the residual water vapour that passed through the chiller at the chiller's outlet temperature and pressure.\nThe calculated NO X,dry shall at least amount to 95 % of NO X,ref .\n(e)\nSample dryer\nA sample dryer removes water, which can otherwise interfere with the NO X measurement. For dry CLD analysers, it shall be demonstrated that at the highest expected water vapour concentration H m the sample dryer maintains the CLD humidity at ≤ 5 g water/kg dry air (or about 0,8 per cent H 2 O), which is 100 per cent relative humidity at 3,9 °C and 101,3 kPa or about 25 per cent relative humidity at 25 °C and 101,3 kPa. Compliance may be demonstrated by measuring the temperature at the outlet of a thermal sample dryer or by measuring the humidity at a point just upstream of the CLD. The humidity of the CLD exhaust might also be measured as long as the only flow into the CLD is the flow from the sample dryer.\n(f)\nSample dryer NO 2 penetration\nLiquid water remaining in an improperly designed sample dryer can remove NO 2 from the sample. If a sample dryer is used in combination with a NDUV analyser without an NO 2 /NO converter upstream, water could therefore remove NO 2 from the sample prior to the NO X measurement. The sample dryer shall allow for measuring at least 95 per cent of the NO 2 contained in a gas that is saturated with water vapour and consists of the maximum NO 2 concentration expected to occur during a vehicle test.\n4.4.\nResponse time check of the analytical system\nFor the response time check, the settings of the analytical system shall be exactly the same as during the emissions test (i.e. pressure, flow rates, filter settings in the analysers and all other parameters influencing the response time). The response time shall be determined with gas switching directly at the inlet of the sample probe. The gas switching shall be done in less than 0,1 second. The gases used for the test shall cause a concentration change of at least 60 per cent full scale of the analyser.\nThe concentration trace of each single gas component shall be recorded. The delay time is defined as the time from the gas switching ( t 0 ) until the response is 10 per cent of the final reading ( t 10 ). The rise time is defined as the time between 10 per cent and 90 per cent response of the final reading ( t 90 – t 10 ). The system response time ( t 90 ) consists of the delay time to the measuring detector and the rise time of the detector.\nFor time alignment of the analyser and exhaust flow signals, the transformation time is defined as the time from the change ( t 0 ) until the response is 50 per cent of the final reading ( t 50 ).\nThe system response time shall be ≤ 12 s with a rise time of ≤ 3 seconds for all components and all ranges used. When using a NMC for the measurement of NMHC, the system response time may exceed 12 seconds.\n5.\nGASES\n5.1.\nGeneral\nThe shelf life of calibration and span gases shall be respected. Pure and mixed calibration and span gases shall fulfil the specifications of points 3.1 and 3.2 of Appendix 3 of Annex 4A to UN/ECE Regulation No 83, 07 series of amendments. In addition, NO 2 calibration gas is permissible. The concentration of the NO 2 calibration gas shall be within two per cent of the declared concentration value. The amount of NO contained in NO 2 calibration gas shall not exceed 5 per cent of the NO 2 content.\n5.2.\nGas dividers\nGas dividers, i.e. precision blending devices that dilute with purified N 2 or synthetic air, can be used to obtain calibration and span gases. The accuracy of the gas divider shall be such that the concentration of the blended calibration gases is accurate to within ± 2 per cent. The verification shall be performed at between 15 and 50 per cent of full scale for each calibration incorporating a gas divider. An additional verification may be performed using another calibration gas, if the first verification has failed.\nOptionally, the gas divider may be checked with an instrument which by nature is linear, e.g. using NO gas in combination with a CLD. The span value of the instrument shall be adjusted with the span gas directly connected to the instrument. The gas divider shall be checked at the settings typically used and the nominal value shall be compared with the concentration measured by the instrument. The difference shall in each point be within ± 1 per cent of the nominal concentration value.\n5.3.\nOxygen interference check gases\nOxygen interference check gases consist of a blend of propane, oxygen and nitrogen and shall contain propane at a concentration of 350 ± 75 ppmC 1 . The concentration shall be determined by gravimetric methods, dynamic blending or the chromatographic analysis of total hydrocarbons plus impurities. The oxygen concentrations of the oxygen interference check gases shall meet the requirements listed in Table 3; the remainder of the oxygen interference check gas shall consist of purified nitrogen.\nTable 3\nOxygen interference check gases\nEngine type\nCompression ignition\nPositive ignition\nO 2 concentration\n21 ± 1 %\n10 ± 1 %\n10 ± 1 %\n5 ± 1 %\n5 ± 1 %\n0,5 ± 0,5 %\n6.\nANALYSERS FOR MEASURING PARTICLE EMISSIONS\nThis section will define future requirements for analysers for measuring particle emissions, once their measurement becomes mandatory.\n7.\nINSTRUMENTS FOR MEASURING EXHAUST MASS FLOW\n7.1.\nGeneral\nInstruments, sensors or signals for measuring the exhaust mass flow rate shall have a measuring range and response time appropriate for the accuracy required to measure the exhaust mass flow rate under transient and steady state conditions. The sensitivity of instruments, sensors and signals to shocks, vibration, aging, variability in temperature, ambient air pressure, electromagnetic interferences and other impacts related to vehicle and instrument operation shall be on a level as to minimise additional errors.\n7.2.\nInstrument specifications\nThe exhaust mass flow rate shall be determined by a direct measurement method applied in either of the following instruments:\n(a) Pitot-based flow devices;\n(b) pressure differential devices like flow nozzle (details see ISO 5167);\n(c) ultrasonic flow meter;\n(d) vortex flow meter.\nEach individual exhaust mass flow meter shall fulfil the linearity requirements set out in point 3. Furthermore, the instrument manufacturer shall demonstrate the compliance of each type of exhaust mass flow meter with the specifications in points 7.2.3 to 7.2.9.\nIt is permissible to calculate the exhaust mass flow rate based on air flow and fuel flow measurements obtained from traceably calibrated sensors if these fulfil the linearity requirements of point 3, the accuracy requirements of point 8 and if the resulting exhaust mass flow rate is validated according to point 4 of Appendix 3.\nIn addition, other methods that determine the exhaust mass flow rate based on not directly traceable instruments and signals, such as simplified exhaust mass flow meters or ECU signals are permissible if the resulting exhaust mass flow rate fulfils the linearity requirements of point 3 and is validated according to point 4 of Appendix 3.\n7.2.1.\nCalibration and verification standards\nThe measurement performance of exhaust mass flow meters shall be verified with air or exhaust gas against a traceable standard such as, e.g. a calibrated exhaust mass flow meter or a full flow dilution tunnel.\n7.2.2.\nFrequency of verification\nThe compliance of exhaust mass flow meters with points 7.2.3 and 7.2.9 shall be verified no longer than one year before the actual test.\n7.2.3.\nAccuracy\nThe accuracy, defined as the deviation of the EFM reading from the reference flow value, shall not exceed ± 2 % of the reading, 0,5 % of full scale or ± 1,0 % of the maximum flow at which the EFM has been calibrated, whichever is larger.\n7.2.4.\nPrecision\nThe precision, defined as 2,5 times the standard deviation of 10 repetitive responses to a given nominal flow, approximately in the middle of the calibration range, shall be no greater than ±1 per cent of the maximum flow at which the EFM has been calibrated.\n7.2.5.\nNoise\nThe noise, defined as two times the root mean square of ten standard deviations, each calculated from the zero responses measured at a constant recording frequency of at least 1,0 Hz during a period of 30 seconds, shall not exceed 2 per cent of the maximum calibrated flow value. Each of the 10 measurement periods shall be interspersed with an interval of 30 seconds in which the EFM is exposed to the maximum calibrated flow.\n7.2.6.\nZero response drift\nZero response is defined as the mean response to zero flow during a time interval of at least 30 seconds. The zero response drift can be verified based on the reported primary signals, e.g. pressure. The drift of the primary signals over a period of 4 hours shall be less than ± 2 per cent of the maximum value of the primary signal recorded at the flow at which the EFM was calibrated.\n7.2.7.\nSpan response drift\nSpan response is defined as the mean response to a span flow during a time interval of at least 30 seconds. The span response drift can be verified based on the reported primary signals, e.g. pressure. The drift of the primary signals over a period of 4 hours shall be less than ± 2 per cent of the maximum value of the primary signal recorded at the flow at which the EFM was calibrated.\n7.2.8.\nRise time\nThe rise time of the exhaust flow instruments and methods should match as far as possible the rise time of the gas analysers as specified in point 4.2.7 but shall not exceed 1 second.\n7.2.9.\nResponse time check\nThe response time of exhaust mass flow meters shall be determined by applying similar parameters as those applied for the emissions test (i.e. pressure, flow rates, filter settings and all other response time influences). The response time determination shall be done with gas switching directly at the inlet of the exhaust mass flow meter. The gas flow switching shall be done as fast as possible, but highly recommended in less than 0,1 second. The gas flow rate used for the test shall cause a flow rate change of at least 60 per cent full scale (FS) of the exhaust mass flow meter. The gas flow shall be recorded. The delay time is defined as the time from the gas flow switching ( t 0 ) until the response is 10 per cent ( t 10 ) of the final reading. The rise time is defined as the time between 10 per cent and 90 per cent response ( t 90 – t 10 ) of the final reading. The response time ( t 90 ) is defined as the sum of the delay time and the rise time. The exhaust mass flow meter response time ( t 90 ) shall be ≤ 3 seconds with a rise time ( t 90 – t 10 ) of ≤ 1 second in accordance with point 7.2.8.\n8.\nSENSORS AND AUXILIARY EQUIPMENT\nAny sensor and auxiliary equipment used to determine, e.g. temperature, atmospheric pressure, ambient humidity, vehicle speed, fuel flow or intake air flow shall not alter or unduly affect the performance of the vehicle's engine and exhaust after-treatment system. The accuracy of sensors and auxiliary equipment shall fulfil the requirements of Table 4. Compliance with the requirements of Table 4 shall be demonstrated at intervals specified by the instrument manufacturer, as required by internal audit procedures or in accordance with ISO 9000.\nTable 4\nAccuracy requirements for measurement parameters\nOptional to determine exhaust mass flow.\nThis general requirement applies to the speed sensor only; if vehicle speed is used to determine parameters like acceleration, the product of speed and positive acceleration, or RPA, the speed signal shall have an accuracy of 0,1 % above 3 km/h and a sampling frequency of 1 Hz. This accuracy requirement can be met by using the signal of a wheel rotational speed sensor.\nThe accuracy shall be 0,02 per cent of reading if used to calculate the air and exhaust mass flow rate from the fuel flow according to point 10 of Appendix 4.\nMeasurement parameter\nAccuracy\nFuel flow\n± 1 % of reading\nAir flow\n± 2 % of reading\nVehicle ground speed\n± 1,0 km/h absolute\nTemperatures ≤ 600 K\n± 2 K absolute\nTemperatures >600 K\n± 0,4 % of reading in Kelvin\nAmbient pressure\n± 0,2 kPa absolute\nRelative humidity\n± 5 % absolute\nAbsolute humidity\n± 10 % of reading or, 1 gH 2 O/kg dry air, whichever is larger",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "F",
      "label": "F1",
      "text": "Inserted by Commission Regulation (EU) 2016/427 of 10 March 2016 amending Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) (Text with EEA relevance)."
    },
    {
      "type": "F",
      "label": "F2",
      "text": "Substituted by Commission Regulation (EU) 2016/646 of 20 April 2016 amending Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) (Text with EEA relevance)."
    },
    {
      "type": "footnote",
      "label": "f1",
      "text": "Optional to determine exhaust mass flow."
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "Optional parameter."
    },
    {
      "type": "footnote",
      "label": "f3",
      "text": "To be decided once equipment becomes available."
    },
    {
      "type": "footnote",
      "label": "f4",
      "text": "Optional to determine exhaust mass flow."
    },
    {
      "type": "footnote",
      "label": "f5",
      "text": "The accuracy shall be 0,02 per cent of reading if used to calculate the air and exhaust mass flow rate from the fuel flow according to point 10 of Appendix 4."
    },
    {
      "type": "footnote",
      "label": "f6",
      "text": "This general requirement applies to the speed sensor only; if vehicle speed is used to determine parameters like acceleration, the product of speed and positive acceleration, or RPA, the speed signal shall have an accuracy of 0,1 % above 3 km/h and a sampling frequency of 1 Hz. This accuracy requirement can be met by using the signal of a wheel rotational speed sensor."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eur/2008/692/annex/IIIA/appendix/2",
    "retrieved_at": "2026-11-01T14:52:09.943760+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}