(h)

Appendix 5 is amended as follows: The following section 1.2.3 is added: ‘1.2.3. Use of precision blending devices The gases used for calibration and span may also be obtained by means of precision blending devices (gas dividers), diluting with purified N2 or with purified synthetic air. The accuracy of the mixing device must be such that the concentration of the blended calibration gases is accurate to within ± 2 %. This accuracy implies that primary gases used for blending must be known to an accuracy of at least ± 1 %, traceable to national or international gas standards. The verification shall be performed at between 15 and 50 % of full scale for each calibration incorporating a blending device. Optionally, the blending device may be checked with an instrument which by nature is linear, e.g. using NO gas with a CLD. The span value of the instrument shall be adjusted with the span gas directly connected to the instrument. The blending device shall be checked at the used settings and the nominal value shall be compared to the measured concentration of the instrument. This difference shall in each point be within ± 1 % of the nominal value.’ Section 1.4 is replaced by the following: ‘1.4. Leakage test A system leakage test shall be performed. The probe shall be disconnected from the exhaust system and the end plugged. The analyser pump shall be switched on. After an initial stabilisation period all flow meters should read zero. If not, the sampling lines shall be checked and the fault corrected. The maximum allowable leakage rate on the vacuum side shall be 0,5 % of the in-use flow rate for the portion of the system being checked. The analyser flows and bypass flows may be used to estimate the in-use flow rates. Alternatively, the system may be evacuated to a pressure of at least 20 kPa vacuum (80 kPa absolute). After an initial stabilisation period the pressure increase Δp (kPa/min) in the system should not exceed: Δp = p / V s × 0,005 × q vs where: Another method is the introduction of a concentration step change at the beginning of the sampling line by switching from zero to span gas. If after an adequate period of time the reading is about 1 % low compared to the introduced concentration, these points to calibration or leakage problems.’ V s | = | system volume, l q vs | = | system flow rate, l/min The following section 1.5 is inserted: ‘1.5. Response time check of analytical system The system settings for the response time evaluation shall be exactly the same as during measurement of the test run (i.e. pressure, flow rates, filter settings on the analyzers and all other response time influences). The response time determination shall be done with gas switching directly at the inlet of the sample probe. The 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 % FS. The concentration trace of each single gas component shall be recorded. The response time is defined to be the difference in time between the gas switching and the appropriate change of the recorded concentration. The system response time (t 90) consists of the delay time to the measuring detector and the rise time of the detector. The delay time is defined as the time from the change (t 0) until the response is 10 % of the final reading (t 10). The rise time is defined as the time between 10 % and 90 % response of the final reading (t 90 – t 10). For time alignment of the analyzer and exhaust flow signals in the case of raw measurement, the transformation time is defined as the time from the change (t 0) until the response is 50 % of the final reading (t 50). The system response time shall be ≤ 10 seconds with a rise time ≤ 3,5 seconds for all limited components (CO, NOx, HC or NMHC) and all ranges used.’ Former section 1.5 is replaced by the following: ‘1.6. Calibration 1.6.1. Instrument assembly The instrument assembly shall be calibrated and calibration curves checked against standard gases. The same gas flow rates shall be used as when sampling exhaust. 1.6.2. Warming-up time The warming-up time should be according to the recommendations of the manufacturer. If not specified, a minimum of two hours is recommended for warming up the analysers. 1.6.3. NDIR and HFID analyser The NDIR analyser shall be tuned, as necessary, and the combustion flame of the HFID analyser shall be optimised (section 1.8.1). 1.6.4. Establishment of the calibration curve 1.6.5. Alternative methods If it can be shown that alternative technology (e.g. computer, electronically controlled range switch, etc.) can give equivalent accuracy, then these alternatives may be used. 1.6.6. Calibration of tracer gas analyser for exhaust flow measurement The calibration curve shall be established by at least 6 calibration points (excluding zero) approximately equally spaced over the operating range. The highest nominal concentration shall be equal to or higher than 90 % of full scale. The calibration curve is calculated by the method of least squares. The calibration points shall not differ from the least-squares best-fit line by more than ± 2 % of reading or ± 0,3 % of full scale whichever is larger. The analyser shall be set at zero and spanned prior to the test run using a zero gas and a span gas whose nominal value is more than 80 % of the analyser full scale.’ Each normally used operating range shall be calibrated Using purified synthetic air (or nitrogen), the CO, CO2, NOx and HC analysers shall be set at zero The appropriate calibration gases shall be introduced to the analysers, the values recorded, and the calibration curve established The calibration curve shall be established by at least 6 calibration points (excluding zero) approximately equally spaced over the operating range. The highest nominal concentration shall be equal to or higher than 90 % of full scale The calibration curve shall be calculated by the method of least-squares. A best-fit linear or non-linear equation may be used The calibration points shall not differ from the least-squares best-fit line by more than ± 2 % of reading or ± 0,3 % of full scale whichever is larger The zero setting shall be rechecked and the calibration procedure repeated, if necessary. Former section 1.6 becomes section 1.6.7. The following section 2.4 is inserted: ‘2.4. Calibration of the Subsonic Venturi (SSV) Calibration of the SSV is based upon the flow equation for a subsonic venturi. Gas flow is a function of inlet pressure and temperature, pressure drop between the SSV inlet and throat. 2.4.1. Data analysis The air flowrate (QSSV) at each restriction setting (minimum 16 settings) shall be calculated in standard m3/min from the flowmeter data using the manufacturer's prescribed method. The discharge coefficient shall be calculated from the calibration data for each setting as follows: Text of image QSSV = A0d2Cdpp √ [1 T (rp1,4286 - rp1,7143) × (1 1 - rD 4rp1,4286)] where: To determine the range of subsonic flow, C d shall be plotted as a function of Reynolds number at the SSV throat. The Re at the SSV throat is calculated with the following formula: Text of image Re = A1 QSSV dμ where: Because Q SSV is an input to the Re formula, the calculations must be started with an initial guess for Q SSV or C d of the calibration venturi, and repeated until Q SSV converges. The convergence method must be accurate to 0,1 % of point or better. For a minimum of sixteen points in the region of subsonic flow, the calculated values of C d from the resulting calibration curve fit equation must be within ± 0,5 % of the measured C d for each calibration point.’ Q SSV | = | air flow rate at standard conditions (101,3 kPa, 273 K), m3/s T | = | temperature at the venturi inlet, K d | = | diameter of the SSV throat, m r p | = | ratio of the SSV throat to inlet absolute, static pressure = Text of image 1 - ΔP PA r D | = | ratio of the SSV throat diameter, d, to the inlet pipe inner diameter = Text of image d D A 1 | = | a collection of constants and units conversions Text of image = 25,55152 (1m3) (min s) (mm m) Q SSV | = | air flow rate at standard conditions (101,3 kPa, 273 K), m3/s d | = | diameter of the SSV throat, m μ | = | absolute or dynamic viscosity of the gas, calculated with the following formula: Text of image μ = bT 3/2 S + T = bT 1/2 1 + S T kg/m–s b | = | empirical constant = Text of image 1,458 × 10 6 kg msK 1/2 S | = | empirical constant = 110,4 K Former section 2.4 becomes Section 2.5. Section 3 is replaced by the following: ‘3. CALIBRATION OF THE PARTICULATE MEASURING SYSTEM 3.1. Introduction The calibration of the particulate measurement is limited to the flow meters used to determine sample flow and dilution ratio. Each flow meter shall be calibrated as often as necessary to fulfil the accuracy requirements of this Directive. The calibration method that shall be used is described in section 3.2. 3.2. Flow measurement 3.2.1. Periodical calibration 3.2.2. Carbon flow check 3.2.3. Pre-test check 3.3. Determination of transformation time (for partial flow dilution systems on ETC only) 3.4. Checking the partial flow conditions The range of the exhaust gas velocity and the pressure oscillations shall be checked and adjusted according to the requirements of section 2.2.1 of Annex V (EP), if applicable. 3.5. Calibration intervals The flow measurement instrumentation shall be calibrated at least every 3 months or whenever a system repair or change is made that could influence calibration.’ To fulfil the absolute accuracy of the flow measurements as specified in section 2.2 of Appendix 4 to this Annex, the flow meter or the flow measurement instrumentation shall be calibrated with an accurate flow meter traceable to international and/or national standards. If the sample gas flow is determined by differential flow measurement the flow meter or the flow measurement instrumentation shall be calibrated in one of the following procedures, such that the probe flow q mp into the tunnel shall fulfil the accuracy requirements of section 4.2.5.2 of Appendix 4 to this Annex: The flow meter for q mdw shall be connected in series to the flow meter for q mdew, the difference between the two flow meters shall be calibrated for at least 5 set points with flow values equally spaced between the lowest q mdw value used during the test and the value of q mdew used during the test. The dilution tunnel may be bypassed. A calibrated mass flow device shall be connected in series to the flowmeter for q mdew and the accuracy shall be checked for the value used for the test. Then the calibrated mass flow device shall be connected in series to the flow meter for q mdw, and the accuracy shall be checked for at least 5 settings corresponding to dilution ratio between 3 and 50, relative to q mdew used during the test. The transfer tube TT shall be disconnected from the exhaust, and a calibrated flow measuring device with a suitable range to measure q mp shall be connected to the transfer tube. Then q mdew shall be set to the value used during the test, and q mdw shall be sequentially set to at least 5 values corresponding to dilution ratios q between 3 and 50. Alternatively, a special calibration flow path, may be provided, in which the tunnel is bypassed, but the total and dilution air flow through the corresponding meters as in the actual test. A tracer gas, shall be fed into the exhaust transfer tube TT. This tracer gas may be a component of the exhaust gas, like CO2 or NOx. After dilution in the tunnel the tracer gas component shall be measured. This shall be carried out for 5 dilution ratios between 3 and 50. The accuracy of the sample flow shall be determined from the dilution ration r d: Text of image qmp = qmdew rd The accuracies of the gas analysers shall be taken into account to guarantee the accuracy of q mp. A carbon flow check using actual exhaust is recommended for detecting measurement and control problems and verifying the proper operation of the partial flow system. The carbon flow check should be run at least each time a new engine is installed, or something significant is changed in the test cell configuration. The engine shall be operated at peak torque load and speed or any other steady state mode that produces 5 % or more of CO2. The partial flow sampling system shall be operated with a dilution factor of about 15 to 1. If a carbon flow check is conducted, the procedure given in Appendix 6 to this Annex shall be applied. The carbon flow rates shall be calculated according to sections 2.1 to 2.3 of Appendix 6 to this Annex. All carbon flow rates should agree to within 6 % of each other. A pre-test check shall be performed within 2 hours before the test run in the following way: The accuracy of the flow meters shall be checked by the same method as used for calibration (see section 3.2.1) for at least two points, including flow values of q mdw that correspond to dilution ratios between 5 and 15 for the q mdew value used during the test. If it can be demonstrated by records of the calibration procedure under section 3.2.1 that the flow meter calibration is stable over a longer period of time, the pre-test check may be omitted. The system settings for the transformation time evaluation shall be exactly the same as during measurement of the test run. The transformation time shall be determined by the following method: An independent reference flowmeter with a measurement range appropriate for the probe flow shall be put in series with and closely coupled to the probe. This flowmeter shall have a transformation time of less than 100 ms for the flow step size used in the response time measurement, with flow restriction sufficiently low as to not affect the dynamic performance of the partial flow dilution system, and consistent with good engineering practice. A step change shall be introduced to the exhaust flow (or air flow if exhaust flow is calculated) input of the partial flow dilution system, from a low flow to at least 90 % of full scale. The trigger for the step change should be the same one used to start the look-ahead control in actual testing. The exhaust flow step stimulus and the flowmeter response shall be recorded at a sample rate of at least 10 Hz. From this data, the transformation time shall be determined for the partial flow dilution system, which is the time from the initiation of the step stimulus to the 50 % point of the flowmeter response. In a similar manner, the transformation times of the qmp signal of the partial flow dilution system and of the q mew,i signal of the exhaust flow meter shall be determined. These signals are used in the regression checks performed after each test (see section 3.8.3.2 of Appendix 2 to this Annex). The calculation shall be repeated for at least 5 rise and fall stimuli, and the results shall be averaged. The internal transformation time (< 100 msec) of the reference flowmeter shall be subtracted from this value. This is the “look-ahead” value of the partial flow dilution system, which shall be applied in accordance with section 3.8.3.2 of Appendix 2 to this Annex.

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Source: EUR-Lex (Cellar) · retrieved 2026-11-10 · Text as adopted (Official Journal); later amendments are not incorporated in this text.