[F1ANNEX IIIA U.K. VERIFYING REAL DRIVING EMISSIONS
Textual Amendments
Appendix 1
Test procedure for vehicle emissions testing with a Portable Emissions Measurement System (PEMS) U.K.
4. PRE-TEST PROCEDURES U.K.
4.1. PEMS leak check U.K.
After the installation of PEMS is completed, a leak check shall be performed at least once for each PEMS-vehicle installation as prescribed by the PEMS manufacturer or as follows. 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 shall read approximately zero in the absence of a leak. Else, the sampling lines shall be checked and the fault corrected.
The leakage rate on the vacuum side shall not exceed 0,5 per cent 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 Dp (kPa/min) in the system shall not exceed:
Alternatively, a concentration step change at the beginning of the sampling line shall be introduced by switching from zero to span gas while maintaining the same pressure conditions as under normal system operation. If for a correctly calibrated analyser after an adequate period of time the reading is ≤ 99 per cent compared to the introduced concentration, the leakage problem shall be corrected.
4.2. Starting and stabilising the PEMS U.K.
The PEMS shall be switched on, warmed up and stabilised according to the specifications of the PEMS manufacturer until, e.g. pressures, temperatures and flows have reached their operating set points.
4.3. Preparing the sampling system U.K.
The sampling system, consisting of the sampling probe, sampling lines and the analysers, shall be prepared for testing by following the instruction of the PEMS manufacturer. It shall be ensured that the sampling system is clean and free of moisture condensation.
4.4. Preparing the EFM U.K.
If used for measuring the exhaust mass flow, the EFM shall be purged and prepared for operation in accordance with the specifications of the EFM manufacturer. This procedure shall, if applicable, remove condensation and deposits from the lines and the associated measurement ports.
4.5. Checking and calibrating the analysers for measuring gaseous emissions U.K.
Zero and span calibration adjustments of the analysers shall be performed using calibration gases that meet the requirements of point 5 of Appendix 2. The calibration gases shall be chosen to match the range of pollutant concentrations expected during the emissions test.
[F2To minimise analyser drift, one should conduct the zero and span calibration of analysers at an ambient temperature that resembles, as closely as possible, the temperature experienced by the test equipment during the RDE trip.]
Textual Amendments
4.6. Checking the analyser for measuring particle emissions U.K.
The zero level of the analyser shall be recorded by sampling HEPA filtered ambient air. The signal shall be recorded at a constant frequency of at least 1,0 Hz over a period of 2 min and averaged; the permissible concentration value shall be determined once suitable measurement equipment becomes available.
4.7. Measuring vehicle speed U.K.
Vehicle speed shall be determined by at least one of the following methods:
a GPS; if vehicle speed is determined by a GPS, the total trip distance shall be checked against the measurements of another method according to point 7 of Appendix 4,
a sensor (e.g. optical or micro-wave sensor); if vehicle speed is determined by a sensor, the speed measurements shall comply with the requirements of point 8 of Appendix 2, or alternatively, the total trip distance determined by the sensor shall be compared with a reference distance obtained from a digital road network or topographic map. The total trip distance determined by the sensor shall deviate by no more than 4 % from the reference distance,
the ECU; if vehicle speed is determined by the ECU, the total trip distance shall be validated according to point 3 of Appendix 3 and the ECU speed signal adjusted, if necessary to fulfil the requirements of point 3.3 of Appendix 3. Alternatively, the total trip distance as determined by the ECU shall be compared with a reference distance obtained from a digital road network or topographic map. The total trip distance determined by the ECU shall deviate by no more than 4 % from the reference.
4.8. Check of PEMS set-up U.K.
The correctness of connections with all sensors and, if applicable, the ECU shall be verified. If engine parameters are retrieved, it shall be ensured that the ECU reports values correctly (e.g. zero engine speed (rpm) while the combustion engine is in key-on-engine-off status). The PEMS shall function free of warning signals and error indication.]