Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p34
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 34/57)
Character Range: 185316–188133

time

              The 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 paragraph 4.2.7. but shall not exceed 1 second.

              7.2.9. Response time check

              The 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 in less than 0.1 second is highly recommended. The gas flow rate used for the test shall cause a flow rate change of at least 60 per cent full scale 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 (t0) until the response is 10 per cent (t10) of the final reading. The rise time is defined as the time between 10 per cent and 90 per cent response (t10 to t90) of the final reading. The response time (t90) is defined as the sum of the delay time and the rise time. The exhaust mass flow meter response time (t90) shall be ≤ 3 seconds with a rise time (t10 to t90) of ≤ 1 second in accordance with paragraph 7.2.8.

              8. Sensors and auxiliary equipment

              Any sensor or auxiliary equipment used to determine temperature, atmospheric pressure, ambient humidity, vehicle speed, fuel flow or intake air flow, for example, 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 A5/4. Compliance with the requirements of Table A5/4 shall be demonstrated at intervals specified by the instrument manufacturer, as required by internal audit procedures or in accordance with ISO 9000.

       Table A5/4
       Accuracy requirements for measurement parameters

Measurement parameter  Accuracy
Fuel flow[19]          ± 1 % of reading[20]

Air flow[21]           ± 2 % of reading

Vehicle speed[22]      ± 1.0 km/h absolute

Temperatures ≤600 K    ± 2 K absolute

Temperatures >600 K    ± 0.4 % of reading in Kelvin

Ambient pressure       ± 0.2 kPa absolute

Relative humidity      ± 5 % absolute

Absolute humidity      ± 10 % of reading or, 1 gH2O/kg dry air, whichever is larger

Annex 6

Validation of PEMS and non-traceable exhaust mass flow rate
       1.  Introduction

              This annex describes the requirements to validate under transient conditions the functionality of the installed PEMS as well as the correctness of the exhaust mass flow rate obtained from non-traceable exhaust mass flow