Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p35
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 35/57)
Character Range: 187838–190910

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 meters or calculated from ECU signals.

       2.  Symbols, Parameters and Units

a0  —  y intercept of the regression line

a1  —  slope of the regression line

r2  —  coefficient of determination

x   —  actual value of the reference signal

y   —  actual value of the signal under validation

3. Validation procedure for PEMS
              3.1. Frequency of PEMS validation

              It is recommended to validate the correct installation of a PEMS on a vehicle via comparison with laboratory installed equipment on a test performed on a chassis dynamometer either before the RDE test or, alternatively, after the completion of the test. For tests performed during type approval, the validation test is required.

              3.2. PEMS validation procedure

              3.2.1. PEMS installation

              The PEMS shall be installed and prepared according to the requirements of Annex 4. The PEMS installation shall be kept unchanged in the time period between the validation and the RDE test.

              3.2.2. Test conditions

              The validation test shall be conducted on a chassis dynamometer, as far as possible, under type approval conditions by following the requirements of UN Regulation No. 154 on WLTP for a 4-phase cycle. It is recommended to feed the exhaust flow extracted by the PEMS during the validation test back to the CVS. If this is not feasible, the CVS results shall be corrected for the extracted exhaust mass. If the exhaust mass flow rate is validated with an exhaust mass flow meter, it is recommended to cross-check the mass flow rate measurements with data obtained from a sensor or the ECU.

              3.2.3. Data analysis

              The total distance-specific emissions [g/km] measured with laboratory equipment shall be calculated in accordance with UN Regulation No. 154 on WLTP. The emissions as measured with the PEMS shall be calculated according to Annex 7, summed to give the total mass of pollutants [g] and then divided by the test distance [km] as obtained from the chassis dynamometer. The total distance-specific mass of pollutants [g/km], as determined by the PEMS and the reference laboratory system, shall be evaluated against the requirements specified in paragraph 3.3. For the validation of NOX emission measurements, humidity correction shall be applied in accordance with UN Regulation No. 154 on WLTP.

              3.3. Permissible tolerances for PEMS validation

              The PEMS validation results shall fulfil the requirements given in Table A6/1. If any permissible tolerance is not met, corrective action shall be taken and the PEMS validation shall be repeated.

       Table A6/1
       Permissible tolerances

Parameter [Unit]   Permissible absolute tolerance
Distance