Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p33
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 33/57)
Character Range: 182718–185585

of Annex 6.

              In addition, other methods that determine the exhaust mass flow rate based on non-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 paragraph 3. and is validated according to paragraph 4. of Annex 6.

              7.2.1. Calibration and verification standards

              The measurement performance of exhaust mass flow meters shall be verified with air or exhaust gas against a traceable standard such as a calibrated exhaust mass flow meter or a full flow dilution tunnel.

              7.2.2. Frequency of verification

              The compliance of exhaust mass flow meters with paragraphs 7.2.3. to 7.2.9. shall be verified no longer than one year before the actual test.

              7.2.3. Accuracy

              The accuracy of the EFM, defined as the deviation of the EFM reading from the reference flow value, shall not exceed ± 3 per cent of the reading, or 0.3 per cent of full scale, whichever is larger.

              7.2.4. Precision

              The 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 not exceed 1 per cent of the maximum flow at which the EFM has been calibrated.

              7.2.5. Noise

              The noise 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.

              7.2.6. Zero response drift

              The zero response drift 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.

              7.2.7. Span response drift

              The span response drift 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.

              7.2.8. Rise 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