Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p31
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 31/71)
Character Range: 296360–299355

The response factor (Rf) for a particular hydrocarbon species is the ratio of the FID C1 reading to the gas concentration in the cylinder expressed by ppm C1.

              The concentration of the test gas must be at a level to give a response of approximately 80 % of full scale. The concentration must be known to an accuracy of ± 2 % in reference to a gravimetric standard expressed in volume. In addition, the gas cylinder must be preconditioned for 24 hours at a temperature of 298 K ± 5 K (25 °C ± 5 °C).

              The test gases to be used and the recommended relative response factor ranges are as follows: methane and purified synthetic air 1,00 ≤ Rf ≤ 1,15
              propylene and purified synthetic air 0,90 ≤ Rf ≤ 1,10 toluene and purified synthetic air 0,90 ≤ Rf ≤ 1,10
              These values are relative to the response factor (Rf) of 1,00 for propane and purified synthetic air.

1.8.3.                        Oxygen interference check

              The oxygen interference check shall be determined when introducing an analyser into service and after   major service intervals.

              The response factor is defined and shall be determined as described in Section 1.8.2. The test gas to be used and the recommended relative response factor range are as follows:

                            propane and nitrogen 0,95 ≤ Rf ≤ 1,05

              This value is relative to the response factor (Rf) of 1,00 for propane and purified synthetic air.

              The FID burner air oxygen concentration must be within ± 1 mole % of the oxygen concentration of the burner air used in the latest oxygen interference check. If the difference is greater, the oxygen interference must be checked and the analyser adjusted, if necessary.

1.8.4.                        Efficiency of the non-methane cutter (NMC, for NG fuelled gas engines only)

              The NMC is used for the removal of the non-methane hydrocarbons from the sample gas by oxidising all hydrocarbons except methane. Ideally, the conversion for methane is 0 %, and for the other hydrocarbons represented by ethane is 100 %. For the accurate measurement of NMHC, the two efficiencies shall be determined and used for the calculation of the NMHC emission mass flow rate (see Annex III, Appendix 2, Section 4.3).

1.8.4.1.                    Methane efficiency

              Methane calibration gas shall be flown through the FID with and without bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows:

              where,

              concw = HC concentration with CH4 flowing through the NMC concw/o   = HC concentration with CH4 bypassing the NMC
1.8.4.2.                    Ethane efficiency

              Ethane calibration gas shall be flown through the FID with and without bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows
              where,

              concw = HC concentration