Document ID: chunk:federal_register_of_legislation:F2024C00356:reg:21:p17
Version: federal_register_of_legislation:F2024C00356
Segment Type: reg
Provision Reference: reg 21 (pt 17/35)
Character Range: 334528–337543

to the satisfaction of the technical service that alternative technology (e.g. computer, electronically controlled range switch, etc.) can give equivalent accuracy, then these alternatives may be used.
              2.2.  Analyser Verification Procedure
              2.2.1.  Each normally used operating range shall be checked prior to each analysis in accordance with the following:
              2.2.2.  The calibration shall be checked by use of a zero gas and by use of a span gas that has a nominal value within 80-95 per cent of the supposed value to be analysed.
              2.2.3.  If, for the two points considered, the value found does not differ by more than 5 per cent of the full scale from the theoretical value, the adjustment parameters may be modified. Should this not be the case, a new calibration curve shall be established in accordance with paragraph 1. of this appendix.
              2.2.4.  After testing, zero gas and the same span gas are used for re-checking. The analysis is considered acceptable if the difference between the two measuring results is less than 2 per cent.
              2.3.  FID Hydrocarbon Response Check Procedure
              2.3.1.  Detector response optimisation
                The FID shall be adjusted, as specified by the instrument manufacturer. Propane in air should be used, to optimise the response, on the most common operating range.
              2.3.2.  Calibration of the HC analyser
                The analyser should be calibrated using propane in air and purified synthetic air (see paragraph 3 of this appendix).
                Establish a calibration curve as described in paragraph 2.1. of this appendix.
              2.3.3.  Response factors of different hydrocarbons and recommended limits
                The response factor (Rf), for a particular hydrocarbon species is the ratio of the FID C1 reading to the gas cylinder concentration, expressed as ppm C1.
                The concentration of the test gas shall be at a level to give a response of approximately 80 per cent of full-scale deflection, for the operating range. The concentration shall be known, to an accuracy of 2 per cent in reference to a gravimetric standard expressed in volume. In addition, the gas cylinder shall be pre-conditioned for 24 hours at a temperature between 293 K and 303 K (20 and 30 °C).
                Response factors should be determined when introducing an analyser into service and thereafter at major service intervals. The test gases to be used and the recommended response factors are:

  Methane and purified air: 1.00 < Rf < 1.15

  or 1.00 < Rf < 1.05 for NG/biomethane fuelled vehicles

  Propylene and purified air: 0.90 < Rf < 1.00

  Toluene and purified air: 0.90 < Rf < 1.00

                These are relative to a response factor (Rf) of 1.00 for propane and purified air.
              2.3.4. Oxygen interference check and recommended limits
               The response factor shall be determined as described in paragraph