Document ID: chunk:federal_register_of_legislation:F2011C00805:reg:3:p17
Version: federal_register_of_legislation:F2011C00805
Segment Type: reg
Provision Reference: reg 3 (pt 17/18)
Character Range: 342289–345428

are used in the following formula to calculate the mass change.

         where:

                   MHC = hydrocarbon mass in grams,

                   MHC,out = mass of hydrocarbons exiting the enclosure, in the case of fixed-volume enclosures for diurnal emission testing (grams)

                   MHC,i = mass of hydrocarbons entering the enclosure when a fixed-volume enclosure is used for testing diurnal emissions (grams)

                   CHC = hydrocarbon concentration in the enclosure (ppm  carbon (Note: ppm carbon = ppm propane x 3),

                   V = enclosure volume in cubic metres,

                   T = ambient temperature in the enclosure, (K),

                   P = barometric pressure, (kPa),

                   K = 17.6;

         where:

              i is the initial reading,

              f  is the final reading.

          3. CHECKING OF FID HYDROCARBON ANALYZER

          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.

          3.2.                                        Calibration of the HC Analyser

           The analyser should be calibrated using propane in air and purified synthetic air. See paragraph 4.5.2. of Annex 4 (Calibration and span gases).

         Establish a calibration curve as described in paragraphs 4.1. to 4.5. of this Appendix.

          3.3.  Oxygen interference check 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 preconditioned 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 reference gas to be used is propane with balance purified air which is taken to give a response factor of 1.00.

         The test gas to be used for oxygen interference and the recommended response factor range are given below:

         Propane and nitrogen:       0.95  Rf 1.05.

          4.  CALIBRATION OF THE HYDROCARBON ANALYZER

         Each of the normally used operating ranges are calibrated by the following procedure:

          4.1. establish the calibration curve by at least five calibration points spaced as evenly as possible over the operating range. The nominal concentration of the calibration gas with the highest concentrations to be at least 80 per cent of the full scale.

          4.2. calculate the calibration curve by the method of least squares. If the resulting polynomial degree is greater than 3, then the number of calibration points shall be at least the number