Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p24
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 24/57)
Character Range: 158418–161528

±1 per cent of full scale, the test shall be repeated;

                     (vi) The oxygen interference EO2 [%] shall be calculated for each oxygen interference check gas in step (iv) as follows:

                   where the analyser response is:

                   where:

cref,b  is the reference HC concentration in step (ii) [ppmC1]

cref,d  is the reference HC concentration in step (iv) [ppmC1]

cFS,b   is the full scale HC concentration in step (ii) [ppmC1]

cFS,d   is the full scale HC concentration in step (iv) [ppmC1]

cm,b    is the measured HC concentration in step (ii) [ppmC1]

cm,d    is the measured HC concentration in step (iv) [ppmC1]

(vii) The oxygen interference EO2 shall be less than ±1.5 per cent for all required oxygen interference check gases.
                     (viii) If the oxygen interference EO2 is higher than ±1.5 per cent, corrective action may be taken by incrementally adjusting the air flow (above and below the manufacturer's specifications), the fuel flow and the sample flow.

                     (ix) The oxygen interference check shall be repeated for each new setting.

              4.3.4. Conversion efficiency of the non-methane cutter (NMC)

              If hydrocarbons are analysed, a NMC can be used to remove non-methane hydrocarbons from the gas sample by oxidizing all hydrocarbons except methane. Ideally, the conversion for methane is 0 per cent and for the other hydrocarbons, represented by ethane, is 100 per cent. For the accurate measurement of NMHC, the two efficiencies shall be determined and used for the calculation of the NMHC emissions (see paragraph 6.2. of Annex 7). It is not necessary to determine the methane conversion efficiency in the case where the NMC-FID is calibrated according to method (b) in paragraph 6.2. of Annex 7 by passing the methane/air calibration gas through the NMC.

              (a) Methane conversion efficiency

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

              where:

cHC(w/NMC)    is the HC concentration with CH4 flowing through the NMC [ppmC1]

cHC(w/o NMC)  is the HC concentration with CH4 bypassing the NMC [ppmC1]

(b) Ethane conversion efficiency
              Ethane calibration gas shall be flowed through the FID with and without bypassing the NMC; the two concentrations shall be recorded. The ethane efficiency shall be determined as:

              where:

cHC(w/NMC)    is the HC concentration with C2H6 flowing through the NMC [ppmC1]

cHC(w/o NMC)  is the HC concentration with C2H6 bypassing the NMC [ppmC1]

              4.3.5. Interference effects

              (a) General

                  Other gases than the ones being analysed can affect the analyser reading. A check for interference effects and the correct functionality of analysers shall be performed by the analyser manufacturer prior to market introduction at least once for each type of analyser or device addressed in paragraphs 4.3.5. (b)