Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p36
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 36/56)
Character Range: 395042–397833

follows:
(a) Methane and purified synthetic air 1.00  rh  1.15;
(b) Propylene and purified synthetic air 0.90  rh  1.1;
(c) Toluene and purified synthetic air 0.90  rh  1.1.
 These values are relative to a rh of 1 for propane and purified synthetic air.
9.3.7.3. Oxygen interference check
 For raw exhaust gas analyzers only, the oxygen interference check shall be performed when introducing an analyzer into service and after major service intervals.
 A measuring range shall be chosen where the oxygen interference check gases will fall in the upper 50 per cent. The test shall be conducted with the oven temperature set as required. Oxygen interference check gas specifications are found in paragraph 9.3.3.4.
(a) The analyzer shall be set at zero;
(b) The analyzer shall be spanned with the 0 per cent oxygen blend for positive ignition engines. Compression ignition engine instruments shall be spanned with the 21 per cent oxygen blend;
(c) The zero response shall be rechecked. If it has changed by more than 0.5 per cent of full scale, steps (a) and (b) of this paragraph shall be repeated;
(d) The 5 per cent and 10 per cent oxygen interference check gases shall be introduced;
(e) The zero response shall be rechecked. If it has changed by more than 1 per cent of full scale, the test shall be repeated;
(f) The oxygen interference EO2 shall be calculated for each mixture in step (d) as follows:

                     EO2 = (cref,d - c)  100 / cref,d (73)

                     With the analyzer response being

                      (74)
Where:
                     cref,b  is the reference HC concentration in step (b), ppm C
                     cref,d  is the reference HC concentration in step (d), ppm C
                     cFS,b  is the full scale HC concentration in step (b), ppm C
                     cFS,d  is the full scale HC concentration in step (d), ppm C
                     cm,b is the measured HC concentration in step (b), ppm C
                     cm,d is the measured HC concentration in step (d), ppm C
(g) The oxygen interference EO2 shall be less than 1.5 per cent for all required oxygen interference check gases prior to testing;
(h) If the oxygen interference EO2 is greater than 1.5 per cent, corrective action may be taken by incrementally adjusting the airflow above and below the manufacturer's specifications, the fuel flow and the sample flow;
(i) The oxygen interference shall be repeated for each new setting.
9.3.8. Efficiency of the non-methane cutter (NMC)
 The NMC is used for the removal of the non-methane hydrocarbons from the sample gas 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