Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p30
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 30/71)
Character Range: 293594–296589

shall be recorded. (The analyser is in the NO mode).

1.7.6.                        NOx mode

              The NO analyser is then switched to the NOx mode so that the gas mixture (consisting of NO, NO2, O2 and N2) now passes through the converter. The indicated concentration a shall be recorded. (The analyser is in the NOx mode).

1.7.7.                        Deactivation of the ozonator

              The ozonator is now deactivated. The mixture of gases described in Section 1.7.6 passes through the converter into the detector. The indicated concentration b shall be recorded. (The analyser is in the NOx mode).

1.7.8.                        NO mode

              Switched to NO mode with the ozonator deactivated, the flow of oxygen or synthetic air is also shut off. The NOx reading of the analyser shall not deviate by more than ± 5 % from the value measured according to Section 1.7.2. (The analyser is in the NO mode).

1.7.9.                        Test interval

              The efficiency of the converter must be tested prior to each calibration of the NOx analyser.

1.7.10.                      Efficiency requirement

              The efficiency of the converter shall not be less than 90 %, but a higher efficiency of 95 % is strongly recommended.

                  Note: If, with the analyser in the most common range, the ozonator cannot give a reduction from 80 % to 20 % according to Section 1.7.5, then the highest range which will give the reduction shall be used.

        Figure 6

        Schematic of NOx converter efficiency device

1.8.                            Adjustment of the FID

1.8.1.                        Optimisation of the detector response

              The FID must be adjusted as specified by the instrument manufacturer. A propane in air span gas should be used to optimise the response on the most common operating range.

              With the fuel and air flow rates set at the manufacturer's recommendations, a 350 ± 75 ppm C span gas shall be introduced to the analyser. The response at a given fuel flow shall be determined from the difference between the span gas response and the zero gas response. The fuel flow shall be incrementally adjusted above and below the manufacturer's specification. The span and zero response at these fuel flows shall be recorded. The difference between the span and zero response shall be plotted and the fuel flow adjusted to the rich side of the curve.

1.8.2.                        Hydrocarbon response factors

              The analyser shall be calibrated using propane in air and purified synthetic air, according to Section 1.5.
              Response factors shall be determined when introducing an analyser into service and after major service intervals. 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