40 CFR 89.317 - NOX converter check.
(a) Prior to its introduction into service, and monthly thereafter, the chemiluminescent oxides of nitrogen analyzer shall be checked for NO2 to NO converter efficiency. Figure 2 in appendix B of this subpart is a reference for the following paragraphs.
(b) Follow good engineering practices for instrument start-up and operation. Adjust the analyzer to optimize performance.
(c) Zero the oxides of nitrogen analyzer with zero-grade air or zero-grade nitrogen.
(d) Connect the outlet of the NOX generator to the sample inlet of the oxides of nitrogen analyzer which has been set to the most common operating range.
(e) Introduce into the NOX generator analyzer-system an NO-in-nitrogen (N2) mixture with an NO concentration equal to approximately 80 percent of the most common operating range. The NO2 content of the gas mixture shall be less than 5 percent of the NO concentration.
(f) With the oxides of nitrogen analyzer in the NO mode, record the concentration of NO indicated by the analyzer.
(g) Turn on the NOX generator O2 (or air) supply and adjust the O2 (or air) flow rate so that the NO indicated by the analyzer is about 10 percent less than indicated in paragraph (f) of this section. Record the concentration of NO in this NO O2 mixture.
(h) Switch the NOX generator to the generation mode and adjust the generation rate so that the NO measured on the analyzer is 20 percent of that measured in paragraph (f) of this section. There must be at least 10 percent unreacted NO at this point. Record the concentration of residual NO.
(i) Switch the oxides of nitrogen analyzer to the NOX mode and measure total NOX. Record this value.
(j) Switch off the NOX generator but maintain gas flow through the system. The oxides of nitrogen analyzer will indicate the NOX in the NO O2 mixture. Record this value.
(k) Turn off the NOX generator O2 (or air) supply. The analyzer will now indicate the NOX in the original NO-in-N2 mixture. This value should be no more than 5 percent above the value indicated in paragraph (f) of this section.