40 CFR 90.323 - Analyzer bench checks.
(a) Prior to initial use and after major repairs, verify that each analyzer complies with the specifications given in Table 2 in Appendix A of this subpart.
(b) If a stainless steel NO2 to NO converter is used, condition all new or replacement converters. The conditioning consists of either purging the converter with air for a minimum of four hours or until the converter efficiency is greater than 90 percent. The converter must be at operational temperature while purging. Do not use this procedure prior to checking converter efficiency on in-use converters.