40 CFR § 60.176 - Test methods and procedures.
(a) In conducting the performance tests required in § 60.8, the owner or operator shall use as reference methods and procedures the test methods in appendix A of this part or other methods and procedures as specified in this section, except as provided in § 60.8(b).
(2) The continuous monitoring system of § 60.175(a)(2) shall be used to determine the SO2 concentrations on a dry basis. The sampling time for each run shall be 2 hours, and the average SO2 concentration for the 2-hour period shall be computed as in § 60.175(b). The monitoring system drift during the run may not exceed 2 percent of the span value.