(a) The initial performance test after installation of the continuous emissions monitoring system (CEMS) for sulfur dioxide in exhaust gases and the relative accuracy test audits required by 40 Code of Federal Regulations (CFR) Part 60, Appendix F must be conducted using United States Environmental Protection Agency (EPA) Test Method 6 or 6C (40 CFR Part 60, Appendix A).(b) Performance tests and relative accuracy test audits must be conducted using a method in subsection (a) and EPA Test Method 2 (40 CFR Part 60, Appendix A) for exhaust gas flow and following the measurement site criteria of EPA Test Method 1, §11.1 (40 CFR Part 60, Appendix A), or EPA Test Method 19 (40 CFR Part 60, Appendix A) for exhaust gas flow in conjunction with the measurement site criteria of Performance Specification 2, §8.1.3 (40 CFR Part 60, Appendix B).(c) Alternate methods as approved by the executive director and the EPA may be used.