40 C.F.R. § 60.642

(a) During the initial performance test required by § 60.8(b), each owner or operator shall achieve at a minimum, an SO2 emission reduction efficiency (Zi) to be determined from table 1 based on the sulfur feed rate (X) and the sulfur content of the acid gas (Y) of the affected facility.

(b) After demonstrating compliance with the provisions of paragraph (a) of this section, the owner or operator shall achieve at a minimum, an SO2 emission reduction efficiency (Zc) to be determined from table 2 based on the sulfur feed rate (X) and the sulfur content of the acid gas (Y) of the affected facility.