On or after the date on which the performance test required to be conducted by Sec. Sec. 63.7 and 63.626 is required to be completed, the owner/operator using a wet scrubbing emission control system must maintain daily averages of the pressure drop across each scrubber and of the flow rate of the scrubbing liquid to each scrubber within the allowable ranges established pursuant to the requirements of Sec. 63.625(f)(1) or (2). [67 FR 40818, June 13, 2002]