(a) You must calculate the 30 operating day rolling arithmetic average emissions rate in units of the applicable emissions standard (lb NOX/ton 100 percent acid produced) at the end of each operating day using all of the quality assured hourly average CEMS data for the previous 30 operating days.

(b) You must calculate the 30 operating day average emissions rate according to Equation 1:

Where: E30 = 30 operating day average emissions rate of NOX, lb NOX/ton of 100 percent HNO3; Ci = concentration of NOX for hour i, ppmv; Qi = volumetric flow rate of effluent gas for hour i, where Ci and Qi are on the same basis (either wet or dry), scf/hr; Pi = total acid produced during production hour i, tons 100 percent HNO3; k = conversion factor, 1.194 × 10−7 for NOX; and n = number of operating hours in the 30 operating day period, i.e., n is between 30 and 720. [77 FR 48445, Aug. 14, 2012; 79 FR 25681, May 6, 2014]