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FLOW RATES <br /> Flow rates are measured at the site by use of orifice plates . <br /> A one inch orifice is placed in line for each well and a three <br /> inch orifice is used to measure the total flow. <br /> An orifice plate restricts the flow of air across it . This <br /> restriction causes a pressure drop across the orifice . By <br /> measuring the resulting pressure change across the orifice it is <br /> possible to calculate the air flow rate . <br /> The flow rate .is calculated by the pressure drop (millimeters (mm) <br /> water) across a square edge orifice plate. <br /> Ve = CK sgr(P) Q = AVe <br /> Where. <br /> Ve= velocity in feet per minute ( fpm) <br /> C = Orifice Coefficient = 0 . 65 (for orifice used) <br /> K = Constant = 794 . 6 mm water <br /> P = Pressure differential across the orifice <br /> Q = Flow rate in cubic feet per minute (CFM) <br /> A = Area orifice in square feet. 1" = 0 . 00545 ft2 <br /> 3" = 0 . 04909 ft2 <br /> Q = A X 0 . 65 X 794 6 X sgr(P) <br /> 5 <br />