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FLOW RATES <br /> Flow rates are measured at the site by use of orifice plates . A one <br /> inch orifice is placed in line for each well and a three inch <br /> orifice is used to measure the total flow. An orifice plate <br /> restricts the flow of air across it. This restriction causes a <br /> pressure drop across the orifice. By measuring the resulting <br /> pressure change across the orifice it is possible to calculate the <br /> air flow rate. The flow rate is calculated by the pressure drop <br /> (millimeters (mm) water) across a square edge orifice plate . <br /> Ve = CK sqr(P) Q = AVe <br /> Where: <br /> Ve= velocity in feet per minute (fpm) <br /> C = Orifice Coefficient = 0 65 (tor 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 /> page 4 of R603, 01/18/94 <br />