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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. (see Appendix A , orifice <br /> Flow Calculation) <br /> The orifice plates used to determine the €low rate are the square <br /> edged type C--0.65. <br /> VWE )las developed a table for calculating the flow across an <br /> orifice of known size. (see Appendix A, Flow Rate Table) . <br /> CALCULATIONS <br /> To calculate the pounds (lb) per day the concentration is <br /> multiplied by the volume of air produced in one day. <br /> The lab reports the Concentrations (C) of the air sampling in <br /> ug/liter. The first step is to convert this value to lbs/cf <br /> (pounds per cubic foot) . <br /> . 1 ug/l x 0.000001g/Ug x 0.0022051g/g x 28 .321/cf = 0 .00O0006211b/cf <br /> The volume of air produced in one day, equals the flow rate (Q)x <br /> the time of flow. <br /> V = Q x T = cf/day = cf/min x 1440min/day <br /> The volume must -be corrected to standard temperature and <br /> pressure(STP) . <br /> P = Pressure = 14.7 lb/in7- @ STP <br /> V = Volume cf <br /> T = Temperature im degrees above absolute Zero = 491 .58-R @ STP. <br /> Using the Ideal Cas Lav P1V1/T1 = P2V2/T2 <br /> Solving for V2 =P1VlT2/P2T1 <br /> Assuming P1 = P2 = 14 . 7 lb/int , P cancels from the equation <br /> leaving V2 = V1T2/Tl. <br /> V1 = Q cf/m x 1440 min/day <br /> T2 = 491.58-R <br /> T1 = 459.58 + T-F at sight. <br /> V2 = Q cf/min z 3440 min/day x 491 .58-R/ ( 459.58- + T-F) <br /> S lb/day = C ug/l S 0.0000000621 lb 1/ug cf x Q cf/min x <br /> 1440 min/day x 491 .58-R/ ( 459.58,0 + T-F) <br />• <br /> 4 <br /> e <br />