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M <br /> Assumptions <br /> The average velocity of a turbulent air stream in a pipe is equal to 0.9 <br /> that of the center-line velocity. <br /> Atmospheric pressure is 30 inches of mercury. <br /> Soil vapor is a ideal gas with a density equal to pure air. <br /> Variables <br /> P = Pressure of the soil vapor at the pitot tube <br /> Vp = Differential pressure measured by the pitot tube <br /> a .= Soil vapor flow rate in cubic feet per minute <br /> u = Soil vapor velocity at the pitot tube <br /> A = Cross-sectional area of the pipe interior <br /> D = Inside diameter of pipe <br /> e = Soil vapor density <br /> Pb = Absolute static pressure of soil vapor at the pitot tube <br /> T = Absolute temperature of the soil vapor at the pitot tube <br /> T, = Temperature of the soil vapor at the pitot tube <br /> Calculations <br /> llM <br /> A = (pi)R2 (Inches) <br /> Pb = 30-V (Inches of Hg) <br /> T = T, +460 (Degrees Rankine) <br /> e = 1 .325(Pb/T) <br /> u = 1 ,096.2(Vple)12 (u in feet/minute) <br /> i <br /> a = uA (Q is in cubic feet per minute) <br /> VOC Extraction Calculation <br /> The mass of VOC extracted and produced by the SVS may be estimated by <br /> multiplying the volume of air through the system per day by the number of moles <br /> of gas flowing through the system per day. An example calculation form a <br /> spreadsheet is attached. <br />• <br />