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EQUATIONS AND EXAMPLE CALCULATION <br /> The hydrocarbon flow rate may be determined by the following expression <br /> M=C x Q x 000032 [EQ 11 <br /> where <br /> M=hydrocarbon flow rate(pounds per day) <br /> C =hydrocarbon concentration in the air flow(parts per million by volume,ppmv) <br /> Q=air flow rate(standard cubic feet per minute, scf n) <br /> 0 00032 = units conversion factor, which assumes the average molecular weight of the <br /> hydrocarbons in the flow is 86 <br /> Pitot tube measurements are used to determine the air velocity through the system piping Once the air <br /> velocity is determined, we can calculate the air flow rate since we blow the cross sectional flow area of <br /> the pipe <br /> • Q=V x A x Ts/Tx P/Ps [EQ 21 <br /> where <br /> V=air velocity(feet per minute) <br /> A=pipe cross sectional area(square feet) <br /> T= air temperature(absolute),Ts=standard temperature( = 528 R) <br /> P= air pressure(absolute),Ps=standard pressure(= 29 9 inches of mercury) <br /> Air samples collected for analysis of hydrocarbon concentrations are brought into thermal and <br /> mechanical equih`bnium with the atmospheric environment Therefore, the air flow rate is corrected for <br /> temperature and pressure in EQ 2 <br /> To determine the velocity with the picot tube pressure deferential readings we apply the expression <br /> below,which follows from Bemoulh's Equation <br /> V= 1096 2 4(Pv/D) [EQ 3] <br />