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3". <br /> A sample port for the effluent is located in the exhaust stack of <br /> the final canister. The flow pressure from the exhaust is great <br /> enough to fill a tedlar bag. Sterile poly tubing is fitted to <br /> the exhaust port and the tedlar bag. Then the sample valve of <br /> the tedlar bag is opened and the bag is filled with the sample. <br /> Once the tedlar bag is full, the valve is closed and locked, the <br /> sample port closed, and the appropriate label is placed on the <br /> bag. <br /> The labels for both the influent and effluent tedlar bag samples <br /> show the date, time, sample ID# and analyses to be run. <br /> Both the influent and effluent tedlar bag samples are then placed <br /> within a cooler, on ice, and are hand delivered to WEGE' s <br /> laboratory that same day <br /> The vapor sample �s thep injected into an FID (Flame Ionizing <br /> Detector) chromatograph and the resulting chromatogram compared <br /> to standard chromatograms of known TFH (Total Fuel Hydrocarbons, <br /> gasoline) and BTEX (benzene, toluene, ethylbenzene, and xylenes) <br /> concentrations . <br /> FLOW RATES <br /> Flow rates are measured at the site by use of orifice plates . A <br /> one inch orifice is placed in line for each well and two one inch <br /> orifices in parallel are 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 <br /> (mm) 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 . I" = 0 . 00545 ft2 <br /> Q = A X 0 . 65 X 794 6 X sgr(P) <br /> page 3 of R604, 01/19/93 <br />