Information Circular1983 |
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117 V switched auxiliary outputs bubble meter bubble transit calibration curve calibration graph CLM-A CLM-B coefficient of variation compression fittings control console controller flow rate controller output voltage CORRECTED FLOW RATE corrected to 25 counters and displays curve for controller cylinder detector digital panel meter diluent diluted gas dilution ratio dynamic gas-mixing system F₁ flip-flop flow rate corrected flowmeter fume hood gas detection instrument gas dilution system gas flow gas instrument gas mixtures Gas output gases Ground Manifold Hg versus scaled hydrogen sulfide linear manifold console manual selector valves mass flow controller mbar measured controller flow methane concentration milliliters ml/min on-off operator output voltage command PANEL METER READING phototransistors potentiometer range reading of controller run gate scaled digital panel select gate selected time base solenoid valves test gas TEXAS INSTRUMENTS timer tion Tylan versus scaled digital voltage command signal volume
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Page 2 - The use of trade names is for identification only and does not imply endorsement by the Public Health Service or the US Department of Health and Human Services.
Page 1 - Thus, gas mixtures can be made over a wide range of concentrations, from the percent region (by dilution of a pure single-component gas) to fractional parts per million (by dilution of a premixed standard, eg, a 1,000-ppm mixture) . This system is especially useful in determining the response of gas detection devices over the entire range of their measurement. Because the controllers are voltage controlled they lend themselves easily to automated control using computer-based systems.
Page 1 - All authors are with the Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA.
Page 1 - ... of the setting. This dynamic gas-mixing system reduces the cylinder inventory and the demurrage charges for special gas mixtures. Gas mixtures that cannot be shipped commercially, such as flammable mixtures of methane in air, can be conveniently prepared by this system. The maximum dilution ratio is 2.5 x 104.
Page 13 - It is a small thin-walled tube with a ball welded to the end. The seat is a cone. Inside the tube is a heater wire that causes the tube to expand relative to the outer shell, moving the ball relative to its seat and thereby varying the flow.