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Correct way to measure FID flow rates
Posted: Tue Oct 27, 2009 2:37 pm
by unhpian
What is the correct way to measure FID flow rates? I have a digital flow meter with a button to change the gas being measured which accounts for difference in density. Our FID calls for a H2 flow rate of 40 mL/min, and air of 450 mL/min, and I have been measuring it using the meter set to the appropriate gas, which presumably gives a "adjusted" flow rate. Is this correct, or should I just use the "air" setting for both, that way the ratio is a true volumetric ratio?
Posted: Tue Oct 27, 2009 3:05 pm
by Consumer Products Guy
If you really care that much: measure each gas with the flow meter set for that type of gas.
Posted: Tue Oct 27, 2009 3:12 pm
by Peter Apps
If the flow meter really is calibrated for different gasses it must be correcting for more than just density (thermal conductivity for a start I would think). I'm with CPG; if it has a setting for each gas go ahead and use them.
The only reason that I can think of for correcting for only density is if the readout is in mass per unit time. Which would be strange. What make and model is it ?
Peter