Measuring volume of flow?

[AllenR]

I am looking for a way to measure volume of gas consumed by a diaphragm operated pump over a length of time. The pressure ranges from 5-85 psi and the volume can be from almost zero to roughly 22 cfm. What is a good way to measure this, as flow is not consistent I think I will probably need some type of data logging equipment. Any help would be greatly appreciated.

thank-you
Allen

 

[MJCronin]

AllenR,

Contact the pump vendor or go to a website that has the same or similar sized pump..

Most vendors of newer AOD pumps will give you a measure of the CFM/stroke of all of the models that they offer..

Try YAMADA pump....

MJC

 

[zdas04]

I've had good luck measuring flows this variable with an accumulator vessel, an actuated ball valve, a pressure-acutated solenoid, and a counter. This technique requires a gas source with some extra pressure. The way it works is: (assuming you need 85 psig for pump operations and have a source of gas with over 150 psig) (1) pressure the vessel to 150 psig; (2) when the pressure drops to 100 psig, cycle a ball valve to quickly fill the accumulator to 150 psig; (3) quickly shut the ball valve and count the evolution. It is quite easy to calculate the SCF added to the accumulator each cycle with known beginning and ending pressures and feed that into a flow computer as the "k-factor" on a turbine meter. The ball valve needs to big enough to fill the accumulator quickly, but small enough to keep from over-shooting your upper target (for the quantities you mentioned above, a 1-inch would probably be a good place to start your calculations). The accumulator vessel needs to be big enough to keep from having to cycle the ball valve too often (I'd probably shoot for a max around twice/hour--you can reduce the number of cycles by increasing the upper pressure to store more SCF in the same volume).

The problem I've had with using the manufacturer's CFM/stroke data with changing demand is knowing how long you were at each demand point on the curve when the flow changes from moment to moment. Square-Edged orifice equipment would work for changing demand, but you're talking about a small tube and orifice and the corelations aren't going to be real good. Turbines would probably not spin at this demand. The pressure is probably too low for ultrasonic, but that might get you close.