water flow to air flow conversion

[Kmech88]

I have a unit which has 2 nozzles requiring .4 gallons/min water flow rate and has to be tested on an assembly line. I was considering implementing a system which utilizes compressed air instead of having to fill the unit with water to save time. However, I haven't found any reliable way of converting a measured flow of compressed air to units which would be comparable to GPM. Any ideas?

 

[BigInch]

Check out the methods used to size safety relief valve throats. I would think that you could size an orifice for your liquid flow rate, then using that size and the temperature and pressure at which you will inject your air during your standardized testing proceedure, you will be able to find an "equivalent" air flow rate. Depending on how much your device differs from a safety relief valve or an ideal orifice, you might have to do some calibration to finally get it right. It sounds feasible... at first glance anyway.

http://virtualpipeline.spaces.msn.com

 

[Golestan]

I have done similar experiments. The equivalent of air to water is about 3.8~4 SCFM of air to 1 gmp of water. It was a long time ago and I don't remember how I got there but it worked out well and we proved it in the lab.

hope this works for you.

Fred

 

[hydtools]

Do lab tests. Use known good nozzles and run your proposed air flow setup to establish equivalent air flow for your nozzles. Run a quantity of nozzles so you don't have a single sample data point. Determine your air flow range for acceptable nozzles. Write the setup in the production test procedures.

Ted

 

[Kmech88]

Fred,
Thanks a lot for the input. I'm still in the initial design/set-up phase for the system and am grateful for the approximate air-water equivalence. When working calculations and running tests in lab at least I'll have a ballpark idea of if my numbers are on the right track.


Kurt