# Thread: PSI to GPM calculation

1. ## PSI to GPM calculation

I'm a chief of a small town FD with myself or any of our firefighters trained very much in pump operations. My question is to see if anyone has a simple equation or table to convert PSI to GPM. Our pumper is a '75 Brucco with a Hale pump. It works pretty good for our purposes, but no one knows how to convert the PSI gauges to tell how many GPM we're putting out. Any help at all is GREATLY appreciated!!

2. You have only one part of the equation!
EP=FL+NP+/- any elevation gain or loss.
Engine Pressure (EP) doesn't mean too much unless you know friction loss (FL) and nozzle pressure (NP). To complicate things more, for friction loss, you need to know your flow! For instance, a gauge reading 100 psi pumping an 1 3/4 and a gauge reading 100 psi pumping a 5" line will have vastly different flows! You'll need to get ahold of a friction loss chart and a pitot gauge or some manufacturers info on your nozzles. Contact your local equipment distributor for some help. Many times they have the test equipment and charts, sometimes they will even bring a manufacturer rep out to give you a hand. A good book for you guys to start with maybe the IFSTA Fire Streams manual. Easy to read and has lots of charts. Good Luck

3. http://www.fofd.org/engineer/

Check these guys out too, they have a pretty cool hydraulic calculator page.

[This message has been edited by Halligan84 (edited June 02, 2000).]

[This message has been edited by Halligan84 (edited June 02, 2000).]

4. I made life easy for myself...for every line we carry I made a chart plotting the Friction loss and GPM. It gives me or whoever runs the pump the pump pressure that is required to get the flow selected at the nozzle. My data was all done via theoretical calculations, i didnt do actual flow tests...but I still am closer to accurate than guessing. I can actually email it to anyone who is interested in seeing it.

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The information presented herin is simply my opinion and does not represent the opinion or view of my employer(s) or any department/agency to which I belong.

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