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Sunday, August 3rd 2008, 12:54am

Calculate psi based on gpm?

Am designing an irrigation system that will be supplied by a tank and pump. The distance between the supply and valve manifold is ~100’ via 1 ¼” pvc with ~5’ of lift. I need to know gpm and psi to properly design system. I ran pump to check volume at this distance/grade. Pump produced ~34gpm. Question ... with above data, can I calculate PSI?


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Posts: 5,280

Location: Metro NYC


Sunday, August 3rd 2008, 10:11am

Now you can add a tee and a shutoff valve and a pressure gauge to your pipe near the manifold location and run your test again. Since the pressure gauge will be upstream of the added shutoff valve, you can partially close the valve until you get a certain pressure reading - say 30 or 40 psi. Then you measure the flow. Simple, and no guesswork required.

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