# Hunter PGP nozzle question



## Glen_Cove_5511 (Jun 13, 2020)

I have 70 PSI and 12 GPM for my irrigation supply, I have one zone that has 3 PGP rotors and I'm looking for nozzle advice. I'd like to get the most distance from these. Given my GPM flow, can I only use up to a 4 GPM nozzle in each? Thanks


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## pp6000v2 (Mar 8, 2021)

Where are you measuring the 70 psi reading? Remember their GPM rating is based on the pressure at the head. So looking at the Blue nozzle chart, a 4.0 nozzle on the first head may put out 4.8gpm at 65psi, and on the last head may only put out 3gpm at 25psi.

As an example, one of my zones has a run of unlooped pipe, so the last heads on the line are only getting about 20psi, where as the ones near the valve are getting ~50-55.

Does your zone piping loop around like a 'P', or is it a straight run like a 'L' ?


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## Glen_Cove_5511 (Jun 13, 2020)

70 psi was a static measure at the manifold. The pipe is very close to a straight line, each head is connected via funny pipe to a 1" supply.


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## pp6000v2 (Mar 8, 2021)

Sorry to hit and quit.

If the line isn't run in a loop, the pressure your last head on the line will be less than the first head gets. Hunter makes a pitot gauge to measure the pressures at PGP heads, but it's hard (and expensive) to find. I built one with a pitot tube off amazon and a 0-100 pressure gauge for ~$22. There's an assembled unit for $27 if you want. Measuring is the only way you're going to know what the difference between the ends is. Maybe it's 5psi, maybe is maybe it's 20. Either way, you'll be using catch cans to measure the output.


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## Glen_Cove_5511 (Jun 13, 2020)

Thanks @pp6000v2, I appreciate the feedback!


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