On Jun 20, 1:09*pm, dnoyeB wrote:
What dictates the pressure a sprinkler pump will deliver? *I have looked
at several. *Many show GPM for 30PSI. *However, they don't specify what
controls the 30PSI. *Is that the max PSI? *They don't say.

In reading about centrifugal pups this is what I think happens.

1. *Pump attepts to reach max flow. *If no resistance, then pump will
deliver its max rate with very little PSI.

2. *If there is resistance, then pumps flow will reduce based on the PSI.

My sprinkler heads are rated for a GPM at a specific PSI. *But the pump
does not try to deliver a PSI it tries to deliver a GPM. *And the PSI only
goes up when the GPM can't be achieved.

So I should be good so long as my sprinkler pump is rated for more GPM
than my heads.

Which is odd because from 1/2 HP up to 2 1/2HP the GPM is very much the
same. *The stronger pumps are not delivering that much more. *Why buy a
strong HP sprinkler pump?

Carl

Reno gives a very good explanation. Requires you to do a bunch of
planning and math. The simple solution is to go to any irrigation
pump supplier, provide him with your system diagram (including
elevations) and let him figure it out. You can be in and back out the
door carrying the correct pump in a few minutes. I have built 2 of my
own systems but have gone the 'let them figure it route' both times.

Harry K