Calculating pressure

[Tony]

Question:

How do I determine the maximum pressure in the line before the CSV (i.e. between the pump and CSV) in a system with a 1/2HP 12GPM pump set at 65ft depth with the CSV set to 50PSI with shower running?

[Tony]

Other than installing a pressure gauge

[Cary Austin]

If you know what pump you have a pressure gauge is not necessary.  I looked up a 12 GPM, 1/2HP Red Lion pump and it can do max 240' of head, which is the same as 103 PSI.  You can deduct from that 1 PSI for every 2.31' it is to the static water level.  If it is 23' to the water level you will have 93 PSI max at the surface.

[Tony]

Thanks Cary.

It is this pump:
https://www.zoellerathome.com/wp-content/themes/zoeller/content/literature/025095-Zoeller-4inSub-Instr-2-wire_190128_100819.pdf

Model #1450-0011

If I read the performance chart right it should be capable of 40 psi and ~9GPM at 65ft. Static water level is ~20ft.

I don't know how this translates with the CSV1A between the pump and the tank tee running @50PSI.

I'm using 160psi poly so I don't think I am stressing it.

[Cary Austin]

Don't know why Zoeller can't publish a pump curve like any respectable pump company should.  But a 12 GPM, 1/2 HP is a 12 GPM, 1/2HP and there isn't much difference between brands.  Can't find a pump curve anywhere.  But from the stupid chart I can see it matches the numbers of other such pumps so the max pressure will also be the same.