Max pressure created by my pump

[Fishyone]

I have a goulds 18gs20412cl. 2hp 18gpm. whats the max pressure. If its important the pump is set at 240ft. 5" well casing, Static depending on time of year 70- 110.' 11/4" drop pipe tdh 248'

 

[Fishyone]

the reason for this question and the question of "whats best for the pump " which i posted at the same time is cycling of the pump. I am aware that the pump should run at least 2mins before cycling, i am also aware that valveman will be along shortly to inform me that all my problems will be solved by using a csv. that may be true, but i have some specific things that need to be addressed first. i have schedule 80 pvc drop pipe (psi 260)from the well head to the pump and schedule 40 pvc from the well head to the house where the tank and pressure switch is. I am concerned with the back pressure created by the csv. If the csv is placed at the well head and i have 30/50 pressure switch at the 81 gal. tank i think that the only pipe i would need to worry about is the drop pipe which has a 260 psi value. Note that the pump is an goulds 18gs20412cl . the pump is set at 240 the static ranges 70-100 and the pipe is 1 1/4 and the tdh is 247. So there you have it .I have attempted to find the max pressure of the pump on line, but can't seen to find it, so i am asking here. I have lived with house wells for 50years without a problem until last year when my 1hp pump would not build pass 30pds as the static level dropped (this after 22 years) during that time i never gave the cycling of the a pump a second thought. But with the price of wells and pumps in todays market one should pay more attention.

 

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[Reach4]

2 minutes is a nice number, but 50 seconds is not terrible.

I would think schedule 80 pvc would have a lot higher pressure ability than 260 psi. https://www.aetnaplastics.com/site_...tnaproduct/204/PVC Sch 80 Pipe Dimensions.pdf

I don't know what derating would be called for due to the threads.

You can run your pump deadhead into a pressure gauge for a few seconds. Probably a minute would not hurt, but you can get that gauge reading pretty quickly. For the highest reading, do it with the water level at max.

18GS20 deadheads at 183 psi at the surface if the water is 20 ft down.
See page 11 of https://www.pumpsok.com/sites/pumpsok/uploads/documents/water_systems/GOULDS_5-25GPM_eGS_SERIES.pdf

 

[Valveman]

You are right to check the pressure of your pump and the rated pressure of your pipe. As Reach said the 18GS20 can build 190 PSI max. With 20' static at surface you would see 183 PSI. With a static of 70' max pressure at the surface like on the underground pipe and CSV will be 160 PSI. But the pipe in the well will see 190 PSI.

1 1/4" Sch 80 is rated for 520 PSI. Threading cuts out about half the plastic so it cuts the pressure rating in half as well. But that leaves you with 260 PSI rated pipe and a pump that can only do 190 PSI, which is good. It is rare for the pump to build too much pressure to work with a CSV, but we always like to check to make sure.

Then the actual burst pressure of pipe is 2-5 times the rated pressure, which makes it even better.

As long as the pipe, CSV, and pump are rated for enough pressure as in this case, adding a CSV will solve all your pump system problems.