Shur Align Schedule 120 Question

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ElkRock

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Is my pump set too deep? 6" new well drilled to 720 feet, Yields about 3gpm. Goulds 7GS pump and 2hp motor. 34 picks of Shur-Align threaded drop pipe, 1 1/4" Sch 120. Pump set at about that depth, around 680 feet. Static water level is around 150 feet. 5 check valves. Looking at the Sch 120 discharge pressure charts, each foot x .433 +my 50 psi setting, seems like if I ever pump down to around 600 feet, I am close or at the bursting point.
Do I have this right? Should I be worried?

If so, how can I protect the system from pumping down past that point? Will my Pump Saver help?
 

Bannerman

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5 check valves
The water hammer created by each of those check valves, will be more likely to damage the pipe and other components. The only check valve should be located directly at the pump. For redundancy incase of the check valve within the pump becomes compromised, a 2nd check valve will often be installed directly onto the pump's outlet connection.
 

Valveman

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I show Sch 120 is good to 300 PSI, which is the same as lifting 693'. 1" pipe is good to 370 PSI or 854'. You should be fine on the depth and pressure as the burst pressure of pipe is 2-5 times the rated pressure. Although as Bannerman said, those check valves are going to cause way more pressure than the lift from 700'. One or two good spring loaded check valve(s) within a foot of the pump is best. Any other check valves on the way up gives a place for the water to crash into, which causes several times more pressure than the pump can even build. Five check valves cause the water to crash into five brick walls before it gets to the cistern tank. I know, I know, I know, that is what the "book says to do". But the guy that wrote that book sells check valves and doesn't care if you have water hammer. Also, only one check valve on the pump causes the pump to start under some pressure, which is best for the pump. The pump does not start against much pressure when there are multiple check valves. Oh and BTW, every time water crashes into a check valve the resulting shock wave travels all the way down to the thrust bearing in the motor, and can shatter the bearing in the worst case scenarios.

Also, a 7 GPM, 2HP pump needs a minimum of 480' of lift or 207 PSI pressure against it to prevent upthrust damage to the pump. Use a 10 GPM Dole valve to keep the pump in its curve as it will not be until the water level drops to 480' deep.
 
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