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Breaking Siphon Drawing Water From Pump Station After Pump Stop

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AFEDEC

Civil/Environmental
Jun 17, 2024
1
US
I have an application with a sewer pump station that is required due to long run of nearly flat pipe after an initial few feet drop. On install, siphon action is continuing the flow from pump station after pump Off Setpoint is reached due to the overall drop in elevation. We want to place a means to draw air into the forcemain to break siphon. The complication is that due to ledge, the forcemain leaving the pump station is not the high point in the piping. There is about an 8" rise in pipe elevation outside the tank. Ability to dig piping up and place a valve to introduce air at the actual high point and place it in a structure so that no sewage gets discharged if there is an issue is limited by ledge. Will placing a valve within the pump station at the point slightly lower (8") than the FM high point be adequate to break siphon? Would weep holes drilled within the pump station on the dual pump lines on the upstream side of the system's check valves be adequate to break siphon (i.e. once pumps stop and line isnt pressurized, will the bleeding of water out weepholes be enough to break siphon).

Any thoughts or suggestions would be welcome.
 
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OP,
The high point would only be required if you wanted to drain the entirety of the line. If you only want to break suction, I'd place a tee and check after the pump with the outlet of the check going to atmosphere over the sewer pit. I would caution against weep holes just due to the fact that sewage has particulate matter in it that would likely plug a weep hole. If possible, I would add a pressure switch just downstream of the tee, interlocked with your pump contactor via a timer, that if the pump doesn't pressure up after so many seconds it kicks the pump out. This prevents the obvious dry running but also if your check becomes stuck, it prevents the pump from continuing to run.
 
Can you draw our sketch this in section showing elevations?

Show this tank, liquid level, high point, pump exit and pipe level .

What does "nearly flat" mean?

Can you not install an actuated valve?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
Solution is to use of cylinder type control valve Singer, ClaVal, Dorot. This can be set up as a pressure sustaining valve. It maintains an upstream pressure.

Or you can use an open/close diaphragm type valve.
 
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