Looking for a valve that will open at minimum pressure

[ChefBryRD]

Hello all. We have a 20 acre vegetable farm, and for irrigation water we use solar to pump water from a cistern about a half mile away to above ground storage tanks next to our barn (inlets at the top). From there we open a ball valve on the bottom outlet of a given tank, and run a 70gpm centrifugal pump set on a timer to run that tank dry. The outlet of the pump is situated about 2' above the outlets of the tanks.

I'm trying to figure out a solution where, if we forget to turn off the ball valve coming off the pump outlet, the water doesn't then start slowing bleeding out through the top of the pump once the tank level refills above the pump outlet. Essentially a check valve that only opens above a certain, high pressure. This is obviously only a mild inconvenience, so simple, low-cost options would be appreciated. Thanks for your help!

 

[WorthFlorida]

The outlet of the pump is situated about 2' above the outlets of the tanks. ????????????????

I'm trying to figure out a solution where, if we forget to turn off the ball valve coming off the pump outlet, the water doesn't then start slowing bleeding out through the top of the pump once the tank level refills above the pump outlet. Essentially a check valve that only opens above a certain, high pressure. This is obviously only a mild inconvenience, so simple, low-cost options would be appreciated. Thanks for your help!

Please reword this a bit. Sorry but I'm having a hard time understanding what you want to do. From what I can figure out float switches may all that is needed.

You want to do is when the above ground storage tank is full you want the cistern pump off or when the storage tank runs dry you want the 70 gpm centrifugal pump off? Is there power at the storage tanks and what is the distance from the centrifugal pump and the above ground tanks? Where is this check valve, if there is one now?

When you write "turn off the ball valve coming off the pump outlet" that is the tank ball valve before going to the pump?
The "outlet of the pump", is the the pressure side of pump or from the tank to the pump?

 

[Sponsor]

 

[wwhitney]

Maybe a spring check valve with enough spring pressure to overcome the head difference between the full level of the tank and the outlet of the pump?

But maybe there's a better way that just involves reconfiguring the pump location relative to the tank or the piping in between.

Please reword this a bit. Sorry but I'm having a hard time understanding what you want to do.

The OP has a tank that gets filled by an intermittent source. And to use water, they have a pump that stays connects to an outlet at the bottom of the tank. And then when the tank is full, if the tank outlet valve is open, water will come out of the (open?) pump outlet due to the head difference.

Cheers, Wayne

 

[LLigetfa]

Wire a solenoid valve to open with the power to the pump motor and inversely close when when power is removed. That way you don't have to rely on you remembering to open and close the valve.

Alternately, you could look for a check valve with a stronger spring or replace the spring with a stronger one. The pump's suction then has to overcome the spring to pump water. Spring loaded check valves usually require somewhere around 2 PSI to open. Factor .43 PSI per foot of water elevation. Of course, that is an unintended use for a check valve so YMMV.