Preventing water tank from draining through pump

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goltec

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Hello,

I am looking for a solution to prevent a water tank standing on ground level, from draining on gravity pressure through the pump system when the pump is turned off. (no electricity feed I mean)

After the pump there is no manual valve or water tap.
So that is why the tank can drain.

A pump (this pump) does not close the water flow from tank to outlet of pump when turned off (electricity).
I think most pumps, if not all , don't.

After the pump I do not want a manual valve or water tap.
It is for a garden sprinkler system so the outlets should always be open.

Of course I could work with a solenoid valve on a timer, but I rather put the PUMP on a timer to save money.
This way I do not need a solenoid valve, a pressure switch, a pressure tank and a safety pressure relief valve.

But if the pump is not turned on , the water from the tank slowly flows through the pump on it's gravity pressure, causing the tank to drain through the outlet of the pump.

I was thinking to install in reverse position a check valve with a spring after the outlet of the pump, but the spring of the check valve is not strong enough to stop the water from opening the valve.

If the spring would be strong enough, the gravity pressure would not be high enough to push the valve open, but when the pump turns on, the pressure of the pump would be high enough to push the valve open.

Or is there a simple other solution of which I don't know.......
 

Valveman

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This company makes adjustable spring check valves. Looks like you can get a 1" with springs from 1 to 17 pounds.
https://www.ndspro.com/PDFs/Catalogs/NDS-Flow-Management-Catalog.pdf

You could also use a normally closed solenoid that is energized when the pump starts. This would keep the pump from seeing the extra friction loss from a heavy spring check valve.
 

Reach4

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A pump (this pump) does not close the water flow from tank to outlet of pump when turned off (electricity).
I think most pumps, if not all , don't.
I presume you don't have a submersible pump. For a suction pump, the check valve would be part of the foot valve. A sand point should have a check valve as soon as practical before the pump. If water cannot flow back into the well or lake, there is no way water can be flowing from your gravity tank through the pump.
 

goltec

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Thanks for the answers.

@ valveman: the solenoid valve switched together with the pump at the same time would be good I think.

I assume the solenoid should be installed before the pump and not after......

In case I choose a different set up..... a question just for me to understand .
Has not much to do with the above:

What will happen if the outlet of the pump is obstructed (for example by a closed solenoid) and there is no water flow possible, but the pump turns on.....
I guess this could lead to a dangerous situation in which things can burst or explode due to the high pressure of the pump that builds up.
(for example a failing pressure switch while a solenoid already shuts the outlet of the pump off but the pump keeps on running)

Is it wise to install a safety pressure relief valve right after the pump ?
One of the adjustable check valves that you referred to on a T-section maybe ? as an overpressure escape route...

@Reach4: it is not a well pump. just a pump after a water tank to feed the sprinkler system. the pump does not feed the tank, the tank feeds the pump.
 

Reach4

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Usually you put the check valve between the water tank and the pump.

I am not a pro.
 

goltec

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@Reach4, yes usually you do,,,, to prevent the water from flowing backwards..... but in this case we want to prevent the water from flowing forward. And..... we are not talking about a check valve now,,,,but about a solenoid valve.... :) but thanks for your input... :)
 

Valveman

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Anytime you use a pump start relay or a timer to run the pump, and a solenoid is installed, a pressure relief valve is important. That kind of pump can probably only build 60-70 PSI max, so a pressure relief isn't to prevent the pipe from bursting. The pressure relief is to dump enough water to keep the pump from getting hot if the solenoid fails to open. However, you need an adjustable pressure relief. A 75 PSI relief valve does absolutely no good for a pump than can only build 60-70 PSI max.
 
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