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Back Pressure Regulating Relief Valve...

Back Pressure Regulating Relief Valve...

Back Pressure Regulating Relief Valve...

I have a system with a 40 gpm pump and I need to regulate the discharge to 200 psi. Downstream I have solenoid valves which could all be open or closed. If they are all closed I need to bypass the 40 gpm back to the inlet of the pump which is fed with city water pressure (20-80 psi). I have tried the inexpensive cast brass adjustable bypass relief valves and have very loud chatter and eventually spring failure.

Some people I have talked to are saying use a trapped pressure unloader, others say use a back pressure regulator. I have looked into all of them and have just gotten my self even more confused.

Does anyone have a good product or info for this type of application?

RE: Back Pressure Regulating Relief Valve...

A pressure control valve needs damping to be stable.  
Backpressure regulators are like relief valves that are intended to be open for substantial periods of time, i.e., they have damping that's not present in a relief valve.

It would be more energy-efficient to regulate the pressure by controlling the motor speed.

Or cycle the pump and use it to fill a water tower.  Got a mountain nearby?  You only need ~440 feet of elevation to get 200 psi.


Mike Halloran
Pembroke Pines, FL, USA

RE: Back Pressure Regulating Relief Valve...

Try a pilot operated unload valve

RE: Back Pressure Regulating Relief Valve...

This might be a little more complicated than you want to try, but instead of regulating the pressure, try regulating the flow.
When you open a feed solenoid, close a venting solenoid.
Keep relief in system to prevent overpressure only and set above the 200 PSI threshold you need. if OK.
Valve 1  10 gpm, close 10 GPM venting valve back to inlet
Valve 2  10 gpm, close 10 GPM venting valve back to inlet
Valve 3  10 gpm, close 10 GPM venting valve back to inlet
Valve 4  10 gpm, close 10 GPM venting valve back to inlet
You will have to balance the flows when everything is open to get your deliveries the way you want them.

Tom Nelson
Application Engineer (CFPS)
CATCO Parts and Service
St Paul,MN

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