Relief vs Check Valve

[JeremyO]

Hey all,

Just started a new job. A project I was given is looking at a new supplier as cost reduction for a manifold. In the current manifold there is a 50 psi relief valve used, and the potential new supplier is suggesting replacing it with a 50 psi check valve. Operating pressure is in the 3000 psi range. Is there an advantage to one over the other? To me the check valve makes more sense, but I can see how they accomplish the same thing-don't let any flow pass until 50 psi is reached, prevent back flow.

Thanks in advance.

 

[LittleInch]

Depends what you mean by pressure relief.

If you mean a small thermal relief valve then there probably isn't much difference, but a true relief valve is quite different from a check valve ( what type by the way? Spring and ball?

Relief valves will be designed not to lift until a set percent below set - point ( 5-10%), they are usually able to be calibrated, checked and adjusted and also designed to lift such that at max relief flow rate, the pressure is less than 10% above set pressure. They are also commonly restrict max flow to a certain figure so that the flow downstream the relief is not so big that it damages something. A spring loaded check valve won't do any of that.

So it all depends on the use, the normal operating pressure, what flow is required, what guaranteed percent above set pressure you want not to exceed, what flow you don't want to exceed.

Sorry just re-read this - you say 50 psi relief valve but it operates at 3000psi??? Please explain.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JeremyO]

Screen capture of that portion of the circuit below. Pressure line and tank lined labeled. Relief valve in current setup highlighted, with it being proposed to be replaced by a check valve (yes ball and spring, 50 psi spring)

Spool valve controls motor direction. When coils are energized in either direction, all the flow is forced over the relief valve. I honestly don't get it.

 

[LittleInch]

I wouldn't call that a relief valve in the way it is generally accepted so looks like a spring loaded check valve would seem to be acceptable in this situation.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[uaepiping]

Pressure relief valves not to be replaced with the check valves, if the pressure on upstream side is greater than the downstream of check valve, there shall always be flow. PRVs are normally joined to flare headers or blowdown systems (meaning whatever passes through PRVs is waste and shall be burnt). So I could not understand how the check valve can replace a PRV.
Where is your downstream line connected to?
Check and discuss with process.