Relief valve opening 2

[Mountaineer63]

A high pressure air(1800 psi) valve (2") supplying air to a test fixture closes rapidly. Up stream a controller senses the pressure spike and is supposed to secure the air source by closing another valve. However, it can't react fast enough and the pressure spike lifts a relief valve (2000 psi) in between. Any ideas on how to stop this?

 

[JJPellin]

It depends on how the valve is actuated. If it is pneumatically actuated with a diaphragm, it could be as simple as a orifice in the air line to the actuator so that it reacts slowly. If it is actuated with an electronic solenoid then there are fewer options. This would probably require purchasing a different valve that is designed to move more slowly. If it is motor actuated it might be possible to change to a lower speed motor. If it is mechanically actuated from some other mechanism then I don't know what is possible. If it is not possible to slow the valve down, then an accumulator on the line in between the valves could be installed to absorb the pressure pulse and keep it from popping the relief valve. You can find information on accumulators on line.

 

[Assumptions]

I would suggest that the "relief" valve is operating correctly and that perhaps the air supply system is set too high for the downstream service.

If it is a case where the normal operation is lifting the safety valve then the upstream conditions should be changed to prevent the overpressuring of the downstream system.

 

[Drazen]

Tell me, when your control system closes on-off valve (after sensing pressure spike) what happens with pressure upstream of on-off valve? It has to be reliefed by some additional relief valve, isn't it?!

That way it seams that you could get rid of this on-off valve and install regulating relief valve instead (it is similar to safety vlave, but designed in a manner that can survive lot of openings during operating life while maintaining precise pressure - you can find it in many catalogues).

Your safety valve should have higher setting than this regulating valve and should serve to protect against apparent malfunction - not to open all the time.

 

[MortenA]

Shall your upstream valve allways close when you downstream valve closes?

If so is the downstream valve a pneumatic actuated valve (with e.g. spring to close)

if yes: Why not put the two valves on the same solenoid valve so that when one valve close the other will close too?

Best regards

Morten

 

[BSQUAREDBUCKEYE]

I read this questions the other night and still don't think there is enough information about the system to provide a solution.

Slow down the valve that isolates the test ridge so the controller and air isolation valve can catch up.

Install a pilot operated relief valve and dampen the supply line to the pilot.