PRV pops every 1/2 second until compress turns off.

by Michael
(Dallas)

Hello, my tank which max at 175 psi, will run and shut off normally, except PRV at the start of intercooler pops air every 1/2 second or so until the compressor hits 175 psi.


The PRV is new with correct spec spring.

First I thought it was the oil that ran a little low, but that wasn't the problem.

Please help.

Thank you very much!

-mike

_______________________________
Bill says....

Mike, is your air compressor a two stage one, with the second cylinder increasing the pressure of the air going into the tank?

That being the case, you may want to check out the intake valve on the secondary pump cylinder.

Cheers,

Bill

Comments for PRV pops every 1/2 second until compress turns off.

Click here to add your own comments

Aug 26, 2011
2 stage
by: Michael

Hi Bill, thank you for the reply.

Yes, it's 2 stage 7.5 HP unit.

The intake valve on the secondary pump cylinder as you've mentioned is where the air goes in from the intercooler?

-mike

__________________

Believe so. Check the flow path from cylinder one, to cooler, and then to cylinder two. The valve inside the head where the line reaches cylinder two is the possible culprit.

B.

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressor PRV Valve Opens.

pop off valve - Wayne Mod# 6378-SH

by Al McDaniel
(Newark, Oh)

Hi Bill,
I have a Wayne Mod# 6378-SH air compressor; it is a V-Twin.

The low side relief valve on one of the compressors pops off when the lines pressure gets to about 120psi.

I figured I had to have a valve hanging open or closed so I started removing the manifolds’ looking for a stuck or malfunctioning valve. All valves were free and could not see any problems. I reassembled the unit and still had the same problem.

I replaced the check valve knowing it was a long long shot but said what the heck.

I can't think of any thing other than a malfunctioning Exhaust valve for the low pressure side that would cause the valve to pop off.
Any ideas or suggestions are deeply appreciated.

Thanks,
Al McDaniel
__________________
Al, my goodness, aren't these 1950's vintage air compressors you have?

One thing you didn't try is to replace the PRV. It is possible, remotely so, but still possible that it's failing and letting go early.

Still, if this is a 2-stage compressor, and I believe it is, and the low pressure cylinder feed line to the higher pressure cylinder has it's PRV let go, and it's not the PRV itself, I'd still think it was the valve on the high pressure cylinder reacting to pressure some how.

Anyone else?

I also found this for you, for parts:

www.aircomparts-air-compressors.com/tools-pump-head-replacement-valves-wayne/

Cheers,

Bill


Click here to post comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressor PRV Valve Opens.

Pressure - pvr opens

by David
(Bloomington)

My compressor builds up pressure fine but when it gets to the normal cut off the pvr opens n releases the air down to about 40 psi so it keeps running the motor could it be the pressure switch? Thanks
__________________
Hi David. If the pressure switch cut out is, for example, 120 PSI, then the air compressor should shut off at that pressure.

If the pressure switch fails with current passing it to the motor, the compressor will continue to run and pump pressure into the tank, until the tank pressure reaches the PRV release pressure point, and the PRV opens to vent overpressure.

You say "gets to the normal cut off the pvr opens n releases the air" then if the PRV is opening at the pressure switch normal cut out pressure setting, then it is the PRV that is suspect, not the pressure switch.

Cheers,

Bill

Click here to post comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressor PRV Valve Opens.

compressor wont turn off

by red
(wi.)

compressor kicks in but wont shut off even after prv blows and after switching off , I must turn off at breaker panel.

_______________________
Bill says...

Red, if the power is still flowing from the pressure switch to the electric motor after the air pressure in the tank has reached the normal cut off set point, then the pressure switch has not done it's job.

From what you've written, I think it's time for a new pressure switch.

Cheers,

Bill

Click here to post comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressor PRV Valve Opens.

airmate 12/25.0 OL230 -- safety valve trips

by Jan Kent

safety valve trips before compressor gets to stop at max pressure.
If I cut the power before the safety trips and then put it back on,the pumps stays off while I use the tool (nail gun or stapler) and when the pressure drops by around 30psi the compressor comes back on. So as long as I substitute for the max pressure switch I can work. It used to work and I don't know if I have done something that has made the safety operate too low or if I have somehow set the Max switch too high.
_______________
Jan, if by the safety trip you mean the PRV lets go to bleed off excessive pressure, then it is either that you have adjusted the compressor cut out setting to a set point higher than the PRV release pressure, or the PRV is failing.

At what pressure is the PRV letting go?

Cheers,

Bill

Comments for airmate 12/25.0 OL230 -- safety valve trips

Click here to add your own comments

May 08, 2012
Fixed it?
by: Jan Kent

Hi Bill
I consulted my brother in law. The relief valve was tripping at the rated pressure of 8bar so we concluded that for some reason the maximum pressure switch had drifted too high. Removing the cover on the control unit revealed a nut marked + and - so we turned it anti clockwise. The pressure switch now cuts the compressor off at around 7.8bar and all works as it used to. I guess the vibration of my last drive might have shaken the the nut off its correct setting.
Thanks for your input and I hope this helps someone else in the future ;-)
regards Jan Kent

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Compressor PRV Valve Opens.