I think the pressure relief valve is faulty

by Mike Dickson
(West Loon Lake Nova Scotia Canada)

The valve in question on 2 HP Snap On air compressor

The valve in question on 2 HP Snap On air compressor

I have a cast iron, single piston, oil filled crank, direct drive, 2 HP Snap On air compressor on a 5 gallon tank.


At the outlet of the compressor there is a Tee fitting. One side goes to the tank through a manifold with regulators and pop off valve and the other side has what I think is a Pressure Relief Valve.
I have replaced this valve because it was blowing off. The new valve was only in for about a minute of operation and it popped off.
My question: is the compressor making too much pressure at the outlet of the pump? If so what can I does to fix this. Would too much oil in the crank case cause this valve to pop off?
Any help you could offer would be appreciated.

Thanks;
Mike ...
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Mike, I don't think the pressure relieve valve is faulty, though it's possible. Given that it's your second one though, I'd bet it's something else.

Try this. Shut the compressor down, drain all the air, pull the line from where it enters the tank, remove and clean the tank check valve, reassemble all, then test again.

Any change?

Post your response here as a comment, please.

Bill

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prv valve releases pressure yet compressor continues to run

by doug
(dallas)

i have an older sears 100 psi air compressor. Everything works fine except when it gets to 100 psi, the prv value releases and the compressor continues to run. What mechanism is it that turns off the compressor? Thanks

_________________
Bill says...

Howdy Doug.

Have a look at pressure switches and it sounds to me like you need a new one, right away!

Cheers,

Bill



Comments for prv valve releases pressure yet compressor continues to run

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Feb 26, 2015
I had the same problem.
by: Claude Lussier

Sometime the compressor won't stop just because the release valve is slightly leaking. Doing so you never reach the "stop" point.

The release valve could have a damaged "O" ring if it has been put too tight.

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Pressure dropped and won't rise again.

by Larry
(Indio California, USA)

Hi I have a campbell/hausfield pancake compressor.

I was useing it the other day and it was setting idle after it had pressured up. I heard a little pop sound and the motor started. It slowly lost pressure and would not pressure up after that. The motor will run all day, but it will not build pressure. Is it the pressure swtich?






Bill says...

Howdy Larry.

Check your PRV valve.

If it's let go, then it's bleeding all the air out as fast as the compressor can compress it.

If it's not that, check for leaks while the compressor is running.

If it was the PRV, why did it pop? Is your compressor over-pressurizing? If it is, then it might be the pressure switch.

If the compressor turns on when the pressure drops, and it's trying to compress air and can't, then that normally isn't the pressure switch.

Cheers,

Bill

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Relief Valve at Compressor keeps popping while running

by Jerry
(Michigan)

We have a Snap-On air compressor that has a valve located between the first and second stage that keeps "popping" whenever compressor is running
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Well Jerry, that suggests that the line keeps getting pressure build up to a level that is higher than the PRV setting.

Typically when this happens it is because the there is a flow impediment into the second cylinder, and that generally means the air intake valve on the second cylinder may be causing a problem... ie: wearing out or failing.

Bill

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