I think my compressor pressure relief valve is faulty

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by Mike Dickson
(West Loon Lake Nova Scotia Canada)

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

The Valve In Question On 2 Hp Snap On Air Compressor
The Valve In Question On 2 Hp Snap On Air Compressor

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.

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 findings here as a comment, please.

Another PRV issue – PRV valve releases pressure yet compressor continues to run?

by doug

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


Howdy Doug.

That “mechanism” is the pressure switch.

Have a look at the ‘buying a new pressure switch’ page on this site as it sounds to me like you need a new one, right away!

And Jerry says – Pressure Relief Valve at compressor keeps popping while running?

by Jerry

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

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.

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