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compressor check valve sticking open - repair?

I picked up an old 1 hp comp (cast iron pump, twin "hotdog" tanks, a real Dayton 1725 rpm, 1hp motor) several years ago. This compressor used pneumatic actuated valves on the compressor - motor ran continiously. I changed it over to a conventional pressure regulator / check valve / pop off valve. I bought the check valve (w/ unloader port) at Grainer:

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After about 25 on/off cycles the valve sticks open when the compressor is not running - air escaping thru the unloader valve - so the compressor now cycles on once every min to 90 sec with a compress time of (guessing) 20-25 sec. when there is no air usage. I whacked at the valve with a 3/4 inch bar stock - no hammer close by and with each whack the air flow reduced. After about 3 or 4 whacks the air leakage was gone and the comp opperated correctly during cycling - for a while and then it started loosing air at the unloader valve.

I'm working on reroofing a house this weekend and I can't keep on running down the ladder every time the valve sticks. I also do not want to leave one of my other (better) compressors outside in the backyard of the house that I'm working on. I'm tempted to open the valve up - it looks like the check valve parts are inserted from the side that has the large hex. So, what is inside of a check valve - tiny loose parts that will spring out at me and get lost? Right now its a pain in the ass, but if I take the valve apart and can't get it to work it will be a much bigger pain to be with out a compressor.

Reply to
aribert n
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. After about 25 on/off cycles the valve sticks open when the

They are all a bit different but usually they can be cleaned without having to fully disassemble

Remove and clean it by soaking in soapy water and/ or alcohol, re-install....

In my experience, synthetic oils tend to clog air valves and so forth worse than a straight non-detergent oil will and so if the compressor has synthetic oil in it you might to replace.

Reply to
PrecisionmachinisT

--snip--

I have the same valve on my compressor, under the cap on the side is just a plastic disk & a spring.

I'll wager the spring broke, a quick fix is just the stretch out the larger remaining piece of the spring & re-assemble until you can get another spring.

MikeB

Reply to
BQ340

The unloader is there to protect the motor from drawing excessive current. I know that it's heretical, but I've run small compressors with the unloader plugged and I had no problems. If you're in a pinch, that's what I'd do.

Reply to
Denis G.

Mine's a ball (metal, marble sized) and a spring about 3/8" in diameter; for some unknown reason some previous owner had removed the ball.

If you lose either part you're toast, so don't try the disassembly over grass.

Reply to
Tim Wescott

Just a quick follow-up. I took the check valve apart numerous times to clean with no improvement - it was a simple disc with a very light spring. I stretched the spring to provide some additional force - that just made the poppet have a non parallel relationship to the valve seat. I tried to use a heavier compression spring but I was unable to get the poppet to seat what so ever.

I called CDI on Tuesday and received a call back on Wednesday from an individual in their engineering dept. I had selected a check valve that was inapproproate for my application. Apparently not all check valves use the back side pressure to augment the spring to seat the valve. I was quite pleased in getting a response from CDI (even if it did not solve my immediate issue). Short term, I ended up plugging up the unloader port and lowering the cut in pressure by about 10 psi - no more tripped breakers (1hp straining to start rotating on a 20A circuit).

Reply to
aribert n

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