Compressor Pressure Switch leaking air

[slash007]

The pressure switch on my Curtis 5HP compressor is constantly leaking air. Usually after it cycles, the air will run for a few seconds out of the hole in the nut that attaches to the pressure switch and then it stops, but now it is constantly running and getting worse. Is there something that I can clean out to fix it, or do I need to replace it?

 

[SLEDGE]

Replace unloader valve or pressure switch depending on what type of pressure switch you have. Mine is a condor and has a pressure unloader. have replaced two in the last few years. Hope this helps.

 

[slash007]

Replace unloader valve or pressure switch depending on what type of pressure switch you have. Mine is a condor and has a pressure unloader. have replaced two in the last few years. Hope this helps.

View attachment 1270 Here is the cover of what I think is a pressure switch. Also a picture of the plate on the compressor. View attachment 1271

I found this:https://www.zoro.com/square-d-pressure-switch-dpst-135175psi-14mnpt-9013fhg49j59x/i/G0257984/
Would that work? I think what I have is set at 175.

Or this one? https://www.supplyhouse.com/Square-...N98-oyQn91lOWydS2LGkwiLGd64NF6NcaAvv6EALw_wcB

 

[SLEDGE]

Yes sir. I have one of those for back up. the numbers on yours match the numbers on the one I have. its a simple relacement. just be sure to wire it up the same as your old one.

 

[slash007]

Perfect. Thanks for the quick response. I will by the one from Supplyhouse as it is cheapest. Might as well buy 2.

 

[MEP001]

If it quits leaking when the compressor is running, it's not the pressure switch, it's the check valve in the tank.

 

[I.B. Washincars]

If it quits leaking when the compressor is running, it's not the pressure switch, it's the check valve in the tank.

What MEP001 said.

 

[slash007]

I'm pretty sure it does quit leaking when the tank runs. Where is the check valve?

 

[I.B. Washincars]

It’s usually screwed right in the top of the tank, where the main line from the pump attaches.

 

[SLEDGE]

And yes if it is leaking when not running then what MEP001 said.

 

[MEP001]

I'm pretty sure it does quit leaking when the tank runs. Where is the check valve?

It's under where the main copper pipe from the compressor connects. There's also a smaller tube that goes to the pressure switch. That tube is meant to bleed off the pressure from the pump so the motor starts without load. There's a valve on the side of the pressure switch that only opens when the switch is open. So if the check valve in the tank fails, instead of dumping the pressure off the head it's trying to dump the whole tank. Since the valve on the switch closes when the switch closes to start the motor, it doesn't leak while it's running.

 

[mjwalsh]

Mep & the others are correct about the upper tank check valve.

Just to add ... we had specific check valve start to go out on us much more frequently & one of my co-workers said that he was pretty sure that we weren't changing the large intake air filter on Ingersol Rand 2 stage often enough. Since we changed the filter the check valve has not gone bad (leaking) in over a year now ... so I tend to believe the dirty or worn out air filter was the problem ... dirty intake air?... not sure. The repeated failures were really baffling at the time.

 

[slash007]

Thanks for all of the information and help. Makes sense now. Haven't really done much to the compressor other than change the oil and filter occasionally. Where is the best place to get a check valve for the tank?

 

[MEP001]

Google's first result:

https://www.northerntool.com/shop/t...MIm4CB_an63wIVRdbACh3Y_QWtEAQYASABEgIHzfD_BwE

So they're not proprietary. This one is 1/2" NPT into the tank. You'll have to get one to fit your compressor.

 

[mjwalsh]

Thanks for all of the information and help. Makes sense now. Haven't really done much to the compressor other than change the oil and filter occasionally. Where is the best place to get a check valve for the tank?

You may be able to match all the specs for the check valve in your town-city. Otherwise, what I did was google the exact part number from the parts breakdown of our compressor & a bunch came up via some kind of cross-referencing of the part number.

 

[slash007]

I found the manual, but it only references the motor etc. and nothing about the tank. It is 3/4" and looks like it's female on top with a male/male adapter.

 

[MEP001]

Does it not have a compression fitting and nut for the tube from the pump?

https://www.grainger.com/product/CDI-CONTROL-DEVICES-Brass-In-Tank-Check-Valve-6X209

 

[mjwalsh]

slash007,

If possible ... I would take the check valve to a local air compressor seller ... I think you will find that some fittings are JIC flare etc. & they do need to match unless you (gulp) modify the copper tubing attaching to it.

 

[slash007]

It does have a nut that attaches the tube from the pump. I thought the CV had a fitting in it, but hadn't realized there were male/male versions, so I just bought this: https://www.zoro.com/cdi-control-devices-valve-check-34x34in-c7575-1ep/i/G0266007/

 

[MEP001]

slash007,

If possible ... I would take the check valve to a local air compressor seller ... I think you will find that some fittings are JIC flare etc. & they do need to match unless you (gulp) modify the copper tubing attaching to it.

I doubt any of them are JIC flare. Large compressors usually have a compression nut with either a brass or a rubber compression ring.