I have a 7.5 HP Ingersoll Rand air compressor that’s popping my breaker.

by david
(whiteville nc )

Its a ingersoll rand air compressor with a 7.5 hp electric motor and a 2475 pump.

Ingersoll Rand 7.5 Hp 80 Gal 230 V 1 Ph Vertical Air Compressor
Ingersoll Rand 7.5 Hp 80 Gal 230 V 1 Ph Vertical Air Compressor

We have put a brand new electric motor on it and it still pumps up normally at first then but when it cuts back on it will run for about 10 seconds and pop the breaker.

It seems that the pump is seizing?

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7.5 I/R popping breaker
by: Doug in s.d.ca

Have you checked the check valve at the tank?

I think you’ll find you can start from an empty tank to whatever the cut-out is all day long, but if you let it come on at cut-in pressure, it’ll pop the breaker.

Classic.

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May be different check valve
by: Doug in s.d.ca

…and when I wrote my last comment, I forgot that’s a two stage, so it could also be a check between the heads.

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Replaced check valve
by: david

I replaced the check valve but its still popping the breaker when it comes back on at cut in pressure. The check valve was bad though.

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popping breaker
by: Doug in s.d.ca

OK, that’s progress, anyway.

Is there another check valve? I dunno which one you found bad, but if one was bad and there’s another, it’s probably bad too. Either between heads, or at the tank.

If no other check valve, then look at the unloader.

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No other check valve
by: David

I replaced the check valve on the tank.. i cant find any other check valves.. and the unloader was not working properly, but i did relieve the pressure through the unloader valve and then when it cut back on it did the same thing and popped the breaker.

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Relieve the pressure through the unloader valve?
by: Bill

David, how did you relieve the pressure through the unloader valve? Is it possible that you relieved the tank pressure using the pressure relief valve instead of the unloader? Are you certain that the unloader valve is working properly?

Are you saying then, that even if there is no pressure in the tank at all, that the compressor stalls after a few seconds?

That being the case, did you check the capacitors?

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Check valve
by: Doug in s.d.ca

OK, right, there is no other check valve.

Looking at the pump diagram, it has two sets of finger valves in each piston head – a set for intake and another to act as a check valve.

So, if all else fails you may need to tear it down to check them, but you can probably tell by just removing the connector tube. the big side should push, but not create vacuum (suck). The little one should suck, but not push air.

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Unloader
by: David

I relieved the pressure by pushing up on the needle of the unloader. It was not working properly, i had to move the screw down to get it to function normally.

It runs fine if i take the pop off valve at the tank out and let the compressor run free. It then will not drag or pop the breaker….also this is the second electric motor we have installed. The first one was rebuilt and the one on it now is brand new and they both are doing the exact same thing.

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Ingersoll Rand unloader valve
by: Bill

David, please see the unloader valve page if you have any question about what they do and how they work.

If your unloader valve is not working properly, the symptoms your compressor is undergoing can be caused by a faulty unloader valve.

That your air compressor starts normally from zero tank pressure (meaning that all air over the pistons is gone too ) and does not start properly with air in the tank, points to an unloader problem as being all or part of the culprit.

Once you resolve that the unloader valve is working properly – by replacing your failed one I expect – then Doug’s advice about tear down and valve function is advice you follow next.


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