Water in the oil

by Chuck Howard
(Franklin, Ohio)

This is a 2 stage compressor. It has a belt driven crankshaft with 2 pistons.

There are two of these unit mounted to the receiver tank.

The one we are having trouble with gets water in the oil.

We have not noticed any loss of air pressure or volume, so we don't suspect worn piston rings.

The units alternate so one is not ran any more than the other and both are subject to the same environment. I believe oil loss is due to displacement w/ water.

This is an Ingersoll-Rand Model 242.

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Bill answers...

Howdy Chuck...

I didn't see a question here, though I suspect it's "how come we've got water in the oil?".

By having water in the oil, I'm assuming that you're draining oil from the compressor head, and there's water in it. You don't indicate what quantity, and if you are changing the oil regularly, I'm not sure how big a problem it is.

One source is water vapor condensing inside the oil sump. And that means that compressed air must be bypassing the piston rings and getting below the piston seals into the oil sump. Where else would water vapor come from?

When you drain the receiver, is there a lot of oil coming out with the water? If compressed air is getting by the piston seals, then you've got oil migrating the other way, and getting in to the air tank too.

Bill