Air Compressor "Filter"

[gerahead]

I am looking for someone who may have solved a solution to my problem. I'm sure I'm not the first to have run into this and I am hoping someone here has devised a remedy. I have an older air compressor with an 80 gallon tank. The crankcase for the compressor simply has a spun filter element at the end of the fill point in the case. Think of a small piece of circular scotch-brite pad. I use my compressor a lot and the tank and everything around it is getting covered with a fine coat of oil from the air venting out of the case. I was thinking that some sort of catch can system like those used in the vacuum evacuation systems seen on high performance race car engines. Has anyone here found a cure for this ailment and is willing to share their solution? Thanks for your help in advance! L8r
Jim

 

[rlitman]

It sounds like you either just need a thicker filter, or perhaps your crank case is overfilled.

For the former, the crank case needs to be vented to prevent pressure buildup, but it doesn't need to breathe all that much. You could make up a filter out of a few layers of non-abrasive scrubbing pads, or reticulated foam, or even steel wool. It just needs to not get clogged with oil so much that the filter gets sucked into the case.

In fact, many old engine crank case breathers use something like steel pot scrubbers (very coarse steel wool), and that's pretty much what my 80 gallon 2-stage uses. It has a pipe threaded into the top of the crank case sticking up about 4", filled with something like coarse steel wool.

As for the oil level, some manufacturers state to fill the oil to the center of the sight glass, some to the top, and some to the bottom. If you're overfilled with oil, you'll get excessive oil mist escaping.

Oh, and breathing in oil mist is very bad for your lungs. Just FYI.

 

[matt_i]

A coalescing filter with an element would do fine.

As would any sort of metal can.

You can tube or hose the "blowby" to a lower point and pout the free end into a coffee can. If you wanted to get an old oil bath air cleaner off a 1950s tractor I believe the metal gauze inside of the filter would do the converse and help to concentrate the oil mist.

The concept is same as a PCV system in an IC engine. So potentially you could route it back to the air intake/air filter.

The advantage with an air compressor (due to no combustion) is that as long as the return air from the crankcase doesn't pull in dirt/grit, it will come in pre-lubricated, which is an advantage to the mechanism as far as I'm concerned. It doesn't have the issues of generating smoky soot particles and killing the fuel's octane rating very effectively as it does in the IC engine.

 

[rlitman]

...The concept is same as a PCV system in an IC engine. So potentially you could route it back to the air intake/air filter.

The advantage with an air compressor (due to no combustion) is that as long as the return air from the crankcase doesn't pull in dirt/grit, it will come in pre-lubricated, which is an advantage to the mechanism as far as I'm concerned. It doesn't have the issues of generating smoky soot particles and killing the fuel's octane rating very effectively as it does in the IC engine.

I don't think I'd try that. I would be worried that oily air on the intake would risk carboning up the valves. Compressors don't have floating valves like an IC engine, and risk dieseling as well.

The catch can, or coalescing filter, or oil bath air cleaner should all work.

 

[MacMcMacmac]

Many compressors vent the crank blowby directly into the inlet. Use compressor oil and carbon build up won't be an issue.

Every Kellogg I have seen has a vent tube directly to the intake.