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Air compressor getting water in the oil

ahall

Stainless
Joined
Aug 4, 2004
Location
OK, USA
I have an older (1970's I think) 2 stage speedair air compressor.
The tag says model 32754 or 3Z7542, its a bit hard to tell.
Its your basic 5 hp, twin cylinder in the same head with vertical 60 gal tank.
The only tag on the compressor says TF144925.

The oil in the sight glass looks milky. It was changed a few months ago (again, milky looking oil) and is used very little. The compressor is indoors in a dry environment. Its probably run a few hours at most sense its last oil change. Most of the time it sits idle, with the outlet valve shut.

The tank has a shut off valve at the tank, so I doubt its running a lot when I am away.

I would expect a unit this old to make a little water, but every few hours of operation says something is wrong.

The unit has a small copper line from the outlet side to the crank case and the crank case is vented.

What is likely to be the avenue for water to get into the crank case and what do I do about it.

Who actualy built the compressor and how do I locate parts?
 
Run it till the compressor get's good and hot, then run it for a few more hours. Buff a car with an air buffer or something.

That oil will clear ;-)
 
From what I believe to be true, Speedaire compressors are manufactured by Campbell Hausfeld. I never had to call them, but I know they have technical support if you call 1-800-543-6400. They are open until 4:30 EST, so you might have to call on Monday.

No matter the vintage, old or new, all compressors are going to take in water because of the humidity in the air. The longer the compressor runs, the hotter the compressor receiver gets, meaning more condensation will occur inside the tank.

I hope CH can steer you in the right direction. Have a nice weekend.
 
Outfits like W. W. Grainger sell oil specifically for compressors. Automotive oil is formulated to absorb water, which is why it is not a good choice for applications like rust prevention.

Bill
 
9100 hit on what was to be my question... what kind of oil are you running in it? If it's auto oil, drain and refill with a proper compressor oil. Compressor oils (Anderol 456) are formulated not to absorb water.
 
One thing I would check...

I've seen this happen on locomotive compressors!!!

One thing I would check...

I'd assume that the machine has an unloader valve... check to make sure that the unloader is properly sealing after unloading.

What CAN happen, and in the case of yours... is that the unloader is slowly leaking back, and as that air expands, it chills, and precipitates, pushing precipitant up onto the top of the cylinders with just enough pressure to backflood the cylinders, and push it past the rings into the crankcase.

This can happen on all types of compressors, but typically it will NOT go unnoticed on single-stage systems, because the lack of proper unloading causes the drive motor to stall or lug. It most often goes unnoticed on multistage compressors because there's check-valves between stages... the compressor will start okay (albeit just a tad sluggish) with head pressure on one secondary stage, but none on the primaries.

Whatever you do... DON'T SEAL THE CRANKCASE! It'll blow the seals right out of the crankcase, and you'll have a lovely mess.

IF you DO find that the unloader leaks back, you can pop the check valve out (typically threaded into the tank) and clean it, but another thing you can do, is unhook the line between compressor head and unloader, and install a SMALL air reservoir, and put an inexpensive automatic drain valve in the bottom (Horror Fright has 'em for under ten bucks). The ADV is backpressure-operated... when the unloader activates after shutdown, the small tank will dump, and the ADV will allow any back-flow condensate to drop out before being siphoned up into the head. Added bonus: This will also help dry your compressed air!!
 








 
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