Filtering (of water) in a portable air compressor

by Bob
(Worcester, MA, USA)

I have a 17 gallon portable air compressor.

What is the effectiveness of installing an air filter directly upstream of the regulator for the purpose of removing water?

I have read that a filter placed that close to the tank output will have very little effect at reducing water, as most of the water at that point is in a vapor form and not free water, and that the water vapor will just continue to flow down the 50ft. rubber hose to be deposited into my air tool. Is this correct?

If so, what alternatives do I have to remove water, other than completely plumbing the compressor, as I wish to have it remain a portable unit?

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Bill answers....

Hi Bob:

The points you make are quite valid.

If the compressor receiver is getting nice and hot from constant use, you're right. There's going to be a high level of water vapor in the compressed air, and it will cool in the hose, and you will have condensate running out your air tool along with the compressed air.

Before we tackle what to do about that, let's examine the filter at the regulator on the discharge port of your compressor for a moment.

If you aren't draining the tank often enough, water will collect in the tank, and when there's a downstream demand for air, some of that water will escape into the air lines along with the compressed air. The filter in-line right after the tank will remove that free water.

So having a filter right after the air tank does have some value in reducing the amount of free water downstream, and in this case, running through your regulator.

But yes, you are right, it won't do anything for the water vapor.

Things you can do is plumb a small in-line filter into your air hose just before the coupler to remove free water that's condensed in the hose. This will help.

A better idea might be putting an in-line air dryer (these often fit within the O.D. of the hose) just before the coupler to strip the water vapor from the air stream too.

Depending on your volume of air required and it's relative humidity, you might changing out dryer cartridges fairly often, but at least you'll save your air tools from a bath.

The need for portable air creates it's own set of air-preparation problems, doesn't it?

Cheers,

Bill