condensation problems in air gun

[rustisacolour]

Hi

Whats the best way to stop water coming out of my compressor? Its mixing with the paint stuffing the paint work.

Thanks

[Roncla]

You need a moisture trap. Readily available from a hardware store like Bunnings.

[A.R.C.]

I`m assuming its hot there right now. I always drain my tank after using and keep the drain valve open during hot weather so condensation cant build inside it, and make sure my Compressor and lines are always in a shaded, cool area. I also run 2 filters. A big oil/water seperator at the pump and a smaller filter at the gun.

[Art Anderson]

Hi

Whats the best way to stop water coming out of my compressor? Its mixing with the paint stuffing the paint work.

Thanks

OK, a bit of a tutorial here: Air, when compressed, heats up, and when the pressure is let off, it cools down. With high humidity (and yes, in Indiana from spring until late fall, the air is humid a fair amount of water vapor in it) when air is cooled suddenly, the water vapor will condense on almost any surface, and that includes on the inside of an airbrush hose.

This condensation then moves down the length of the hose, and will come out of the nozzle of any spray gun, from a body shop spray gun down to an airbrush. This is where a moisture (water) trap becomes necessary.

In my experience, a moisture trap is best used in the middle of an air line (not right at the outlet from the compressor or air tank), as this gives some length of hose (or pipe, doesn't matter!) for the moisture to condense, the movement of the air down through the hose pushing the condensation to the moisture trap (and this is something most hobby shops don't know, but anyone knowledgeable will).

I have used my moisture trap for 50 years now (a Binks unit I had to get for my Binks Wren airbrush (same concept as the Badger 350 and Passche H) and their compressor. The setup uses a 6' length of hose between the compressor (which is now a Badger 180-1) and the moisture trap, with the common 6' hose between the moisture trap and the airbrush. This setup dries the air supply completely (I NEVER get moisture spitting through my airbrushes!).

Putting the moisture trap directly on the compressor outlet just doesn't quite do it, as the water vapor needs that length of hose to act as a condenser so that liquid water can be moved to the moisture trap.

All based on now 50+ years of experience airbrushing.

Art

[LoneWolf15]

To add to Art's comment ...... If you are using a small hobby compressor from Badger , Iwata , Paache , etc , be aware that these units produce quite a bit of condensation . Not only that , they produce it quite rapidly !

This type of compressor requires a large moisture trap , especially if the unit is run for an extended period of time .

[Guest G Holding]

Art and Donn are 100%....Make sure if you have a tank, to drain before use!

[Ace-Garageguy]

Art is indeed correct, and I was going to post his explanation if he didn't.

There is one more thing to remember. When the compressed air comes out of the tip of the airbrush (or spraygun) it immediately expands as the pressure drops, cooling it rapidly (if you remember high school science) and forcing whatever water is still in the air as vapor to condense out. The traps and filters in the lines don't always get all the moisture. This cooling effect is in large part responsible for condensation-blushing of lacquers shot in very high humidity.

I run my airbrush from my full-size shop compressor, and in high humidity, it makes a huge amount of water in the lines.

I've been using this design of final water-trap / filter AT THE GUN on 1:1 paint jobs for many years, and they work. They're available at auto-body supply stores and by mail order and cost about 7 bucks each. They're designed to work in any position, which standard, hard-mounted water traps aren't, and work well either at the gun, or at the beginning of the last few feet of hose before the gun, or airbrush. It's cheap insurance, IMHO.

Edited December 12, 2012 by Ace-Garageguy