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Water Separator for Compressed Air

Posted: Wed Sep 23, 2009 5:39 pm
by Maverick
Humidity in the Southeast US presents a challenge when painting or sandblasting. I've found a small water separator in the air line just isn't adequate.

Here's my home-made water separator for compressed air. Used it once to bead blast and sand blast with no condensation issues. Air blasted out of an air nozzle after going thru the separator doesn't have any noticeable water drops in it. Think its solved my problems.



Picked up a 5 gal portable air tank ($20) from Tractor Supply, 20' of 5/8" OD copper tubing ($40), and some pipe nipples and fittings. The separator is placed in a plastic tub (same one I used for electrolytic rust removal) and covered with 4 bags of ice to chill the compresed air and condense the water vapor.

Air from the compressor goes into the top of the copper tubing coil, is chilled as it goes around the coil, goes into the tank at the bottom of the coil, and out of the tank at the top. Both the coil and the tank are covered with ice and act as heat exchangers.

An 1/8" pipe is connected to the bottom of the tank and run up the outside to a small shutoff ($5) like the one used on the supply for a toilet tank or sink faucets. Opening the valve at the top of the 1/8" pipe allows any collected water to be forced up the pipe and out. Holes were drilled and fittings welded onto the top of the tank to accomodate the air exit and into the bottom for the water drain.

Black iron fittings would have made for decent welds -- just weren't available where I was shopping. I had big-time problems with the galvanized. I welded galvanized before without any big issues but not this time. Even after grinding off the layer of galvanizing, pin holes would develope right thru the fittings. Anyway, it ain't pretty but its done and it's functional. Like always, I could do it better the second time.

Image

Posted: Thu Sep 24, 2009 6:28 am
by markss327
The prototype is never pretty. But, beauty is in the eyes of the beholder. I like it!

In my field of Quality Control, we have CMMs (Coordinate Measuring Machines) in our inspection dept. Rather precision measuring devices. Day to day accuracy\repeatability to .0002in. Anyway, they require compressed air, and have -0- tolerance for moisture. We employ 'air dryers'. They look like a small, window A\C unit. Same principal as yours - chilling the air, then pulling the condensation out.

I vaguely recall from Lincoln Eclectic welding school, the fumes from welding galvanized metal, are really bad. :shock:

Posted: Thu Sep 24, 2009 9:52 am
by Maverick
markss327 wrote:I vaguely recall from Lincoln Eclectic welding school, the fumes from welding galvanized metal, are really bad. :shock:
I gotta look into that. I made a lawn roller from a galvanized water tank 30 years ago and wondered if the fumes had a role in some weird health issues. This time I should have kept looking for the black iron fittings. :oops:

Posted: Thu Sep 24, 2009 10:17 am
by markss327
Well, not really bad....

http://www.sperkoengineering.com/html/a ... anized.pdf

This may explain some of your pin hole issues.

Posted: Thu Sep 24, 2009 10:55 am
by Maverick
markss327 wrote:Well, not really bad....

http://www.sperkoengineering.com/html/a ... anized.pdf

This may explain some of your pin hole issues.
Yes, it does. And, guess I'll have to keep looking for the cause of my weird medical stuff. Apparently, not zinc.

Thanks for the good poop.