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Worried about flux in copper air lines


New Member
Hello this is actually my first post on this forum. I embarked on my first restoration job earlier this year and found this forum when I was researching what I would need to do to paint. This forum has been an unbelievable resource and I'm certain I'm in a much better position having found it.

Right now I am in the process of building the copper air lines I'll need for my air setup. I am running ~45 feet of copper tubing ahead of the water separator, regulator, and filter etc. My problem is as I'm soldering the fittings together I can see that I'm getting some flux into the air lines. I assume this is definitely a problem but I haven't been able to find any posts about it after an extensive search. Is this something I need to be concerned about? Is there a way to clean it out before I start using it? I am going to use a Motorguard M60 as a filter but am not sure if it would catch flux residue.

I've attached a photo showing what I'm talking about regarding the flux as well as a photo of the lines I'm building. The air enters at the bottom right and exits at the top left. The lines will be mounted on the wall such that they are all tilted slightly toward the right causing the excess water to run into the drop lines.


Welcome to the forum. I wouldn't worry about it. My current air pipe is all soldered copper, 28 years. Modified it 3 or 4 years ago with more soldered copper. I suppose you could rig hoses up and run water through it but I never did anything like that and didn't have problems. A compressor break down with oil later on would be a worse problem and I think there are ways to deal with that. Others here may offer different ideas.
Welcome I also did what you and Metalman did I sort of made an air cooler with soldered copper lines last summer to add to my lines. I flushed with plenty of air and no problems. Add some drains at the drop legs.
After I soldered up my copper intercooler I had flux keeping my check valve open. Had to remove check valve and clean out but worked good since then.