Air compressor question.

[Bill Douglas]

I've got an air compressor. Just a 3hp with a 60 liter cylinder. It's for my new-ish hobby of car painting

Someone said I should let out the air when I'm finished with it. I use it once every few days or so as it's handy for using the air to clean out carburetor jets etc. Does it really need to have the air pressure let out?

[JackDidley]

If you are painting you need to drain it often so water does not make it to the paint gun. Its a good thing to do from time to time anyway. Condensation can build in the air tank pretty quick.

[wdfifteen]

No don't let all the air pressure out, but do drain it from the bottom long enough to let accumulated water out. In addition to that you need an air drier in the line near the paint gun. Nothing worse that water in your paint job.

[Bill Douglas]

Thanks guys. I've got a water trap on the regulator. And I tried the little drain plug on the bottom, but no water came out of that. Great I don't have to let the air pressure out as it sure is handy to have it there and ready to go. Wd, do you think I should get a second(miniature) water trap to have at the gun end of the air hose? The air hose is fairly short.

[wdfifteen]

Originally Posted by Bill Douglas

Thanks guys. I've got a water trap on the regulator. And I tried the little drain plug on the bottom, but no water came out of that. Great I don't have to let the air pressure out as it sure is handy to have it there and ready to go. Wd, do you think I should get a second(miniature) water trap to have at the gun end of the air hose? The air hose is fairly short.

You need a dessicant air dryer to suck out suspended air molecules. A trap is not adequate.

[cabmandone]

I ran a Campbell Hausfeld moisture trap and desiccant setup when I painted.
Similar to this
https://www.usaindustrialsupply.com/index.php?dispatch=products.view&product_id=31935&gclid=Cj0KCQjw5s3cBRCAARIsAB8ZjU0O68nHDUl0LydV5hJ7 nq0-mfyUVwKdBeZHsL2cpSCLDlI0rm6d_oMaAqlFEALw_wcB

[asphaltgambler]

Originally Posted by wdfifteen

You need a dessicant air dryer to suck out suspended air molecules. A trap is not adequate.

This- you need a good dryer setup, it's essential if you're painting anything. Not just a single cartridge unless you live in Nevada. From experience I ruined an inside paint job on a truck cab. Cost me a ton if time and twice the materials. I promptly bought a passive 5- stage dryer setup at a cost of @$500. This is a good home shop / 'average' system that has replaceable filters/ cartridges. Its awesome for what I do. You can certainly spend a lot more.

[KFC911]

I used to always let the air out after every use....don't anymore....there was a thread. On my small tank compressor that I use for nailers, etc., just opening the bottom screw will not typically get any/all the water out if level...I discovered after many years. Pick it up and tilt it....see if yours is the same for draining. I leave it full of air during projects...and I am SLOW and they can go on for a long time....

I figure it's harder on the motor to refill even a small tank regularly instead of the water toll...

[Bill Douglas]

Thanks for the good tips guys.

WDfifteen and Gambler, I think that's where a problem has been occurring. I've got a water trap but getting a few fish eyes. I have a 10 meter air hose. Should I get a larger Desiccant in-line filter and position it after the water trap and before the hose? Or get a miniature Desiccant filter and have it attached to the spray gun?

[cabmandone]

I say do both. I had some issues with moisture even with the setup I was using. I ultimately ended up buying a refrigerated air dryer setup. Worst part is, I don't paint anymore so it doesn't get used very often.

[fintstone]

I used to paint cars (as a hobby or to flip) back when lacquer was the bomb. Could spray a car in the driveway and sand/polish out any imperfections. The stuff dyed almost on contact. Just don't do it any more as pros here are cheap and do a great job...and no mess on my end...and no breathing paint and bond dust. In fact, I had just bought a huge compressor and a couple of guns when I stopped...so just cluttering the garage now.

It is a safety issue. If you don't drain the water, it will eventually rust out the tank. Personally, for a small tank that you don't use every day....it is relatively quick and easy to drain often.

If you paint, you need to get any water and oil out of the airy are spraying. Also, if you have an inline oiler for air tools, don't use the hose after that for paint. Get a different one for paint.

[T77911S]

water in the tank can make it rust out. as said, water I the tank increases chances of water at the gun.

they sell water filters that go ON the gun. I always used one of those.

drain it

[widebody911]

In my shop, I have an air dryer followed by one of those toilet paper filters.

https://smile.amazon.com/gp/product/B0009K6CQ2
https://smile.amazon.com/gp/product/B000WZYKAE

[Bill Douglas]

Thanks Guys.

Not a very good pic. But I've ordered this online. It's an Airline Desiccant Dryer that has blue moisture beads in it. I'll have it inline after the regular water trap. It's reasonably large.

[wdfifteen]

Originally Posted by widebody911

In my shop, I have an air dryer followed by one of those toilet paper filters.

I just throw TP out when I’m through with it. So you filter and reuse?

[willtel]

I painted a car in a home garage in the middle of a Georgia summer and didn't have any issues with moisture. Dryers are nice but you can work around them on a budget.

From the compressor I had a standard moisture separator and filter that fed into two 50' air hoses. One hose was coiled in a shop sink filled with ice water. At the end of the second hose I used a DeVilbiss Desiccant Snake which is a 3' hose filled with desiccant beads. On the end of that before the gun I used the little inline filters and replaced them every time I filled the cup. It was a decent amount of effort but not nearly as hard as redoing a panel because of moisture or oil issues.

IMG_4350 by willtel, on Flickr

[cabmandone]

Originally Posted by Bill Douglas

Thanks Guys.

Not a very good pic. But I've ordered this online. It's an Airline Desiccant Dryer that has blue moisture beads in it. I'll have it inline after the regular water trap. It's reasonably large.

Good call! I think I'd still consider putting one on the gun just to be safe. I'm assuming you're using an HVLP. If the gun drains the tank and the compressor runs a lot you'll tend to have more moisture. The filter at the gun might help with the fish eye issue as well.
BTW, I think you can buy an automatic drain for your compressor. If you're having moisture issues it might not be a bad idea to add the drain, that way you don't have to worry about draining the moisture.

[T77911S]

someone posted a pic of when their air comp blew up. it blew the bottom of the walls out, I would assume from rust

[cabmandone]

Originally Posted by T77911S

someone posted a pic of when their air comp blew up. it blew the bottom of the walls out

I have seen pictures of things like that. It always makes me think I should get the 500 gallon propane tank I use as and air tank off the ceiling of my office.

[asphaltgambler]

Also - don't overlook worn piston rings on your compressor pump. Had another ruined job where oil was getting past the rings. It was a case where the pump had a ton of time and was cheap to begin with. I fixed that too......