With all the talk about air compressors for air brushes I have a question.


B

blues90

Member
Looking at older Paasche D compressor with the air tank which had a pressure switch to turn it on and off and a regulator . Yet it did not have any sort of moisture trap or any sort of drain on the tank. Yes one can easily add a moisture trap and add an in line moisture trap as well .

Here is my question.

Every air compressor creates heat which in turn creates condensation by nature. So why no tank drain on most air brush compressors ? Also when one uses an air tank like one would use to fill with air with a compressor at home or say at a gas station . Mainly they are intended to have a supply of compressed air for filling tires or any other use yet they have no tank drain value either.

My old sears motor /belt driven two piston compressor 12 gallon tank army green unit has a tank drain as well as a built on regulator and pressure shut on/off switch and I added a Paasche regulator/water trap with gauge and it has a pressure gauge on the built on regulator and a gauge that reads the actual tank pressure before regulation . I drain the tank after every use. Now win no tank drain on any air tank whether the Paasche unit I described or a portable air tank seems to me the water will just remain in the tank until it rusts through which could take decades or the water will slowly find it's way out through draining the regulator /water trap . I added on 10 gal air tank to my sears compressor yet instead of the tank sitting with the value on top I hung it upside down didn't use the brass valve and hose it comes with to fill tires , I just added a gauge and a new hose down to a port on my sears compressor with a quick disconnect so any water in the add on tank would drain down the 5 feet into the sears tank then I could drain both tanks and if I didn't need the extra 10 gallon tank just use the quick disconnect on the hose . If I fill the extra tank I do it from the compressor through the hose not the included tire/air valve and insert a regulator /water trap to the tanks quick disconnect fitting pull disconnect the hose , shuts off release of air from tank , later added an air value , then I have a dry tank with a regulator / drainable water trap as the Paasche one is and then I can use the tank/air brush anywhere .

I suppose a drain can be welded or rather a fitting welded to any tank so a water drain valve can be added .
 
Do not weld a fitting yourself or have one welded on by your neighbor or the handyman down the street. Airtanks are pressure vessels and welds must be done to ASME code requirements. I have taken and passed many ASME code weld tests but I would never weld on an air tank because I don't have the ability to do any nondestructive weld tests on the finished product. Without a way to examine the weld below the surface you have no way of knowing if you will be standing next to a bomb! Defects in the weld due to improper technique or welding rod storage to defects in the tank due to pitting from moisture or manufacturing defects or even from a small, barely noticeable dent are all possible causes of catastrophic failure. There is no way of knowing what's there without a proper inspection which usually means RT (X-Ray) or UT (ultrasound) testing. 90PSI is a tremendous amount of force and many compressor tanks are subjected to even higher pressures. Please think of everyone's safety and do not have ANY welding done on an air tank.
 
I guess if the Paasche compressor doesn't have a drain it's because they chose not to include one. I have two Iwata airbrush compressors with tanks and both have drain fittings. You get what you pay for. I suppose you could add a drain fitting to an existing tank, but I have no clue what an ASME shop would charge for this, because in addition to the weld they have to test the tank. Probably cost you more than a new one.
 
I wasn't thinking about adding a drain . I know welding any tank is a risk . I know when tanks are made they weld the drain in first before they weld the ends and it's all done by special equipment . Some tanks have a seam down the length and some have either two end caps and some are welded using a solid cylinder and end caps and a seam around the center.

I was just curious why on earth due to the high pressure tanks are under some don't have drains because rust will in time cause a tank to rupture. . I also know the old Paasche D compressor with tank does not go much higher than 30PSI which is close to a car tire blowing nothing like 90 to 150 PSI .

I looked at my old sears compressor it has a 12 gallon tank with a drain and 1 hp electric motor and will produce 5.8 SCFM @ 90 PSI and 6.9 SCFM @ 40 PSI. It's a two cylinder piston compressor that has oil in a crank case. If I recall the pressure switch shuts off at 90 PSI .

Here is a sears breakdown of the compressor I have . I got mine in 1985 used and it does not have the belt guard or cover around the regulator and ports or stock pressure gauges. works just fine without them I just stay away from the belt , keep that side near the wall.

http://www.mastertoolrepair.com/sears-craftsman-106175540-p-64037.html
 
Back in 83 I needed to have an air brush set up that made no noise & produced no water vapor. At the time I was friends with a guy who was heavily into Karting. He used 20 pound C02 bottles & a regulator for his race tools instead of a compressor because electricity wasn't always available. I looked at his system & it was portable, noiseless & water free. I used it in my office & nobody ever knew it was there. I could regulate it down to any pressure I needed & I rarely went over 10 pounds. And at that pressure a $15 fill lasted a year or more, and I was using it more than 10 times a day. One of the side benefits is take it when you go on a trip, you can fill your tire if you have a problem or fill your air mattress quick! Actually there's quite a few things you can do with a set up like that.
 
Last edited by a moderator:
I bought a bargain compressor myself and even that el cheapo has a drain on it. I don't know enough about the various offerings on the market to state this with any certainty, but may be that your airbrush compressor is an anomaly rather than the norm.
 
I've looked at some air brush compressors on line and the few that I did see appeared to be tankless types that would have no need of a drain. I'm not familiar with these compressors, the ones that I have experience with are the small, handyman types from the big box stores to large industrial types, many of which are tankless.
 
Guys, he already said he knows about moisture separators in the first paragraph. He was just starting a discussion about why some tanks have drains and some don't, not asking about how to remove moisture from the line.
 
You must log in or register to reply here.



Back
Top