Airlines in the shop

Mon Jan 18, 2010 1:07 am

Before I begin, let me apologize in advance, I am about to tick some of you off. I am posting to caution others against using any form of plastic pipe/tubing not labeled for use in a compressed air system to plumb their garages and shops. Now that I have thrown down the gauntlet, I have no intention of arguing with anyone my statement might have offended. I did not make this thread to offend anyone, and I will be delighted if I offend no one, but that is not generally the case with this subject.

I created this thread because the topic is often overlooked, and actually the hazard is denied by many. However, there is the real potential for injury with this hazard, and the subject has been talked to death on many mechanic forums and sites. In the workplace it is actually against the law, OSHA writes citations for this, and lines do actually explode, though many folks will dismiss this reality. At any rate, when you plumb the air lines in your shop, if you want to do it the safe way that is correct, use copper, or steel pipe, or plastic tubing (labeled for compressed air systems) but never, abs, pvc, cpvc, or anything else not rated for the job.

Well, I hope I offended no one, but that is not usually the case with this topic, it usually rubs someone the wrong way. So, if you did not like my topic here, at least try to be cordial, I know I will be. More important, if one guy learned something then the thread was worth it!

Re: Airlines in the shop

Mon Jan 18, 2010 7:25 am

Uncle Buck - I agree. I know that some run pvc, cpvc and abs air lines but it flat scares me. And yes, other materials can fail as well but with proper materials you are much safer.
My shop is fairly small and I used an overhead run of tubing rated for the job from the compressor to a hose reel near the center of the shop.
If you have kids near your shop at any time you need to make sure it is safe.
Thank you for your reminder.

Re: Airlines in the shop

Mon Jan 18, 2010 10:04 am

I will second you on that Buck. I know the pvc is easy to work with and rated for pressure sufficient to handle what we normally run our hobby compressors at, but I have seen pictures of fittings that exploded form over pressure, and it scares me. They are like small hand grenades in the way they throw shrapnel. Due to the light weight of the plastic they may not travel far, but in close proximity they can be devastating. I was at a tractor and machinery shop last week when I noticed they had ! inch PVC lines run all over the shop. It was evening and the compressors had been shut down, but even so I was a little uncomfortable with the residual air in the tanks.

Re: Air lines in the shop

Mon Jan 18, 2010 11:19 am

Uncle Buck:

Your point is a valid one and it can prove to be a life-saver. Exploding air lines create projectiles that can harm one seriously if struck and has the potential to even take a life. So using the proper materials for the job at hand not only makes sense but should be a primary consideration when contemplating adding a compressed air system to one's shop. There is so much information on how to set up compressed air in a shop on the net today that there really is no excuse to build a system with sub-standard parts. Misplaced frugality could end up being the most expensive option if materials are not chosen carefully.

When I built my cabinet shop over 22 years ago, I wanted to plumb the shop with 1/2" steel pipe or copper for my compressed air system. Unfortunately at the time, the funds for that just were not there. So, the company that did the install, used commercial grade compressed air plastic hose for the job. At that time this was a pretty drastic departure from the norm here and many including me were a bit leary of using such a product for this purpose. Also I was not so impressed with the crimp-on fittings that were used at the time but surprisingly over the years, they have held up very well and in fact I have yet to experience a failure. All in all I am pretty happy with the setup that I have. The looks of the install could have been improved, but efficiency, safety and cost heavily outweighed that aspect.

I now have the manifolds I need to extend my compressed air system into the pole barn, and I have to decide how I am going to plumb this. I am seriously thinking that I may continue to use the plastic hose provided the costs are still reasonable, simply because it is so easy to route around obstacles and such.

Re: Airlines in the shop

Mon Jan 18, 2010 12:31 pm

Awile ago someone posted where a compressor went through the roof of a shed, due to a bad fitting or some other reason. It was left on during the overnight, and it happened overnight, no one was hurt, but lots a damage in the picture. Reminding use to deplete the air in the tanks when done, and to not just leave them plugged in.

Re: Airlines in the shop

Mon Jan 18, 2010 7:34 pm

Very well put. Thanks for your thoughts. I hope it helps everyone.

Re: Airlines in the shop

Tue Jan 19, 2010 11:36 am

I agree 100%. Had a neighbor that had a line explode (schedule 40) and a chunk of it was embedded about a half inch into an oak 2x6. Imagine what that would have done to soft flesh. Good reminder!!

Re: Airlines in the shop

Tue Jan 19, 2010 3:28 pm

I've had PVC in my garage, replaced it not too long ago, and it did hold at 100 PSI for a number of years. I replaced it because I dropped a soldering iron on it and melted a hole in the line. My new system is done in 1/2" copper, last I looked it was about .80$ a foot. Maybe less if you buy bulk from a plumbing supply.

In my shop I did a manifold with a moisture trap and a drain, then it runs in two directions, one to the front of the garage so I can fill tires outside, and one goes along behind the tool bench, all my pipes terminate with a T down to a drain valve, with a drop ear 90 and quick connect. If possible run gently down hill to encourage all water to drain out.

Flexible works well too, just depends what you want. 1/2" flexible air hose seems to run about .40-.60 cents a foot, but the connectors are more expensive, and it requires barbs, crimps, hose clamps, thread adaptors etc to terminate. I would have melted a flexible air hose just like the pvc pipe.

Re: Airlines in the shop

Mon Jan 25, 2010 9:09 pm

I ran iron pipe in my shop. One of the benefits is to encourage condensation. I have about a 30 foot run along the ceiling of 3/4" pipe to a ceiling to floor drip leg. About midway down, I put my traps and dryer and then went back up to run the pipe to my retractable hose and other access points. A friend of mine used some plastic for his drops, but I am not sure what kind. He is pretty careful and said it was rated for the pressure he was running, but i feel secure with my iron.

Good topic for a post.

Re: Airlines in the shop

Tue Jan 26, 2010 10:50 am


I forgot about the drip leg and condensation in the lines. I might go that route. I need to make sure that condensation is not a problem. I went to the pole barn yesterday and the one plastic line I had out there got plugged. I guess there was a bit of water somewhere in the line and it froze. I like the idea of a drip leg. I was thinking that the idea of an air hammer in plumbing would be a good idea but only reversed... instead of up... orientate it down to catch water and then use a valve petcock to drain it. I got lots of schedule 40 hanging around and a bunch of water traps.

Is there anything I need to do when mating with an aluminum manifold :?: Dissimilar metals tend to do weird things at the junction... :roll:

Re: Airlines in the shop

Tue Jan 26, 2010 11:07 am

More interesting reading... ... ystem.html

Re: Airlines in the shop

Tue Jan 26, 2010 11:21 am

I use brass fittings into aluminum and connect the iron pipe to the brass. That seems to work out fine and that is what the purification train manufacturer (Sharpe) used in between the cast aluminum housings- brass. With iron pipe you should use teflon tape on the threads and then use a paste over that and you will not get any air leaks. make sure you put some unions in your piping layout in case a leak test shows a leak somewhere so you can work on a limited number of fitting at a time rather that the entire layout. Also you never know when you may want to add another tap somewhere so I put in a few tees with plugs for future consideration. The only leaks I has were with valves. The ball valve supplied with the compressor needed adjustment and one of the cheapy drain valves on the Sharpe dryer leaks and I need to order a 1/4" ball valve for that but I have not gotten around to it. I couldn't find the small ball valves locally and found to be a great company to do business with. Sort of like the Mcmaster Carr of plumbing supply. They have everything and I am not burning up a tank of gas looking for that one oddball thing I need.

A friend of mine ran some well pipe underground out to his tool shed with enough pressure to be able to blow off his mowing deck and fill tires. I know it is plastic but I would think this tough material should be able to handle air pressure at the same level as rated water pressure.

With condensation, the first line of accumulation is the tank which needs to be drained frequently, especially in humid summer months. I set my dryer up next to the tank to get shop air right away but the farther away you can put your dryer the better as the metal will condense out water that will shorten you media life. I don't use a lot of air, but I did paint the tractor in 2008 and I just had to remove the gel beads and bake them out on the wood stove (just heat them on a flat pan until they turn from pink to blue- cool to watch them pop-over) a month ago so the condensation and drip leg really extended the service interval on the dryer.

I put a drip leg in any vertical drop but I use a cap in all the locations after the dryer. Eventually I will need to flush the lines of dirt and scale but that will not be that frequent so I can isolate the line, depressurize it, and remove the cap and flush it out just like the city does with a water main.

Re: Airlines in the shop

Tue Jan 26, 2010 11:37 am

Don McCombs wrote:More interesting reading... ... ystem.html

Good read Don. Thanks

Re: Airlines in the shop

Tue Jan 26, 2010 5:56 pm


Thanks for that link. Very interesting reading indeed. I think I will think on this for a while before I decide what to do in the pole barn. :idea:

Re: Airlines in the shop

Thu Jan 28, 2010 8:48 am

Uncle Buck I agree with you 100 %