Hey fellas, I have had pvc for compressed air in my shop for 7 years. All my drops are into black pipe. Is this a bad practice, unsafe, the pvc psi rating is like 400 psi’s. Its been working for years. I’m asking becouse I will be setting up my new shop soon.
Thanx, Lou
Replies
Lou,
Yes, this is an unsafe practice! The PVC can certainly handle the pressure, but what happens if you happen to hit one of the pressurized pipes while moving something and crack it. Now you have sharp edged PVC shrapnel flying around the shop. I would go with the black pipe everywhere.
Rob
No pvc manufacturer approves it for compressed gases. Copper or black pipe is really the way to go.
PVC, unless it is completely boxed in, is against code in most locales and it is against OSHA regulations. PVC ages due to oil, moisture and sunlight. When it ages it gets brittle. When it fails is project shards with great force which can be very dangerous.
Ditto what everyone else said. The pressure rating for PVC pipe is for noncompressible liquids only. While copper or steel lines will bend or crack if they're damaged, PVC will shatter and the compressed air will blow shrapnel all over the place.
There is at least one brand of ABS pipe that is rated for use with compressed air (I forget the brand name at the moment, so check first before buying if you go that way) and there are some aluminum air line systems out there that may be worth looking into, considering what copper goes for these days. There are some good discussions about what materials to use and how to set up the air lines over on the garage journal forum, at http://www.garagejournal.com/forum/
Hey Lou,
Use copper. You won't regret it.
Paul
Paul,
Would you expound a little on the benefits or ease of copper? I have been using PVC for about 6 years with no problem. My b-i-l for about 10.
However, I am aware of the issues everyone says there is with PVC. So, I have been thinking about swapping out.
I figure I could do copper, but I don't have anyway of threading black pipe. I know I could get it done, but I would never get all the measurements right.
Thanks,
Alan - planesaw
You can get the steel pipe threaded by most vendors. HomeDesperate, and Lowers will both give you two free cuts and threads per joint of pipe. They once gave me five joints of PVC coated gas line rated pipe, because nobody knew how much to charge for the extra cuts and threading. They kept me standing around for an hour while they tried to figure it out. The manager came back from lunch, tried to figure it out for about ten minutes, asked me how long I had been waiting for an answer, and when I told him since before he left for lunch, he apologized for the wait, and told me to take the pipe and leave. Next time I went through the plumbing section they had a price posted.
It doesn't need to be exact. If you plan it right and draw it out, (even if it is just on the wall), you will be close enough. They make nipples in every inch length so you can "stretch" it a bit if you must. You can almost always tighten things a bit if you need to shorten it, (just remember that you can never back off a pipe threaded fitting with out it leaking). If you put a u shaped section in the middle of the runs it will allow quite a bit of flexibility, and you need them on long runs anyway to allow for thermal expansion/contraction. The other option is to use flex lines at the corners. If you are swapping out an existing PVC system, you should be able to cut it out and use it for a template to lay out the iron pipe.
I saw an article in one of the magazines a while back, where they plumbed all the air lines in a shop with flexible hose, and barbed fittings using iron pipe only for the drops that needed to be solidly attached to the wall. PEX isn't designed for it but would probably work. The stuff they used was a reinforced rubber hose. High quality large diameter garden hose would probably work if you don't have too long of runs, or need to move large volumes of air.
Thanks for the warning!!! I will run copper. What size copper tubing should I use.
Thanks, Lou
I used 3/4" copper for the main lines and 1/2" for the drops. Only use solder with no lead, solder with some silver in it is the best.
Life is what happens to you when you're making other plans .
This isn't a potable water line, so: Why only no lead solder?
Because you don't want to be inhaling the lead fumes while soldering.
There isn't much difference in the difficulty of soldering without the lead.
Hal
Solder with lead has the lowest joint strength that could lead to a joint bursting when used on a air line. Lead solder is not recommended for air line use. Solder with some silver has the highest strength, melts quickly and is easy to work. I did more than 100 joints in my shop with Aquabond solder and not one leak or joint had to be re-done.
Life is what happens to you when you're making other plans .
Hi Planesaw,
A friend of mine had a rather large shop he had plumbed for compressed air with 3/4" PVC. One day we were working there and my friend went to attach an air hose to a coupling when the end blew off and stuck him in the arm . But I've heard a lot of stories of people using PVC for years without any problems.
When it came to running air in my shop I decided just to bite the bullet and run copper ( I have already dented it with a piece of lumber that would have broken PVC , I'm sure) . So, it is mostly a safety issue for me. I ended up making up sections down below where it was easy to work on and then assembling those up where they needed to go( it saved some time soldering on a ladder). It's almost as easy to work with as PVC.
Paul
I used to have black pipe, but no matter what I tried, I could never get an air tight fitting on all the joints. If I get around to do compressed air plumbing again and something new and better doesn't come along, I think I will try copper. A good soldered joint just doesn't leak.
Lou, the article on using rubber air hose instead of hard lines was in the September 06, "American Woodworker".
The 1/2-=inch hose used is available from MSC Industrial Supply.
http://www.mscdirect.com
as #48563720
This will get you to the hose:
http://www1.mscdirect.com/CGI/N2DRVSH?SISECT=0000000807&SIS0NO=00000555804
Sizing depends on how many cfm you want to push, how many feet, at how much pressure loss. This is a good link on that topic.
http://www.about-air-compressors.com/air-lines.html
If you have access to the installation tool I would recommend Wirsbo. It is very strong and very flexible. It is much less than copper and much easier to work with. Most plumbing distributors will sell you a 300' roll for less than $150 (Canadian). You can do many shops with that much pipe.
Is pex approved for compressed air? I've never heard of anyone sing it for that. It would be easy to install but I think over the long haul I would prefer rigid lines since they can be pitched to keep condensate from accumulating in the lines. I would think over time the droop on pex would accumulate condensation.
The previous owner of our shop had ran PVC for compressed air. It worked for many years. Then for no reason at all, a section of it blew up. It sent plastic everywhere. Luckily, no one was hurt.No one disturbed it. It just blew up.I had all of it replaced with iron pipe.
I am familiar with the problems with pvc. I plan to use copper on mine.
I've repairing messed up air sytems in shops for years because no one checks with the compressor people how to set it up properly. The big problem with pex besides not being rated for air is it deteriorates in sunlight. I've talked with the Pex folks on this several times and different companies. Try and get written documentation to use it for air.
T drops are supposed to go up then down. Chem-aire makes a polyurethane plastic rated for airlines.
http://www.indelco.com/c-347-chemaire-compressed-air-fittings.aspx
http://www.tptools.com/StaticText/airline-piping-diagram.pdf
http://www.garage-pak.com/
There's also others such as garage-pak which is more that steel but easier to set up. Kaeser compressor has an aluminum alternative as well but it's not cheap. L or K copper would be a common option. There are compression fittings available now so soldering is an option.
Edited 4/16/2007 8:34 am ET by RickL
PEX is rated for compressed gasses. Inexpensive and easy to use. The pressure rating vaires by size and by manufacturer. So check the tubing, it will be printed on it.
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