PVC for Compressed Air Line

[Gary Hoemann]

if you wanted to, why couldn't you just use air hoses. They always seem to be cheap

[Robert Mickley]

These are great responses and ideas! So much for my hope to use PVC.

Chris has the citation for the magazine article I mentioned. But this method still requires sweating copper for the drops. The nylon tubing idea from Robert is something I've not seen before. It sounds like it could meet all the requirements I have, especially if it can be accomplished with compression fittings. I'll look at the Grainger catalog, but any other ideas for sources?

Thanks to everyone from your help.

Greg

Most likely why you haven't seen it before is, it's most common use every day is on air brake systems for trucks. You will also find it on industrial equipment that use's phnuematics for things like clamping and other repitive operations.

Grainger may carry it but it will be pricey. Just get your yellow pages out and look for truck parts. Any place that sells truck parts and equipment will have it. Try to stay away from the dealers.

I think up ideas like this since I tend to think outside the box a lot. If I had been thinking when we ran the air line from the front shop to the back one it's what I would have done. As it stands I need to run lines around the shop yet and this is how I will do it.

[Chris Padilla]

Could PEX handle the pressure? This is the new "copper" plumbers are running in new houses.

http://www.sawmillcreek.org/showthread.php?t=40514 is a good thread to read, too. Has a link to a nice diagram in a post from Tod.

[Al Willits]

I have tried PVC as air lines, with 165psi I blew the end cap off the end of one run, it didn't rupture at the glue joint, but about 2" from it.
fwiw I'd stay away from PVC

Personally I like black pipe, its strong,resists puncturing and with a pipe threader not to bad to work with, and I'd disagree that it leaks easily, I had about 80-100' of it run, and the only leaks I had were the quick connects I use.
On the other hand I used a 18" and a 24" pipe wrench....

Teflon impregnated pipe dope seems to work better that the tape, for me anyway.

Al

[Dan Oelke]

Disclaimer - I haven't yet plumbed my shop for air...

The thing I don't like about using hose (as I saw in that article) is that it is too easy to get a sag someplace where moisture can puddle. With rigid piping you can set it up with a slope and know that all the moisture will come out of one of the drops.

The other really nice thing about metal lines is that they will act as a radiator and cool and to some degree dry your air. I know someone here on the creek has posted a thread where they showed in their shop a lot of pipes snaking around just to get that effect. A plastic line, or hose just won't have that cooling effect.

[Joe Mayo]

Repeat after me ....
I will never, ever, ever use PVC for compressed air.
I will never, ever, ever use PVC for compressed air.
I will never, ever, ever use PVC for compressed air.

If the integrity of the PVC is compromised, it doesn't just break. It explodes, sending lots of shrapnel all over the place.

Now that we got that out of the way … Black pipe or Type "L" copper tubing works well for compressed air. There was an article in FWW's Tool & Shop issue a couple of years ago describing how to run the pipe. They used 3/4 inch for the main line and 1/2 inch for the drops. Put a Tee fitting at each drop with a regulator on one side of the tee and a drip leg with a valve on the other side. When you connect your drops to the main line, go up towards the ceiling and solder 2 elbows together, doing a 180 to come back down. This will, in theory, keep the air drier. Finally pitch your main line back towards the compressor so that any water in the system drains back to the tank. Hook it up like you did the drops by using a tee with a drip leg and a valve. Don't forget to put a shutoff valve at the compressor. Then you won't have to discharge your system to drain the water from the drip legs. To reduce any vibration from the compressor to the lines, use a short piece of rubber hose connecting the shut-off valve on the compressor to the tee fitting at the beginning of the main line.

Good Luck,
-Joe

[Lars Thomas]

If you used regular hose and it was severed, wouldn't the head-end start whipping around from the pressure releasing?

[Rick Lizek]

I thought about the Pex as an airline some time ago and put the question to the manufacturer. They would not stand behind Pex for airlines. The only plastic suitable for air lines is the Chem-aire productI linked to before.

[Al Killian]

go to a local Napa auto store or truck stop and ask about 3/8 air line. It is rated for 175 PSI.

[Robert Mickley]

I thought about the Pex as an airline some time ago and put the question to the manufacturer. They would not stand behind Pex for airlines. The only plastic suitable for air lines is the Chem-aire productI linked to before.

Pex would be pricey for airline

Nylon tubing is approved for air, If it wasn't they couldn't use it for brake systems on trucks.

I still think it's the most economical way to go, properly anchored your not going to hav an issue with sagging. No reason why it couldn't sloped the same as any ridgid pipe. and its rated up to 550 psi, what more do you want. I doubt you would puncture it, even if you did it would take all of 4 or 5 minutes to fix. Cut it with your pocket knife and install a union, Done!

I can understand not being familar with a product, but don't discount till you have looked it over thoroughly

[Robert Mickley]

Besides with push to connect fittings you don't even need wrenchs

http://www.imperialinc.com/grp299.shtml

150 working PSI 900 PSI burst
http://www.imperialinc.com/items.asp?item=0908060

Not strong enough?
980 PSI working pressure
http://www.hudsonextrusions.com/nylo...tm#javascript;

[Bruce Wrenn]

Saw that article and wasn't the least bit impressed. Many sags in lines equates to a lot of traped moisture. Copper is the way to go. When you turn off a faucet quickly, the resulting shock waves (known as water hammer) are in the multiple hundred pound range. Copper will take this with no problem, so normal (100- 150 psi) should not be a problem. Go to copper institute web site and look for info on running copper air lines. If you don't know how to solder copper, then learn. Go to plumbing supply house and get a jar of Lacco brand flux. It is what all the pros here use. With copper it is easy to cut in a drop. They make special repair couplings that don't have a ridge in the middle just for slipping over copper pipe and then back to area of cut in pipe. Remember that copper is basically a lifetime deal- once and done forever.

[Rick Christopherson]

The notion of PVC exploding is more fear than reality. Not to say that it can't shatter, just that it is not as prevelent as the fear mongers make it out to be. I installed PVC in my shop 10 years ago because it had a 300 psi rating. In that time, I have had two ruptures. The first was when a plumber was sweating a copper fitting and didn't realize he was heating up the charged air line too. The rupture was a blister in the side of the piping, and did not shatter. The second rupture was when a fitting let loose. This was an explosive separation of the joint, but the pipe did not shatter.

That being said, I am planning on replacing the primary lines with copper. Not because I worry about the shattering, but because I have now learned that the joints have age limitations. My primary manifold where I have my dryers, regulators, and several valves is leaking at several joints. I don't regret using the PVC because it was very cost effective for the several hundred feet of piping, except for the feeder that is buried in the wall leading to my garage. If the joints fail on this line, I won't be able to access them for repair. I'm not going to replace the whole system, just the main line between the compressor and the manifold.

[Steven Wilson]

PSI rating isn't the only rating you need to consider. You must consider if the material you want to use is rated for handling gasses under pressure. PVC pipe is not rated to handle gas under pressure, PVC's pressure rating is for incompressible fluids (i.e. water). Do not confuse these ratings. PVC is a well known hazzard for handling compressed gasses, only fools use PVC for air systems. Copper, black pipe, aluminum (some) and some other plastics can all be used for air and all share the ability to fail plastically (i.e. split open, not break up into shards). Make sure your using a material that works for gasses then take into consideration the PSI ratings.

No PVC ever.

[Russ Filtz]

Here's a link to an engineering forum discussion on the subject. Not sure if these links are OK. If not, please delete!

http://www.eng-tips.com/viewthread.cfm?qid=122826