PVC for Compressed Air Line

[Edward Norton]

"Just say no to PVC" for this application. It's not rated for compressed air. Yes, some people have used it successfully, but it's not the right product for the job. Copper is easy and inexpensive.

As to the flexible hose, I use the Flexeel hose that Chris mentions and have a review of it on my web site.

Just as most have mentioned copper is expensive. I see everyone here talking about PVC but nobody talking about CPVC. HUGE difference in the wall thickness as well as pressure ratings.

CPVC is rated at 100 PSI @ 180 degrees and 400 PSI @ 73 degrees. I have several friends that have had CPVC pipe for air lines in their garages and shops for years with no bursts or problems.

I am getting ready to do my garage using CPVC. I think one of the major things to consider here is to not run your air settings through the roof. I use all sorts of air tools in my garage from a simple brad nailer through a 1" impact wrench for truck tires and none of them require more than 90 PSI.

If I were worried about bursting then I would run the pipes through the stugs and them run a 1x2 along them as a shield.

Copper, galvinized & black iron are all good choices as well but you'll spend upwards of 200% more using these. Also unlike the other piping options CPVC does rust.

Just my thoughts...

[Pete Shermet]

I used type "L" copper for the higher burst pressure, black pipe is what they install in the auto shops but I don't have a threader but I do have a torch and know how to sweat a copper joint together!
Best Regards
Pete

[Chris Padilla]

FYI, Ed dug up a post that is 2.5 years old! Still good stuff...just letting folks know.

[Raymond Gerdes]

Our Lowes Denton,TX has grey sch 80 pvc.

I used shd 40 white pvc (not 200) and was careful to twist each joint and was quite pleased. I like it that it permits modification so easily.

Ray Gerdes in beautiful Texas

[phil harold]

copper can be easier to work with than threaded pipe

3/4" m pipe seems to hold enough pressure for me 611psi at 250 degrees
http://www.ccbda.org/publications/pu...ationptb6.html

joints are 200psi lbs with 95-5 solder
http://www.ccbda.org/publications/pu...tionptb11.html

[Walt Nicholson]

Chris, I noticed the date on this one as well and since the original post, Pex has introduced a new product called AL-Pex. http://www.pexsupply.com/Mr-PEX-PEX-...-Tubing-389000

It has good pressure ratings, is easy to work with and the fittings use special ferrels and ends that can be installed with two crescent wrenches (or the right size end wrenches for the purists) instead of some of the special (spendy) tools the other Pex products require.. (No affiliation with the company) I just bought some for the new shop and it works great. So far I just did a little short run as a test but hope to have the whole shop done soon. The fittings are a little spendy ( I used black iron for elbows instead of theirs) but I bought a 300 foot roll for $139 bucks. The last time I worked with copper was not a pretty sight and I was always worried about my lack of expertise with the sweating/soldering process. Like a lot of other folks, have heard some real horror stories about pvc.

[Edward Norton]

FYI, Ed dug up a post that is 2.5 years old! Still good stuff...just letting folks know.

Sorry about that. I was doing a search when I came across this site and post so I joined just to put in my 2 cents!

BTW I put together a test pipe using 3/4" CPVC and cranked up the air pressure. The pipe did burst but not before it reached a bit over 300 PSI! I don't know any shop running that much pressure.

The pipe did not shatter & throw shards of razor sharp plastic everywhere as some indicated it would. The pipe did came apart at a connector with an interesting kinda noise followed by the sound of a mad rush of air. The only thing harmed was my undies!

Ok I am done with the 2 1/2 year old post.

[Larry Prince]

FWIW; I've been using PVC in my shop for about ten years now with no problems. I don't know what schedule it is, but I got it from Home Depot and its marked at 480PSI.

A friend of mine who happened to work for an automobile company which shall remain nameless used their testing facilities to find out what happens when PVC is over-pressured. A 2" piece was capped off and placed in an enclosure with a glass view. Air was pumped in at increasing pressures until at about 600PSI the side of the PVC started to balloon. A few more pounds and the balloon split. That was it, no shrapnel, no explosion, just a split. (Chuck if you're watching feel free to correct my number. It might not have been quite that high).

YMMV. Something I think about is that all plastics seem to get brittle with age, which could seriously hamper their strength and result in that shrapnel we hear so much about. I've considered a simple shield over the pipe that would deflect any shards.

[Brian Backner]

Just a few comments.

The concern about PVC pipe shattering into shrapnel is only partly due to overpressurization. The real concern is what happens when a pressurized length of PVC is hit hard enough, by a board or whatever, to cause the pipe to crack. If Larry's buddy were to go back and repressurize a piece and set up an impact test at the same time, I wouldn't be surprised if the results weren't a little more "spectacular."

One of the concerns mentioned about the use of black pipe regarding leaking threaded joints can be easily solved by a product used by gas fitters (they obviously cannot allow ANY leakage!!!). Use a pipe dope called X-Pando - you mix it with water before using. Stuff expands to seal every little space in the made joint and sets like a rock. Stuff is rated to handle to 5,000 psi! It is almost impossible to break a fully cured joint unless you happen to be King Kong.

http://www.xpando.com/pjc.html

Brian

[Rick Christopherson]

Since the time I made my previous posting in this very old thread, I have replaced all of my original lines with copper. Well actually, I can't afford to put as many lines in as I originally had, because I went with extreme overkill the first time around. I had dual pressure lines running all the way around an 1800 sqft shop. I think I originally had 14 drops, but over time I realized that I only needed a couple standard drops and a dedicated drop for my sander (plus a new line going upstairs into the garage).

I have no regrets with putting in the original PVC (I think it was CPVC) because it was cost effective and lasted 10-12 years before I started getting a lot of joint failures. It fit my budget and needs at the time.

As I already said, the risk of shattering a line is more fear mongering than reality. I replaced the lines because I was getting joint failures (leaks) with the aging lines, not because they were exploding and killing small animals. Yes, the PVC will shatter, but you have to take a full-swing with a hammer to do it, and even then, it frequently takes two hits to actually break the line....yes, this was my chosen method for quickly removing the old lines.

If I had to do it over, I would do the same thing. I would put the PVC lines in again under a tight budget, and replace them later when the shop could afford the more expensive copper. Regardless of cost, I wouldn't even consider black pipe unless I was a plumber with all of the cutting and threading tools at my disposal. The only regret is that I didn't install copper up to the garage before I closed the walls with sheetrock.

[Dave Lessley]

Rubber air hose decomposes over time and will provide you with little bits of rubber in your air stream. As someone else mentioned it will sag and create pockets to collect water.

The reason to use metal pipe is it encourages the process of condensing the water out of the air. That process happens more quickly with Black or Galvanized pipe than Copper or PVC.

There are a couple of schools of thought and you can probably make a case for a bunch more. You want to get the water out of the air. It is usually recommended to run 50 feet of metal pipe before your outlet to let the condensation process take place. You want to have a drain to let the water out.

Usually it's recommended to slant the pipes that feed your outlets back to a water filter which is at the end of that 50 feet of pipe and then slopethe 50 feet of pipe back to the compressor or towards the water filter. Water being heavier than air it will go to the bottom of your tank little will remix with your air the water comes from the compressed air being hot and condensing in the pipes. Thats also why the manufacturer however tells you to drain your tank daily. This also helps keep your tank from rusting out. You want to keep your water filter as close to your outlets as possible. You want to use as short of hose as possible the more hose you have running accross a concrete floor especially if your not using a water filter and your hose is coming directly out of your compressor it will condensate in your hose. Not good for air tools or finishes.

Sorry this is a little convoluted I'm at work and need to go get some lunch so I'm kind of in a hurry.

DaveL

[John Fricke]

PVC for airlines "USED" to be used extensively in farm shops in my area. (farms are not subject to osha inspections" PVC airlines are a ticking time bomb with shrapnel included. I have not heard of any major injuries but I have heard of several instances of lines exploding. For the few hours and dollars you save to plumb a small workshop it is not worth it in my opinion. Steel would be my first choice. Like others said rent the equipment for a weekend and have a teachable moment.

[David Hostetler]

I haven't been able to keep up with the posts, so I don't know if anyone has mentioned this, but...

PVC pipe is NOT rated for compressed air, under the high pressure load of air systems, PVC can rupture suddenly and explosively producing small bits of shrapnel that would be more than happy to embed itself in whatever body parts were within range.

DO NOT USE PVC PIPE FOR COMPRESSED AIR!

My fist career was as an auto mechanic, and I have seen the end results on the job of this poor plumbing decision. You DO NOT want those results. I was lucky, I wasn't near the rupture, a coworker of mine required fairly invasive surgery and suffered facial scars and required several surgeries over it. The shop we worked at was shut down over this...

[David Freed]

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

Over the years, I have repaired many rubber air lines by cutting the damaged area and using hose clamps to fasten the new end or splice. I have had the ends pop off a few times (sometimes months after the repair), and the hose does fly all over the place. It probably could cause an eye injury, but I have been slapped a few times by a runaway hose and it doesn't hurt. I just turn the air off at the shutoff valve and fix it again.

When a 1/2" hose with 175 psi pops, I'm not sure which jumps farther, me or the hose.

[Curt Harms]

and I hope no one here gets to experience it. In the event of a fire with pressurized air lines, if the sweated joint melts and fails the fire is now being fanned by high pressure air. That doesn't seem like a healthy situation. Of course if you shut the air off at or near the compressor this wouldn't be an issue. I guess if you were really a tinkerer, you could install a solenoid at the compressor outlet and wire it somehow that when you turn the lights out or whatever the solenoid closes and the lines downsteam would no longer be pressurized.

Curt