I get quite a number of questions about whether or not it is a good idea to use PVC air lines to plumb compressed air, since PVC pipe appears to be well priced as compared to other ways of plumbing and installation is pretty easy, with typical, around-the-house plumbing tools.
So, do I, or do I not, use PVC pipe to plumb my compressed air?
PVC pipe is poly-vinyl chloride. If you look at the manufacturers markings on the pipe, it will often say that the pipe is pressure rated for 140 PSI or 150 PSI, somewhere in that range, depending on the manufacturer and the pipe diameter.
PVC Air Lines = Misleading Pressure Ranges
The problem with considering using the PVC pipe for compressed air at the pressure levels stenciled on the pipe, is that folks may not read the whole specification. That listed pressure is temperature specific. By that I mean that as the temperature changes, so too does the pressure rating of the PVC pipe.
Does the temperature ever get to 90 degrees, maybe 100 degrees, or even hotter where you are? If it does, then the pressure rating of your PVC pipe just dropped dramatically, and all of a sudden, a 120 PSI air pressure inside when the outside air is cool, can now rupture the pipe as the pressure rating for that PVC pipe has dropped below the danger level as the temperature where it was installed rose!
PVC Pipe Could Shatter
If PVC pipe is over pressurized that pipe can experience a catastrophic failure. It does not just form a bubble and then pop, which is what happens to polyethylene tube when you overpressure that material. When a PVC pipe lets go, it shatters. All of a sudden you could have sharp plastic shards of pipe flying and ricocheting all over the workshop or plant.
If you over pressurize PVC pipe, your pipe could undergo catastrophic failure, with disastrous and life threatening results.
Some Specially Plastic Pipe For Air Lines
I do know that there are manufacturers that make a PVC blend pipe that they claim is suited for using as piping in a compressed air system. I suspect if this material will be priced at a level that may make the traditional compressed air plumbing materials shine in comparison.
I know that before you use any PVC material to plumb any pressure of compressed air, you do want to contact the manufacturer and get them to confirm, in writing (emails are wonderful), that their material is suitable for use in a compressed air plumbing application.
I Would Not USE PVC Air Lines
No, I would not use PVC air lines.
In order of materials that I would choose for plumbing my compressed air, and if price were no object, I would pick copper pipe as the best route for problem free compressed air plumbing.
Next I would use rubber air hose (see the hose page for info), and if I did not need a high flow of air, my next choice would be polyethylene tube.
Yes, P.E. Tube Is Plastic
Yes, polyethylene tubing is a plastic. It is a different family and formula than PVC however, and I can tell you from personal experience, that if you over pressurize the P.E. Tube, all that happens is that a bubble forms at a weak spot, the bubble grows, and eventually, the bubble pops.
Yes, you lose air when the tube pops, but there is no real safety issue with using P.E. tube that is rated for industrial air pressures.
Next, and way down on the list, but sometimes necessary due to the relative low cost and the large pipe diameters available for air mains, is black pipe for air lines. It has drawbacks including difficult installation and the generation of rust and debris inside the pipe as time goes on, but black pipe has its proponents too.
All of these air-line plumbing products are discussed at length on the various pages of this website.