Using PVC for air lines in shop

[Tom Maple]

I've appreciated the opinions and advice from all you folks as I assemble machinery for my shop. It's valuable to be able and view so many people's experiences and hopefully avoid some mistakes.
An area I am going to be tackling soon is routing the air lines from my compressor to various areas in the shop. I have used 1/2" sch 40 black pipe in the past and have seen others use copper plumbing pipe. I have several twenty foot lengths of 1/2" sch 40 PVC which is rated at 600 psi. Is there any reason I can't use it for my air supply lines? I can't come up with a reason why it wouldn't work. But I don't want to install it and then find out "you never use PVC for air because..."
Your advice is appreciated,
Tom

[Jim Becker]

Do not use PVC for air lines unless you buy the special type that is rated for compressed air. The PVC you see in your local stores is rated for liquid, not compressed gases. It's prohibited by OSHA for compressed gases (air), too.

Yes, some folks have successfully used it, but the danger from shattering, etc. is there. Type L copper is easy to install, safe to use and while more expensive than it used to be, still affordable for most shop air systems.

[Mark Lessard]

Tom,

I have used 1/2 pcv pipe for airlines without any problems, I did how ever use rubber hose from the compressor to the pipe for vibration dampening.

Also clamps at the quick releases, since tripping over hoses is likely at some point.

Mark

[Brad Schmid]

Don't do it!
If you do a search, you'll find we've discussed it here several times.

Although rated for internal pressure, if PVC sustains an impact under pressure of a compressible substance, it can/will explode like a bomb. Air/gas is compressible, water is not, thats why it won't explode with liquid, just leak..

[Ken Fitzgerald]

Here's OSHA's feelings on it:


http://www.osha.gov/dts/hib/hib_data/hib19880520.html

[Rod Peterson]

...to tell you NOOOO!. It is a bad idea. Although the pipe is rated for that pressure, it's intended for a liquid. Gasses behave somewhat differently when pressure is released, consequently, the pressure (even though your compressor will deliver far below that rated value) of a gas is a bad thing in PVC. It's so bad that OSHA, gas industry groups, and PVC manufacturers all counsel against it. Do a search and you will find plenty of data.

Also, you will find it's been discussed a lot on various fora over the years.

What will happen with the PVC under the pressure of gas? Shatter, sending shards of hard, sharp plastic throughout the space. It's not the pressure. PVC becomes brittle under pressure. Liquid provides support--gas does not. It can shatter when struck.

Stick with copper or steel. There are some specialty plastics designed particularly for pressurized gas, but you'll probably discover that they are hard to find, not cost effective, and not easily customized after installation.

[Jim Becker]

Sorry, Rod...you'll have to settle for fourth place... :D

[Rod Peterson]

Five answers in eight minutes, the first being just six minutes after the original query.

Well done, guys.

[Tom Maple]

Thanks everyone,
I felt it was too good to be true, inexpensive and easy to work with, there had to be a catch.
Being new to this, I appreciate your expertise on this. You saved me from making a potentially dangerous mistake.
I haven't been succesful with the search function so I didn't search the archives on this subject. Maybe I'm doing something wrong. For example, if I search for "Router Table" I get every thread that also mentions "Table Saws". I looked for a way to search using all words and didn't find it. Any tips? Or is there an optional search function I overlooked?
Thanks,
Tom

[James Suzda]

One bad thing about using PVC that is seldom thought of but was instrumental in the destruction of a small factory near where I live. They used PVC for airlines and when a small fire broke out at night near one of the pipes the pipe melted and burst. When this happened there was a high pressure source of air to fan the fire which caused it to burn much hotter than what would have been without the steady supply of high pressure air.
This supply of air was fanning the fire until the breakers tripped. I think there would have been less damage if not for the high pressure air.
Jim

[Rob Bodenschatz]

Tom, about searching...

Use "Google Sawmill Creek". The regular "Search Forums" sucks.

A few quick tips, put a "+" in from of each word, like this +Router +Table. That will require that each word preceded by a plus sign is in the post. Also, try putting quotes around the phrase: "Router Table".

[Steven Wilson]

Go ahead use PVC. While you're at it try drinking and driving or run around the woods with antlers on during deer hunting season.

There are some hard plastics that can be used for air but PVC isn't one of them. You want a material that is designed to carry compressed gasses. PVC pipe has a pressure rating for compressed liquids and not compressed gas.

[Tom Maple]

Tom, about searching...

Use "Google Sawmill Creek". The regular "Search Forums" sucks.

A few quick tips, put a "+" in from of each word, like this +Router +Table. That will require that each word preceded by a plus sign is in the post. Also, try putting quotes around the phrase: "Router Table".

Rob,
Thanks for the search tips. I should have better luck now.
Tom

[Ben West]

The problem is that gases are compressible and thus pose a safety issue as pressures become higher. Liquids are much less compressible than gases and, as a result, no explosion occurs if there's a failure in the pipe or other container.

[Chris Jenkins]

Clearly I don't have to tell you what everyone else has. I ended up going with black pipe, pretty much the standard and I can say do yourself a favor take Jim Becker's advise. Try copper

I went with black steel on small gas projects in the past and didn't have a problem with it then, but after installing only half of my air system (yeah that's how much I don't like this project anymore) I can say I regret not spending a few extra dollars.

Prices of copper and steel are comparable out by me, though with building season here copper is going up again.

Here is why I reccommend the copper. One swinging two pipe wrenches around sucks in general, let alone if you are close to a rafter or wall this is really a pain.

Copper can be cut to any length for about 10 dollars for a cutter. Steel requires you to have someone cut it for you or you have to play mix and match with pre-threaded varying length pipes. That is unless you want to drop 200 for a nice Rigid cutter and then it becomes a muscle match.

Modyifing copper will be easier than black steel. I even put in several Tee's with caps for future expansion, but you never know what the future will bring. I also recommend putting in a few extra unions too cause taking steel apart is a one way system to the nearest union...

Don't forget to slope line for drainage and come off the top of the line for drops to minimize water in the air (important if spraying finishes)

[Bill White]

In my new shop I will be using a PEX product specifically rated for gasses. I have plumbed the house with IPEX (metal core), and when we pressure tested last week-narya leak. This stuff is good. Check out your local plumbing supply.
Bill

[Jim Becker]

Bill, how do you intend to be sure your flexible lines will drain properly? That was a problem I always had with the temporary installation I did with hose prior to implementing the copper air system.

[Glenn Clabo]

Bill,
Dumb question...What kind of "special" tools do you need. I think when I looked they were very expensive but I wonder if the "sharkbite" system would work.

[Lou Ferrarini]

If you want to save a little time and money and still be safe, you can do what I did. I ran PVC fom my compressor (which is outside the shop in its own little shed) to the attic of the shop (where I don't go when the compressor is on) and then the drops to the shop are metal pipe.

[Scott Taylor]

So I take it using PVC for compressed air is BAD??? lol Well if you use PVC after those posts.....


I just have one question, does anyone need 200 feet of 1/2 inch pvc pipe?????? I won't be needing it.

[Rick Lizek]

I do a lot with airlines professionally and am always looking for new technology to use. My research says pex isn't rated for air. It deteriorates in sunlight so it must be hidden in walls. Plus the techs at pex say it's not rated for air. There is a polyurethane that is rated for air...http://www.indelco.com/c-347-chemaire-compressed-air-fittings.aspx
There's other alternatives such as aluminum like http://www.garage-pak.com/compressed-air-piping-general-information/compressed-air-piping-system-safety.html and Kaeser Compressor has introduced an aluminum system.
For copper airlines (type L or K, not M) you can now get compression fittings so no soldering is required.

[Cliff Rohrabacher]

You can use Black Iron pipe and it'll last forever.