shop air lines

oj · Sep 1, 2008

Any one know if you can use Pex for air lines? We"re in the process of finishing off our shop right now, electrical is nearly all done, just lining steel to go plus a bit more insulation, and i wondered if i could use Pex for the air lines, other wise i guess it will be copper or something else. i was thinking lines of an inch or greater to provide maximum air flow to the tools. Any one want to suggest anything else??

Thanks of all the info.

Gary from Va · Sep 1, 2008

3/4" should be plenty big enough, 1" might be overkill. Not sure about Pex, might want to go with cpvc, or copper. Check the max. pressure ratings, they should be printed on the side of the tubing. I'd go with at least 200 psi rating. An air line that blows can send schrapnel flying everywhere. Another route is to use plastic air brake tubing like they use on big trucks. It will definately hold the pressure, you can get it in 3/4", it's pretty affordable and easy to get from any truck parts store, and it's flexible enough to be routed around obstacles without a lot of extra fittings.

Gary

Ken(Ark) · Sep 1, 2008

I have 3/4 PVC routed all over the place . I can cut in a new outlet without any problems anywhere the need arises . The contacts got stuck and pumped the normally 125 max psi to 180 psi causing the blow by to pop open . No damage to the lines .

A propane torch held 6 inches away will soften up that stuff to make some of the prettiest curves you ever saw .

Roy in georgia · Sep 1, 2008

I have seen pvc blow apart not sure how pex would work I would get steel pipe or just run a few short air hoses off a t to provide the # of lines you need. you can get 1/2 inch steel in 20 foot lengths and add a t with the correct size for your air hose to screw into and even get shorter pipe to add more lines not worth the savings if someone looses a eye from the blown pvc.

Sean McDonnell · Sep 1, 2008

The problem with PVC or CPVC is not so much the working pressure, it's the fact that it cracks if struck. I had a PVC water line blow under 40psi from a hairline crack and it sent shards of plastic clear across my garage. Lucky for me it was above the height of my head when it happened. My shop is plumbed with Polyethylene Tubing (sprinkler hose) It's softer than PVC so it won't shatter and it's easy to run. I used it for all of the overhead runs and have "3/4 copper for all of the drops. Just my 2cents.

M w J · Sep 1, 2008

Hydralic hose work good can be made to any length.

Ken Crisman · Sep 1, 2008

No way would I ever try PVC for air lines . That stuff has blown apart numerous times around here with the pressure the city has on the water lines . Did you ever get hit by a line blowing apart . Well let me tell you , I have & it hurts big time . The companies that build air compressors specifically state to use galvanized steel pipe through out a shop due to hi volume air pressure . I used 3/4" galvanized pipe for my main lines & wherever I made a drop I reduced it to 1/2" with a gate valve . I used to install air compressors for an auto parts store that sold them to guys . And I was told that if the customer had any plastic , black pipe , or copper lines , not to hook the compressor up due to law suits & liability accusations . So apparantly there is a reason these companies don't recommend anything but galvanized pipe for air . HTH ! God bless, Ken

Mark-Mi · Sep 1, 2008

I'm no pex expert.When I checked into it for that use it was 150 psi maximum.Not enough for me.
I used heavy schedule 80 I think it's called.Been in for 20 years with no problem.Mark

Anonymous-0 · Sep 1, 2008

i have all schedule 40 1 in. lines in for over 10 years under air 24 hr.a day never turn it off and never have had a blow out. the schedule 40 is 450 PSI and the thin wall is 200 PSI. also the air is a lot dryer with PVC over steel

Sean McDonnell · Sep 1, 2008

I'd agree that steel is the way to go in many cases but I see no problem with hard copper lines for air supply. Most compressors have copper line from the factory between the compressor and tank. Also the plant that I work in has a pair of 120hp screw style compressors that put out 200psi and every inch of the main air lines are 3" copper with the exception of the "clean room" drops that are 316 stainless. We get inspected by safety agencies several times a year and in 18 years never had a problem with our air system.

Mark-Mi · Sep 1, 2008

http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

Check it out.Mark

Anonymous-0 · Sep 1, 2008

I use pex-al-pex for my air lines. It is currently running about $0.75 per foot for 3/4 inch from the Blue Ridge company, among other vendors. It is way, way cheaper than copper or steel.

Pex-AL-Pex is a PEx and aluminum sandwich. It is stronger than regular PEX, but retains the ductility of polyethylene. The manufacturer even suggests its use for compressed air.

PVC is unsafe for compressed air. It is banned in the workplace by OSHA, and the PVC manufacturers strongly disclaim any use of PVC for compressed gasses. When PVC fails, it explodes with a brittle fracture mode, sending shrapnel around the shop. If you don't believe this, put on safety glasses and smack a chunk of pipe with a hammer.

RobMD · Sep 1, 2008

"A propane torch held 6 inches away will soften up that stuff to make some of the prettiest curves you ever saw"

Schitt, don't want to be enjoying those sights anywhere within 20 feet.

Doug in IL · Sep 1, 2008

I've worked for over 30 years in the shops of the largest heavy manufacturing company in the state of Illinois. Air lines were almost exclusively black pipe. From the largest mains to the smallest drops, black pipe. That's whats in my shop too.

HENRY E NC · Sep 1, 2008

For many years in the 70's and 80's I plumbed air lines from everything including black pipe, galvanized, sched 40 and sched 80 and copper. My personal choice is sched 80 pvc for safety and versatility. Most air lines were run across ceiling with drops so hitting them with something wasn't a problem.. My favorite job was 65 feet up in a factory . All schedule 80. Nuff said Henry

Ken Crisman · Sep 2, 2008

All I know is what is written in the instruction papers from the manufacturers of the compressors I worked with . I even talked with reps from one company about the pipe issue & they said galvanized only . Black pipe isn't coated on the inside & with the moistured caused by the compressor , the inside of the pipe will rust & flakes of the rust will move thgrough the pipe into whatever tool a person uses or else act like a projectile when blowing air through an air gun . Me , I go by what the experts tell me . I figure they build them , I use them & as mentioned installed them for the company years ago . When autobody shops need clean safe air they got it when I installed their compressor & lines . Have had no problems from them or my own shop . A guy can do what he wants on his own stuff but if he asks for help or advice , I share my expertiences & knowledge . As a matter of fact I still have paperwork here somewhere from a couple manufactures of compressors I worked on years ago . God bless, Ken.

jose bagge · Sep 2, 2008

used to do everything in galvanized, got tired of cutting threads. Never had an issue with PVC "blowing apart"- and never had it break unless my guys tore it loose from it's clamps.
Isolate it from compressor vibration with flexible hose (you'd do this with steel hard lines as well)

RodinNS · Sep 2, 2008

For a modest air system I'd be using Synflex as found on every single heavy truck built in the last 20 years. I think you can get it up to 3/4" ID which should be sufficient for most home/farm shop applications unless a person is getting into sand blasting...
Syn is easy to run, uses basic compression fittings and will stand up to a lot of temperature and environmental extremes on a truck, so I'd think it would have quite an easy life in a shop.
Did I mention it's cheap???
If I needed larger line I think it would be either copper or black iron...

Rod

Anonymous-0 · Sep 2, 2008

OSHA and MSHA do NOT ban PVC for air they just came to the shop last week and all was fine we get inspected about once a year or once or for sure one in a year and a half and for over 10 years they have never said a thing

msb · Sep 2, 2008

Don't knock oversized lines. They also serve as a reservoir if you need lots af air for a short period of time like some air tools do. Compressor oil will eventually serve top soften PVC. I would never use the stuff regardless of how many people have used it successfully.

T.C. in Tx · Sep 2, 2008

I went through the same "what to use" exercise two years ago for my shop. Of course all the naysayers advise strongly against PVC.

My final choice was PEX--the regular stuff because it was available at the local building supply superstore along with all the fittings I needed.

It has been in service for over two years now without a hitch. I would do it again. While I have not run a consistent pressure above 110 psi, I believe it is rated up to 180 psi depending on the temperature. Since I am in central Texas, sometimes it gets hot up there near the roof where I ran a line overhead to the opposite side of the shop. I put drops below the air outlets to be sure that condensation could be drained, but I have never experienced any problems with that.

I did find that the PEX that is used for heated floors, etc. is actually rated for air service. Good luck on your choice.

Ken(Ark) · Sep 2, 2008

You heat it when you are installing the line , theres no pressure . Making a 1" dogleg in the pvc is neat to make the line hug the wall or a 30 degree bend to fit the slope of the roof , etc .

I guess heating it with 125 psi would be exciting too , he he .

Ken Macfarlane · Sep 2, 2008

Please realize the pressures you can use with water in the pipe is completely different than with compressed air.

Compressed water stores almost no energy, compressed air is literally a bomb in the piping.

Glen D Anderson · Sep 2, 2008

There's no way to go wrong using black pipe(80)........it what's been used in every shop I've worked in(old shops though), but I've always been intrigued by the plastic options available(PEX, PVC, etc.)for ease of installation and eliminating corrosion/rusting in the pipes................I must say though, the story of the shrapnel from the the PVC and pressure ratings of only 180 psi. are somewhat discouraging!

Anonymous-0 · Sep 4, 2008

I have wondered about that too. Pex is a lot cheaper and seems very easy to work with.

I plumbed my airlines in 1" copper, before it got so awfully expensive. One of the things I liked about using copper is that it is a good radiator of heat and that way the air at the end of the line where I hook up to paint is a lot cooler than it was coming out of the compressor. Pex, being a plastic would not release the heat as well, I would think.

It will be interesting to see how Pex holds up over the years as water pipes. Lots of houses built over the last 10 years or so around here have the Pex plumbing. I did my house in copper, because it was proven technology that I was very familiar with. But if I was going to build one today, I would use Pex. I helped my son in law plumb their new house with Pex. It sure is easy and costs much less than copper. But only time will tell if Pex is a good very long term solution.

Good luck! I hope Pex works out great for you, if you decide to use it.

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