pvc? metal?

what's the best stuff to use to plumb compressed air around a shop?

i am also concerned about potential issues with OSHA, if there are any rules concerning this.

[Edited on March 16, 2010 at 12:44 PM. Reason : osha]

3/16/2010 12:43:47 PM

never seen a pvc air line before

3/16/2010 12:52:55 PM

aluminum.

http://www.parkertransair.com/jahia/Jahia/site/transair/filiale/usa/lang/en_US/site/transair/home?isFromMapMonde=true or http://www.garage-pak.com/


Same stuff, just big commercial vs personal and small commercial outlet.

3/16/2010 2:44:15 PM

yeah, dont know that ive ever seen pvc.. someone suggested using [natural] gas line.

3/16/2010 4:23:18 PM

^ yeap

ive worked at a place that had pvc line but id the thought of plastic and metal threads and just doesnt do anything for me

3/16/2010 4:51:51 PM

Do not use standard PVC. My first job out of college had PVC pneumatic lines and they catastrophically failed over the weekend. Its been close to 10 years ago now so I don't remember the specifics, but I believe it happened at a 4"-2" T junction near the compressor. No one was injured, so luckily OSHA didn't find out about it. Seems like I remember reading that OSHA frowns upon it, but I don't remember.

I did some looking into and found out that PVC is not designed to handle pneumatic loads (i.e. varying pressures). The pressure rating stamped on standard schedule 40 is for water at some specific temperature, altitude, etc.

We were in the process of setting up a new plant at the time. I ended up making them replace the PVC with galvanized in the existing plant and putting galvanized in the new plant.

/cool story

[Edited on March 16, 2010 at 7:11 PM. Reason : .]

3/16/2010 7:09:47 PM

i'm not an expert but i think you want to add drain valves at all low points(including quick-connects) in the system to drain excess water build up from water in the lines

3/16/2010 8:31:50 PM

^that's what these thingies are for (that, and well, regulating, as the name implies). besides, there's generally an air cooler/dryer after the compressor.

3/16/2010 8:43:53 PM

I'd go with black iron or galvanized. And you should have a downcomer with a drain petcock at several of your junctions, especially after a long run. A water separator only works so well, and only on condensate unless you have a dessicant bag in yours.

I, too, have worked in a shop with pvc airlines. Be damned if I'd use the shit. pvc does NOT handle heat well at all, and will separate VERY quickly if heated past a couple hundred degrees. Hell, standard pvc isn't even rated for hot water service (you use cpvc).

3/18/2010 9:13:11 AM

PETCOCK DOWNCOMER

3/18/2010 10:34:16 AM

DO NOT USE GALVANIZED FOR AIR LINES

The galvanized coating reacts with the oil and water in the lines and creates a corrosive stew that gets blown into tools, thus shortening their life. Black iron is the standard. The new aluminum piping systems are fairly cheap, like $200 for a one-car garage space, and easy to install. AlumiPex is also a good alternative although pricey.

When PVC shatters it splinters and sends shrapnel everywhere. Its burst strength is greater than most air systems will deliver but it is still alot less than the metallic piping.

I used 3/4 black iron for the main run in my shop and branched off in copper to the drops due to it is what I had on hand.

Also consider doing a closed loop system so that if one drop is eating alot of flow the downstream drops can still be fed by the other side of the loop.

3/18/2010 1:02:28 PM

i have been looking into black pipe or galvanized.

^ most people have the opposite view. black pipe is more likely to corrode than galvanized.

it is for our new shop. it will basically be run across the back wall (~50') with outlets on either end and a few along the run. also, at least one or two lines run out towards the center of the space for a hose on a reel.

after looking into it a bit, i was thinking about having a drop from every outlet with a drain at the bottom, as well as a separator at least at the compressor outlet.

i also saw somewhere (googled it) where they said to run the main line at a 1"/10' slope with a drain at the low end.

edit:
as far as pvc, i've pretty much decided to not do that. apparently OSHA has a bulletin out on compressed air piping suggesting you not use it. it splinters when it fails, which is not a good thing, obviously.

[Edited on March 19, 2010 at 12:42 PM. Reason : edit]

3/19/2010 12:41:19 PM

black iron will oxidize to a certain point, then generally stop, thats why its often used for gas piping. As ^^ said, its the galvanic coating that reacts with oil and water over time to create a mess. If that galvanized coating breaks loose and you have zinc particles mixed with water sitting in your aluminum bodied air tools, you are screwed. iron oxide+ water generally doesnt eat aluminum as quickly.

3/19/2010 12:57:48 PM

I saw a guy try to use PVC on a paintball gun to carry pressurized CO2.

The only bang ive heard that was louder was when i , ironically enough, blew up a plastic 2L coke bottle with dry ice+hot water.

3/19/2010 2:38:55 PM

my dad's old shop behind the house had pvc air lines. we never had a problem. it was probably a bad idea, but it was cheap and easy.

3/20/2010 5:25:46 PM

The shop i work in has copper lines but it isn't running more than 80 lbs or so

3/21/2010 11:46:15 AM