Pipe for air compressor??

Splinter · 11-09-2008, 11:34 AM

Is 1/2" or 3/4" PVC pipe okay to use for piping air from an air compressor around a shop?

Anyone know of any good articles on piping air around the shop to multiple locations?

jmauldin · 11-09-2008, 12:21 PM

Yes, but use 3/4 instead of 1/2 and be sure it is rated for high pressure. That is what I use in my shop and have had no problems. Of course, the BEST would be 3/4 copper, but who can afford it? Also, be sure to put cut-off valves at each outlet, that way if something goes wrong you won't have to shut down and drain the whole system.
Jim in Mayberry

JimmyC · 11-09-2008, 12:21 PM

Dolan,
Go to www.woodweb.com and punch in air piping. There are a bunch of discussions on it. The main problem with pvc is that when it lets loose, supposedly it's shatters and if you're around that could be very dangerous. Copper and black or galvanized pipe just develop holes.

Good luck

woodylarry · 11-09-2008, 12:23 PM

Here's a link with specs for diff PVC

http://www.engineeringtoolbox.com/pv...res-d_796.html

JimmyC · 11-09-2008, 12:47 PM

Just one other note, OSHA doesn't allow PVC for compressed air and insurance companies won't insure for it (that is why you won't see it in pro shops).

Glennbear · 11-09-2008, 01:01 PM

Having seen first hand shrapnel from a 3/4" PVC airline puncture 1/2" sheetrock I totally agree with the OSHA ban. An air line system properly laid out using galvanized threaded pipe is best IMHO. From the North Carolina Woodworker download library here is a helpful link : http://www.ncwoodworker.net/forums/d...do=file&id=158

FredP · 11-09-2008, 02:29 PM

I use air hose. I cut up a 100' hose and put conectors on the ends with tee's and such. Its flexible, easy to do and its rated for the presure. Just put a tee in wherever you want a drop. I use the springy hoses for drops but you can use hose reals or
whatever trips your fancy. Its also much cheaper and safer!

electrical conduit clips can be used to hold it up on the ceiling if your shop has a finish ceiling.

merrill77 · 11-09-2008, 02:49 PM

I second the warnings - most PVC is NOT designed for pressurized systems and the results can be dangerous. I like the flexible air hose idea. Before that suggestion, I would have suggested threaded galvanized pipe.

Gotcha6 · 11-09-2008, 03:24 PM

Galvanized pipe & fittings are more expensive than black steel and not really necessary. Automobile shops use black steel in most cases.
I used 1/2" PEX because it isn't as brittle as PVC & is good for 140psi below 90 degrees. The problem with PEX is that the fittings & crimpers are so costly, though.

JimmyC · 11-09-2008, 03:43 PM

I'm not saying Pex isn't any good, but it also is not allowed under OSHA standards and it can't be insured therefore you won't find that in pro shops either. I think OSHA only allows K and L copper, black and galvanized pipes or systems that are specifically designed to convey compressed air.

Gotcha6 · 11-09-2008, 04:55 PM

That's okay, Jimmy. I'm sure an OSHA Inspector would have a coronary if they went into most garages & shops (let's don't get started on drop cords, eye, & ear protection). They're not like the lady that gave me the permit to wire my shop. When asked if I needed to take any kind of formal or basic test, she replied. "Honey, if you wanna burn down your own house, that's YOUR problem!"

Travis Porter · 11-09-2008, 07:56 PM

Bite the bullet and put in copper. It only hurts once. I too would not use pvc, pex, or plastic. You may never have an issue, but then again, the opportunity/risk is there. You have to ask yourself is it a risk you are wiling to take.

Plus, I think the price of copper is way down now. Even if you don't want to solder, you could always do compression fittings.

Jim M. · 11-09-2008, 08:12 PM

Originally Posted by FredP

I use air hose. I cut up a 100' hose and put conectors on the ends with tee's and such. Its flexible, easy to do and its rated for the presure. Just put a tee in wherever you want a drop. I use the springy hoses for drops but you can use hose reals or
whatever trips your fancy. Its also much cheaper and safer! electrical conduit clips can be used to hold it up on the ceiling if your shop has a finish ceiling.

I second Fred...

I did the same in my shop, and it's worked fine. Just my two cents. Jim

junquecol · 11-09-2008, 09:34 PM

A vote for the copper. Use the lightest weight, as it will stand up to about 500 psi. go to the copper pipe web site. As for soldering, go by a plumbing supply house and pick up a small jar of "Laco" flux. It's self cleaning. Make up drops so the air comes off the top of the supply line. Slope line AWAY from the compressor, with a drain at far end. This way, each time you use air, moisture will be forced towards drain. Sections can be joined using "Alligator" (Lowes), or "Shark" (HD) push on connectors. Kinda pricey at about six bucks each though. Bruce 20+ years a P-1 plumber.

scsmith42 · 11-09-2008, 09:52 PM

Well, I may be the only person responding that has used all six options listed at various times and in various shops (PVC, Pex, copper, air hose, black pipe, and galvanized pipe).

The commercial plants that I've been in used black pipe, and that's what will be in my next shop (along with a PEX feed from the compressor). I've run PVC in one building for several years w/o any problems, but the concerns re shattering and shrapnel are valid.

No matter what you use, I would suggest the following:

1 - Use a minimum of 3/4" for your main lines (I prefer 1" or 1-1/4"). There are significant friction losses through pipe and bigger is better.
2 - Plan for water accumulation in the pipe. When you come out of the compressor and go up to the ceiling, slope the pipe downward from there so that water will flow downhill to a drain valve. Any taps that come off of the main line should be pointed up and then go through a 90 degree elbow to drop down the wall to your connector. That helps keep the water inside the main line that is sloped down to the drain valve.
3 - Use a good quality water separator in-between the compressor and the main line. HOWEVER, you will probably still get water in the line when/if you're using a lot of air.
4 - Mount the compressor on blocks several inches above the floor to allow easy access to the water drain on the bottom. Drain the water on a regular basis.
5 - I do not recommend in-line lubricators that are installed by the compressor. They will put a film of oil into all of your distribution lines, and when/if you want to do some painting (or air sanding) you'll have a problem with oil contamination. If you need an oiler, it's better to use one that you can plug into the air coupler that's closest to the air tool that requires the oil.
6 - Copper is a nice way to go. If you really want to show it off, consider polishing it when you're done and applying a clear coat on it. It will definitely look sharp!
7 - Shut the power off to the compressor when you're not in the shop. About twenty five years ago I had an air hose blow during a holiday weekend, and the compressor ran continuously for three days. Not a good thing...
8 - If you have the option of placing the compressor in its own enclosure, (such as in a shed attached to the outside of your shop) I would recommend it for noise control.

Good luck with your project.

Scott

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