Copper Shop-air lines

johnnydmetal · Sep 18, 2006

I just finished plumbing my shop air with 1/2 inch copper. I Have to thank the forum for the idea. I remember a post from last year talking about the different optional choices for running the shop air such as PVC, copper, and Iron.
Since I have small children and I value my saftey as well, PVC's potential for explosive shrapnal eliminated it as a choice for me. Iron is great if you have the right threading dies so you can cut the custom lengths. I only have a 1 inch die and the amount of pipe I needed made the cost comparable to the copper. Copper came out on top for me for a couple of reasons: Saftey, ease of assembly, and the release of heat which helps keep the moisture in the downspouts and not in my tools. I also installed tool pressure regulator guages so as to allow me the ability to dial in the proper presur for the tools.
Thanks Guys
John

John_tx · Sep 18, 2006

The piece of mind is worth the extra cost. I did mine years ago in 1" copper, no rust, no failures.

SouthBendModel34 · Sep 18, 2006

JohnnyD,

Which schedule of copper pipe did you choose?

What kind of solder?

Sounds like a really "DeLuxe" installation, one you can be proud of forever. The satisfaction of having done it RIGHT will outlast the memory of how much it cost.

John Ruth

Cyclotronguy · Sep 18, 2006

Hi all,

Some years ago I did some failure testing on 3/4 inch Sch 40 CPVC (the grey electrical grade stuff) just for fun.

Crushed a sample in a bench vise with serrated jaws and bent it 90 degrees each direction about 10-15x, at the crush point. Then took it over to the anvil and smacked the stressed area smartly with a 2 lb engineers hammer, until I got bored with the task.

Glued up caps and adapters with primer and glue, then placed the damaged piece in my hydraulic test stand. Pumped it up to 1100 psi with some fear, let it set for 24 hours and called the test "good enough!

Oh yeah, almost forgot, the CPVC didn't fail.

Cyclotronguy

Carl Darnell · Sep 18, 2006

I have been using the same schd 40 3/4" white PVC for air in two different shops for a total of 13 years now with no signs of stress. I use 120psi in the lines. It will not explode at those pressures and even if a joint failed it would just blow apart and lose the air.

Michael Moore · Sep 18, 2006

I used the 3/4" M copper when I did my garage this summer. I suspect that the 1/2" would have been fine (as well as less expensive) but I was trying to plan ahead for some unknown device that would benefit from the 3/4" trunk lines.

I used the paste flux and solder from the Home Despot where I got the rest of the stuff.

It was interesting how many times I went back to get "just two more fittings". I pretty much worked from the diagram at TP Tools:

http://www.tptools.com/statictext/airline-piping-diagram.pdf

Each line has a shut off where it begins, so I don't have to pressurize a section that isn't being used.

cheers,
Michael

appliedproto · Sep 18, 2006

So when did this "fear" of PVC as a conduit for compressed air spring about? I know that folks have mentioned that oil in the lines will degrade the welded fittings...but their filters should be taking care of that anyhow. Does anyone have a personal "horror story" about using PVC?

macona · Sep 18, 2006

Maybe by the manufacturers of that green for-air pvc pipe. My best guess they are afraid of people using something like SCH 20. But even that I dont think the mass of a chip with 120psi behind it could travel very far. Maybe an eye hazard.

kenh · Sep 18, 2006

Perhaps one cause of PVC blowing is not isolated from compressor with a flex connection, and viberation does it in.

Michael Moore · Sep 18, 2006

I used the Oatey "H20-95" water soluble tinning flux and Oatey "Safe Flo silver lead free solder" in the 1/2 pound .117" diameter size.

It seems to me that if you get a good joint (I think the intersection is about 3/4" long) most any solder would do fine, as the surface area is probably a bigger factor than the actual strength.

This solder is safe for use in drinking water lines, and I figured I may as well use that so if I ever need to do a repair on the house water system I've got something appropriate on hand.

cheers,
Michael

Pete22 · Sep 18, 2006

I was working on a new plant installation and saw a piece of 2" sch 40 PVC blow up and send a 2"x2" missile across the shop.

Didn't even make it to startup. All the PVC was removed before we could commission the shop; I don't remember what replaced it.

Compressor oil is always a contributing factor.

They came out with the "green stuff" with 5 pages of instructions listing oil you could use or couldn't use. Neved did see it used much.

Pete

ken moss · Sep 18, 2006

IN the shop I use to work at we had pvc sch40 air lines and I was repaing it all the time 120 psi on the system. It was all ways blowing up or had a hole in it. Ken

fen2art · Sep 18, 2006

Was in the shop shortly after the shop foreman had added onto the air system.(PVC) After what was considered by the owner and foreman to be enough time for the glue to set up, the system was recharged. About 15 min IIRC after the system was re-pressurized, the freshly added section let loose!!! After every one in the shop did personal inventory we got the compressor shut down & checked on our co-workers. After changing our shorts we started gathering the pieces of the PVC valve that had blown directly down into the concrete floor. Pieces had deflected in all directions to the extant of the shop. Fortunately no one was hit by any of the considerable projectiles. One guy was about six feet away from the "explosion". Some time after we started picking up the pieces, the owner came out of his office. Always wondered if he was under his desk with carry piece drawn waiting for some one to come through the door. Since then I've favored copper. IIRC the line pressure in that shop was around 120 PSI.

fizzissist · Sep 18, 2006

My dad did our shop in 3/4" copper back in the '60's ( w/regular ole slobber)....we ran 100psi all the time, always having water problems in the summertime, and never once did we have any issues at all.

JRouche · Sep 18, 2006

I have been using the same schd 40 3/4" white PVC for air in two different shops for a total of 13 years now with no signs of stress.

And that is the problem. No warning of brittle PVC until it blows.

I have 3/4" copper line. JRouche

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

lazlo · Sep 18, 2006

I used 1/2" M copper when I did my multi-drop garage air line this Summer. I used the same schematic that Michael posted above.

One big advantage of copper is that it cools down the air a lot faster than PVC if you're worried about condensation in the air lines for painting. Sata recommends a minimum of 50 feet of copper pipe before the first airline that will be used for a spray gun, 75 feet if using black pipe.

I didn't have that much space in my garage, so I built a copper zig-zag coil system with a total length of 35' coming right out of the air compressor, and the thermal differential from the beginning to the end of the run is amazing!

Evan · Sep 18, 2006

Type M copper water pipe isn't approved for compressed gases. It must be type L or K. Type M is prohibited by code. Also, copper pipe shop air systems must be brazed, not soft soldered.

PVC also isn't allowed by OSHA and most codes.

Marshall Henderson · Sep 18, 2006

I worked for an Ingersoll Rand dealer as tech for air compressors. Basicaly if a plant had any type of PVC used for airline, we didn't step inside. The oil from a compressor will work from the inside out, no warning till it lets loose. There was one plant in SE Iowa that we went into after a PVC pipeline failure, looked like a war zone, PVC fragements stuck in wood bench tops, door frames, etc. The plant was very lucky that the pipe blew on a weekend. Usually a failure will start at one point and then progress down the line like a lit fuse.
A normal air filter will not remove enough oil to make PVC safe, it just slows down the time bomb! A cololesncing (sp) filter will remove 99.99 percent of the oil.
Even if nothing happens for years, it is not worth the risk to use PVC.
Marshall

northof54 · Sep 18, 2006

Any info about PEX as airline?

thanx, mike

matt_isserstedt · Sep 18, 2006

One possibility (my tack) is to use Stay-Brite #8 solder on the airlines. It costs a pretty penny but has basically double the tensile strength of the "no lead" plumbing solders you find in the big box stores. It also doesn't creep under load.

Use the Stay-Clean flux that comes with it and it wicks like the old leaded solders (although absolutely no lead) and is very easy to use with a regular propane bottle-torch.

I purchased this at a refrigeration (HVAC) supply store.

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