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Compressed Air Lines


DavidAU
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I am thinking of installing fixed compressed air lines around my garage/workshop and wondered what is normally used these days. Gal pipe?, copper pipe?, PVC ???

The only ones that I have ever noticed (and that was a fair while ago) were 3/4 inch galvanised pipe.

Maybe there is something better now or maybe just run it in flexible hose but that would collect water in all the low sag points.

lets know what you have used and what size pipe you used.

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In Aust there are several brands of poly air line - compression type fittings eg.

http://www.calair.net.au/products/compressed-air-pipe/

http://www.polair.com.au/

http://www.compressedairsystems.com.au/

http://www.ultramax.net.au/

Plastic pipe & fittings are expensive but quick to install. Espically if you do not access to a threading machine. With threaded galv expect to loose a lot of air due to leaks (dusy- oil stains after several months) In industrail plants can 25-40%

For home workshop 25 mm is OK. I expect you will only be using 1 air tool at a time.

Edited by 1939_buick (see edit history)
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Galvanized has the advantage of conducting heat and cooling the air thereby reducing moisture delivered to your tools. Plastic installs quickly but needs to be supported at regular intervals. The heat produced by compressing air tends to cause the plastic to sag dramatically unless adequately supported.

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Anytime that I hear of plastic pipe used for an air line I think of what would happen if the pipe were to be exposed to a fire, and the resulting spread of the flames when it melts.

<O:p<O:p19880520 The Use of Polyvinyl Chloride Pipe in Above Ground Installations

OSHA Safety Hazard Information Bulletin on

the Use of Polyvinyl Chloride (PVC) Pipe

in Above ground Installations<O:p></O:p>

Of course you are not bound by OSHA in your home, so go right ahead and kill your family if you wish.

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DO NOT use PVC, it's not rated for pressures like you get in a compressed air system.

There are plastic lines specifically designed for use with compressed air that use their own fittings, but they're pricey. There are also some that use aluminum lines--I think Griot's was selling them, but I haven't seen them on the market in a while. Personally, when I did my garage I used galvanized, but using a filter and water traps are important, and even more so with black iron, which will rust. I've heard of quite a few guys using copper, which is probably ideal, but pricey and you need to be good at sweating your joints.

I think next time I do my garage, I'm going to use stainless tubing and SwageLok fittings, which I can get inexpensively from a friend who works there (forget buying them, they're like gold and cost as much). If I didn't have that option, I think I'd try copper just because it's easy to work with and doesn't rust.

Hope this helps.

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I used the Garage system Eastwood offers with all the fittings and junction blocks. I bought 2 garage kits and ran it around about half of my 1600 square foot Shop. It's Block so I had alot of hammerdrilling to anchor everything but it went pretty quick with tapcon fasteners and tubing clamps I got from the electrical section at the hardware store. I like the system. I have it going into black iron pipe before my Blast cabinet. It took about a day to put it all in without a helper. If I didn't need the extra connectors I could have gotten away with one kit I think. Definately alot better than hoses running everywhere just waiting to be tripped over or pull something over on one of my cars. I don't know about the fire danger but with evrything we have that's flammable in our garages I'm not concerned about the combustable nature of my tubing.

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According to ASTM D2466 - 06 Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40, the minimum burst pressure is 1540 lbs for 3/4 inch PVC, Schedule 40. Maximum operating pressure is 283 PSI. Most small shop compressors shut off at 125 PSI or thereabouts. I think there is more to these stories of catastrophic failure than we're being told. I'm not for or against PVC for compressed air, just a bit skeptical of some of these, possibly, anecdotal stories.

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I ran all of mine in Schedule 40 PVC, because it was easy and fairly inexpensive to run. I also have read that you should run them in black pipe, but at the time didn't have time or money. I have also worked in a shop that used all black pipe and water was still an issue, so I'm not sure it's really a big deal either way. If you put traps in every so often and drain your tank & lines I'm sure it will be fine with whatever you chose. They also sell automatic drain kits for the tanks. Pressure is no problem with the PVC either. I shut my air off at the tank every time I am done, so I don't see much of an issue with fire. There will always be little leaks in your system, so you should shut the valve of at the tank when done anyways. Just my two cents.

Jason

Advanced Electrical Rebuilders - Antique Auto - Marine - Agricultural - Industrial

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I too used schedule 40 3/4" I. D. plastic 15 years ago. It's not expensive, easy to install and seems to be holding up very well. As mentioned it is pressure rated for well over the normal compressor pressure levels. You can buy pipe and all the needed fitting at your local hardware store or Lowes, etc. I'm running a 2 stage compressor with 150-160 # maximum.

Martin Lum

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This topic came a year or two ago and I was electronically bludgeoned for even mentioning PVC as an option. As 58mustang correctly stated PVC is rated plenty high enough for shop air. One drawback is its not as forgiving if improperly installed. For example if a joint is not properly glued it could blow apart where if a threaded black pipe fitting is not screwed together good enough all it will do is leak. PVC also doesn't offer good resistance to physical damage so if the pipe is where it could get hit with something heavy, its probably not a good idea. I know of several scheduled 40 PVC air line installations that have been in place for many years both in industrial and residential environments. So it has its place for use but the environment its in must be considered.

I personally ran 1/2" copper with sweat joints in my shop. If you look at the flow rates of 1/2 copper it far exceeds what any typicaly shop compressor can make. Sweating joints was easier and cheaper for me vs threading galvanized or black pipe.......which are also good choices but a little overkill for a home shop.

There are diagrams on the net on the proper way to run a shop air line to minimize condensation water getting to the point of use.

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I used 3/4" black iron and am happy with it, more or less. I have a filter/regulator unit at each outlet and after 5 years have had no problems, but if I were doing it again I would probably use galvanized to try to avoid rust. I guess some guys used black iron but coated the inside with POR 15, which sounds good. I would not use PVC or other plastic, although others seem to have been OK with it.

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Well, I didn't want to mention it, for fear of being pilloried by the net nannies, but I have had Schedule 40 PVC in my home shop for 25 years without a single death or dismemberment. I'll continue to knock on wood and trust my installation and the manufacturers specs.

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Whatever material you install, take the point of use connections from the TOP of the piping. This prevents most of condensate going to point of use. Find a low point in the piping and install a drain valve.

Stainless is forever, and no rust issues, and expensive. Sure is nice, though......

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I used 3/4" copper rigid tubing when I did mine. Slope all lines to drain legs. Angle fittings up where they come off the main line, so the water flows by to the drain legs.

The copper thieves would have to get into the shop first to steal the copper. Lots of better stuff to steal in my shop then the copper though.

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My "barn" has been up more than 20 years now and we put sched 40 PVC in when it was built. It's been no prob. I've got adequate water drops and drains. For me a big advantage was being able to add a couple of sections later with ease. I know several others using it and they have no issues. We've got some humidity here in SE Virginia and Iron seems to have a lot more condensation problems.

Terry

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I did quite a bit of research a couple of years ago on this and I used the Rapid Air system for my garage. I've put drops for my work table, near my parts washer and across the garage to handle the blast cabinet. Was installed effortlessly and looks good. I use the flexible tubing version which works fine for my use. For more industrial use you can go to the aluminum piping they sell. It's basically the same as Eastwood sells for flexible tubing air system but much cheaper. I suspect Eastwood gets it from them. I'm 100% satisfied with my system. Their web site is Compressed Air Piping, Compressed Air Systems, Do It Yourself Air Tool System

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I think there are two basics here:

mechanical strength - pretty simple, just look at the pressure ratings.

corrosion resistance - you can expect moisture in the line. Plastic or alloy pipe will be superior. Copper, iron and steel all react with water.

I would think cast iron would be the worst for pressure loss at equivalent ID due to roughness.

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I did quite a bit of research a couple of years ago on this and I used the Rapid Air system for my garage. I've put drops for my work table, near my parts washer and across the garage to handle the blast cabinet. Was installed effortlessly and looks good. I use the flexible tubing version which works fine for my use. For more industrial use you can go to the aluminum piping they sell. It's basically the same as Eastwood sells for flexible tubing air system but much cheaper. I suspect Eastwood gets it from them. I'm 100% satisfied with my system. Their web site is Compressed Air Piping, Compressed Air Systems, Do It Yourself Air Tool System

I'm installing a new system in my garage this summer. Has anyone else had experience with Rapidair's system?

I had galvanized pipe in my old system, and had some issues with rusting inside the pipes. (The garage is pretty humid most of the time.)

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Our company has been installing air lines for years. The worst material is galvanized pipe because the galvanizing will flake off. The preferred material is black steel pipe with black malleable fittings. We use this in all sizes but it is important to pitch it and install drip drains at low spots. In some body shops we install air dryers to take the moisture out of the air. I have seen some small shops install copper and it seems to work fine for them. It is important that all the piping is secure. I have a 3/4 inch main with 1/2 inch drops in my shop. You should have a drip leg with pet-cock at each drop and your connection comes off the T. I have a oil and water trap and pressure regulator at each outlet. Works good.

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"The copper thieves would have to get into the shop first to steal the copper. Lots of better stuff to steal in my shop then the copper though."

Yes, but some of these bozoes are not the brightest bulbs on the Christmas tree...

Around here, they've been caught stealing everything from copper pipe to bronze cemetery markers to copper wire from LIVE services ( with crispy & fatal results ).

Might not be a "real" problem everywhere, but most foreclosed & vacant houses in my little corner of PA have been looted of their wiring and plumbing.

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One more thing, from a safety standpoint. If you put in a filter bowl, or regulator with a moisture trap, be careful putting in polycarbonate bowls. I worked for a company that used these all over a plant, until a maintenace person was draining and it exploded, he lost an eye. The Poly carbonate can develop cracks, and as soon as he started turning the drain, the bowl came apart violently.

Even in a garage, safety glasses are a good thing.....be careful out there!!

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  • 2 months later...

At one time or another I’ve had shops set up with PVC, Iron and copper.

PVC, as many others have noted, can be very dangerous; the pipe is not designed to be used with air and has integrity issues with changes in temperature and any exposure to sunlight.

Iron was safe and secure but had several issues: it was a pain to install because we had to thread almost every joint and after about six months started to become a maintenance nightmare as the rust in the lines started causing issues with my machines. Even just using the blow guns was messy with all of the rusty spray going everywhere.

Copper is what I had in my last shop and overall was a good system; secure, safe and while not maintenance free (there were some electrolysis issues) it was a solid system. The only negative things about it were: it was very expensive! That copper’s not cheap and while easier than iron to install it still took a long time to sweat all the joints.

I built a new, and hopefully last, shop a couple years ago and used a new aluminum pipe system that i wish had been available back when i did my first shop. It has all the "pros" and none of the "cons" of every other system I’ve used. It is safe and secure, extremely easy to install (it took a helper and myself less than a day to install air completely throughout my 8000sqft shop), to date I’ve not had any maintenance or contamination issues, and best of all it was inexpensive - especially compared to copper!

If you want to see any pictures of my latest (last, if I have anything to say about it) shop let me know and I’ll shoot you a couple. Here is the place where I purchased my system Air Delivery Systems - They were easy to work with and helped me out with the design layout a lot.

So to boil it all down I’d say no to PVC and Iron and yes to either Copper or Aluminum.

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I have pictures of my compressor line setup under Our Cars and Restoration projects forum, 1929 Roosevelt Restoration. No leaks, simple, cost effective. I heard that if PVC fails it can send shards flying.

That's why I used copper but would now use the flexible tubing.

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