Compressed-Air Piping for a Woodshop

      Copper is considered the safe choice, but here is a discussion of some alternatives, and tips on a workable setup. April 21, 2007

I'm looking for advice on running copper air lines in our shop.

Forum Responses
(Cabinetmaking Forum)
From contributor S:
Before getting into copper lines and regretting it later when you need to change something, consider Toprings PVC airlines with quick connect fittings. My entire shop is plumbed with it and it's great! I can change or add lines in minutes.

From contributor P:
Copper is pretty easy to work with. It bends a whole lot easier than PVC. I was told that some sort of safety group frowns upon PVC as air line; something about it becoming brittle and shattering. My insurance agent said this. It was one of the questions she asked when writing my new policy. Other things she said I couldn't do were use PVC for dust collection, use a wood heater that was attached to the building (one set a distance away was okay), and do any spraying of a flammable finish without an approved spray booth. I do know of many shops with PVC air lines and haven't heard of any problems. I'm fixin' to plumb mine but will be using black pipe, because I have access to a large pile of the stuff for free.

Check with whoever sells auto paint supplies in your area. There are several little tricks, such as having a sloped line away from the compressor and to a drop with a drain, drops at the end of runs with drains, where to put dryers and on and on.

From contributor M:
We have used 1" PVC for years and no problems. As to the shattering, they refer to the compressors vibrating and cracking the PVC. A simple solution is a couple feet of flex hose to absorb the vibration. Also, use plumbing fittings for special cases; they're cheaper than air fittings and the selection is larger.

From contributor T:
About ten years ago we bought some plastic pipe that was similar to PVC but which had a stated purpose for things like compressed air. We kept intending to get it installed but got really busy. In order to keep the shop running, we strung temporary lines with regular rubber air lines. They are still there today, and we seem to have all the air we need. Some of our lines are copper, but they don't work any better than the rubber lines do. We do have one rubber line that runs to an air dryer which feeds our Butfering sander.

From contributor R:
What is the cost of the Topring system? Particularly pipe per foot and couplings? It does seem like a nice system, but also looks expensive, and they do not list any distributors on their website (says under construction).

From contributor L:
I've heard the same thing about PVC for compressed air being problematic. I don't know, but it was easy enough to run copper. Copper tube comes in three types: K, L, and M. Types L and M are readily available at the great orange father and similar outlets. The difference is that L is thicker walled than M and therefore stronger. If it costs, say, 50% more, and the shop costs $250 to pipe in type M, an extra $125 for peace of mind is quite inexpensive to my way of thinking. Type K is thicker still and I believe is for direct burial underground. This seems like overkill, but would depend on the kind of pressure you run. I have a 60 gallon/5hp Ingersol run at 100 PSI in the tubing and I've not had a problem in 8 years.

I have a rubber whip hose connecting the compressor to the copper. The shop is all 3/4" type L tubing. I put air connections at convenient intervals so I had air anywhere I want it without dragging hoses all over. Coiled air hose connects the tools to the copper air line when I need it and is easily quick disconnected when I'm done.

If I had any advice, it would be to pitch the run downhill away from the compressor and put a drain on the end of the run. I just use a ball valve and a length of tube run to the floor. I also removed the compressor's draincock, put an ell and extension of brass pipe in its stead, and now have a ball valve to drain the compressor as well. I'm able to open and close it while standing up; I use a 3' stick of wood with a loop of wire on it to grab the valve handle. No more crawling on my knees to get to the draincock.

From contributor C:
I read a good article at one of the custom car painting sites about shop air. There is some technical stuff that will help if you happen to stumble across it. The biggest concern was about running pipe for HVLP spray setups (basically it was saying larger pipe and good filters/separators).

I have twice seen PVC pipe hit with boards and rupture. It wasn't as dramatic as you would think. I would be more worried about breaking a fitting (it just seems that they are more brittle and could shatter more).

Overhead reels are nice if you have money to burn. Hose management can become a big factor it you are running more than two tools in the same area. I have also seen the yellow coiled hoses put to good use, but I think that there are different quality hoses in this department.

Having a couple of pressure regulators set up with quick connects in and out so you could move to different outlets as needed is nice too, although one at every outlet would be nicer. We tend to run everything wide open at about 100 psi, but as you know, sometimes it needs to be cut back.

From contributor I:
I was just reading an ad in a trade books from a company selling transparent blue plastic tubing for compressed air. They have simple fittings and the stuff can be installed fast.

We did our shop in copper last year but didn't put a dryer in there and we get a lot of moisture in the lines that I need to take care of. We did slope it and put ball valve drains at the end of the runs. My insurance company also did not like PVC.

From contributor W:
I have the Topring system in my shop, and I feel it is a wonderful system. I suspect that when some are speaking of PVC bursting, they may be referring to water pipes, and not a system like Topring that is designed for high pressure like air. The reason I went with it was that it does not rust like iron, and with expensive CNC machines, as well as other tools on the system, I didn't want the rust flakes getting to the machine filter system. Also, the ID decreases in size as it rusts. I removed iron pipes to do the upgrade, and there was 1/8'' of rust in the 5 year old pipes. We have an expensive air dryer and filter system at the compressor, so do not jump to conclusions that the air is wet.

In terms of cost, the Topring appears more expensive at first. If you can cut and thread your own iron, as well as hang it on the ceiling, the iron will be far cheaper. If this is contracted out, then Topring is less, as anyone can cut and join the system. Copper is also fairly easy to cut and join, and many fittings are easy to get to attach FRL systems (filter-regulator-lubricators).

A company like Topring makes everything required for a state-of -the art system; it has been tested, safety checked and passed, it is easy to install, in stock, and designed with shop use in mind. In today's world, an air system is a vital and necessary tool in our workplace. Spend the money to make it right.

From contributor R:
How much is Topring? You sound like a salesman that tries to build value into the sales pitch :) before giving you a price. What is the cost per square foot, and compared to copper? I bought 3/4" M copper pipes in 10' lengths from Home Depot for approximately $15-20 a pipe (can't remember exactly, have to look at the receipt).

From contributor J:
I think the blue pipe contributor I is referring to is the Transair system. We are planning on changing our black pipe system to this later in the year. The Ring system looks similar with aluminum pipe and plastic fittings. We installed a Kasser compressor 3 years ago and wished we replaced the pipe at that time. I discovered a lot of rust and oil buildup still in our black pipe system from when we had dirty air. We have expensive machines that use a lot of air. Itís just not worth it to take a chance. The other advantage with these purpose made systems is easy to change or add to, no leaks (I hope) and speedy installation. I look at it like our change to Nordfab dust piping. Costs a little more now but will save a lot in the long term. I would make sure the compressor is dry and clean before changing to a system like this.

Compressed air and dust collection are often overlooked in the lean concept of manufacturing.

From contributor W:
First, let me say I am a woodworker, and in no way connected to Topring. I do, however, know something about air systems from working with them for 30 years. The cost we paid for a 12' length of 3/4'' pipe was $28, and I realize that copper or hoses are cheaper. They also have 1/2'' and 1'' pipe, and 1/2'' would be similar to 1/2'' copper in its ID and air flow. When considering cost, also factor in where the system is installed - if from the ceiling, are hangers required? When we arrive at a machine or work station, we need fittings, so are special pieces needed to adapt to the FRL or coupler? Back at the compressor, how do we link the tank to our air pipe network? When a comparison chart is complete, as I did, the total costs may be a surprise.

A big consideration for larger shops may be the interface with machines. I have found that air-hungry machines need 3/4'' pipes, right to the inlet. Consider the costs of copper/iron/PVC to do this. As with any system, the expense is also in the elbows, T's unions, etc.

I have also worked in smaller places where we plugged a hose into the tank and got by. I cannot deny that there are less expensive ways, but also say that investing in a good air network will improve the way the shop works, including machines, hand tools and especially the spray room.

From contributor O:
All the air lines in our shop are 3/4 and 1/2 copper. I have heard too many horror stories about PVC plastic air lines.

From contributor X:
A friend of mine was building his house with attached garage and shop. This was a place that was dug into the side of a hill. To save on space he buried his air tank in the shop's floor with only the compressor and motor sitting out. He had two pipes coming out of the cement which he used to siphon the condensation the tank developed during its use. Worked pretty good. I thought it was unusual. To each his own.

From contributor K:
I've been in many shops where guys ruined the air system by not following simple basics. PVC and Pex should not be used for air... OSHA, insurance issues. Kaeser and a few others have a quick connect aluminum for air. Fast to set up but pricey to buy, so it's neck and neck with black pipe. Copper K and L would be okay. M is too thin for air. The newest and not to be confused with PVC is a polyurethane air line by Chemaire and others. I'd say the Transaire is a similar product.

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