Copper tubing & air lines

[Bruce Page]

I need to replace the white PVC air lines in my shop and would like to use copper tubing this time around. When I went to the Borg, I noticed that they had two types of tubing; L & M with the L looking like it had a little thicker wall. The lines will see 150 psi at times although I normally keep them at 125 psi. My question is this; is the “L” type ok to use or is there another type better suited. Also, are the standard Borg copper fittings ok to use? They only had the one (thin) type available.

Thanks

[Dave Richards]

Bruce, I can't answer on the L or M however I would think the thicker wall would be better. I would suggest however that you see if you can rent a tank of nitrogen to purge the air from the lines prior to soldering. The nitrogen will prevent scale from forming on the inside of the copper during soldering. The scale's not a problem unless it comes loose and ends up in an outlet, a tool or perhaps in your sprayed on lacquer.

All you need to do is run a very small amount of nitrogen through the lines making sure you have a bleed so it doesn't build pressure.

After you've finished sweating all the joints, pressurize the lines and spray the joints with soapy water to check for leaks.

good luck.

Dave

[Bruce Page]

Thanks Dave, I did not know about the nitrogen purge – interesting. I’m with you about the thicker wall being better. I guess what I need to know is if the “L” type is thick enough.

Thanks,

Bruce

[Jim Becker]

Type L coper is the right material for this job...and I'm really glad to hear that you're taking out the plastic air lines. They are DANGEROUS. The plastic pipe is only rated for liquids, not gasses. Both OSHA or the Army Corps of Engineers forbid them. Don't use solder with lead for compressed gas, however. Use the "good stuff".

[Ken Garlock]

Bruce, when I plumbed the air in my shop I used 1/2" type L hard drawn copper. The best available to the common man is type K, but it is difficult to find, and for our purposes type L will work just fine. If you want to get real technical, go to copper.org, and download the copper handbook, a mere 6.3 MB. In the handbook, 1/2" hard drawn(rigid) copper has a max working pressure in excess of 1200 psi, while annealed(coiled) pipe is in the 500 to 700 psi range. I prefer the hard drawn since it comes in 10 ft. pieces and uses sweat fittings.

Stay away from Type M.

[Ken Garlock]

Type L coper is the right material for this job...and I'm really glad to hear that you're taking out the plastic air lines. They are DANGEROUS. The plastic pipe is only rated for liquids, not gasses. Both OSHA or the Army Corps of Engineers forbid them. Don't use solder with lead for compressed gas, however. Use the "good stuff".

Jim, solder with lead IS the good stuff! Lead/tin makes the best joints.

[Mike Cutler]

Bruce. The copper tubings and fittings at the "Borg" will be fine for youe application. Type L copper tubing is manufactured to ASTM B88 standards, type L is the mid range. K is the higher rating and M is a lower rating. The working pressure range of any of these exceeds your requirements. be sure to install low point traps and bleeder valves in your copper tubing runs. Have all of your equipment connection points orientated upward. I'm not sure what the "good stuff" Jim is referring to is? I've used tin/lead many times, in addition to silver solder. Both work fine. I am going to take a moment here to try and correct a misconception I've read at times concerning"plastic" or "PVC" tubing. There are manufacturers of tubing that is plastic and made of PVC that are rated for gas applications "Poly-Flo" is one of them they are easily obtained and use a compression style fitting for assembly, they have tubing with working pressures of 300+ psi and burst pressures of 700psi + in their product lines. I believe that when references to plastic or PVC tubing is made, the actual product being referred to is the white, or black PVC piping available at home centers, which is actually designed for lower pressure applications. I mention this only to point out that there are alternatives to rigid copper airlines, and I know that not everyone is comfortable, or experienced with sweating pipe.With carefull research and a little added cost a more flexible shop air system could be installed that would be immune to moisture corrosion problems. My .02 FWIW

[Bruce Page]

Thank you all,

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I was hoping that the “L” type would be suitable. I will be heading to the Borg this week to pick some up. Mike, thanks for the detailed info. I didn’t think about adding a trap & bleeder valve, but now’s the time to do it!

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Thanks again!

[Bruce Page]

Thank you all,

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I was hoping that the “L” type would be suitable. I will be heading to the Borg this week to pick some up. Mike, thanks for the detailed info. I didn’t think about adding a trap & bleeder valve, but now’s the time to do it!

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Thanks again!

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[Chris Padilla]

Bruce,

If you see needs to change and move around your air lines, going with copper pipe could be a real PITA. I like the Poly-Flo suggestion by Mike. Compression fitting are easy to change...soldered ones are not.

I've often read that aluminum line is the best to use for air. It is lighter than black pipe and I see it used on gas lines around here all the time.

[Allan Johanson]

I'll be plumbing my shop with copper in the future, but was wondering if I should run 1/2" or 3/4". I don't care about the price difference, but was curious if you guys know of any problems with 3/4" pipe.

My plan was to run a line from the compressor in a zig-zag pattern along one wall for about 50 feet of pipe, then install a water trap. Having this much copper can help to draw out the moisture. Then from that point, run the lines around the shop with several drain areas and risers going to each connection point. Always making sure the slope of the pipes are set up so any water in them will automatically go to a drain valve - never pooling in the pipes or at a connection point.

The 3/4" pipe would provide a large area to hold plenty of air - an extension of my tank in a way - and that would help reduce cycling of my compressor.

Have I overlooked anything?

Thanks,

Allan

[Dave Richards]

Allan, how about if you put half that copper in my shop?

Actually, rather than running it in a zig-zag pattern, you could set up a coil of copper and use a small equipment enclosure fan similar to the one in your computer. That would make a fine radiator. You could also forego the fan and put fins on the coiled portion of the tubing. Make the coil run vertically so the water will run down to a trap.

The benefit of larger lines is that you'll see a smaller pressure drop when you trigger a high use device like a sander. You will also have the greater volume you are thinking of.

Put a water trap right before the radiator and if you like, one right after. If your tubing is soldered cleanly, you shouldn't need more than one dirt leg and that can be right by the compressor.

Do like I said with the nitrogen and you won't get any junk in the lines to collect in a dirt leg down stream.

As part of my job, I deal with miles of copper lines carrying medical (breathable) gas. We have no dirt legs at the outlets and no water traps since the gas is cleaned and dried at the source. Some of our devices have water traps but I've never seen a drop of water in any of them.

[Dean Baumgartner]

Bruce,
Here's a picture of the air system I finished not long ago. All 3/4" type l.

Dirt legs and drains at low points and all other connections off the top of the pipe to prevent material from making it to the tool connections.


Dean

[Bruce Page]

Dean, that’s a really nice setup – mines not going to be anywhere near as professional as that!