Is 15mm copper plumbing pipe safe to use with compressed air, ie for operating paint spray equipment?

Question

I want to extend the distance between my compressor and the air gun. Is it safe to use copper pipe with suitable couplings rather than the flexible reinforced rubber/plastic tubing?

Answer 1

Hmmm - tricky one, this

compressors cause a lot of injuries in workplaces - ca' canny.

15mm copper is good for mains pressure water, which can reach 20 bar (200m) - pretty strong stuff. I would have a bit of concern over the fittings, though - compression fittings might not do the job you want, and leaks waste a huge amount of energy. Maybe go for soldered fittings?

I *think* that a failure with high pressure air would be worse than a failure with water, because air is compressible so a burst is effectively an explosion. However, the mechanical strain might be less because you won't be getting any water hammer with air, so less chance of a burst.

The clincher is probably vibrations. I guess it's a recip compressor. Copper is no use at all in fatigue loading, which you will get from a recip, unless you have a very excellent accumulator (with a bladder) and pressure regulator.

The point about pressure drop off is significant. If you stretch the line out and then find that there's no paint coming out because of friction you will be annoyed. Big pipe better of course.

Answer 2

Copper pipe was originally used and for ducting steam in power stations, and is designed to withstand 2000 pounds a square inch pressure, old water pipe if you recall was made of lead, so unless they have changed the spec of copper pipe dramatically it should be more than adequate to contain 150 psi Air Line Pressure, I've used in the past with compression fittings and had no problem, even plastic water pipe can be used for this purpose, so long as the joints are allowed to dry for 24 hours or only half pressure is used after 12 hours, some repair shops use galvanised conduit for this purpose.

Answer 3

All plumbing carries a PSI rating, as do pneumatic lines. Look at the copper pipe and see if it has the PSI load rating printed on it, if it's new(ish) it should. If not look at the same pipe at the hardware store.

Keeping in mind that schedule 40 (PVC) is rated at 300PSI I think you're pretty safe as long as the pipe doesn't have any previous damage.

I'd sweat the fittings rather than use compression fittings.

Answer 4

I would think the pipe is ok but the joints could be the weak point check the manufacturers website and it will tell you the max pressure for all pies and fittings eg Knupler pipe and conex fittings

Answer 5

While I believe BS copper pipe is rated at about 10 bar, it is more vulnerable to damage and joint failure than iron. I have used 1/2"BSP galvanised malleable iron pipe in my workshop. Hard work and more expensive but the safest option.

Answer 6

Copper Yes PVC NO it's not rated for compressed air. it gets brittle with exposure to sunlight and Cold temperatures.

Answer 7

Yes. Copper would be fine. They use copper in factories all of the time. Even plumbers pressurize copper lines in new home construction to test for leaks.

Answer 8

Yes it would probably work, but you may want to go for a smaller pipe....You may loose pressure otherwise.......The question is why would you want to.......You dont need to be standing to far away from the thing that you a spraying.....But hey make sure you have a good seal and give it a go...Let me know if it works.....We have compressor and spray gun, tips may come in handy.........

Answer 9

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Answer 10

Yes but make sure you used heavy duty copper pipe and compression fittings.