Pex for air lines

Darren Wright

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Been thinking about running some air lines around the shop. I've got a regulator directly off my tank, which is normally set to 90 pSI max. Pex is supposed to have a long term max rating of about 160 psi, well above my normal. Anyone used it for piping their shop?

I typically close the main valve when not in use and turn it off, so not much chance of it running if a major break/leak occurred.
 
UV reliability sounds slightly dubious, what the time to failure would be though seems like it might be long enough to be irrelevant. I think perhaps the black PEX may be more uv resistant- the PEX-AL-PEX stuff definitely would be but it looks like it starts to approach or surpass black pipe costs.

You might also have some more condensation issues in plastic than metal (and for horizontal runs more drop out points so moisture may stay in suspension longer).

OTOH it looks pretty compelling from an ease of install perspective and the failure mode isn't catastrophic like PVC so it probably makes sense in some ways. I might consider black pipe for the long horizontal because of the moisture trapped in the droops problem and then use black pex for the drops?
 
I was thinking the opposite, pex for the main runs, black pipe for the drops. Moisture traps towards the drops should help I have one at the compressor too. Figure on strapping it down about every 4 to 6 feet, so if a break occurs it won't have room to whip around.

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Yah, of you're putting moisture traps in the drops it probably doesn't matter to much, you might still want to blow the lines out every so often just to clear them.

Not sure why you'd bother with black for the drops in that case though?
 
Darren u sure about the pex psi rating? Just picked up an 8 ft length and it had 100psi printed on it. Dont know if thats normal or a depot version.

Btw was only CDN $ 3.89 so my trailer manufacturer skimping was saving nothing. Duh.
 
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The tubing should handle the pressure. Ratings are 160 psi at 73 deg F and 100 psi at 180 def F but burst pressures at 73 deg F are up around 850 psi!! I prefer PEX-A over PEX-B (crosslinking method to manufacture) because it has a better bend radius, kinks can be repaired with heat gun, and it is overall a better product. Be careful of how joints are made, personally I'd want to use cold expansion (Uponor style) fittings instead of crimp ring (oetiker or copper ring) because I think they are more stable and they also maintain a larger ID that is less restrictive to flow. Uponor & Rehau are a couple A brands.

Pex-B is usually what big box stores sell (Zurn & Apollo are a couple B brands) and it is typically less expensive. It cannot be expanded so must use a crimp joint and any accidental kinks make it brittle and should be cut out.

Happy experimenting and be safe! I'll be running my shop air lines in black pipe becuase I just can't help my old fashioned self. :)

- Robert
 
Darren u sure about the pex psi rating? Just picked up an 8 ft length and it had 100psi printed on it. Dont know if thats normal or a depot version.

Btw was only CDN $ 3.89 so my trailer manufacturer skimping was saving nothing. Duh.
That's what I saw advertised on the blue borg.

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Pex-al-pex is the only air rated pex the last time I looked. There was/is an ABS type of plastic that is also air rated (different from the building center plumbing stuff), and it cost more then the black iron pipe.
HF, used to sell a Rapidair clone, that you might look up. HF no longer sells it (think they were threatened with a lawsuit), but Rapidair (might be off on spelling) is still out there.
 
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