Compressed Air Piping

SGBARRACUDA said

So how is water PSI different than air PSI? After 33 years as a firefighter, 19 years as a Driver Engineer, inquiring minds want to know.

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Pneumatic pressure has more stored energy than hydraulic pressure. Think of a bursting water balloon versus a balloon filled with air. The water inside the balloon and the balloon itself will just fall. A bursting balloon with air will send the balloon pieces all over.

I've always understood that testing of pipe etc. shouldn't be done over 10bar or about 145psi. I think the link says that somewhere. As I also understand it, although I can never find anything to verify it, that you want to figure that a pneumatic rating will be about a third of a hydraulic rating.

Some reading on the subject:
Pressure Tests of Piping systems-Hydrotest Vs Pneumatic Test – What is Piping

The one thing that's always overlooked when siting PVC pressure ratings is that PVC degrades at higher temperatures. Even as low as 110 degrees, PVC pipe pressure rating is about half of what it is at 73 degrees. At 140 degrees, it's 22%.

Schedule 80 PVC pressure ratings:
https://dpk3n3gg92jwt.cloudfront.net/domains/ryanherco/attachments/spears_Schedule80PVCTechInfo.pdf

Since you are a firefighter, you may appreciate this. I read (somewhere) of a small fire in a guy's garage. The heat was just enough for the PVC pipe with compressed air to rupture. Suddenly, there was a nice source of pressurized air blowing into the fire. It just escalated from there.