IIRC (big caveat here), the writing on the PEX at my local Lowe's, PEX is rated for 160psi at 75 degC and 100psi at 150degC for both the 1/2" and 3/4".Originally Posted by Marty Tippin
Member
IIRC (big caveat here), the writing on the PEX at my local Lowe's, PEX is rated for 160psi at 75 degC and 100psi at 150degC for both the 1/2" and 3/4".
I don't recommend it, but my simple air distribution piping is just left over 3/8" diameter rubber air hose that must 25 years old by now. I have a drop to my garage and one to my shop with a filter/regulator at each end. Guess replacing it goes on my to-do list.
Last edited by Ole Anderson; 07-09-2014 at 10:09 AM.
I bet that is F not C.
I looked up the spec and it is 160 psi max working pressure at 73.4 degrees F with a burst pressure of 475 psi. Some say it is not rated for air but others say it works fine for air, even a PEX manufacturer who uses it for control air but admits it isn't rated for air.
Last edited by Ole Anderson; 07-09-2014 at 10:07 AM.
Member
I agree that PEX would be the preferred piping material for the main line in a compressed air system. I don't see any problem with covering the piping but would purchase brass pex fittings with crimps and avoid the compression fittings. I would purchase the materials from a plumbing supply house. Terminating with a brass valves configured pex to 1/2"pipe thread. From that you can transition to whatever the hookup needs to be.
Never use PVC piping for compressed air. On failure from impact it can send PVC shrapnel.
Member
I can understand why it would be said that PVC is not compressed air rated. But why do they not rate PEX for compressed air? Additionally, does any one have a reference listing the pressure ratings for copper pipe? Specifically I'm looking for ratings for Type M, Type L, and the soft copper tubing (the stuff you can bend by hand)?
Did you try googling "copper pipe specs"? That is how I found PEX specs.
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I did and found quite a variety of ratings. I was hoping someone had a definitive answer or link.
Look on page 26 of this handbook: http://www.copper.org/publications/p...e_handbook.pdf I didn't compare their numbers with other publications, but they seem to include the proper organizations, particularly ASTM, in their references. Annealed tube comes commonly in rolls and is softer than drawn tube which is usually is sold in straight lengths, but some annealed tube is sold in straight lengths. Type K and L have to do with the wall thickness.
Last edited by Ole Anderson; 07-13-2014 at 11:21 PM.
NOW you tell me...
Contributor
PEX degrades with UV exposure; that should be taken into consideration and may influence your choice of material based on the environment in which you use it.
I have the Rapid-Air system—about 200 linear feet of it altogether, with seven drops—surface mounted throughout my entire shop. The only leakage issues I have had are around the threads of the fittings that screw into the distribution blocks. The tape that comes pre-applied to them is, in my opinion, inadequate. I ended up re-teflon-taping my fittings, and that has eliminated all the leaks. I like the system very much, and would use it again. I do not have any pressure falloff over the system, and I run it pressurized at 125psi, served by a compressor/drier that outputs 22cfm at that pressure.
K
Member
Same here.
Member
Update:
The push-to-connect fittings come in two type: NPT and inches/metric. Shark bite fittings are NPT only and as we all all know NPT is its own measuring system. So the SharkBit and other push-to-connect plumbing fittings will not work with the RapidAir Hose. But the RapidAir hose is a standard 1/2" OD and will work with SAE measured push-to-connect fittings available from Watts, SMC, and Legris or though Grainger or McMaster-Carr.
Member
I have the 1/2" rapid air system, and it works fine for me. Easy to install. I used some old 3/8" hoses shortened for connections from compressor to the piping, and a couple other places. Used one of the coiled hoses for the connection to the widebelt sander, so I can slide it out from the wall to check things while it is running. Always check the oscillation before running parts through.
Contributor
I installed the RapidAir system in my shop this summer, and the compressor cycles about every 30 minutes even though I'm not using any tools. Is it normal to expect some leakage in the system? I've checked all of the push fittings several times so I think the leak would have to be on the threaded fittings. I used pipe thread compound on the threads, but somewhere else it said to use Teflon tape. I'm wondering if I need to go back and redo the fittings with the Teflon tape. Any thoughts?
Member
You shouldn't be losing that much air. Get some leak detector solution at the BORG (in the plumbing section) and check every joint for leaks. You could mix up some soapy water but it's honestly just as easy to go buy a bottle of the stuff.
If the air line isn't cut square and clean, it makes it harder to get good connections. So I f you find leaks at the connections, clean up the ends and re-do the connection. I assume you used the cutter that came with the kit - it does a pretty good job for being a cheap flimsy tool.
If you used joint compound on the threaded connections, you're unlike to have a leak there. But check them to be sure.
I've got a slow leak in my rapid-air system that I know I could fix if I felt like chasing it down. Just haven't gotten around to it yet. But the compressor only cycles a couple of times a day so I'm not bothered by it that much.
Contributor
A slosh of dish soap in a paint can with a cup or two of water will save you a trip to the Borg and reveal those leaks pronto!
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