Air Distribution

Most shops I have seen use iron pipe for air, but I was just looking at a
couple on-line specs sheets on PVC and it looks like if I were to distribute
air at 125 PSI in my shop using 1" Schedule 40 PVC I would have about a 30%
safety margin at the worst case scenario. That's based on 120F operating
temperature. While yes it does hit 120F here in the desert once in a great
while I don't think its ever gotten above 105 in the shop building. Better
safe than sorry though.
Wadda ya think?
P.S. I have seen other shops use PVC also, and they said they never had any
problems.
The only real issue I see is that "wish this hose was 2 inches longer"
factor. I could probably mitigate that by using brass fittings at the ends
and securing them properly at the wall, and of course the fact that there
would be air all over the shop instead of in one corner would help quite a
lot.

Reply to
Bob La Londe
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Not regarded as a good idea.
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Gets brittle, fractures, plenty of sharp high-velocity shards.
Dave
Reply to
spamTHISbrp
You cannot use regular Sch. 40 PVC pipe for compressed air, as it is known to explode. The cracks in it run faster than the speed of sound in compressed air, therefore the appearance is that your entire pipe exploded at once.
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Reply to
Ignoramus26567
I was told this is not safe. So, I used copper tubing. Very easy to add a drop, just cut and sweat in a "T". Its worked well for 20 years now.
Karl
Reply to
Karl Townsend
it'll work fine...as long as you run the PVC inside steel pipe.
Reply to
Buerste
I had PVC air pipes for years until the warnings first appeared here. Then I replaced them with iron near the wood stove and copper elsewhere, just before the price skyrocketed. Some of the old PVC pipes fragmented like glass when I tried bending them, others crinkled.
Reply to
Jim Wilkins
DO NOT use PVC for compressed air. It is fine untill it fails - and then it is EXTREMELY DANGEROUS. There is a reason it is NOT ALLOWED by OSHA etc. It turns into high velocity shrapnel on failure.
Reply to
clare
Bob..at least once a year, I get called in to replumb a shop that had PVC pipe that decayed due to compressor oil, heat etc etc and finally blew out, often taking entire banks of florescent lights off the ceiling, blowing shit everywhich way etc.
Im not telling you not to do it. Ive seen some up for as long as 10 yrs with no explosions. But each and every piece Ive taken down had the structural composition of a grahm cracker. Drop it from 3 feet and it shatters like glass.
If you put up PVC...every bit has to be firmly secured to something rigid. After a couple years...putting any strain on it, thumping it, tapping it, pulling on it..and its gonna break. With luck, no one gets hurt.
Just my .02USD worth. My own home shop, is salvaged black pipe, mixed with air hose all running into homemade manifolds with taps for QDs all over the place. Only in places that I need a LOT of volume, such as die grinders, DA sanders and so forth, do I use a lot of pipe.
Black pipe is cheap if you buy it at a wholesale plumbing supply place such as Ferguson Express etc. I think Im paying $11 for a 20' joint of black. One of the tricks in doing a shop is to never ever use 90' elbow. Only use Ts and plug off the unused side. Sooner or later, you will need to put in another run or valve or line there.
Last year, I ran 3000+ feet of pipe air lines in (2) shops, one being 35,000 sqft, the other being about 10,000 sqft, but in 4 different units of a "industrial strip mall", and installed 4 screw compressors and a couple piston pumps total.
Its one of the things I do to make a living..and Im quite qood at it. Ive turned down jobs where they wanted PVC. I dont want the liability.
Gunner
"Human nature is bad. Good is a human product  A warped piece of wood must be steamed and forced before it is made straight; a metal blade must be put to the whetstone before it becomes sharp. Since the nature of people is bad, to become corrected they must be taught by teachers and to be orderly they must acquire ritual and moral principles." ?Sun Tzu  
Reply to
Gunner Asch
Bad idea.
And they'll keep saying that right up until the fragmentation bomb hits. Then they'll be "shocked, just shocked" to find that this has been a known dumb idea for *decades*. You can get special (green?) plastic pipe (Not PVC) rated for air service, but at last look it was more expensive than regular pipe. Copper or iron can be had any any hardware/building supply.
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My personal preference is copper. Costs a fair amount, once. Relatively clean. Easy to add on to.
The usual litany - slope the lines away from the compressor, and put drain legs on the bottom of the line. Take air off from the top of the line (Up over down) and provide additional drain legs at the bottom of each drop leg, extending well below the air connector. Decouple the compressor from the piping system with a section of flex, and decouple the compressor from the tank to reduce one cause of tank fatigue failure. Plumb your air intake outside.
Reply to
Ecnerwal
I've been using PVC, schedule 40, for a decade with no problems. I do however, limit line pressure to 80 psi. Having said that, I am considering replumbing everything with 3/8 nylon tubing. I'm not going to the expense of iron or copper unless I manage to score enough to do the job at scrap prices. Reasons for replumbing is several joints have developed minor air leaks, as well as the ease of adding lines. My consumption is not great enough to worry about flow restrictions. And I happen to have a 100' roll I scored on ebay dirt cheap...
When I finally get into a permanent shop that I own, I'll use copper.
Jon
Reply to
Jon Anderson
I started with PVC years ago, and never had any problem, but that doesn't me you won't. Most building or mechanical codes forbid it because of the possible air born chards due to impact damage.
When I added to my shop a couple of years ago, I switched to PEX. I found that PEX will not shatter even when frozen, and can even be easier to route. The only down side is the cost of the tool.
Reply to
Elliot G
Another problem is that in the case of fire, if the pvc pipe becomes involved, air pressure may convert the pipe into a flame thrower spewing molten burning plastic if it doesn't explode.
The price difference with black or galvanized iron is not *THAT* great and most good hardware stores will cut pipe to length and thread for you. Be sure to include "drip legs" and blow down/drain valves at frequent intervals to avoid water in the lines problems.
Good luck, and let the group know how you make out. Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
Reply to
F. George McDuffee
Bad idea! I also have used PVC pipe for air lines, but after seeing the carnage that ensues when a line fails I tore it all out of my shop. Copper, black pipe, rubber, are fine, but no to PVC! Greg
Reply to
Greg O
If you use copper or iron pipe you will find you can run your line pressure up to 160# or above. Even though you may not want or need the high pressure at your nozzles (etc.) you will find your compressor will be starting and stopping 1/2 as much or less which will extend the life of your compressor motor and starting/running gear.
dennis in nca
Reply to
rigger
If you feel you MUST use galvanized pipe...remember, you are GOING to get flakes of Galv in your tools.
Its a given. Its pretty much Verbotten to use galvanized pipe with CNC machiney, along with teflon tape.
Use both at your own risk.
Gunner
"Human nature is bad. Good is a human product  A warped piece of wood must be steamed and forced before it is made straight; a metal blade must be put to the whetstone before it becomes sharp. Since the nature of people is bad, to become corrected they must be taught by teachers and to be orderly they must acquire ritual and moral principles." ?Sun Tzu  
Reply to
Gunner Asch
This one gets MY vote!
One of the tricks in doing a shop is to never ever use 90°
Pete Stanaitis -----------------------
Reply to
spaco
"no teflon tape, etc. on the downstream side. "
There's nothing wrong with properly applied teflon tape. It's when it's applied to the last and next-to-last thread on a fitting that it becomes a problem. Before I began work- in in the service department I applied tape to thousands of fittiings without problem. Others, less attentive to details, had numerous problems. We were all using the same tape and fittings so I've concluded application is the key.
dennis in nca
Reply to
rigger
I had to replace all the PVC air plumbing in the last shop I worked in because it started to explode. Made one hell of a mess and lots of noise. We used a special plastic pipe for air that was really expensive. No I wonder if maybe PEX would work well. ERS
Reply to
etpm
A sane practice is that for expensive machines that do not tolerate various particles, to install an air filter right on them. Ergo, that's what my plasma cutter does.
This is also what the Dumore No. 24 automatic drilling head (for sale) does.
Reply to
Ignoramus26567
--------- A good point and another reason to use a filter/regulator/oiler immediately before your air tool or other equipment and no teflon tape, etc. on the downstream side.
For an example see:
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?itemid=45009&CategoryName=&SubCategoryName=and many others.
Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
Reply to
F. George McDuffee

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