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PVC pipe for compressed air

R

RScott

Well Known Member
This has been discussed before, but here is a little info from the Washington Department of Labor that just came to my attention. I pass it on for die hard PVC pipe users or for those setting up their shop now:

"Last year, a section of PVC pipe being used for compressed air exploded 27 feet above a warehouse floor. A fragment of the pipe flew 60 feet and embedded itself in a roll of paper. Fortunately, nobody was in the area at the time."

"A PVC pipe explosion in a new plant in Selah broke an employee's nose and cut his face."

"PVC piping buried 3 feet underground at a Yakima manufacturing plant exploded, opening up a crater approximately 4 feet deep by 3 feet across."

Ref: http://www.osha.gov/dts/hib/hib_data/hib19880520.html
Safety Hazard Information Bulletin
 
I've owned a machine shop for 26 years and have always used regular black pipe for air lines. I built a home shop a few years ago and decided to try PVC because of ease of installing it. About a year later one section broke a glue joint and shot a four foot piece across the shop. Besides making me change my underwear it nearly hit me. When the piece hit the shop wall it exploded in a bunch of fragments. Now I have all black pipe everywhere. Be sure not to use galvanized pipe for air lines also. I've been told that it can flake off the inside and come out like tiny bits of shrapnel.
Jim Wright RV-9A wings 90919 Arkansas
 
Shop air lines

I've read the posts with much interest as I would like to install a large compressor outside and route lines inside for sound and convienance.
I'm in the construction business too, and I know that threading black iron pipe is no easy task. Seems like copper pipe would be as stable and easily soldered system to use? One could even use the soft copper tubing is straight sections were hard to route. Anybody know of problems with Copper??
Thanks,
Bob Martin, RV-6 Flying...but you always need a shop!!
 
Bob,

Copper is capable of handling the pressure but I think the problem is one of volume and price. To get a pipe large enough in diameter to handle the volume of air, you would be paying a pretty good price for it. I don't know specifics, but I know that it's much more expensive than BIP.

BIP is not that hard to install. Just go to a tool rental place and rent a pipe thread cutter. They're pretty easy to use, electric, and make putting pipe together a piece of cake. They come with multiple dies and include a cutter and fluter all in one unit.
 
Shop Air piping

Randy,
Thanks for the response, I tend to agree but lets discuss it some.
What size BIP...(Black Iron Pipe) ...like used in Natural Gas lines.
Seems 1/2 inch ID copper is larger than the ID of any or most air hoses??
Does length of hose or pipe play into this equation?
I hadn't considered the size of the pipe as storage but I'm now thinking it would add up, especially if using ...say..3/4 copper piping..
Regards,
Bob Martin
 
Bob Martin said:
Randy,
Thanks for the response, I tend to agree but lets discuss it some.
What size BIP...(Black Iron Pipe) ...like used in Natural Gas lines.
Seems 1/2 inch ID copper is larger than the ID of any or most air hoses??
Does length of hose or pipe play into this equation?
I hadn't considered the size of the pipe as storage but I'm now thinking it would add up, especially if using ...say..3/4 copper piping..
Regards,
Bob Martin
Click to expand...
Yes, there is a pretty good volume of air stored inside the pipes as they are pressurized. I think the size depends on your compressor and the amount of lines you are running.

My irrigation system uses 1 1/4" lines and when I blow it out with my 3.5 HP Craftsman, it takes a while to get the system to pressure up. I think a 1/2" pipe is probably plenty.
 
Air Piping

I didn't mean to take over the thread...
Thanks Randy and Scott for your input!
Bob Martin
 
Air line plumbing

Check this out to find out how to do it: http://www.sharpe1.com/dr-pipe.htm

FWIW, I used 3/4 inch copper. Works fine, except I have some "choke points" between the compressor & the copper and at the water separator. If I use a lot of air, such as with a die grinder, when I stop I can hear a hiss of air as the pressure catches up downstream.
 
Pressure loss

Assumptions:

100 feet of Clean Commercial Steel Pipe
10 each 90 degree elbows
2 each ball valves
10 SCFM
100 PSIG
70 degress F

1/2" pipe shows a TOTAL loss of 0.449 psi
1" pipe shows a TOTAL loss of .035 psi

Want to check other parameters/materials?

http://www.freecalc.com/gasfram.htm

Even at 50 SCFM the loss is only 10 psi. But then, at those rates, if you can aford the compressor the pipe should be incidental!

Dave
 
Bit OT but involving air lines.

Two years ago our hockey team installed a ships horn in the rink to signal their goals. IIRC the air line was run with 3/4" copper about 150' and there is a solenoid valve right next to the horn. I'm not sure about the exact pressures involved but I would imagine that they are fairly excessive. The SPL is in the neighborhood of 115 dBa. Other fun facts... its rated by the coast guard for a 210' ship. It was custom made in new england for us. The cost of the Horn was ~$15k, the installation was at least 20k ;-). the best part? They didn't have any money in the budget for anymore than a 3% pay raise for everyone that year. Oh yeah, the team imploded and lost almost every game after that... Gotta love NCAA athletics...
 
Copper airlines

I plumbed my airlines using the Sharpe diagram. I used 3/4" rigid type L copper(it's a thicker wall thickness than type M that many homes are plumbed with). I picked up everything at Home Depot. If I were doing it again I'd just get 1/2" type L copper. Installation would be a little simpler because of smaller holes to drill in the wall studs and plates, plus 1/2" fittings are easier to find. Most of us are using 3/8" airhose, and probably 1/4" quick connectors and regulators so I don't think there is much benefit to 3/4" copper unless you have really long runs. I have a 24'X32' shop with an air drop in the middle of each wall, plus one in the ceiling.
 
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