any PVC pipe as air line blow out proof?

mlcasey13 · Mar 30, 2010

Before anybody tells me its not a good idea I just want to state that ive already heard that. My question is does anybody have proof, pictures of blown out pvc pipe used as air lines?

I have been researching air lines for my shop for a while now and was going to use PVC because my dad has had it in his farm shop for probably 12 yrs now with no problems. This pipe is rated for something like 250+ psi and that is the working load there is no telling what the actual burst strength is probably around 1000 psi for 3/4sch40. My other problem with this paranoia is what is the difference between having the same pressure water in the pipe vs air? PVC is used all the time to carry water at the same pressures a normal air compressor produces.

I am really interested to see if anybody has any kind of proof that this can be a problem.

Thanks,

mlcasey

D KRAGER · Mar 30, 2010

Oh boy you opened up a can of worms!!!!!!! You will get plenty of replies. I personally use pvc, but from hearing about the possibility of it exploding, I only use where it won't hurt anyone, (attic areas, ect).

Ray-CA · Mar 30, 2010

The problem with PVC pipe isn't that it fails. It's that if/when it fails, it tends to explode sending PVC shrapnel in all directions. With water pressure, the pipe trends to split, air makes the pipe swell then burst. Picture a balloon over-filled with water then over-filled with air. Same concept.

Ray

GeorgiaHybrid · Mar 30, 2010

Think of it this way. Take a scuba tank, fill it with water and apply pressure to the tank by hooking a pipe to a water tower next door. It the tank springs a leak, water will come out but note that water cannot be compressed so you only have the volume of water coming out that the pipe will flow.

Take that same tank, fill it with 80 cubic feet of air compressed to fit the tank (air is compressible) and hook it to a nice compressed air supply. If the tank ruptures now, the air will expand to its normal volume as it escapes. This allows the air to expand in volume from whatever pressure you have (example: 150 psi) to normal air pressure (14.7 psi). In this example, the air would expand to over 10 times its compressed volume state.

That is the difference in water and air. One will create a leak that will spray a lot of water and the other can explode rather spectacularly at times....

mlcasey13 · Mar 30, 2010

GeorgiaHybrid said:
Think of it this way. Take a scuba tank, fill it with water and apply pressure to the tank by hooking a pipe to a water tower next door. It the tank springs a leak, water will come out but note that water cannot be compressed so you only have the volume of water coming out that the pipe will flow.

Take that same tank, fill it with 80 cubic feet of air compressed to fit the tank (air is compressible) and hook it to a nice compressed air supply. If the tank ruptures now, the air will expand to its normal volume as it escapes. This allows the air to expand in volume from whatever pressure you have (example: 150 psi) to normal air pressure (14.7 psi). In this example, the air would expand to over 10 times its compressed volume state.

That is the difference in water and air. One will create a leak that will spray a lot of water and the other can explode rather spectacularly at times....

This is the kind of explanation Ive been looking for. For some reason I just couldn't come up with a good explanation. Everybody just says don't use it it explodes! This makes sense.

It would still be cool to see some pictures though!

mlcasey13 · Mar 30, 2010

Also what about just using good quality flexible air lines between fittings and attach them to the wall with pipe straps?

Kevin54 · Mar 30, 2010

He said "PVC AIRLINES" :scared:

Charles (in GA) · Mar 30, 2010

Simply put, compressed air is "stored energy" while water, being incompressible, does not have any stored energy. Its this "stored energy" that does all the harm. As noted above, air compressed to 150 psi will expand ten times over as it decompresses back to ambient pressure.

Take a high pressure gas bottle like oxygen, nitrogen, etc. filled to 3000 psi. Then pump water, hydraulic fluid, etc, to 3000 psi in a similar bottle and close the valve. Now, take a sledge hammer and break off the valve on the bottles...................

Charles

Dragster Racer · Mar 30, 2010

Kevin54 said:
He said "PVC AIRLINES"

Run Forrest! Run!

But seriously, didn't he ask if anyone had seen it or had pictures?

D KRAGER · Mar 30, 2010

mlcasey13 said:
Also what about just using good quality flexible air lines between fittings and attach them to the wall with pipe straps?

I use hydraulic hoses for anything that needs a bend to it. Visit your local farm store they will have some pre-made, make sure you get the ones with pipe thread.

Ch3No2 · Mar 30, 2010

DOT rated truck air line is about the best you can get...1/2" should be about 400psi

Kev442 · Mar 30, 2010

http://www.osha.gov/dts/hib/hib_data/hib19880520.html

Methinks that any corporation, school or individual that has a failure is reluctant to photograph the evidence of going against OSHA recommendations! A quick browse of the internet does turn up dozens of failures. Some nuts still defend PVC, saying things like, "it's only broken twice in 10 years". :wtf:

1320stang · Mar 30, 2010

I don't have a picture as this happened pre-internet, so pre-digital cameras.

I was in my buddy's chassis shop when a 2" or so PVC line blew and a shard about 6" long, pointed on both ends like a dagger, flew about 10' behind his head about head high and lodged in the insulation 60' across the shop. The pipe was behind the compressor, in a location that nothing would fall on it, the only thing I can think of was failure due to vibration. His compressor was an industrial horizontal unit, probably 200 psi. Scared the sh!# out of us both.

rsanter · Mar 30, 2010

I used to work for a manufacturer that made PVC fittings
I always thought pressure was presure and did not see the big deal

we had a testing unit there to test burst pressure so I decided to run a couple of experiments.
I filled the pipe and fitting manifold with water (bleeding out the air) and then pressurized. the setup failed at double or so the rated pressure, but the failure happened such that the pipe started to expand like a balloon blowing up so the test was stopped.
repeated the test but did not bleed the air. I left the air in that it started with and then the system pumped in water. the manifold exploded at about half of the rated operating pressure. over several years I re-tested this several times in different ways as water hammer was a large cause of failed parts and insurance claims.
it always seemed to be that failure was always around half of the rated pressure.

I am not recomending it, but if I were to use PVC I would go to sch80 and be sure to stay under 50% of rated (based on what I saw)

bob

rockchucker · Mar 30, 2010

Interesting information. I would like to see some carnage pictures as well.

This is one reason why there are no stupid questions.

BioHazard · Mar 30, 2010

Several years ago I took a peice of 2" PVC about 2' long and put a cap on both ends. Then I added a tire valve and pressurized it to 180 PSI.

I then took a long walk and shot it with a .22 rifle. KA-*******-BOOM! I wish I would have taken pics, there was no "pipe" left.

Plumbers normally test copper/steel pipes for leaks by pressurizing with air at relatively low pressure. I believe this is not allowed with PVC.

MP&C · Mar 30, 2010

Complete with pictures:

http://www.monroefiredept.com/Incidents.cfm?IncidentID=56

.

Torque1st · Mar 30, 2010

No PVC line is rated for compressed air. No matter how thick it is.

I saw the results in a shop down the road from me. No camera or pictures. The 1" pipe exploded in the middle of the night so nobody was hurt. Plastic shrapnel was everywhere. The shop owner just replaced that section with another section of PVC. I don't go there anymore.

Joe69 · Mar 30, 2010

I'm going to use nylon air brake tubing.

Joe

smooth72 · Mar 30, 2010

I Tried it, the heat from the compressor melted it. My neighbor has a body shop and tried it at 175lb.Put his in wall behind sheet rock. It exploded and removed the sheet rock. Might be able to run 125 lb and run metal pipe first. My new one all black 3/4 pipe.

Mr_fixit · Mar 30, 2010

MP&C said:
Complete with pictures:

http://www.monroefiredept.com/Incidents.cfm?IncidentID=56

.

I see a ceiling. I don't see any pipe...?

And 2" pipe ? Doesn't sound like a realistic exaple of a busted pipe.

I'd like to see some real pictures, too.

So anyone that has em, please post. or if you need to make up some, go ahead, I'd like to see those , too.

RbrtAWhyt · Mar 30, 2010

MP&C said:
Complete with pictures:

http://www.monroefiredept.com/Incidents.cfm?IncidentID=56

.

From the above referenced article:

"Maintenance personnel were inside fixing the piping and were expected to back up and running by the morning"

Doesn't sound like they replaced it all, just fixed it...

slip knot · Mar 30, 2010

I've seen PVC pipe explode when used as airline. Was at a welding shop I was working at. I was outside working and heard one hell of a boom. Dust and **** was blowing out of the shop. The owner was walking around inside in a daze. Little pieces of PVC pipe was scattered all over . we didn't find a piece bigger than 3" anywhere. spent the next three days replacing what was left of the PVC pipe with black iron. The PVC piping had been in use @15yrs before failure. I think excessive heat and oil probably contributed to failure.

When I built my shop in 04 I put 1" black iron air line exclusively. I used a 1" Hydraulic hose for a whip to connect the compressor to the piping. 3500# burst strength.

jake00 · Mar 30, 2010

Lhorn · Mar 31, 2010

There's a thread on another auto related message board about this subject. One poster said that his neighbor was killed by sch 80 PVC that blew at 130 psi pressure. Whether that is true or not is anyone's guess. I don't see why I would doubt it.

I'm sure that it's very uncommon. I also know that PVC under pressure can be a bit fragile. There's no reason to tempt fate. If you don't have the money to run copper or iron, get the plastic tubing stuff from HF. Heck, use a 50 foot hose. I can't see why people are so stubborn on this issue (this statement is not pointed at anyone specific).

BioHazard · Mar 31, 2010

If you really want to cheap out use PEX. It's rated for at least 180 PSI and it won't explode into shrapnel like PVC. I don't know if it's "approved" for airline use, but I asked about it a few weeks ago and nobody seemed to have a problem with it. I plan on running PEX main lines with a few copper drops.

santagary · Mar 31, 2010

best prices on black metal pipe...? my plumber says that would be best.

BioHazard · Mar 31, 2010

santagary said:
best prices on black metal pipe...? my plumber says that would be best.

1/2" at Home Depot is about $10, roughly $1/foot. Copper is actually cheaper, and better, in my opinion...

Daniel Dudley · Mar 31, 2010

jake00 said:

Guys in the second video are laughing like idiots. Must have big angels looking after them.

PVC = brittle = shatter. :wtf:

henrys103 · Mar 31, 2010

i don't understand why some of you guys would want to take such a risk anyway,,, just to save a couple of bucks?,,just cause it's easy to work with?,,,
just install the steel pipe and be done with it, and know that you won't have any "possible" problems like with pvc
how could you feel comfortable using pvc, knowing that at any time there could be an explosion, what if your family was in there when it happened?
:twak:

mlcasey13 · Mar 31, 2010

Thanks for the help guys! I'm convinced now I just need to convince my dad to change out his shop before anything happens! I had looked into using flexible tubing but was unsure of what would work for long term and what would hold up but somebody mentioned air brake tubing and I was like DUH that stuff holds up to pretty much anything. Im thinking about something like this and just use some compression fittings from somewhere like mcmaster carr.

Again thanks for the info.

mlcasey

AMCguy · Mar 31, 2010

Metal air lines will dissipate heat better than a rubber hose will. As the heat leaves, the moisture in the air inside will condense on the lining and be carried away to a trap. With a rubber line you will get more moisture in your tools, paint gun etc.

toyoguy81 · Jun 22, 2014

Resurrecting this thread, ready to install an airline in my shop?? What did OP ended up using?? Did you run a continuous loop back to compressor?

NUTTSGT · Jun 22, 2014

toyoguy81 said:
Resurrecting this thread, ready to install an airline in my shop?? What did OP ended up using?? Did you run a continuous loop back to compressor?

I doubt you find out. The OP hasn't been active in over a year and that post above, was his last post.

I'd suggest not using PVC, been there, replaced that.

CudaDude · Jun 22, 2014

Not to say it can't happen, but the only occurrence I've personally witnessed is at my FIL's barn that has PVC air lines. When it happened there the PVC just spit. It did NOT explode and send pieces of PVC shrapnel flying everywhere. PVC just seems to flexible to me burst into pieces, unless it's very old and brittle.

rdn2blazer · Jun 22, 2014

CudaDude said:
PVC just seems to flexible to me burst into pieces, unless it's very old and brittle.

This is the problem. It's flexable when new and WILL hold up for a long time IF not over pressured. It's the OLD dry brittle stuff that will explode at some point because all plastic drys out with age. PVC has it's purpose and many many other purposes, but airline shouldn't be one of them. Not for the saving of a few bucks. Or if PVC gets too cold it will shatter too.

LS6 Tommy · Jun 22, 2014

From another good website:

http://www.practicalmachinist.com/vb/general/ruptured-pvc-air-lines-what-not-do-230253/

Tommy

LS6 Tommy · Jun 22, 2014

BioHazard said:
If you really want to cheap out use PEX. It's rated for at least 180 PSI and it won't explode into shrapnel like PVC. I don't know if it's "approved" for airline use, but I asked about it a few weeks ago and nobody seemed to have a problem with it. I plan on running PEX main lines with a few copper drops.

There is no "regular" PEX rated for compressed air, but Al-PEX is...

Tommy

LS6 Tommy · Jun 22, 2014

rdn2blazer said:
This is the problem. It's flexable when new...

The PVC in the above video was brand new...

Tommy

rdn2blazer · Jun 22, 2014

Only way to keep it from shattering is to spiral wrap it with duct tape or some other decent tape. Thats just more work for what? Buy quality airline tubing and be done with it for decades unless it's steel pipe and you don'd have a dryer, then it will rust to hell over time and ruin all your air tools and anything you paint.

So no I wouldn't recommend black pipe either, anything that will rust. Air compressors make moisture when pumping so steel is death with air systems. Copper or aftermarket aluminum tubed, plastic lined air systems. I went with an after market system thats cleanroom and hospital sterile level rated. Bought the 100' kit and some extra fittings. Was an easy install and I've been totally happy with it. It's plumbed from compressor to a huge filter to a refrigerant air dryer out to four air chucks, one at about each corner of my small 2 car garage and a cnc mill.

any PVC pipe as air line blow out proof?

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