# Pex for compressed air?



## Drewp311

I am running about 300' of compressed air. It will have 140-160 psi. Will pex hold that much pressure and last or is it best to just use iron pipe?


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## Mississippiplum

Iron is the best

sent from my iPhone 10.5


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## rjbphd

Mississippiplum said:


> Iron is the best
> 
> sent from my iPhone 10.5


 Huh??? No way.. sch 80 are the best, no rust, etc.. that's what body shop requested..


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## Drewp311

I have heard that PVC will deteriorate quickly though. Will sch 80 last longer?


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## rjbphd

Drewp311 said:


> I have heard that PVC will deteriorate quickly though. Will sch 80 last longer?


 Pvc deteriorate from what??


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## plbgbiz

PVC will get brittle and poses a safety hazzard.

Steel is the better choice.

If you don't run steel you could try Sicomat nylon pipe and fittings.

http://www.sicomat.com/EN/tubes-fittings-accessories-compressed-air-distribution.htm


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## PLUMBER_BILL

REALLY... You get any OK from a PEX manufacturer to use PEX for compressed air ... Please pass the info along ... 

In the meantime think ... Blow up a balloon to 7" diameter, then fill another to 7" diameter with water. Then prick them both with a pin ... Observe what happens [one leaks water all over --the other one explodes rather violently] I would not want to be in the line of fire when the PEX lets go.


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## mtfallsmikey

A long time ago,I used Sched. 40 PVC/pressure fittings to pipe a customer's screen printing company. Had a bad blowout about a year and a half later, blew a 90 off, shattered the pipe, they were on a budget then, and I was game for a science project...No substitute for black, especially at those kinds of pressure.


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## OldSchool

Pex and Sharkbites are the way to go....

I wonder how long it would last...


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## futz

PLUMBER_BILL said:


> In the meantime think ... Blow up a balloon to 7" diameter, then fill another to 7" diameter with water. Then prick them both with a pin ... Observe what happens [one leaks water all over --the other one explodes rather violently] I would not want to be in the line of fire when the PEX lets go.


PEX won't explode violently - PVC *will*. PEX might burst, but it won't throw shrapnel. I've done air lines with PEX. They've held up fine for many, many years in a cabinet-maker friend's shop.

The only concern I would have with PEX (and other plastics) for air is the fire/flammability thing. The last thing you want in a fire is the air lines melting and feeding the fire with a nice high pressure air supply. There are companies out there selling lines of low flammability plastic made-for-compressed-air pipe & fittings.

PEX will handle the pressure with no problem. When PEX was new my father was worried about how the pipe swivels on the crimp fittings so easily. So he crimped up a bunch of test fittings and a gauge, twisted the hell out of them for a while and pumped them up to close to 1000 PSI with his hydrostatic pump and left them for a week. No pressure loss.

Many years ago when I was a dumb apprentice I was ordered to do air lines at a car wash in PVC. Even then I thought that was a bad idea, but whattya gonna do? The boss says, "DO IT!" They had some bad/frightening air line explosions (PVC shrapnel all over) in that brittle crap within months of the grand opening. We got sent back and replaced what we could with steel. 

But really, do it in black iron. It's relatively material-cheap (though somewhat labor-expensive) and can take abuse and will last "forever". It's probably the best way.


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## RealLivePlumber

PVC will not blow up violently. Its in several repair shops around here. We fix leaks in them all the time. Usually at the joints, sometimes a split in the pipe. They just sit there and hiss away.....


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## Drewp311

Black pipe it is. I hate doing stuff twice. Rather do it once and be done with it.


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## SPH

PVC will blow up. Get ready for a lawsuit if you go that route.


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## Donahue756

Anybody use copper ?


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## Gettinit

Donahue756 said:


> Anybody use copper ?


I have used copper for these little labs that make teeth for dentists. 

I had to pump up some pex to 200psi to pacify an inspector. It held but I wouldn't use it for air lines. Too many people in a rush and may cut it thinking its a water line.


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## Catlin987987

We have done it in Aquatherm before. It doesn't rust, which is a plus.


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## futz

Donahue756 said:


> Anybody use copper ?


I've run a few air lines in copper, long ago. There's nothing wrong with copper for air lines. But these days the price is just out of this world. The labor is probably the same or higher than black iron too, so you don't save anything there either.


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## Redwood

RealLivePlumber said:


> PVC will not blow up violently. Its in several repair shops around here. We fix leaks in them all the time. Usually at the joints, sometimes a split in the pipe. They just sit there and hiss away.....


Really?:whistling2:

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

http://www.charlottepipe.com/Documents/PL_Tech_Man/Charlotte_Plastics_Tech_Manual.pdf see Page 6


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## JK949

Donahue756 said:


> Anybody use copper ?


A bike shop I frequent has their air lines ran in copper. Looks good too.


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## James420

JK949 said:


> A bike shop I frequent has their air lines ran in copper. Looks good too.


Copper is the way I used to run air lines, Dentist offices or Auto shops. When I got into the refinery work it was all schedule 80 threaded and back welded or just socket welded. Socket welds were the way to go, especially with stainless piping. I think people would be surprised how fast welding is.

Since I have a welder, its the only way I would do it now.


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## ChrisConnor

A friend had pvc for air line in his screenprinting shop back in the 90's. He told me that the guys that put it in said it was completely safe up to 400 psi, then it exploded while he was talking about how safe it was. Nobody was injured, but it blasted bits of pvc into the sheetrock.


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## Drewp311

Changed my mind. Going to use copper. From the research I have done blk pipe is only rated @ 150 psi. Copper is @ 400 psi. Little more expensive but worth it in the long run I think.


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## Protech

My brother has all his air lines in his shop ran in pex. The only thing you have to watch out for is heat buildup near the compressor. The nice thing about it is that it will NOT shatter and shoot shrapnel everywhere like pvc or cpvc.


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## Catlin987987

Watch your pipe sizing. Tools need CFM and Pressure. Your not going to be using a impact drill on a 1/2" line thats 100' Long.


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## Drewp311

Catlin987987 said:


> Watch your pipe sizing. Tools need CFM and Pressure. Your not going to be using a impact drill on a 1/2" line thats 100' Long.


I was going to run 1" trunk line and branch off with 1/2" @ five different openings.


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## Fast fry

Drewp311 said:


> Black pipe it is. I hate doing stuff twice. Rather do it once and be done with it.


That's what she said:laughing:


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## No-hub

Copper or black iron or galv. Compressor oils deteriate plastic pipe.


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## Gettinit

Drewp311 said:


> Changed my mind. Going to use copper. From the research I have done blk pipe is only rated @ 150 psi. Copper is @ 400 psi. Little more expensive but worth it in the long run I think.


You may want to call the manufacturer. It has been a while since I had to worry about this issue but if memory serves many show their Max pressure ratings based off of steam pressure. Also, there are several other thicknesses beyond sch. 80. Not sure that it would be cheaper but I would want steel vs copper on higher pressure jobs, especially with larger volume. Most any small or mid size air jobs will not have a pressure above 150 anyways due to those little compressors. The only times when pressure was ever an issue for me was with steam/process related jobs.


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## Drewp311

Black iron sch 80 is what I have to use now. It is in a natural gas pump station that pumps through a 42" main across the state. They can't have anything less than sch 80 in the station (fear that if explosion happen they don't want compressed air feeding the fire; understandable). Would have been nice knowing this before I started. Now the 80 pipe and fittings are going to cost $1100 more than what I bid. 
Is there anything else that I might run into that I "should have already known"?


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## AlbacoreShuffle

Drewp311 said:


> Black iron sch 80 is what I have to use now. It is in a natural gas pump station that pumps through a 42" main across the state. They can't have anything less than sch 80 in the station (fear that if explosion happen they don't want compressed air feeding the fire; understandable). *Would have been nice knowing this before I started. Now the 80 pipe and fittings are going to cost $1100 more than what I bid. *
> Is there anything else that I might run into that I "should have already known"?


 Ouch !!
Did they make this change after you won the bid ?
If so you may be Ok with a nice big change order.


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## Drewp311

AlbacoreShuffle said:


> Ouch !!
> Did they make this change after you won the bid ?
> If so you may be Ok with a nice big change order.


Luckly I have not started the job yet. And yes I do plan on putting in a change order. I did not receive any paperwork stating that it had to be sch 80 pipe before I bid it, so they can't just expect me to eat that money.


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