# PEX for air compressor lines



## Daniel Holzman (Mar 10, 2009)

200°F at 80 psi
180°F at 100 psi
120°F at 130 psi (1/2" Wirsbo AQUAPEX tubing only)
73.4°F at 160 psi
These are Uponor ratings for their PEX, however since PEX is a relatively standardized product their rating is likely to be comparable to other manufacturers.


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## joecaption (Nov 30, 2011)

I'd pass on that idea.
This is how a properly layed out air system is done.
http://www.sharpe1.com/sharpe/sharpe.nsf/Page/Air+Piping+Layout

No one that knows what there doing is going to ever suggest using copper,

Use black iron pipe instead, reason being a filter will remove rust.


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## PoleCat (Sep 2, 2009)

Back in the early 90's I worked at a facility that had multiple outlets in two separate buildings all plumbed to one big compressor. The director was a bit of a safety nazi and decided the aging iron & galv. piping had to be replaced before it ruptured. The replacement was a green plastic pipe. I remember being skeptical about this idea at the time. I wonder if it is still in service.


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## joecaption (Nov 30, 2011)

Here's a tip and time your running an air manifold use the largest pipe possible.
The pipe acts like an accumulator and and increaces the avalible flow to the tool so it does not start off with full pressure then slow down from lack of air.
Just going from 1/2 to 3/4" increases the flow by about 25%.


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## Nailbags (Feb 1, 2012)

Pex is not rated for air! it is rated for water PSI of 150 you want the air rating take that 150 and divide it by 3 you get 50 PSI max rating for your air line. Now you know. use stainless steal tubing with nutts and ferrels.


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## Nailbags (Feb 1, 2012)

joecaption said:


> I'd pass on that idea.
> This is how a properly layed out air system is done.
> http://www.sharpe1.com/sharpe/sharpe.nsf/Page/Air+Piping+Layout
> 
> ...


I would use stainless steal better and less long term problems.


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## 1985gt (Jan 8, 2011)

Used Pex in our shop, been going strong for 5 years now, will let you know in another 5, then another 5. A good drier/filter is a must.


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## 123pugsy (Oct 6, 2012)

Nailbags said:


> Pex is not rated for air! it is rated for water PSI of 150 you want the air rating take that 150 and divide it by 3 you get 50 PSI max rating for your air line. Now you know. use stainless steal tubing with nutts and ferrels.



I thought pressure was pressure?

I do know that a pound of feathers is lighter than a pound of lead though.....:whistling2:


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## Nailbags (Feb 1, 2012)

123pugsy said:


> I thought pressure was pressure?
> 
> I do know that a pound of feathers is lighter than a pound of lead though.....:whistling2:


PSI is PSI the manufacure of Pex states not to use compressed air and if you do take the rating and divide by three. for safe operations. Theirwords not mine.


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## Thurman (Feb 9, 2009)

@"PoleCat": I also have seen/used the "greenish" colored "plastic" type pipe for compressed air. We ran a lot of this in the mid '80's in our plant. I was skeptical of this at first but it proved to be a quality product. Then just as I was convinced that this was a good product and was useful to us, some contractors came in to run some new fire protection piping using an orange colored "plastic type pipe product". At first thought one may say: "Well, this stuff will surely melt if there is a fire". Yes it will. But by the time the temperature around this pipe gets that hot, the fires too big for the sprinkler system to fight anyway. I currently have my entire shop ran with 1" CPVC piping with four 3/4" drops within the shop. Not one leak since 1996. My training and understanding is that PVC/CPVC will not "explode" if there is a weak spot in the piping. Rather, it will just develop a crack running with the run of the pipe along the piping and allowing air to escape loudly.


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## joecaption (Nov 30, 2011)

CPVC and PVC should never be used for at least two reasons. One if you happen to have a compressor that uses oil, the oil bypasing the ring will degrade the tubing.
And any plastic pipe can expode!!

Pressure is differant for water and gas
So much for Boyle's law.


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## Maintenance 6 (Feb 26, 2008)

Nailbags said:


> PSI is PSI the manufacure of Pex states not to use compressed air and if you do take the rating and divide by three. for safe operations. Theirwords not mine.


Which manufacturer and where can I read that? Seems pretty odd that they would say not to do something and then give you a formula to follow just in case you do decide to ignore their advice.


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## Daniel Holzman (Mar 10, 2009)

Seems like there are a lot of opinions that are not specifically backed up with verifiable facts. Couple of points to bear in mind. From the perspective of a pipe, pressure can come from any fluid, whether that fluid be air, water, mercury, or for that matter any liquid or gas. The pipe from a mechanical standpoint behaves exactly the same whether it is subject to 50 psi from air or water, so there is no basis to the claim that 150psi water is the same as 50 psi air.

Certain types of pipe are not rated for specific chemicals. This is a chemical, NOT a mechanical issue. For example, if you want to carry nitric acid, you need glass pipe, because other common types of pipe degrade when in contact with nitric acid. All plastic pipes have temperature ratings, as they typically weaken with rising temperature, hence their pressure rating is temperature dependent. Dry compressed air should not chemically interact with any commonly available plastic pipe.

If a specific PEX manufacturer states that their PEX pipe is not rated for compressed air, that probably means only that the manufacturer has never tested their product for use with compressed air, hence they are not going to warranty it for that particular use. This says nothing about allowable code use. It also says nothing about whether PEX will work acceptably with compressed air, it simply means that manufacturer is not going to warranty their PEX for use with compressed air. 

I have found a number of articles claiming that PEX-AL-PEX, which is a particular type of PEX tubing which includes aluminum as an air barrier, is acceptable for use with compressed air. I cannot verify this, however a call to Wirsbo or another manufacturer of this particular type of tubing, commonly used in hydronic heating applications, should confirm if it is OK with compressed air.


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## A Squared (Dec 19, 2005)

joecaption said:


> The pipe acts like an accumulator and and increaces the avalible flow to the tool so it does not start off with full pressure then slow down from lack of air.
> Just going from 1/2 to 3/4" increases the flow by about 25%.


You're going to be hard pressed to find air tools outside of an industrial setting that will be limited by a 1/2"pipe. 1/2 " pipe should be good to about 20cfm/100psi for 50' of pipe. Gonna be tough to find an air tool in a home shop that nees even half that.


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## Maintenance 6 (Feb 26, 2008)

Here is a paragraph that will explain the difference between air at pressure and liquids at pressure. PSI is PSI, but the reaction is different. The link to the whole article is at the bottom and comes from the OSHA website.

To Whom It May Concern: 

From time to time, I receive inquiries as to the suitability of using PVC pipe land fittings in compressed gas piping systems. While the benefits of use may be enticing, it is a very dangerous and, in some states, illegal thing to do. For example, MIOSHA (Michigan's branch of OSHA) prohibits the use of PVC plastic in compressed gas systems unless properly encased in steel, cement, or some other approved material. Please check your local and state regulations. 

The main problem with using PVC pipe and fittings for compressed gas is not that it spontaneously explodes but that PVC is a brittle material that can be broken or shattered with external force unless properly protected. Compressed gasses can be best described as being analogous to a coiled spring. When a PVC pipe or fitting fails when under stress from compressed gas it literally explodes like a bomb, sending shards of plastic flying several feet in all directions. Liquids, on the other hand, being compressed by only 1/10th of 1% contain very little stored energy. When pressurized systems with liquids fail, the energy is dissipated very quickly, thereby creating a much lower potential for hazard. 

Colonial Engineering does not recommend the use of PVC plastic pipe fittings in compressed gas service. 

If you have further questions regarding this matter please feel free to contact me directly. 

Sincerely, 

Jack Roach 



ESLON THERMOPLASTICS, INC.
P.O. BOX 15894, CHARLOTTE, NC 28210
DATE: July 11, 1988
704-889-2431 800-438-7881 

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


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## Ibwaldo (Jul 8, 2015)

I also couldn't find a definitive answer to using PEX for air line. So I went to Northern Tool and bought 100 ft 1/2 PVC air hose. Using worm gear clamps and brass fittings I constructed a great system. I can run 150 psi but I'm still using the regulator at the compressor to set tool pressure. 

I also added "wet legs" below each hose connection to catch condensation that accumulates when the compressor is off. An air tank bleeder valve at the end of each wet leg allows me to easily drain the water. ☺


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## TheMasterPlan (Oct 27, 2015)

I've seen so many yellow coiled hoses fail that people use in both shops and manufacting plants that I refuse to waste money on one at home. Now these are under pressure from shop air also. No was was ever hurt by any failures even though they were using the hoses at the times they failed. I've had ends blow off, hose breaks even using them myself. I've never been hurt...scared by the rush of air, but never hurt. 

You did install some shut off somewhere in your system correct? Go get another coiled hose to blow again at a later date, turn on shut off valve and get back to work.

That being said if pex will hold up to 160 @ 70°F that is all I need to know. I plan using it as the main lines inside the walls of my shop/garage. I have a bunch of air barrier pex I bought at an auction. Already have the crimp tool so I just need fittings. If it lasted 5 years like it has for someone else, it will have paid for itself already. 

I would see nothing wrong with it used that way, protected from damage inside a wall cavitiy. Being used as the distribution lines, NOT as a line that would be handled an any way. 

Most shop airlines are exposed to damage, fork lifts, carts, boxes, etc etc. I can see why in industial/manufacting/shipping would have steel pipes. Home use inside a wall by a home owner? Steel is overkill and moisture inside would cause rust in pipes while moisture on the outside would cause insulation issues.

What they get $'s for Rapid Air is insane!
This is a DIY chat correct? Stainless steel air lines??? Really?


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## ron45 (Feb 25, 2014)

Money trumps even health.


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