pex for air lines?

[phil harold]

I know there is rapid air system
but I saw a shop that had waterline pex for his airlines

pros cons ?
thanks

[Jim Becker]

PEX is designed for liquids and shouldn't be used for air lines. The tubing is "likely" ok, but the fittings are not, AFAIK. There is a similar product out there, however, that is designed for air. A lot of people do a lot of things that they probably shouldn't... ;) In some cases it's merely risky; in others, it's merely life-threatening dangerous.

[Mark Hennebury]

Hey Jim, i resemble that remark.

Many years ago, i used a large clear plastic water filter as an air filter on my airline; it stated on the label that it could take up to 125 or 150 ( don't remember exactly) psi and i was only running 100 psi. so i figured what could go wrong.
It worked well for months, then one day it exploded, like i mean exploded. It sounded like a bomb. It sent huge chunks of razor sharp plastic shrapnel 100' across the shop. Luckily i was the only one in the shop and i was on the other side of the shop safely protected by large machines. My shop was in a huge old mill with dozens of other businesses, everyone on my floor came running to see what happened. So it was a little embarrassing.

The thrills and spills of the "lets give it a try and see what happens" mindset.

It was a similar filter to this one, i don't remember the brand.
395633

[phil harold]

frome a previous thread...

I sent an email to a company that supplies PEX (pexconnection.com) here is what he said when I asked about using PEX for compressed air in a hobby woodworking shop

" Air is routinely used for pressure testing PEX plumbing systems, and we use it here to distribute the air for our air compressor, so I would say that it should not be a problem for you to do that."

Then I asked about exposure to fluorescent lights in my shop. And his reply was:
"For best results, you will most likely need to cover it. PEX should not be exposed to direct UV light for more than 30 days. I will say, however, that the PEX we are using (for water and air) is exposed to direct fluorescent light and indirect sunlight and is performing well. Still, the recommendation is that it not be exposed to UV light."

I used PEX for the first time to move a toilet supply in our basement. It is so much nicer to work with than copper.

[Jim Becker]

PEX is all I use for supply line plumbing at this point, but if I were going to use something flexible in my shop, I'd opt for one of the purpose built products.

Here's what Sharkbite, one of the most readily available manufacturers of PEX products says about this:



Q: Can I use PEX pipe for compressed air applications?
A: No, PEX pipe is not intended for compressed air applications.

[Martin Wasner]

I had pex in my last shop for six or seven years. It worked fine.

Pros:
It's cheap
Super easy to modify.

Cons:
Zero ability to cool air down. I had lots of water issues.
UV supposedly breaks it down over time. I don't know how long that is.

[phil harold]

PEX is all I use for supply line plumbing at this point, but if I were going to use something flexible in my shop, I'd opt for one of the purpose built products.

Here's what Sharkbite, one of the most readily available manufacturers of PEX products says about this:

[/FONT][/COLOR]
sharkbite makes connections, not pipe



https://www.zurn.com/support

But it is okay to pressure test pex with air... check FAQ


Is zurn pex tubing OK for use for air compressor lines.
​Air compressor lines is not an application that's covered under our warranty so we can't recommend it. We have heard of people using Pex for this application but we have no data regarding longevity or potential problems.

[Mike Cutler]

I have installed miles of various types of "plastic" tubing in my career. Most is still in place 35 years later, and still airtight.
The con against using PEX is that the manufacturer doesn't recommend it for pneumatic installations, and the fittings are proprietary and expensive.

Look at Poly-Flo tubing and compression fittings. Much more product line flexibility for installations, and rated for pneumatics. I've installed reels of it.
No plastic tubing is going to be rated for direct sunlight, that a normal person can afford. ;)

[Jim Becker]

sharkbite makes connections, not pipe
I have over 100' of PEX in my home that is labeled right on the product "SharkBite".

[phil harold]

I have over 100' of PEX in my home that is labeled right on the product "SharkBite".

my bad
I have only used thier connectors
pipe:
sioux chief
zurn
Nibco

[Steve Rozmiarek]

There are three different types of PEX, A, B and you guessed it, C. They are made with different processes, and have different amounts of crosslinking, which is what gives PEX it's toughness. Sharkbite and Nibco (and others)are B, some Apollo, Sioux Chief, Aquapex (and others) are A, C is generally considered inferior to A and B and I've personally never even seen it in the wild. A can use all fittings including expander, B and C cannot be expanded. Having used quite a lot of the stuff, I'd be comfortable trying some for airline, but I'd use A.

[James Biddle]

PEX is not rated for compressed air and PEX is susceptible to UV damage.

[Rollie Kelly]

When I put my floor heating system in, I used Pex-Al-Pex ( thin aluminum tubing lined and covered with Pex). It may be the same stuff Rapid Aire uses. It costs a little more than regular Pex, but, it is tougher than woodpecker lips. The fittings I used were brass compression type with nut, and "mucho Dinero". If I ever find my circular tuit, this is what I'll use. I'm not recommending just saying. YMMV!

[Jaromir Svoboda]

I had over 130' of PEX left over when I build my shop, so I used it behind drywall to run air thru entire shop, works just fine.

[Steve Peterson]

I have a Rapid Air system running through my shop. The pipe looks a lot like PEX. Both are flexible so they should not shatter and explode if there is a puncture. PEX should be safe in this regard.

Others have already mentioned that the fittings are not rated for air. This might force the compressor to cycle more often.

[John McClanahan]

I would think the effects of water hammer would be more stressful on PEX than running air through it could ever be. My guess is they don't want a potential lawsuit since they haven't tested it for uses other than water supply.

[Jack Frederick]

When I began my apprenticeship in the pipe trades all the soil pipe was lead and oakum. You could fabricate an entire bathroom on the floor, put it on a Hy-lyft and raise it into a couple hangers and you were done. Then we went to no-hub. As the apprentice I quit working with pipe and got to drill 3/4" Redheads into concrete decks all day for all the hanger that were necessary to keep the pipe where it was supposed to go. Same when we went from welded to Victaulic. If you use the pex, put a lot of hangers on it but let it move and put a hanger on each side of every fitting. If one of the fittings blows you will end up with a metal ended whip flipping around to the distance of the last support. There are plenty of things that can hurt you in a shop. Much of our efforts are in reducing them. I don't want to be doing some close work on a bandsaw when an air line lets go.

[Ole Anderson]

I know there is rapid air system
but I saw a shop that had waterline pex for his airlines

pros cons ?
thanks OK, I am being picky, but you do know you can go back and edit major typos in the thread title?

[Jim Becker]

OK, I am being picky, but you do know you can go back and edit major typos in the thread title?
He can't unless it's only a short time since it was posted...but I did. Thanks for the heads up about the misspelling. :)

Jim
Forum Moderator

[Ole Anderson]

I ran across a website that makes air fittings for pex. http://www.logic-industries.com/airbase.htm I am wondering if they have independently determined that pex is ok for air?
http://www.logic-industries.com/images/AirBase1.jpg

[Lee Schierer]

But it is okay to pressure test pex with air... check FAQ

Pvc pipe is also checked with air pressure but is dangerous to use for an air deliver system.

[Ole Anderson]

Pex is not brittle like PVC. Pex is cross linked polyethylene that is why it is flexible. It should rupture rather than shatter if it fails. Polyethylene is what the gas companies use now for most low and medium pressure underground pipelines and is used for most directionally bored pressure water and sewer lines. Not saying you should use it for air lines, but I would, although I like using copper. Frankly I am using an old rubber 3/8" air hose as a distribution line, probably going on 25 years now, picture doesn't show it well, but it is behind the orange hose hanging on the hook. Notice shock mounts on bottom of legs and tank drain?

[Kevin Beitz]

I would like to see answers on this...

[Martin Wasner]

I would like to see answers on this...

I hdad pex in my old shop, it lasted the six years I was in the space. It works fine.

[James Biddle]

So, I think everyone agrees that the manufacturers of PEX tell you it's not rated for air. Wouldn't the PEX manufacturers love to open a new market for their product if it was safe? Because some people have used it and not had an issue does not make it safe or OK. It means they didn't have a problem with it.

[Martin Wasner]

So, I think everyone agrees that the manufacturers of PEX tell you it's not rated for air. Wouldn't the PEX manufacturers love to open a new market for their product if it was safe? Because some people have used it and not had an issue does not make it safe or OK. It means they didn't have a problem with it.


If you think anything is safe, or okay, I want what you're having. Anything and everything can and will fail. Usually at the least opportune moment.



Who knows why they don't? My guess is they can barely keep up with demand as is as they keep pounding up plants and warehouses, and getting some osha/CEL rating for compressed air probably costs a bloody fortune. Second guess is it is worthless at low temperatures. -40º does weird things to plastics and it might become a claymore at 100 psi at those temps. Who knows. It worked just fine for me, and it worked just fine for the cabinet shop up the street from me. And, I was running 180psi in the old shop. Way more than you need.

If you don't want to use it fine. It's cheap, it's ugly, it's easy to modify, and it holds heat way too well. When I plumbed my new shop for air, I did it all in aluminum pipe. I don't know why you'd bother with anything else after putting that system together.

[Mike Cutler]

I would like to see answers on this...

There is only one answer;
Stay within the manufacturers design basis criteria, or accept the risk of operating outside of it.

As I stated earlier, I have installed reels, upon reels, of flexible tubing for a living.
Would I use PEX for air at home? Yes, I wouldn't hesitate.
Would I let someone pay me to install PEX for air? No!

[Bill Dufour]

Note that PVC pipe inside a shop takes about 20-30 years to breakdown and fail catastrophically. Pex is not supposed to be left outside in the sun for more then 30 minutes or so. If pex is going to fail in compressed air duty how long will it take for the stresses to let go? Anyone have a shop plumbed in pex 30 years ago? is it protected form sunlight by the windows? What is the plastic pipe that got banned about 10 years after it was first allowed for water.
Bil lD

[Mark Bolton]

Pex is not supposed to be left outside in the sun for more then 30 minutes or so.

Where in the word does that come from? 30 minutes? We have plumbed numerous ground up homes with pex that probably saw more than 30 minutes of sun between manufacture and delivery to the job. Are the reels rushed from manufacturing to the delivery trucks with strict log sheets as to how often the door was opened on the tractor and trailer? Then unloaded at the distributor in the dark of night? Delivered to our plumbing supply house and then to us strictly under the darkness of night? What about a facility floor or a pole barn for that matter that has radiant in the floor? Do they cover the tubing with napkins while they attach it to the mesh so its ready for the concrete truck to come in a couple days and deliver the concrete? The reels are shipped in clear shrink wrap for gods sake? They are not even in a box?

Excuse my sarcasm but we have installed MILES of pex in homes, concrete, and so on,..... 30 minutes? Thats just plumb nuts.

I would NEVER install PVC air lines in my shop, and we have installed miles of PVC. And I probably wouldnt install pex either because we run 175PSI mains and it gets warm in here so the 160 PSi at 7X degrees F would shy me away even though Im sure it would hold and I wouldnt be worried about at deadly failure.

These things are hilarious to read. Why in the world would I ever plumb my, or someone elses, home with a material that was so fragile that a mere 30 minutes of sun exposure is an issue? That makes ZERO sense. There are more than 30 minutes of reflected sun exposure in a basement with 2 small windows in it to fry the pex? The pex in a new home is often going in while the home is wide open, no windows, being roughed in... the reflected sun is hours, weeks, months.

Now people will talk about he UV from fluorescent lights and the pex... good god.

[Mike Cutler]

More info
Here is a link the engineering specs for PEX. UV exposure is 1.5.2. 60 days is defined as a short time period that PEX can be exposed to.

https://api.ferguson.com/dar-step-service/Query?USE_TYPE=SPECIFICATION&PRODUCT_ID=2886838

[Mark Bolton]

Sure. Sixty days.. sitting on a pallet, outside a neglected job site, in clear shrink wrap, in full sun every day, in death valley or Arizona.

Kroikies. Let's get real here people.

[Steven Wayne]

For the life of me I can't understand why anyone would risk anything in this realm, thinking they know better than the manufacturer and the products ratings.. I have a mix of Rapid Air MaxLine and FastPipe. It's great stuff. Easy to work with. The MaxLine is pex-al-pex and is rated for compressed air. I am certain if something happened and insurance got involved using something not rated for compressed air would be their easy out of a claim.

[Brad Adams]

The MaxLine is pex-al-pex and is rated for compressed air.

It’s not pex. It’s hdpe plastic. Pex doesn’t like the oil in compressed air lines.

[Ole Anderson]

It’s not pex. It’s hdpe plastic. Pex doesn’t like the oil in compressed air lines.

PEX is cross linked polyethylene, very similar to HDPE. It is rated at the same pressure for motor oil at 73 degrees as for water, only at 140 degrees is it derated to 50%. So that argument does not stand unless you run PEX directly from the compressor where heat may become an issue. Heat rapidly diminishes as you distance yourself from the compressor. Interesting that in the attached table, they rate PEX at 100% up to 180 degrees with nitrogen.

Certainly the expensive HDPE-AL-HDPE product from MaxAir would be an even better choice.

"PEX has significantly enhanced properties compared with ordinary PE. ... Almost all PEX used for pipe and tubing is made from high-density polyethylene (HDPE). PEX contains cross-linked bonds in the polymer structure, changing the thermoplastic to a thermoset." If you believe the internet.

https://mrpexsystems.com/wp-content/uploads/2016/04/MrPEX-Chemical-Resistance-Chart.pdf

[Brad Adams]

I’m just going by what the manufacturers tell us. I’ve been installing pex since it came out. There are better alternatives.

[Steven Wayne]

I have the MaxLine and FastPipe stuff in my shop. I feel it was well worth the relatively low cost. I have over 300 ft of tubing and dozen or so drops. Zero issues with it and installation went well.