Has anyone used PEX for compressed air line?

dbonne · May 24, 2013

I took a leap of faith and installed 3/4 pex in my shop walls and ceiling for air distribution. I simply went by the rating of the material as my determining factor, 175 PSI @ 73 degrees, or 100 PSI @ 180 degrees. I am planning to run 125 PSI system pressure and my mean ambient temperature is in the 60-70 degrees. Granted I have this installed in insulated walls and one drop is on the sunny side of the building. I installed the pex close to the ceiling (in the attic) as possible and will have at least R-38 on top of it. I will be running through an air dryer, my hope is that it will cool the air enough to keep my temp's within the pex rating.

Has anyone out there in GF land used pex? What pressure are you running. Give me your success or failure stories. I need that warm fuzzy feeling that I did not screw up just going off of the product ratings.

mayday0017 · May 24, 2013

Have seen several posts of people talking about possibly using PEX but haven't seenanyone do it yet... Post up pics if you have them, they won't help answer your question but at least we will have a documented install...

DirtRoad · May 24, 2013

My neighbor used pex in his shop (massive shop). It was left over from his in floor heat. He said it hasnt given him any trouble and its been up for 12 years. His isnt in the walls though.

uncletater · May 24, 2013

Yep. I just did.

Two friends of mine have done it in the past and they love it.

Mine has been under a pressure test for two weeks at 250 psi and no problems what so ever.

It will not shatter like PVC. I would give it a go. Copper and Iron is a pain in the ****.

DirtRoad · May 24, 2013

I would like to do it also.
i just dont know how to install it, never done it before. Plus i dont know if there is any cost savings or aggrevation savings compared to getting the rapidair kit.

66dave · May 24, 2013

You stated that a majority will be in the wall, but if any part of it is outside the wall
be very careul as pex breaks down with UV light. If the lines run in an area of direct sunlight you may want t cover the lines (latex paint, tape or foam).

A professional plumber friend of mine warned me as I have a water softner in the garage, and due to the way my house is postioned (garage door opening west) in the late afternoon the sun can shine on the piping.

to calculate line pressure change youcould use the very basic univarersal gas law (pv=nrt), hold everything constant with the exception of temp and pressure you can see what your true pressure swings will be.

Jack90210 · May 24, 2013

Subscribed. I hadn't thought of this as a possibility.

66dave · May 24, 2013

I also just noticed you are in southern Idaho, I bet your attic hit 140-150'f in the summer...I am in Meridian, and I know my attic easly hits that daily in July and August.

Where in southern Idaho are you?

dbonne · May 24, 2013

66dave said:
You stated that a majority will be in the wall, but if any part of it is outside the wall
be very careul as pex breaks down with UV light. If the lines run in an area of direct sunlight you may want t cover the lines (latex paint, tape or foam).

QUOTE]

None of the pex is in direct sunlight.

You guys are going to be pissed, I did not take any pictures before I installed the OSB on the walls. I will, however be more diligent from here on out detailing my progress and success.

I gave it a pressure test to 175 PSI and it did not blow apart, well except where I forgot to crimp one of the test plugs. Holy Balls I am glad I wasn't anywhere near where it shot out. Still haven't found it.

dbonne · May 24, 2013

66dave said:
I also just noticed you are in southern Idaho, I bet your attic hit 140-150'f in the summer...I am in Meridian, and I know my attic easly hits that daily in July and August.

Where in southern Idaho are you?

I am Jerome county, My place is 5 miles from Twin Falls. Yes, you are right, the Attic will get that hot in the summer. Hopefully being close to the tin ceiling and under a foot and half of insulation will keep pipe temps low enough.

Highbeam · May 24, 2013

I worry about the temperature of the compressed air PLUS the heat picked up in the attic. When you start using lots of air, that tank gets pretty warm. Anybody have any idea what the discharge temp from the tank is under heavy use?

The pressure rating on the pex is for water. Not sure if that matters, might be that air is easier on the pex since air is compressible and there won't be water hammers going on.

I own the pex crimping tools and want to do the same thing. Sharkbite copper ring compressor tool is less than 60$ at HD for 1/2" and 3/4". Pex is cheap.

You still want to slope the airline to allow water to run to your low points. RUnning pex in free air it will sag and create a bunch of low spots between mounting points. THese will each fill with water over time. Iron is easier to build with a slope.

Stuart in MN · May 24, 2013

mayday0017 said:
Have seen several posts of people talking about possibly using PEX but haven't seenanyone do it yet... Post up pics if you have them, they won't help answer your question but at least we will have a documented install...

It comes up about every two weeks, I think. The trouble is the search function here doesn't recognize words with three letters or less, so looking for previous posts can be difficult.

MScott · May 24, 2013

The main problem I can see with PEX as opposed to copper or iron is that it will be less effective in removing moisture from the lines. The metal piping cools better and thus condenses moisture out of the air. You may need to add an "intercooler" or air dryer if you are doing painting or sandblasting.JMO

66dave · May 24, 2013

"The pressure rating on the pex is for water. Not sure if that matters, might be that air is easier on the pex since air is compressible and there won't be water hammers going on."

Fuild dynamics is the same wither you are using liquid or gas, the primary difference is gas compresses, fluid doesn't (hence hydraulic rams).

DirtRoad · May 24, 2013

Stuart in MN said:
It comes up about every two weeks, I think. The trouble is the search function here doesn't recognize words with three letters or less, so looking for previous posts can be difficult.

Use a wild card, like this:

Pex*

Mr onetwo · May 24, 2013

All I'm going to say on this is there must be a reason that no PEX manufacturer has come out with an airline rated type of PEX.I would be very, very worried about no only the temperature of the system air, but contamination with oil from the compressor.Who knows what the combination of heat,vibration and oil contamination will due to this pipe over time. IMHO Steel,copper and the new-compressor rated aluminum pipe are the ONLY proper and safe materials for this service!I'm all for saving money, but not this way.

DirtRoad · May 24, 2013

I dont see the point when you can get this kit, and its cheap.
http://www.northerntool.com/shop/tools/product_200367525_200367525

To go out and buy all you need to install an air system using PEX, what would be the cost in comparison?

My neighbor used PEX only because he had a **** ton left over after installing his in floor heat.

Abeo · May 24, 2013

66dave said:
"The pressure rating on the pex is for water. Not sure if that matters, might be that air is easier on the pex since air is compressible and there won't be water hammers going on."

Fuild dynamics is the same wither you are using liquid or gas, the primary difference is gas compresses, fluid doesn't (hence hydraulic rams).

The compressible portion has more of an impact than just water hammer. In a failure, compressible gas lines need to be able to arrest a fracture, while liquid lines just need to release the small amount of liquid that is causing the pressure. A small crack in a liquid line could end up being a running/exploding crack in a compressible gas line.

This is the reason that pipeline companies specify different material testing between liquid lines and gas lines; gas lines need to be strong and tough/ductile.

oldtractors · May 24, 2013

I used Pex in my shop. It is now 4 years old with no problems. Very cheap and easy to add addtional drops.

bfarroo · May 24, 2013

DirtRoad said:
I dont see the point when you can get this kit, and its cheap.
http://www.northerntool.com/shop/tools/product_200367525_200367525

To go out and buy all you need to install an air system using PEX, what would be the cost in comparison?

My neighbor used PEX only because he had a **** ton left over after installing his in floor heat.

reading the NT link they list it at 150psi and 70*F? I'm hoping that's a typo. We use nylon airline on our machines at work. I'll have to see what a spool of 100' costs.

94m5 · May 24, 2013

Mr onetwo said:
All I'm going to say on this is there must be a reason that no PEX manufacturer has come out with an airline rated type of PEX.I would be very, very worried about no only the temperature of the system air, but contamination with oil from the compressor.Who knows what the combination of heat,vibration and oil contamination will due to this pipe over time. IMHO Steel,copper and the new-compressor rated aluminum pipe are the ONLY proper and safe materials for this service!I'm all for saving money, but not this way.

Yup.

I've run my shop in brazed "L" Copper, secured to the wall on 1-5/8" uni-strut with cush-clamps. I've seen some janked up air systems before, and turned around and walked out of the shop.

DirtRoad · May 24, 2013

bfarroo said:
reading the NT link they list it at 150psi and 70*F? I'm hoping that's a typo. We use nylon airline on our machines at work. I'll have to see what a spool of 100' costs.

That is only the 1/2 inch kit.
The 3/4 inch kit is rated to 175psi.

zcar751 · May 25, 2013

I'm going to give you a +1 for the PEX. The 150psi @70*F rating of PEX is working pressure and shouldn't be confused with burst pressure. On top of that if it is in an attic or wall your biggest concern is having to chase a leak in the future.

I keep seeing people post about the dangers of PVC and quite honestly in 30+ year being around truck shops and in the water treatment industry the only time I have seen PVC shatter is when someone hits it with something. I have seen iron pipe do the same thing at extreme temperatures. I have had dozens of people tell me about what they had seen after the fact but, none could say they saw what cause the break and none would admit to being involved. :dunno:

Air lines need to be protected and secured from hazards in a shop this includes the build up of water in a system which could freeze and fracture your lines then after thawing rupture.

The most important thing to think about when installing a system is are the materials suitable to the task or function. It doesn't take an MIT Engineer to design a system but it does take a little thought and not all materials are equal.

It kills me that some of the same people who have told me they would never use PVC for air line because it is so dangerous will pull out their PVC potato gun and commence to launching 1/2 lb potatoes 200 - 300 yards. :thumbup:

collmorgen · May 25, 2013

I use PEX in my chemical plant for instrument air, inside and outside. We made sure that we used a UV stable type so that it won't degrade. Running nine years now and no problems.

Mr onetwo · May 25, 2013

collmorgen said:
I use PEX in my chemical plant for instrument air, inside and outside. We made sure that we used a UV stable type so that it won't degrade. Running nine years now and no problems.

What size do you use?Are you sure it's not nylon?I always thought "weatherhead" instrumentation tubing was nylon, but I could be wrong. :dunno:

alberto · May 26, 2013

Mr onetwo said:
All I'm going to say on this is there must be a reason that no PEX manufacturer has come out with an airline rated type of PEX.I would be very, very worried about no only the temperature of the system air, but contamination with oil from the compressor.Who knows what the combination of heat,vibration and oil contamination will due to this pipe over time. IMHO Steel,copper and the new-compressor rated aluminum pipe are the ONLY proper and safe materials for this service!I'm all for saving money, but not this way.

This is incorrect. There are a few, here's one: http://www.ipexamerica.com/Content/Products/MarketSegment.aspx?MarketSegmentId=1#Compressed

Here's another: http://www.northerntool.com/shop/tools/product_200367525_200367525

Mr onetwo · May 26, 2013

Alberto...check your facts.The Ipex material is HDPE/AL/HDPE. Very different than regular plumbing PEX that is being discussed.The NT stuff is compressed air rated nylon...not PEX.This is mentioned on the link page.Same stuff as brake lines on tractor trailers.I still maintain that PEX in a compressed air system is not proven and potentially unsafe.

jerryd68 · May 26, 2013

We have pex ran thoughout our plant as air lines, USDA etc. like the looks of the pex tubing ran in stainless uni-strut better than copper or steel. we have had it in place for several years, we run 120 psi on the compressed air system and it is live 24/7. Never had any problems with it.

Alchymist · May 26, 2013

jerryd68 said:
We have pex ran thoughout our plant as air lines, USDA etc. like the looks of the pex tubing ran in stainless uni-strut better than copper or steel. we have had it in place for several years, we run 120 psi on the compressed air system and it is live 24/7. Never had any problems with it.

What type of fasteners were used on the fittings? Crimp ring, compression, swage?

jerryd68 · May 26, 2013

Mostly they have been the crimp ring style, used with stainless fittings and crimp rings, but in a shop you could you the brass fittings without a problem.

alberto · May 26, 2013

Mr onetwo said:
Alberto...check your facts.The Ipex material is HDPE/AL/HDPE. Very different than regular plumbing PEX that is being discussed.The NT stuff is compressed air rated nylon...not PEX.This is mentioned on the link page.Same stuff as brake lines on tractor trailers.I still maintain that PEX in a compressed air system is not proven and potentially unsafe.

OK, if you want to be pedantic about it, here you go: http://www.ardipex.com/pex-al-pex.php

"Gas and air distribution.
The aluminum layer allows Ardi PEX-AL-PEX pipe to stand high working pressure and prevent oxygen/gases from permeating into pipe. Ardi PEX-AL-PEX tube is freely bent that makes the use of numerous fittings unnecessary. Ardi PEX-AL-PEX pipe is your safe and reliable choice of compressed air, gas and oxygen supply."

http://flexalpex.com/
"Excel PEX AL PEX is widely used for:

• Hot and cold water distribution;
• Radiant heating;
• Underfloor heating;
• Compressed Air
• Installation of Water Heaters
• Installation of Clothes Washers
• Solar energy, air conditioning and refrigeration systems"

uniballer · May 26, 2013

PLEASE, tell me you didnt use those crappy plastic fittings?

djjsr · May 26, 2013

Mr onetwo said:
....... there must be a reason that no PEX manufacturer has come out with an airline rated type of PEX.

I asked a plumbing sales guy if he knew anything about using it for air. He picked up the phone, called a manufacturer and they told him they did not rate pex for compressed air because they never tested it for compressed air.

I find that hard to believe. I'm thinking that if they had a product that they could rate for use with compressed air they would certainly do the testing and take advantage of the market. jmo.

Mr onetwo · May 26, 2013

I give up

...Pex/Al/Pex is not what was being discussed...Pex is different stuff.You guys go ahead and take a chance over saving a few pennies....I trust steel pipe or copper and proper installation methods

jerryd68 · May 26, 2013

almost every machine that moves today has poly air lines up to 1/2" so why is PEX any different, it is pliable and not brittle like PVC. I have personally seen is last for 5 + years in and enviroment that get washed down with caustic cleaners and hot water daily and have never seen and issue with it.

Sureshot · May 27, 2013

Worst case is you have to redo on surface with "other" later.

A local plumber known for trying all kinds of things told me when he tried it it lasted but then one day burst for no reason. I know of shops that have ran it though without problem. I may do the same as you in my next shop.

fury9 · May 27, 2013

From what I've read, using black pipe is what I did and I'm glad, easy and cheap don't seem to go together when you're dealing with 175 psi of air. My neighbor blew off his thumb filling a tire at 30 psi

TheShrine · May 27, 2013

fury9 said:
From what I've read, using black pipe is what I did and I'm glad, easy and cheap don't seem to go together when you're dealing with 175 psi of air. My neighbor blew off his thumb filling a tire at 30 psi

"Off"!?!

.....at 30 PSI?

excavator · May 27, 2013

truck air brake tubing works good at 150 psi or less

http://www.airedup.com/store/index.php?main_page=product_info&cPath=23&products_id=924

http://www.fastenal.com/web/products/details/0431208;jsessionid=JTSPRjSG26nnpspqtvkx91TlGDrrMLkW3MLv72wLyn2HZ22BQL7s!423933937!-799979082

Has anyone used PEX for compressed air line?

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