Regular PEX for compressed air lines

[tjdux]

Ok ok i want to start by saying i know regular PEX isn't for compressed air lines. PEX-AL-PEX is, but no where local has it.

All i am curious is if anyone here as had problems with using regular crimp rings amd fittings on regular type a pex tubing for compressed air. I already have about 75 ft of 3/4 line leftover from a different project and I own the crimper and i need new hardlines in my shop. 6 years ago when i started my shop i plumbed in PVC hard lines becauae i didnt know any better and inwas advised it would be fine. I haven't had trouble yet but thats no excuse and i want to do better.

Please don't suggest black pipe or copper because thats way out of budget for me and i cant solder copper to save my skin. I have also looked at the rapid air systems and just not finding anything I feel that fits my needs compared to the price they expect. I figure with either pex system i can reuse all the metal pipe fittings and quick connects I already have.

My compressor is a home use 20 gal 125 psi max. Maybe someday I will upgrade to 150 psi but i dont really have the room for it. If i do upgrade i will use a steel cooler/water seperator.

My questions boil down to:

will crimp rings hold 125psi?

Do they make pex-al-pex that works with standard crimper and rings (all my research has come up with are compression style fittings)

Whats the max psi anyone as used regular pex with and not had leaks/problems?

I will probably go pex-al-pex route but i am just curious if anyone using regular pex since its already paid for and just sitting around.

Thanks

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[CrashmanS]

I ran a 3/4 pex line from one room of my shop to the other. Maybe 40 feet. No issues but I do have the air turned off when I don't need it. My compressor runs about 120 psi. Crimped connectors have held fine. But you take your own risk so ultimately it's your decision.

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[hefnerconstructionlc]

I installed it in my grandfather's shop 15 years ago and it seems to be fine. My brother installed pex in his shop 8 years ago and it is fine. I've had it in my shop for about two years and it seems to be fine. With pex it's very easy to make repairs. So should you have something happen down the road, it shouldn't be too difficult to repair. Also regular pex is cheap even if something does go wrong. I wouldn't overthink it but that's just my opinion.

 

[Streetbu]

To answer your question, yes do it now. That will at least get rid of the PVC. It's not ideal, but if it bursts it won't send shrapnel every where like PVC does.

 

[hefnerconstructionlc]

My own empirical data suggests Pex has no problem at 125 psi. I have many times set it up 140 to 150 psi for certain applications. The brass fittings and crimp rings are very durable. The weakest link I think would be the pex itself.

 

[tjdux]

Thanks guys. I figured i was overthinking it. My biggest concern was leaking at the fittings. Had i known the dangers of pvc bursting i would have found somwthing different from the get go. PVC was actually recomended by a local hardware store employee and I didn't look into it any deeper. When someone in my shop did mention something a good while later i figured risk it for awhile.

I always shut off my drop lines with a ball valve right at the compressors regulator ao that probably has helped for them to only be pressurized when in use (my thread taping abilities at that point weren't great) but now with kids running around and a lot more traffic in the shop plus already having thr materials and its not like the pvc is gonna get safer with age.....Im going to switch it all over this spring. Probably sometime this month.

I won't likely contine this thread but I will write a post on my main shop thread when i do change it over.

Thanks again guys.

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[Markfothebeast]

I prefer copper. M rated 3/4" is what I've been using. It can be had fairly cheap.

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[RVDan]

A long long time ago we plumbed the dealership I was working at with 2" ABS. It was great, there was so much volume everything worked awesome.

Then we got a new service manager. He had a fit and deemed the ABS illegal and dangerous. We cut it all out and replumbed it with pex with crimped on brass fittings. It worked fine, it wasn't as awesome as the ABS but it was trouble free for many years.

Then we got a new service manager who made is disconect it claiming it was dangerous and illegal.

 

[rburke65]

Yes....I gave pex for air lines. No problems so far.

 

[tjdux]

A long long time ago we plumbed the dealership I was working at with 2" ABS. It was great, there was so much volume everything worked awesome.

Then we got a new service manager. He had a fit and deemed the ABS illegal and dangerous. We cut it all out and replumbed it with pex with crimped on brass fittings. It worked fine, it wasn't as awesome as the ABS but it was trouble free for many years.

Then we got a new service manager who made is disconect it claiming it was dangerous and illegal.

Thats is similar to one of my worries. The 3/4 pvc i currently have has way more cfm and pressure loss compared to when i make the change to pex. I will probably only notice it with the impact though so i guess thats another excuse to buy a new dewalt 1/2 20v cordless impact. Suposed to have 700 ft/lbs torque

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[Markfothebeast]

There is ABS that can withstand pneumatic pressure, which I never believed was true until I found some 1-1/2" in my attic - and it was clearly labeled for use with air pressure. This is from the 1970's. And then there is PVC. These are two different materials. ABS appears much more durable when I attempted to saw through it. I would not connect PVC nor ABS to my compressor. These are designed to transport my turds and dishwater to the septic tank. I've had a copper compression line whip off the compressor at 155psi. I wonder what a piece of plastic type material would do?

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[Markfothebeast]

Thats is similar to one of my worries. The 3/4 pvc i currently have has way more cfm and pressure loss compared to when i make the change to pex. I will probably only notice it with the impact though so i guess thats another excuse to buy a new dewalt 1/2 20v cordless impact. Suposed to have 700 ft/lbs torque

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The new 1/2" impact has 700ft lbs? Dang. I have the 20v 1/2" from last year. It is rated at 300ft lbs or less I believe. I recall the Milwaukee 18v being 350 or 400. I'll have to check it out if that's true.

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[RVDan]

Yeah we don't use air powered impacts anymore. I don't even use air drills anymore. I'm trying to remember why I even have an air compressor anymore.

Actually at home I'm doing a lot of renovations and run nail guns a lot. I fill tires a lot too.

At work it's mostly for staple guns.

 

[bowhuntr311]

I asked my plumber when building my house about using wirsbo for airlines. He said go for it. Said the wirsbo i had purchased for my infloor heat was rated at 200PSI at 80 degrees. He pointed out if it does blow out its gonna happen at a crimp. Went on to talk about how easy and cheap it would be. I have it ran in my shop but not hooked up yet.

 

[slowzuki]

Two gotchas that I know of:

-2 stage compressor pressures PEX will creep and stretch.
-you really should have some copper before the PEX if you get a bigger compressor. The pressure rating of PEX drops off rapidly with increasing temperature.

RE you soldering skills, its no harder than the crimp rings other than not setting your shop on fire.

1. Emery cloth and shine up the pipe and the inside of the fitting (battery lug brush works well for this too if using 1/2")

2. Put a thin layer of flux on pipe, no brush is needed just give it a twist laying against the little tin. Put copper in fitting and give it a twist to smear the flux around.

3. Heat fitting with propane torch preferably from the bottom, touch solder to the pipe at the top. Just touch the fitting directly for a second to get it to **** the solder, keep it on the pipe once it ***** in. Don't let the torch melt the solder. Old school leaded acid flux solder works much better than the drinking water safe stuff.

4. Once it melts let it **** in solder until there is a little bead all the way around the fitting. Can even be a little bead at the bottom. Stop adding solder if you get drips coming off the bottom.

5. Don't wiggle the pipe for about 15 seconds and you're done. If you care what the pipe looks like in the future wipe the flux off the pipe or it will go green in a few years.

Even if you do a half arsed job with these steps chances are it will work. Air line copper doesn't have the problem of water pipes which is drips of water coming in a cooling your work mid way through.

 

[tjdux]

The new 1/2" impact has 700ft lbs? Dang. I have the 20v 1/2" from last year. It is rated at 300ft lbs or less I believe. I recall the Milwaukee 18v being 350 or 400. I'll have to check it out if that's true.

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Thats specs on paper and I watched a youtube review and both thr Milwaukee and the dewalt with brushless motors hit 1000ft/lbs in reverse torque and rated is 700 each.... also there are videos of them breaking loose semi truck lug nuts. Thats serious cordless tools right there. I don't need one but i sure want one.

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[tjdux]

Yeah we don't use air powered impacts anymore. I don't even use air drills anymore. I'm trying to remember why I even have an air compressor anymore.

Actually at home I'm doing a lot of renovations and run nail guns a lot. I fill tires a lot too.

At work it's mostly for staple guns.

99% of mine is the same, nailers and staplers and car tires.

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[tjdux]

Two gotchas that I know of:

-2 stage compressor pressures PEX will creep and stretch.
-you really should have some copper before the PEX if you get a bigger compressor. The pressure rating of PEX drops off rapidly with increasing temperature.

RE you soldering skills, its no harder than the crimp rings other than not setting your shop on fire.

1. Emery cloth and shine up the pipe and the inside of the fitting (battery lug brush works well for this too if using 1/2")

2. Put a thin layer of flux on pipe, no brush is needed just give it a twist laying against the little tin. Put copper in fitting and give it a twist to smear the flux around.

3. Heat fitting with propane torch preferably from the bottom, touch solder to the pipe at the top. Just touch the fitting directly for a second to get it to **** the solder, keep it on the pipe once it ***** in. Don't let the torch melt the solder. Old school leaded acid flux solder works much better than the drinking water safe stuff.

4. Once it melts let it **** in solder until there is a little bead all the way around the fitting. Can even be a little bead at the bottom. Stop adding solder if you get drips coming off the bottom.

5. Don't wiggle the pipe for about 15 seconds and you're done. If you care what the pipe looks like in the future wipe the flux off the pipe or it will go green in a few years.

Even if you do a half arsed job with these steps chances are it will work. Air line copper doesn't have the problem of water pipes which is drips of water coming in a cooling your work mid way through.

I would certainly use some metal for the first several feet if i do upgrade. There are only 2 reasons i ever see upgrading to a bigger compressor. 1st is bigger impacts but i dont do too much serious auto work and second would be if i get into serious painting. If i did want to paint i would put up an air dryer/cooler system which would all be metal for at least 20 ft.

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[Angelfire]

I've gone with Pex-Al-Pex and have had to order everything in as like you, nothing local. That being said, fittings for me were a bear to find and not cheap. There are crimp on and compression fittings. I've gone with compression just because I didn't feel like splashing out the $200+ for a crimper I'd only use once. This all being said, I do feel like the PAP will work well although I haven't finished the install to test just yet. Another couple of weeks and I should have it tested and I'll know better. Are you planning to run the PEX in the walls or exposed because if exposed, you'll need to make sure you find something that is resistant to UV.
Cheers.

 

[Trey T]

For the sake of technical argument, if you're fine with PVC, then PEX would be an improvement. In term of safety, PEX is a lot more ductile or flexible than PVC, so you won't get shrapnel if it fail. You don't need to be a material scientist or engineer to figure this out, just go to HD and try to bend them.

The down side of PEX is the lower pressure rating: approximately 150psi @100degF. If you're using PEX, I would only load the line at 100-110psi only.

For me, I wouldn't use it simply bc it's more expensive overall to get installed than those Rapidair kits

 

[tjdux]

For the sake of technical argument, if you're fine with PVC, then PEX would be an improvement. In term of safety, PEX is a lot more ductile or flexible than PVC, so you won't get shrapnel if it fail. You don't need to be a material scientist or engineer to figure this out, just go to HD and try to bend them.

The down side of PEX is the lower pressure rating: approximately 150psi @100degF. If you're using PEX, I would only load the line at 100-110psi only.

For me, I wouldn't use it simply bc it's more expensive overall to get installed than those Rapidair kits

Im not fine with PVC now that i know more about it. For me the rapid air seems way more expensive than pex because i have enough line, and fittings and the crimper to do 75-90% of the job from leftovers of other jobs. I have redone my house entirly with pex and a second house partially with it so im familiar with the material and when i consider lefterovers (even though idid pay for them) as free.

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[fourjeepin]

Im not fine with PVC now that i know more about it. For me the rapid air seems way more expensive than pex because i have enough line, and fittings and the crimper to do 75-90% of the job from leftovers of other jobs. I have redone my house entirly with pex and a second house partially with it so im familiar with the material and when i consider lefterovers (even though idid pay for them) as free.

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I agree. But like you, I put in a bunch of pex in my home. The rapid air kits I have seen that are reasonably priced are the 1/2" which is rather small in my opinion. I am going to use the 3/4" pex.

 

[jdieter]

I have pex in part of my shop for 8 years and no problems. My compressor cycles 120-135 but I keep it regulated at 90psi. I'm planning to add a little more pex soon.

 

[softailtom]

Those of you using pex in your shop how are you securing the lines to the wall?

 

[thofdahl]

I have been using the red 3/4 sharkbite brand pex from home depot with the sharkbite fittings and clamps for about 4 months now. Works great, was easy to install, easy to modify, and everything is available at home depot. However after all of the fittings and adapters and crimp tool that I had to buy I'm not sure it was that much cheaper than copper.

 

[RegeSullivan]

I've read enough about pex that I am O.K. installing it and running 125psi and occasionally a run up to 150psi as long as it's not right off the compressor where it's likely to be hot and the ambient temperature isn't over 100 degrees (if it is, I'm not working anyway). So help me understand understand the reason or logic for using pex-al-pex. I understand the reason for using pex-al-pex in a hydronic heating system as an oxygen barrier but a typical compressed air system in a home shop what is the reason?

 

[forAK]

pex-al has an aluminum layer sandwiched between the plastic so it can hold higher pressure. You wouldn't use it per se in a radiant situation unless you wanted to. You would use oxygen barrier pex.

 

[ishiboo]

I think PEX is fine for compressed air. But keep in mind, it is NOT UV stable... at least the regular stuff. Which means if you put it on the walls and have natural light on it, it's not going to last as long.

 

[jbwilkins]

I have been using the red 3/4 sharkbite brand pex from home depot with the sharkbite fittings and clamps for about 4 months now. Works great, was easy to install, easy to modify, and everything is available at home depot. However after all of the fittings and adapters and crimp tool that I had to buy I'm not sure it was that much cheaper than copper.

When I was shopping...once I added all the extras I'd need(crimper, fittings, clips to mount the pipe, etc.) I came to the conclusion that a 1/2" rapid air system was about the same cost......

 

[Trey T]

I have been using the red 3/4 sharkbite brand pex from home depot with the sharkbite fittings and clamps for about 4 months now. Works great, was easy to install, easy to modify, and everything is available at home depot. However after all of the fittings and adapters and crimp tool that I had to buy I'm not sure it was that much cheaper than copper.

ding-ding-ding-ding!!!!

 

[Markfothebeast]

I was one of the guys a few months ago saying not to use Pex for air pressure. But... after using leftover red/blue Pex for various projects, it is much stronger than I first imagined. I accidently drove a drywall screw in to one as well (with a Dewault 20v impact) and the dang screw broke off before it penetrated the Pex!

Pex is a cross-linked high density Polyethylene plastic. I began delving into standard HDPE plastics when I had a plastic washing machine part that cracked which I repaired with a melted HDPE milk jug. The cross linking process improves temperature and chemical resistance. This, from what I've read makes HDPE (Pex) highly resistant to mineral oils.

I was looking in to the data sheets of the HDPE air lines and these appear to be very similar. Unless I missed something... My concern would be the clamps/rings holding up under pressure with excessive heat. I'd definitely not want to get whipped by one that flies off. I don't see Pex shattering like PVC under air pressure. Possibly "ballooning" up. But I'd expect a fitting joint to fail long before.

As far as price, I buy the fittings and rings/clamps online for about 1/4 of the ridiculous store price. The rings/clamps are hugely cheaper online. I'd prefer the crimp rings over the cinch clamps but the cinch tool cost me much less.

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[CrashmanS]

I was one of the guys a few months ago saying not to use Pex for air pressure. But... after using leftover red/blue Pex for various projects, it is much stronger than I first imagined. I accidently drove a drywall screw in to one as well (with a Dewault 20v impact) and the dang screw broke off before it penetrated the Pex!

Pex is a cross-linked high density Polyethylene plastic. I began delving into standard HDPE plastics when I had a plastic washing machine part that cracked which I repaired with a melted HDPE milk jug. The cross linking process improves temperature and chemical resistance. This, from what I've read makes HDPE (Pex) highly resistant to mineral oils.

I was looking in to the data sheets of the HDPE air lines and these appear to be very similar. Unless I missed something... My concern would be the clamps/rings holding up under pressure with excessive heat. I'd definitely not want to get whipped by one that flies off. I don't see Pex shattering like PVC under air pressure. Possibly "ballooning" up. But I'd expect a fitting joint to fail long before.

As far as price, I buy the fittings and rings/clamps online for about 1/4 of the ridiculous store price. The rings/clamps are hugely cheaper online. I'd prefer the crimp rings over the cinch clamps but the cinch tool cost me much less.

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Those rings are tough! I've never had a failure. On brass fittings with crimp rings. My problem was I couldn't get my crimp tool into alot of tight places. I use the cinch clamps for those applications. Good stuff.

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[-Brent-]

Just keep it out of any UV light exposure and you'll be happy with it. The guy I bought my table saw from plumbed the air lines in his shop with PEX and we chatted about it. He was really happy with the cost and ease of install. He's had if for years (it was left over from a plumbing remodel) without issue. He has a pro-level wood shop (just at home) so his use may be different than yours.

 

[Tim C]

The shop I work in has been plumbed with pex since it was built in 1998. The compressor cycles to 175 and the lines run full pressure. We had two failures last year for the first time. Both were drops going to lifts to release the safety locks, and both failed where they ran by a florescent light. The pex felt brittle within two feet of the light, past that it felt like the new replacement pipe did. If you flexed it where brittle it would crack. The pipes split but did not explode. There was no shrapnel (except maybe in our underware, lol, the boom was loud). Anyway we covered the replacement with heater hoses where it ran near a light. I also plumbed my personal two car garage at home with it since it worked out so well at work. Here's a pic of the replacement line.

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[rlitman]

Different types of PEX have different levels of UV resistance. Some are rated to be left out in the sun for days, while some can survive months, as per the manufacturer's recommendations.

Your heater hose sleeving is certainly a good idea. A couple of coats of exterior latex paint would probably be just as good. I ran a PEX line to my sandblasting cabinet outside. I wrapped the line in aluminum foil tape where it goes outside.

The other concern I would have with PEX is with resistance to heat. If you have a small compressor, it might not be a good idea to connect it directly to the tank. And it is a very bad idea to use PEX for the pump to tank link.

 

[Markfothebeast]

Different types of PEX have different levels of UV resistance. Some are rated to be left out in the sun for days, while some can survive months, as per the manufacturer's recommendations.

Your heater hose sleeving is certainly a good idea. A couple of coats of exterior latex paint would probably be just as good. I ran a PEX line to my sandblasting cabinet outside. I wrapped the line in aluminum foil tape where it goes outside.

The other concern I would have with PEX is with resistance to heat. If you have a small compressor, it might not be a good idea to connect it directly to the tank. And it is a very bad idea to use PEX for the pump to tank link.

Or water heater pipe insulation. It can be found cheap enough.

Pex out of the cylinder head would be a disaster. The line can and usually does get hot enough to burn skin. My compressor gets up to 315F at the head outlet on a single fill cycle. I don't plan to use Pex because I need something to dissipate the heat to remove the moisture. The heat is also stressful on the rotating assembly.

I ran 20' of copper - 3/4" M rated piping out of the tank because it helps cool the air before the water separator. I also ran 14' of 1/2" copper tubing from the cylinder head with an inline separator and it BARELY drops the air temperature enough to separate the moisture before it hits the tank.

But if that's already in the setup I'd have no problem running Pex beyond the output water separator.

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[bastage]

So for the diy systems what is everyone using for a clean outlet type deal.

I'm probably going to do pex in my garage and for that the dog eat 90's would do, but I haven't seen them in 3/4. Also of I did copper I'm not sure what I would use the either.

 

[Markfothebeast]

So for the diy systems what is everyone using for a clean outlet type deal.

I'm probably going to do pex in my garage and for that the dog eat 90's would do, but I haven't seen them in 3/4. Also of I did copper I'm not sure what I would use the either.

What do you mean by clean outlet?

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[Markfothebeast]

Here's how I set up my primary lines for the tank/cyl head. It was the cheapest I could do.

At the (green) hose outlet is preferably where I would tee in Pex IF I was going to do so. The lines are simply just additional runs to cool the air. I'm not running a thousands of dollar compressor but I'd like to keep water out of my painting, tools, plasma cutter, etc


The AC condensor is my future possible cylinder head to tank cooler.

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[tjdux]

So for the diy systems what is everyone using for a clean outlet type deal.

I'm probably going to do pex in my garage and for that the dog eat 90's would do, but I haven't seen them in 3/4. Also of I did copper I'm not sure what I would use the either.

Are you meaning how are people clearing water accumulated in the lines out? Really same way as with any other compressed air hardlines. Tee off a quick connect horizontally and then below that run about 12 inches of line then a ball valve. Or have good enough water seperation to not need it.

Do you mean dog eared 90s to attach the pipe to the wall? There are many different clamps to attach pipe down availible. Plastic conduit clamps are my preferred way to run pvc but PEX is plenty tough enough to just use metal. Besides dog ears are not gonna hold the line everywhere. You would want some regular clamps too.

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