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Regular PEX for compressed air lines

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rowerwet

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Joined
Aug 10, 2012
Messages
175
Location
Merrimack River Valley
I installed some pex on the drain of the compressor at work, 3/4 reduced to 1/2, then down to 3/8 ball valve.
It is the regular old pex secured with crimp rings.
I did this about 5 years ago and it is still going strong.
I didn't waste my money on an expensive crimp tool, instead I use the $25 tool that is squeezed with vise grips.
 

Hondaracer2oo4

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Feb 22, 2016
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229
Location
Canterbury NH
https://www.zoro.com/superior-tool-.../i/G1547935/?gclid=CM6qkfmEvdMCFU9WDQod3AUNPQ
The only thing you need to be careful about using PEX for compressed air, is not to run it inside a larger pipe. PEX allows oxygen through it, bit not air. You could end up with a pipe full of oxygen according to the rep we talked to.

That's a very interesting statement. Air is made up of a mixture of gasses including O2, nitrogen and a bunch of other gasses. No reason for only 02 to pass through and not any of the other gasses.
 
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tjdux

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Feb 4, 2014
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801
Location
Southern Nebraska
bc7081e1e908cbc90574d01d3372267e.jpg

This is what my outlets look like. I have an air dryer at each one as well.


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Do you have any issues/worries abiut UV exposure to the PEX? I have 3 small windows in my shop and light would hit the pipes at least some. I have no clue how much uv light the windows block.

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rlitman

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Oct 18, 2010
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Long Island
...I have no clue how much uv light the windows block...

Glass does not block all that much UV. Does the sun shine directly in through the windows onto the pipes? You could paint or insulate the pipes, or use window tint.
 

Markfothebeast

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Jul 29, 2016
Messages
419
The UV issue I would think would apply to transparent pex.

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tjdux

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801
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Southern Nebraska
The UV issue I would think would apply to transparent pex.

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I think UV issues pertains to all pex no matter the color. Some are rated for longer outdoor exposure and some basically none at all.

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rowerwet

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Aug 10, 2012
Messages
175
Location
Merrimack River Valley
That's a very interesting statement. Air is made up of a mixture of gasses including O2, nitrogen and a bunch of other gasses. No reason for only 02 to pass through and not any of the other gasses.

According to the sales rep, O2 molecules will go easier than nitrogen, enough that it can make an explosive mixture
 

rlitman

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Oct 18, 2010
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Long Island
I think UV issues pertains to all pex no matter the color. Some are rated for longer outdoor exposure and some basically none at all.

Correct. I don't know what's used to add color to PEX, but I suspect that it is not all that opaque to UV.

Some brands of PEX add UV inhibitors, some do not.

According to the sales rep, O2 molecules will go easier than nitrogen, enough that it can make an explosive mixture

Well, according to this:
http://www.getnitrogen.org/pdf/graham.pdf

You may be onto something, but I'm skeptical.
The diffusion rate is ludicrously slow. The space around the PEX would have to be well enough sealed to capture all the escaping gas (one molecule at a time), and yet be not well enough sealed to build up pressure, because if the pressure equalizes, net diffusion stops.
 
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rlitman

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Oct 18, 2010
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24,579
Location
Long Island
any pex supply's you need can be bought here. lot cheaper than the big box stores and better quality also
http://www.supplyhouse.com/

+1 I've dealt with pexsupply a number of times, and they're fantastic!

They also have a better selection of PEX-A (the best stuff for radiant heating) and expansion fittings than anyone else. According to their website, their headquarters is around the corner from my last job, and I know the block well, as I passed it on my commute, but that was before they were there.

I just wish they had a showroom...
 

thofdahl

Active member
Joined
Jan 31, 2017
Messages
29
Location
Minneapolis, MN
Do you have any issues/worries abiut UV exposure to the PEX? I have 3 small windows in my shop and light would hit the pipes at least some. I have no clue how much uv light the windows block.

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From what I read the red and blue pex is UV resistant. I am not worried about it as this will not be a 10+ year solution. I can't imagine I will be at this shop more than a couple of years. So far so good on the pex.. I like it.
 
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tjdux

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801
Location
Southern Nebraska
From what I read the red and blue pex is UV resistant. I am not worried about it as this will not be a 10+ year solution. I can't imagine I will be at this shop more than a couple of years. So far so good on the pex.. I like it.
Yeah mine may be lifetime. I don't plan on spending my whole life in this home/shop but it could happen. Im thinking the pipe insulation or something.

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sfanale

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Sep 13, 2013
Messages
203
Location
California
I read through this thread last night and found it very interesting since I was planning on plumbing my shop with schedule40 PVC airlines. I have had good luck with using sch40 in the past for that application, but I also happen to have a good amount of red/blue pex lying around from another project which I have been debating what to do with.

So you guys are saying sch40 PVC isn't safe to use for airlines because if it fails it throws shrapnel? Having worked with both materials, sch40 is just so much easier to glue together than dealing with the crimp rings on PEX. Plus, its much cheaper once you account for the cost of all the brass PEX fittings...
 

RAYJAY

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Joined
May 29, 2006
Messages
2,638
Location
UNION DALE PA
I read through this thread last night and found it very interesting since I was planning on plumbing my shop with schedule40 PVC airlines. I have had good luck with using sch40 in the past for that application, but I also happen to have a good amount of red/blue pex lying around from another project which I have been debating what to do with.

So you guys are saying sch40 PVC isn't safe to use for airlines because if it fails it throws shrapnel? Having worked with both materials, sch40 is just so much easier to glue together than dealing with the crimp rings on PEX. Plus, its much cheaper once you account for the cost of all the brass PEX fittings...





th
 

sfanale

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Joined
Sep 13, 2013
Messages
203
Location
California

I did not realize this was such a hotly contested debate on GJ, this was the first I had heard about the PVC issue. To be fair, had this post not been bumped, I may have still never heard of the safety issues with PVC and gone ahead plumbing my garage with PVC so...

Also... just so you are aware, for whatever reason when I searched GJ for "pvc" nothing comes up despite the fact I now see there are several PVC safety threads, so bumping an old post like this is actually helpful to someone who is just becoming active on the forum.
 
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rlitman

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Oct 18, 2010
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24,579
Location
Long Island
Also... just so you are aware, for whatever reason when I searched GJ for "pvc" nothing comes up despite...

It is a limitation in the search here. The search function ignores words with three or less characters. It makes a lot of stuff kind of hard to find.
 

sfanale

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Sep 13, 2013
Messages
203
Location
California
It is a limitation in the search here. The search function ignores words with three or less characters. It makes a lot of stuff kind of hard to find.

that explains so much. I couldn't understand why nothing was turning up for PVC and I had to resort to a google search of the GJ domain.
 

beech1948

Member
Joined
Jun 17, 2011
Messages
13
I'm from the UK so things are possibly different here maybe but PEX is PEX the world over.

I have talked to three PEX manufacturers tech departments and all have said PEX is NOT suitable for compressed air. Even their tech docs say the same thing.

Why a) Oxygen permeable, b)UV degradation, c)only tested up to 12 bar so no safety margin d) PEX sensitive to temperature variations so 70*F will take 12 bar at 100*F will take 8 bar.

Here it is as cheap if not cheaper to use nylon pipe rated for compressed air as PEX/PEX-al-PEX or PEX types A,B or C so that is what I have used. Very satisfied with it.

Al
 
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