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Pex for compressed air lines? Yes please!

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Forum topic by William Shelley posted 02-07-2018 07:18 PM 3418 views 1 time favorited 17 replies Add to Favorites Watch
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William Shelley

592 posts in 1643 days


02-07-2018 07:18 PM

Before anyone gets uppity: PEX is NOT PVC. “Plastic” isn’t a generic thing. There are different kinds of plastic.

I think most of us are in the same boat: dragging cords and air hoses around the shop sucks and it’s a tripping hazard. I don’t have a huge shop, but with the compressor all the way in one corner, I didn’t want to have 40ft of hose on the floor all the time.

I was at home depot the other day and noticed that the one closest to me had their 300ft rolls of radiant heating PEX (with oxygen barrier) at a deep clearance price. For 1/2” pipe, the original price was $119 for 300 feet, it was down to $30 (10 cents a foot). From what I’ve read, the PEX-AL-PEX that is used for radiant underfloor heating is good for air because it has little or no vapor permeability, whereas normal PEX can allow tiny amounts of air (like molecules at a time) to leak through the plastic itself. Anyway, I bought one roll and a bunch of fittings and got to work.

I decided to do this project as though it were a typical water line install – home runs from a manifold directly to each outlet with no fittings in between. Because the pipe was so cheap, even one tee would have been more expensive than the extra tubing I used. Plus, and this is the big advantage of pex, without any fittings or junctions between the start and end of the run, there’s no chance for hidden leaks.

I used a 6-port manifold and did 6 runs overall; four to connections mounted on the walls, and two hoses hanging over my workbench area in the center of the shop.

Six runs might be excessive in a 14×25ft shop, but it opens up the possibility to use pneumatic jigs and fixtures. For example, I added a drop near where my shaper sits, because I want to build a coping sled for it with pneumatic cylinders as hold-down clamps.

My total cost for this project was about $180, not including the crimping tool which I already owned ($65).

-- Woodworking from an engineer's perspective


17 replies so far

View jmartel's profile

jmartel

8195 posts in 2324 days


#1 posted 02-07-2018 07:25 PM

Looks good. One thing I don’t see is any drip legs. It would probably be worth putting one in at each leg to help keep moisture away from the tools. Should only be a few bucks in fittings and extra pipe.

The only thing I’d have concern over is sunlight degradation. I don’t know about Pex-Al-Pex, but for normal tubing it will break down in UV light. Since yours is not hidden, I’d be curious if it will be affected or not.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View Kilo19's profile

Kilo19

99 posts in 400 days


#2 posted 02-07-2018 08:14 PM

Great buy and find. Great way to take advantage of deals and making them work.

“i don’t care about what anything was designed to do, I care about what it can do”. Gene Kranz.

-- Justin

View fivecodys's profile

fivecodys

1203 posts in 1810 days


#3 posted 02-07-2018 09:37 PM

Wow! What a great idea!
I was looking a system called Rapidair.

https://www.amazon.com/dp/B0015A11U2/_encoding=UTF8?coliid=I29WIEGTX6COCK&colid=2XJR9WW365WGM&psc=0

Looks very similar.
Thanks for sharing.

-- I always knew I would grow old, But I expected it to take longer!

View William Shelley's profile

William Shelley

592 posts in 1643 days


#4 posted 02-07-2018 09:41 PM

I am concerned about UV degredation. The fluorescent lights in my shop do emit UV. I bought a roll of red duct tape and since UV light doesn’t penetrate anything solid I figure just putting a strip of duct tape over the tubing will be a good way to make it light-proof. Since it’s indoors, I don’t have concerns about the duct tape falling apart over time or anything.

I’ll wait and see if condensation is a real problem before I do any changes RE: drip legs.

-- Woodworking from an engineer's perspective

View Bill_Steele's profile

Bill_Steele

434 posts in 1906 days


#5 posted 02-07-2018 09:58 PM

Congrats on finding this deal and adapting it to your needs. I think this type of Pex pipe is alot like what they use in those RapidAir systems.

As far as the drip legs or condensation traps are concerned—I purchased an IR GarageMate about a year ago and sweat together some copper tubing to connect it to a hose reel mounted on the ceiling. I installed a drip leg, but I have never seen any moisture come out of the drip leg when I open the valve. I do see a little moisture come out of the tank drain when I drain it. I live in MD so maybe it’s not humid enough here or maybe it has something to do with the size of my air compressor (20 gallon). If I ever try spray painting with this compressor I will consider getting a filter or moisture trap.

View AlaskaGuy's profile

AlaskaGuy

4633 posts in 2483 days


#6 posted 02-07-2018 10:20 PM

https://www.rectorseal.com/plumbing-pex-tubing-uv-light-problems/

There are tried and true methods of running air lines.

-- Alaskan's for Global warming!

View jimintx's profile

jimintx

845 posts in 1759 days


#7 posted 02-07-2018 10:27 PM

I appreciate this post as I am and have been procrastinating on what to do for an in-shop air system for about 3 years now. SO I do have air hoses on the floor.

I thought I had found that PEX-AL-PEX was a different product than
“Oxygen Barrier Radiant Heating PEX Pipe”. For now anyway, I can’t seem to sort out what’s what with these products.

I just checked the H Depot website and found I can buy a 100’ coil of the orange, 1/2”x100’, Oxygen Barrier Radiant Heating PEX Pipe for $35. That’s more length than I need, and not a bad price, but not a fantastic deal like you got, William.

-- Jim, Houston, TX

View Bill1974's profile

Bill1974

126 posts in 3159 days


#8 posted 02-09-2018 09:14 PM

For a compressed air line I would not worry about whether it has an oxygen barrier or not. Drip legs are not a bag idea, a filter and drier on the output of the compressor to is a good idea. Even if pex does get a leak or knocked into it does not shatter like PVC does. There are a few PEX pipes that are stated to be okay to use with compressed air but most don’t explicitly state it. Also double check the pressure rating and what you compressor can put out.

View Woodknack's profile

Woodknack

12399 posts in 2554 days


#9 posted 02-09-2018 09:54 PM

I don’t mean this as anti-pex but I always wonder why people in small or hobby shops don’t use air hose? It’s nearly as cheap as pex and rated for compressed air. Someone once said because it droops but that’s an easy problem to solve.

Could you paint the the pex? That would block UV.

-- Rick M, http://thewoodknack.blogspot.com/

View Kelster58's profile

Kelster58

670 posts in 714 days


#10 posted 02-09-2018 11:02 PM

My wife and I have a cabin. My best friend is my neighbor. When his water heater crapped out. I ran 200 feet of pex from my cabin to his cabin. Just laid it on the ground. Put one of those Shark Bite push connect quarter turn valves on too. We did it “temporarily” so he and his wife would have hot water for the weekend. Ten years later that pex pipe and valve are still laying outside on the ground in the North East Pennsylvania weather. The sun, rain, snow haven’t bothered it yet. It’s a Summer cabin so it gets antifreeze over the winter. I was worried about UV too. Stopped worrying about UV 5 years ago….lol

I think it’s a pretty cool Idea to use Pex for an air line.

-- K. Stone “Tell me and I forget, teach me and I may remember, involve me and I learn.” ― Benjamin Franklin

View William Shelley's profile

William Shelley

592 posts in 1643 days


#11 posted 02-09-2018 11:16 PM



For a compressed air line I would not worry about whether it has an oxygen barrier or not. Drip legs are not a bag idea, a filter and drier on the output of the compressor to is a good idea. Even if pex does get a leak or knocked into it does not shatter like PVC does. There are a few PEX pipes that are stated to be okay to use with compressed air but most don t explicitly state it. Also double check the pressure rating and what you compressor can put out.

- Bill1974

This PEX states 180PSI @ 73F. My compressor maxes out at 125PSI tank pressure and I have it regulated down to about 105PSI.


I don t mean this as anti-pex but I always wonder why people in small or hobby shops don t use air hose? It s nearly as cheap as pex and rated for compressed air. Someone once said because it droops but that s an easy problem to solve.

Could you paint the the pex? That would block UV.

- Rick_M

That was my original plan, to use some garbage braided air hose I bought at home depot that is so stiff when it’s cold that you could use it as a fencepost. But home depot doesn’t carry hardly any barbed fittings for 3/8, and the supply houses near me are usually closed on the weekends, and expensive to boot.

And regarding UV… honestly I might just swap out my T8 fluorescent bulbs with LED retrofits. The LEDs will put out no UV light whatsoever, plus use less electricity. However, this shop really only needs to last me a few years until I can afford to buy or build a larger space.

-- Woodworking from an engineer's perspective

View Greg the Cajun Wood Artist's profile

Greg the Cajun Wood Artist

446 posts in 1116 days


#12 posted 02-09-2018 11:53 PM

I use pex in my shop and love it. works excellent for the air lines I have. My compressor is 170psi and 80 gallons.
I ran a main line down the center ceiling of the shop and branched off of it at 6 locations. I added a filter/regulator at each drop. I also installed an electric automatic tank drain on the compressor.
I do have a section of my shop that has a sandblast cabinet and installed the Rapid-Air hose running fron the side of my compressor tank so I could bypass the tank regulator and use a separate regulator and filter directly at the blast cabinet. The Rapid Air tubing is nice and has a metal core layered inside of it…but I now think it was overkill. It was also expensive and difficult to install compared to the pex.

-- Wood for projects is like a good Fart..."better when you cut it yourself"

View LesB's profile

LesB

1838 posts in 3617 days


#13 posted 02-10-2018 01:15 AM

A quick search of the internet gave limited information on using PEX for air lines. One site showed that there is a PEX made for airlines and it has an aluminum layer sandwiched between to layers of PEX. There was no explanation for the aluminum; better strength, UV resistance ???
My problem with air lines has been that the snap on fittings all seem to eventually leak just a little so I keep the number of them to a minimum.

-- Les B, Oregon

View jimintx's profile

jimintx

845 posts in 1759 days


#14 posted 02-10-2018 04:50 PM

I would not think to install regular air hose as a fixed air distribution system simply because of its smaller inside diameter. Maybe that is overthinking.

After this thread, I am going to skip my prior idea of iron piping, and use PEX. I like the idea of it for all the reasons here, plus i want to learn how to use the connectors and be able to apply that skill in future projects i have in mind around our house.

-- Jim, Houston, TX

View Woodknack's profile

Woodknack

12399 posts in 2554 days


#15 posted 02-10-2018 06:31 PM



I would not think to install regular air hose as a fixed air distribution system simply because of its smaller inside diameter. Maybe that is overthinking.

- jimintx


Air hose comes in different sizes. Hose size is matched to the tools and amount of air you need.

-- Rick M, http://thewoodknack.blogspot.com/

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