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Thread: Plastic Air Lines

  1. #1
    Join Date
    Apr 2003
    Location
    Greenville, SC
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    73

    Default Plastic Air Lines

    I have seen (first hand) what can happen if one uses PVC for compressed air lines in a shop (not my shop, it was at a former employer's).
    The reviews I have seen on the commercially available plastic air line systems have been mixed. And they are expensive.

    Since I discovered PEX, I have been wondering about using it.
    This video (https://youtu.be/xYwBh5fGOGU) answers my biggest questions:
    "How much pressure can it handle?"
    "What is its fail mode?"

    What are y'all's thoughts?
    Finding creative ways to turn material into scrap for decades.

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  2. #2
    Join Date
    Dec 2004
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    East Coast, USA
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    7,381

    Default

    Install copper air lines. I had a complete F-n blast building my copper air distribution system in my shop. I was very sad when it was done because it was so much fun.

    http://bbs.homeshopmachinist.net/thr...ts-of-pictures
    Work hard play hard

  3. #3
    Join Date
    Oct 2014
    Posts
    327

    Default

    Copper is best and iron pipe will work but over time can rust. The plant I worked in had iron pipe for an extensive air system. I maintained many machines that had flexible air lines all over them and very seldom did one crack. If you go with a plastic I think you want a flexible plastic, not a hard brittle one. Check McMaster for all the different plastic tubing and what it is suitable for. They usually give a pressure rating too.

  4. #4
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    Jul 2005
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    Chester, NH
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    5,439

    Default

    Quote Originally Posted by 3 Phase Lightbulb View Post
    Install copper air lines. I had a complete F-n blast building my copper air distribution system in my shop. I was very sad when it was done because it was so much fun.

    http://bbs.homeshopmachinist.net/thr...ts-of-pictures
    I think a "blast" is what the OP is trying to avoid!

    I've wondered about PEX, too. I definitely prefer working with copper and refuse to use PEX for my house plumbing but it would quite a bit cheaper to plumb my shop with PEX. If you decide to go that route, keep us updated!

  5. #5
    Join Date
    Oct 2006
    Location
    Ivins, Ut
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    1,302

    Default

    The pressure rating of PEX decreases rapidly with even a moderate increase in temperature. It wouldn't be suitable for places where it might get hot, whether from equipment, sunlight or just from compressing the air.

    I've heard there is a type of PEX specifically rated for compressed air, but I haven't looked into it.

    Where I work, ordinary PEX is used extensively for air lines running at 120psi. (several hundred feet)
    Near as I can tell its working fine, and its been there longer than I have.

  6. #6
    Join Date
    Jan 2014
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    In the desert
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    Default

    I've got a little bit of RapidAire 1/2 " plastic air line in my shop, but most my shop is and all the main runs are all 3/4" plastic aluminum laminate. I've had a couple failures. Always a fitting. Never the line. I would have just run steel pipe, but for me it was a matter of time. Fitting up steel pipe is not very forgiving so it takes time.

    On machines I have 5/32 (4mm), 6mm, and 1/4" and never have had an issue. Some of the ancient airlines on my Hurco mill were starting to fail, but being 30 years old I can't complain. The failures were never catastrophic. The brake line is at 120 PSI and it gets shock loads when I engage and disengage the pneumatic spindle caliper brake. The machine has all new plastic line on it now. 400 PSI rated stuff I bought from a trucking supply company.


    FYI: The 1/2" RapidAire line looks a lot like PEX. I am told it is not the same and it does NOT say PEX on the tube like PEX does. I have some PEX for water lines in the shop as well. The blue PEX looks very similar to the Blue RapidAire line, but it "feels" different when working with it. The RapidAire line feels stiffer to me.
    Last edited by Bob La Londe; 01-09-2019 at 12:17 PM.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  7. #7
    Join Date
    Jan 2005
    Location
    Buffalo NY
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    Default

    If you want the PEX to convey the air, it should be up to the task.
    If you want the PEX to absorb heat energy from the air and re-radiate
    it to the atmosphere, then metallic pipe is better for that task.

    -Doozer

  8. #8
    Join Date
    Jan 2010
    Location
    Germany
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    Default

    Quote Originally Posted by 3 Phase Lightbulb View Post
    Install copper air lines. I had a complete F-n blast building my copper air distribution system in my shop. I was very sad when it was done because it was so much fun.

    http://bbs.homeshopmachinist.net/thr...ts-of-pictures
    OK, you can also install an air distribution system when you come over to organize.
    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  9. #9
    Join Date
    Mar 2010
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    1,066

    Default

    RapidAire blue plastic tubing is nylon. I have had about 50' of it around my shop for 100PSI air distribution for about 10 years and have never had a problem. My neighbor had some as well but did have a blow out about 6" long between fittings. His system was only 3 or 4 years old. I did not see the break, but he surmised there was an internal flaw in the tube wall.

    It is easy to run and the O-ring fittings seem to be leak proof if the tube surface is clean and smooth. I like it.

    RWO

  10. #10
    Join Date
    Jul 2001
    Location
    Green Bay, WI
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    Default

    There is another factor to consider when evaluating Air Line possibilities .
    How much air do you use ?
    Copper air lines give you an important benefit not mentioned here.
    Your compressor heats the air when compressing it and some compressors have intercoolers to help reduce condensate
    Copper lines further cool condensate in the lines and allow for the separation before use , so you can get drier air.
    In humid climates and using PVC or PEC or any plastic tubing you are subject to water when higher volume use occurs.
    If you are a painter, this can be a real pain to a airgun

    Rich

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