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Thread: Flushing copper piping used for compressed air?

  1. #1

    Flushing copper piping used for compressed air?

    Should copper piping be flushed with water after installation to remove flux trapped inside? This is normally done for water systems but I never thought of what effect the flux might have if left inside for air systems. Wiping the outside of the pipe to remove flux is normal practice to stop corrosion. Why not the inside?

  2. #2
    what about a small mouse and put a piece of cheese at the other end.

  3. #3
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    Your question is something I had not even thought of. I am in the process of moving my compressor from the shop to an out building and piping the air back into the shop. Using copper pipe which will probably end up about 120' long.

    Are you using an acid flux? I just went out and looked at my flux. I am using Oatey No. 95 lead free tinning flux.
    Last edited by Robert Hayward; 04-07-2021 at 7:01 PM.

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    Curious, why copper? I can't think of any way to run air lines that more expensive?

    All you need out is the loose solder, just open a dump valve on the end of the line, the air will easily remove the junk, quickly. Works good for periodically clearing the lines of water too.

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    This is the first time I have ever heard it mentioned. I never gave it a thought when I ran my copper lines 20 years ago. I don’t recall having any issues with it.
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    I didn't do anything to my copper air lines in the current shop at all. 'Just got them together, terminated and then fired up the compressor.
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    You should be fine. You there is so little that gets in there I wouldnt worry about it. Half of what you put on the joint exits the pipe. with the remaining half Most of it breaks down as it attacks the surface of the copper. The actual penetration is microscopic.

  8. #8
    Quote Originally Posted by Steve Rozmiarek View Post
    Curious, why copper? I can't think of any way to run air lines that more expensive?
    It was a toss up between copper and galvanized pipe. I have a Ridgid 300 pipe machine so threading wasn't an issue. After factoring in the cost of threaded fittings compared to copper the price (before recent increase) was about the same. In the end I just liked the idea of using copper. Copper has better flow characteristics, is easier to install and is less susceptible to corrosion. In an industrial or commercial setting where the pipe might be hit I think steel is the way to go.

  9. #9
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    In my old garage I did mostly copper but in my current garage I used PEX. I doubt I would go back to something rigid like copper. The PEX runs through the studs next to the electrical.

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    Quote Originally Posted by Steve Rozmiarek View Post
    Curious, why copper? I can't think of any way to run air lines that more expensive?

    All you need out is the loose solder, just open a dump valve on the end of the line, the air will easily remove the junk, quickly. Works good for periodically clearing the lines of water too.

    Copper is good because it acts as a radiator so the air is cooler by the time it reaches the final filters.
    Bill D

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    Quote Originally Posted by Bill Dufour View Post
    Copper is good because it acts as a radiator so the air is cooler by the time it reaches the final filters.
    Bill D
    If he's using that much air volume he needs a good inline drier anyway.

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    Quote Originally Posted by Steve Mathews View Post
    It was a toss up between copper and galvanized pipe. I have a Ridgid 300 pipe machine so threading wasn't an issue. After factoring in the cost of threaded fittings compared to copper the price (before recent increase) was about the same. In the end I just liked the idea of using copper. Copper has better flow characteristics, is easier to install and is less susceptible to corrosion. In an industrial or commercial setting where the pipe might be hit I think steel is the way to go.

    Ok, was just curious why you chose it. I do some residential plumbing so I am quite familiar with PEX, will be putting a few PEX A air lines in my shop next week actually.

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    I did not think pex pipe was to be used with air? I saw a video of pvc being pressure tested and exploding not pretty.

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    Quote Originally Posted by jim sauterer View Post
    I did not think pex pipe was to be used with air? I saw a video of pvc being pressure tested and exploding not pretty.
    PEX is not PVC. I think - I have no experience that PEX failure mode is more to tear or split than to fracture like PVC. Someone please correct me if that is inaccurate.

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    PEX is not PVC and is not subject to shattering. In fact, one of it's endearing qualities in cold climates is that it's less prone to rupturing should the liquid in it freeze and expand. That said, using PEX for compressed air needs a careful installation so that the crimps are done correctly, etc, and the proper crimps are used for the particular PEX tubing being used. (there are multiple types so there's more brand sensitivity)
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