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TNGW1500SE's avatar
TNGW1500SE
Explorer
Sep 26, 2016

1/2" pex is not 1/2"?

On my 2003 Itasca 30B I had a valve blow apart for my city water fill. I took the valve out and just need to cap it off for now. Went to Lowes and bought a 1/2" pex plug but it's to small. The pipe in the RV says 1/2" pex right on it so I'm lost. The RV pipe is white and sort of clear. What am I missing?

UPDATE: It says "Tuffpex by uponor 1/2" on the pipe. It must be 1/2" inside diameter. The pex at Lowes must be 1/2 outside.
Class A
  • Hank_MI's avatar
    Hank_MI
    Explorer
    Sep 26, 2016
    Dutch_12078 wrote:
    1/2" PEX pipe is 1/2" CTS (Copper Tube Size), the same OD as 1/2" copper tubing. PEX push-on fittings are usually marked that way.


    Yup, have the same tubing in our MH. Sharkbite (1/2" Copper, PEX, CPVC) fitting worked perfectly.
  • usersmanual's avatar
    usersmanual
    Explorer
    Sep 26, 2016
    Dutch_12078 wrote:
    1/2" PEX pipe is 1/2" CTS (Copper Tube Size), the same OD as 1/2" copper tubing. PEX push-on fittings are usually marked that way.


    absolutely correct
  • Dutch_12078's avatar
    Dutch_12078
    Explorer II
    Sep 26, 2016
    1/2" PEX pipe is 1/2" CTS (Copper Tube Size), the same OD as 1/2" copper tubing. PEX push-on fittings are usually marked that way.
  • Jim's avatar
    Jim
    Explorer
    Sep 26, 2016
    And to add even more confusion, there is Pex 'tubing' and Pex 'pipe'. I really like the tubing, the pipe...not so much. But my local hardware stores are carrying the piping and supplies, not the tubing. Gah!

    What your local stores chose to carry depends on your area.
  • time2roll's avatar
    time2roll
    Nomad
    Sep 26, 2016
    This always bugged me too. I cut a piece and take it down to match up.
  • coolmom42's avatar
    coolmom42
    Explorer II
    Sep 26, 2016
    jplante4 wrote:
    TNGW1500SE wrote:
    UPDATE: It says "Tuffpex by uponor 1/2" on the pipe. It must be 1/2" inside diameter. The pex at Lowes must be 1/2 outside.


    Traditionally, tubing is measured OD and pipe is measured ID. I guess it then depends on whether pex is considered tubing or piping. I always thought it was tubing, but I'm not a plumber. I assume that since it needs to interface with piping somewhere in a water system, they went ID.


    This is correct, as I discovered during a recent plumbing project at my home. Pex is listed as ID.
  • jplante4's avatar
    jplante4
    Explorer II
    Sep 26, 2016
    TNGW1500SE wrote:
    UPDATE: It says "Tuffpex by uponor 1/2" on the pipe. It must be 1/2" inside diameter. The pex at Lowes must be 1/2 outside.


    Traditionally, tubing is measured OD and pipe is measured ID. I guess it then depends on whether pex is considered tubing or piping. I always thought it was tubing, but I'm not a plumber. I assume that since it needs to interface with piping somewhere in a water system, they went ID.
  • Effy's avatar
    Effy
    Explorer II
    Sep 26, 2016
    Is the 1/2" inside diameter or outside diameter? Makes a difference as you found.
  • jplante4's avatar
    jplante4
    Explorer II
    Sep 26, 2016
    Sounds like you have PVC piping and not pex and have run into the Inside Diameter vs. Outside Diameter issue when dealing with tubing vs. pipe.

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