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What accounts for different PEX ID Measurements?

McMaster Member Posts: 28

I have here PEX from two different manufacturers. One is Infloort Heating Systems BPEX which is installed in my house, the other Rehau, PEXa which I bought part of a used coil (2004) . Both claim to be 3/8". The inside diameters are obviously different as you can see in the picture. The Rehau is about .025 smaller in diameter. 

Any ideas why this might be?

<img src="http://i567.photobucket.com/albums/ss118/gruni42/3_8inchpex.jpg" width="500" height="304" alt="" />


  • kcopp
    kcopp Member Posts: 4,397

    just a slight variation in the extruding machines.
  • McMaster
    McMaster Member Posts: 28

    How common is this between different brands and sizes (1/2", 1")?
  • Ironman
    Ironman Member Posts: 7,354
    I'm not an Expert...

    On the chemistry of Pex, but I can tell you that there's a lot of difference between type A and type B Pex.

    Type A (Rehau) is expandable because it has "memory". In other words, it will return to its original shape and size after expansion. Its life expectancy: up to 200 years.

    Type B is another story. Its not expandable and has a life expectancy of 25 years. Usually comes from china.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • hot_rod
    hot_rod Member Posts: 21,898
    edited October 2012

    is one of the listings that should be on the tube. I suspect the extruder just went a bit out of tolerance.

    I know one company that builds a universial pex fitting that can accommodate tube with ID or OD tolerance issues. The inner part has a taper and dual o-rings, the "olive" or ferrule is segmented to compensate for out of OD or slightly oval shape.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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