I would like to replace the old style shut off valve with the new 1/4 turn angle valve. My question is can I just unscrew the red part and screw in a new 1/4 turn one to the blue part so I don't have to make cuts to the pex pipe?

old style shut off valve

1 Answer 1


This doesn't appear to be PEX pipe but a 1/2' or 3/8" compression inlet. Remove the valve by unscrewing the red part and take it to your plumbing supply store so they can attempt to match the compression face and threads. If the compression sleeve and nut come off the pipe easily, take them with you too. Your valve stem is PVC so I'm curious as to why you want to replace the valve.

  • The valve is old and releases black residual after I turn the knob. So I suppose it's time to change it.
    – Ray Cheng
    Sep 13, 2020 at 19:58
  • @RayCheng It's an easy fix to replace it so go to it.
    – JACK
    Sep 13, 2020 at 20:42
  • Okay, I know how the compression nut secure the valve after watching the video. youtu.be/0XmUoCkdhSo I was wondering, how does the valve stay on the plastic tube, there's a compression ring.
    – Ray Cheng
    Sep 13, 2020 at 23:11
  • @RayCheng There will be a compression ring on your tube. It will probably be plastic.
    – JACK
    Sep 13, 2020 at 23:55

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