I'm currently installing a double check backflow preventer and code says that it needs to be able to be "spun/turned out" for maintenance if required - this is the valve in question.

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Now the pipe that is going into either end of the valve is 1/2" pex and I'm using this 1/2" Brass PEX Barb x Male Pipe Thread Adapter to make the join.

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Given that the pipes wont spin, I'm wondering how I make it easy to "spun/turned out" without cutting the pex?

If I spin the value it will alway get tighter at one end... is the idea that I only half screw it in at end to allow it to spin up that thread whilst coming off the other end or should i be using female adapter on the end of the pex and a male/male adapter which can be spun? Or do I just remove the pex clamp at one end hence disconnecting it from the pipe?

I've seen PVC unions which would make this easy but I haven't seen the equivalent for pex.

  • (Hoping the home centers are seeing this post, so they can make the good Pex unions more commonly available)
    – NPM
    Aug 11, 2017 at 0:36

1 Answer 1


If you don't want to convert over a copper union to Pex (which would probably require a little pipe sweating), the Pex unions available are pretty cheesy pieces of junk.

Luckily for you, Pex will twist on it's own fitting. I wouldn't suggest doing it very often, but the once or twice you may have to remove that fitting from the check valve for "inspection", you'll be fine.

  • Thanks for the help! Whats a copper union look like? I don't mind doing it right if I can... I just didn't know what one would usually do in this case.
    – anthonyv
    Aug 11, 2017 at 2:38
  • It looks like this is what I need youtube.com/watch?v=aFpZfr0YQ28 (see second half of the video), but I can't find it at HomeDepot... maybe I'm not looking for the right thing?
    – anthonyv
    Aug 11, 2017 at 3:58
  • 1
    Oh I think I have it, would this work? supplyhouse.com/…. I'm guessing I could use this instead of 1/2" Brass PEX Barb x Male Pipe Thread Adapter?
    – anthonyv
    Aug 11, 2017 at 4:07
  • That's the one. Not usually available locally, but if you can wait for shipping that will make a professional-looking job.
    – NPM
    Aug 12, 2017 at 11:09

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