PEX backflow prevention

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qwertyjjj

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I'm running a 1/2" PEX to outside (painted for UV protection) where it then splits to a hose branch and a branch for the sprinkler valves.
Is there such a thing as a PEX backflow preventer?
Hose bib vacuum breakers are easy to find but not sure what to put on the sprinkler branch pipe (3/4 polypipe)
 

breplum

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Typically, in mild climate, a drop ear adapter mounted securely to wood, then stub out a brass nipple, then whatever the design calls for, say a brass tee, with hose bibb straight out, then a drop down to a good valve then on to irrigation controls.
Best practice from many pro irrigation installs I see, is to have a pressure reducer right there and operating irrigation at 35 PSI.
 

qwertyjjj

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Typically, in mild climate, a drop ear adapter mounted securely to wood, then stub out a brass nipple, then whatever the design calls for, say a brass tee, with hose bibb straight out, then a drop down to a good valve then on to irrigation controls.
Best practice from many pro irrigation installs I see, is to have a pressure reducer right there and operating irrigation at 35 PSI.
But if you drop down to the irrigation controls like that then there's no vacuum breaker on the irrigation branch only the hose branch?
 

greenmountain

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not sure if this is answering your question but there are "sharkbite" type check valves and backflow preventers, but you can always just go from pex to npt or sweat or whatever... using threaded stuff is no problem esp if you follow breplum's advice and go through a press reducer first

for example: https://www.supplyhouse.com/Dual-Checks-1621000
 

Reach4

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Why would painting PEX with latex paint be a problem?
 

greenmountain

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I would guess that a water based paint might/probably not harm PEX, but petro solvents certainly could.
Also I doubt a water based latex would have much of a bond to PEX... probably peel off after not real long.
 

Reach4

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I would guess that a water based paint might/probably not harm pex, but petro solvents certainly could.
Also I doubt a water based latex would have much of a bond to pex... probably peel off after not real long.
Cohesion should do the job. There should not be mechanical abrasion to deal with. The purpose would be to block UV. I don't know about PEX. Painting PVC is pretty common.
 

breplum

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With irrigation systems, either one uses irrigation valves with anti-siphon on each valve or we use backflow prevention on the system, like Zurn 975XL , Watts 009, Febco 825Y which allows you to use in ground irrigation valves in a valve box.
 
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