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master valve and backflow preventer
I'd like to have a master valve on my system. My backflow device would be a PVB. Is it alright for the master valve to be in front of the PVB? Or does the PVB need to be under constant pressure in front of the master valve? I was wondering because the online installation guides at Watts Regulator website says that to properly place a PVB into service you first open inlet valve to pressurize the PVB and then open the outlet valve. If I had master valve opening and closing all the time in front of the PVB, then I guess the PVB would spit out a bit of water every time right? But would it prevent the PVB from properly protecting against backflow?
Here is what I do:
Install the PVB, then take the pipe down into the ground and elbow it. Add a foot or so of pipe to that elbow then thread/glue on the master valve. It's better off to just install it after the PVB and put it in a 6" valve box.
Definatly after the PVB. Not only does the PVB need to be before everything, but you are right that when the valve opens and closes there is a chance the PVB will start gishing water. It has to be under constant pressure
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers
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