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bbxrider

New Member

1

Sunday, August 7th 2016, 1:15pm

height of backflow preventer

some posts say backflow preventer has to be at 6" above highest sprinkler head, some say 12"
any consensus here for the height?
Also the irrigation valves that are "anti-siphon" as opposed to "backflow preventer", I know they do the
same thing but would the anti-siphon have a different minimum height vs a backflow preventer valve?
thanks

hi.todd

Supreme Member

Posts: 480

Location: Houston, Texas

2

Sunday, August 7th 2016, 2:11pm

This is a great question.
You have already brought up good points. It really all depends on which backflow preventer you have.

The PVB or Pressure Vacuum breaker needs to be 12" above all piping, heads, and outlets.
The AVB needs to be 6" above all sprinkler piping, heads, and outlets.
Special note the AVB is not designed to have more than 12 hours per day with pressure on it. This should not affect you with the type of valve you have.
The DC or Double Check Valve Assembly can be installed below grade with proper drainage.
The RP or Reduced Pressure Principle need only be 12" above grade not in a flood zone, plane, or near Fumes.

That is a generally accepted consensus, per manufacture installation instructions.
Another note all of the backflow preventers are testable with differential pressure gauges but for the AVB. The AVB is not testable with gauges.
:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

Wet_Boots

Supreme Member

Posts: 5,135

Location: Metro NYC

3

Sunday, August 7th 2016, 7:29pm

Remember that these elevation differences are not measured from the top of the backflow preventer, so it helps to add more height to the backflow preventer, so that someone performing an inspection can see at least the prescribed difference in height between the highest sprinkler head and the lowest part of the backflow preventer. That covers all bases.

bbxrider

New Member

4

Monday, August 8th 2016, 12:04am

thanks for the reply todd,
can the anti-siphon technology in say a hunter pgv-asv be comparable to any of the 4 backflow
preventer types you have enumerated, and therefore the height requirements?

hi.todd

Supreme Member

Posts: 480

Location: Houston, Texas

5

Monday, August 8th 2016, 8:28am

Happy to add to the information.
Your valve will fit into the AVB category.
So it will need to be 6" above all pipe, heads, and outlets.
Thanks :thumbsup:
:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

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