Sprinkler Valve Problem

[cbutler]

I have six brand-new Rain Bird anti-siphon sprinkler valves that I just installed. Four of them work perfectly, but for whatever reason, the other two leak profusely whenever the valve is opened. The leak is not from a connection issue or from a crack in the valve, the water is rushing from the bottom of the backflow preventer. All six of the valves emit a bit of water when the valves are initially opened, but quickly subside and stop, these two problem valves just keep on leaking. I'd appreciate any advice or speculation regarding a solution.

Thank you

[Irrigator]

It sounds like the backflow preventer is stuck in one position. Or perhaps there is a diaphragm in there that is stuck. This could be due to regular friction, that the valve is really old, or that in assembly two mating parts are pinching a third and inhibiting its normal function.

Either way you could get replacement valves for free or if you are handy open the thing up and see if you can find a pinch in there somewhere.

Let us know what you decide to do.

Irrigator

[Irrigator]

It could also be that you are using pressure above the valve rating. Can you try to install a simple ball valve to restrict pressure up stream?

[cbutler]

I was having the exact same problem with some really cheap valves that were in, so I replaced all six yesterday with "professional grade" Rain Bird valves. I'm quite certain it isn't a problem with the construction of the valve itself, because the problem is occuring at the same two pipes as before. I'd also be surprised if it had anything to do with pressure, as the valves are rated to 150 psi. The pressure coming into each valve should be almost identical, and only 2 out of 6 are exhibiting the problem. My next step is to try adjusting the flow control on the valves to see if I can cut down on the problem.

Thanks again for the thoughts, and I'd appreciate anything else you can throw my way.

[Irrigator]

I will look into these valves some more and see if I can get any more ideas.
It would be really cool if you could snap a photo of the whole thing.

[Irrigator]

From the rainbird website:

Rain Bird manufactures only the highest quality Anti- Siphon valves. Use Anti-Siphon valves in locations where the use of a pressure vacuum breaker (PVB) or doublecheck valve is not required by city codes. Check your local city codes to determine what type of valves are required. Anti-Siphon valves are installed above ground and will prevent back flow if properly installed. Anti-Siphon valves should always be installed at least 6” above the highest head on the valve line, and should never have another valve installed further down the line from the main valve. Our Anti-Siphon valves also feature our patented vacuum breaker–available for automatic or manual applications. All of our Anti-Siphon valves work with any standard sprinkler timer.

[Irrigator]

From the rainbird manual:

Do not use this anti-siphon valve as a main line backflow device, nor as
a master valve. It is not designed nor approved to be under constant water
pressure on both sides of valve. Do not install any other valves downstream.
If installed incorrectly under constant pressure on both sides of valve, it is
possible that the valve will fail or burst.

[Irrigator]

From manual FAQ:

Valve Leaks
1. Around adapter assembly– tighten adapter to body; be sure O-Ring seal
is in place.
2. Leaking at sprinkler heads– remove adapter and replace piston with
Piston Repair Kit (PRK-100).
3. Check solenoid to ensure fully tight (turn clockwise finger tight). Check
solenoid for debris by removing from assembly. Agitate vigorously in a mild
solution of vinegar and water. Reassemble solenoid to body using finger
tight pressure.

[Irrigator]

FYI,

This is how the valve works

[cbutler]

This forum is amazing. Just for your information, I'm using Rain Bird ASVF 3/4" valves. I'm not using it as a mainline backflow device, it is not under constant pressure from both sides of the valve, and there are no other valves installed downstream. There is a possibility that the valves are not 6" above the higher sprinkler head, but that wouldn't explain why only 2 or the 6 valves are leaking. I'll see if I can get you a picture of the set-up.

[cbutler]

For whatever reason (I make no adjustments or modifications), the leak stopped and everything works just fine.