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Monday, June 6th 2011, 10:00pm

sprinkler valves keep exploding at off or on

I have 4 stations on an electronic timer. In the past several months of operation, I have had valves explode and crack 4 different times. These are real explosions. Twice I've found big pieces of plastic on the other side of the box that blew from the valve. Details:

--1 inch rainbird in-line sprinkler valves. All fairly new, not older than a year or two

--My yard is a slope. The valves are at the highest point of the hill--one of the stations goes downhill and waters yard 50 feet lower

--When they aren't exploding, when they shut off there is a clanking noise about 10 or 12 times that sounds like someone taking a sledge hammer to the side of the house.

--There are 4 valves total in a manifold all with threaded/collared couplers on sprinkler side and main side of the valves.

Let me know if any other information would help solve the mystery


Supreme Member

Posts: 5,288

Location: Metro NYC


Monday, June 6th 2011, 10:22pm

You need a working pressure reducer upstream of the system, most likely


Supreme Member

Posts: 493

Location: Seattle


Tuesday, June 7th 2011, 12:18am

Sounds like a case of Water Hammer .. While water hammer can be a variety of reasons .The 2 most common for sprinkler systems are 1) High Water pressure and 2) The water velocity in the pipes are traveling too fast and above the code of 5/7 FPS

Find a way to get an accurate water pressure reading

If the pressure is higher then 80 PSI I recommend a Water Pressure Reducing Valve

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