SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

What kind of pressure are they getting? Can you throttle down a zone valve?

Quoted from "MrMarkSH"

60 psi at the pump, maybe higher (downhill) at the riser, but they have 30 psi pop-ups.

I'm not a sprinkler pro, so this is just a thought. Maybe the regulator in the 30 psi pop up body isn't regulating right and letting too much pressure through? Does it spin fairly fast right away when you replace a mp rotator or spin normal and gradually increase over time, or does it spin normal for however long and suddenly go crazy the next? How long is it taking them to fail after you install them?

It's easy enough to measure the pressure at the fast spinning heads to find out if there is a pressure problem with the body regulator. SW sells a fitting that connects to the pop up riser of the sprinkler body. the MP rotator screws into the top of the fitting. there is another port on the side of the fitting to connect a pressure gauge, so you can measure the pressure at the problematic sprinkler head. I got one recently and its nice to know what the pressure actually is at the sprinkler head if there is any question about it.

Other than maybe a pressure issue wearing them out, I really don't yet have enough experience with MP rotators to know what a reasonable life span of them would be while operating under reasonable conditions.

I haven't used the MP's a lot. Or any rotory nozzle. I recently experimented in a guys yard with low pressure and an odd installation job. Nothing covered right. I installed the MP's on part of the lawn and the Rainbird rotory nozzle on the other part of the lawn. The entire lawn's in direct sunlight.
Right off the bat the Rainbirds looked better. They have a nice spin to them and a nice pattern. Very pretty to look at.
The MP's turned super slow with tiny streams of water. I thought they were broken.
After a couple of weeks the Rainbird section was nice n green and the MP's had brown spots all over. So I went back and replaced 14 of the MP's with the Rainbirds. Everything's green now.
I beleive the MP's can run on less water than the Rainbirds but I haven't read the specs.
Rainbird Rotory Nozzle