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

I just changed the nozzles on two zones of Rain Bird 1800 Spray Heads from the MPR to the newer Rotary type. All but two (one in each 7 - 8 head zone) are working fine. My question is: what's wrong with the ones that don't - they spray water but don't rotate?

Following Rain Birds Rotary Nozzle Trouble Shooting list; here's what I've tried so far.
1. Checked nozzle filter screens - they're clean.
2. Checked the home water system supply pressure while a zone is running - one is 31 PSI the other is 28. R.B. specifies a minimum of 20 PSI. Is there a way to check pressure right at a zone spray head?
3. Although they were supposed to be set to maximum at the factory, I checked radius reduction screws by opening them 1/2 - 1 turn - no difference.
4. Cycled zones several times to flush any possible grit from nozzles - no difference.
5. Substituted non-rotating nozzles with another one - no difference.

Since one of the mal-functioning nozzles is on a spray head that is at the end of the (1") water distribution line, I wondered about an obstruction in the line itself. However, the second non-rotating nozzle is in the middle of a seven head zone yet all of the others rotate OK. If there was a clog in the line, it seems like the heads down stream of the non-rotating one would be effected as well.

I've completely run out of ideas. I would very much appreciate suggestions regarding diagnosis & correction of this situation.

Best regards, Richard

Hi Wet Boots. So how would one measure nozzle pressure?

Thanks Wet Boots. Borrowing from your knowledge & my ingenuity, I put together a home made device to measure nozzle pressure using a pressure gauge, a foot of vinyl tubing, a garden hose repair piece & a tubing clamp.

With it, I found that the nozzle pressure (as you surmised) was only 9 PSI - nothing like the 28 PSI home water supply pressure measured at the outdoor spigot. This gadget also helped me to discover a reason why the pressure might be so low. There was one (seriously leaking) head that had sunk out of sight below the sod & was forgotten. Once I found & capped it off, the nozzle pressure went up to 21 PSI. Now the rotary nozzles rotate like they should.

Best regards, Richard