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Friday, July 13th 2012, 2:16pm

Hunter MP rotors not working properly

Rotors not opening or rotating.

I just got my shipment of Hunter MP rotors. I attached four of them to shrub adapters on 4" risers. There are four rotors on the circuit of 3/4 plastic pipe. The water pressure at the valve is about 50 psi. When the valve opens two of the rotors appear to work properly (although I am disappointed with the radius). The other two just won't pop consistently and when the do they aren't rotating.

Any suggestions?



Friday, July 13th 2012, 2:25pm

All the symptoms of low pressure.
When you say "won't pop consistently" what do you mean? Are they directly on the riser or on a popup on the riser?
Which models/patterns?




Friday, July 13th 2012, 2:38pm

3 MP3000 90-210
1 MP3000 210-270

they are on a Hunter shrub adapter directly on a 4" inch fixed riser. The rotor itself is not opening all the way each time.

I did not expect 4 rotor on a 3/4 inch circuit to be a problem at 50 psi. The farthest rotor is about 50 ft from the valve where the pressure is measured. I don't have the needed fitting to measure the pressure at the rotor right now.





Friday, July 13th 2012, 3:35pm

After using a head loss calculator it looks like the 3/4 pipe is causing a head loss of about 9psi so I am down to 40psi at the rotor. May have to upgrade to 1" or larger pipe.


Friday, July 13th 2012, 3:36pm

These are variable nozzles.
PSI counts but at some point GPM is more important.
Depending on how you have them set you use from 5.25 to 10.17 gallons per minute.
For a 3/4" PVC pipe you have either Class 200 or Schedule 40.
Class 200 allows for 10 gpm design volume.
Schedule 40 allows for 7 gpm design.
If you have a 3/4" sch 40 pipe it is possible you are overdrawing your supply.




Friday, July 13th 2012, 3:43pm

I'm using 3/4 in, 100 psi coil poly.


Supreme Member

Posts: 309

Location: Northern New Jersey


Saturday, July 14th 2012, 7:51am

What is your GPM at the rotors??????????

Check for debris under the heads

These heads are adjustable. Move the lower ring to adjust when water is flowing

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