# MP Rotator Design



## daviddsims (Apr 15, 2018)

I just had some concrete poured extending my driveway and now I need to redo my sprinkler system on that zone. I currently have hunter pgp rotors but want to replace them with MP rotators. I have a straight line against the concrete that stretches 65 ft in length and I need 14 feet spray. I'm assuming I need new bodies to put the rotator head in but not sure what model works. Also I'm thinking of the MP1000 90-210 spaced about 15 feet apart. Does this sound right? I've always worked with the PGP heads.


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## Ware (Jan 28, 2017)

daviddsims said:


> I just had some concrete poured extending my driveway and now I need to redo my sprinkler system on that zone. I currently have hunter pgp rotors but want to replace them with MP rotators. I have a straight line against the concrete that stretches 65 ft in length and I need 14 feet spray. I'm assuming I need new bodies to put the rotator head in but not sure what model works. Also I'm thinking of the MP1000 90-210 spaced about 15 feet apart. Does this sound right? I've always worked with the PGP heads.


Yes, you will need to replace your rotors with spray bodies. I would use the Hunter Pro-Spray PRS40. They are pressure regulated to 40psi, which is the optimum operating pressure for MP Rotators.

For the nozzles, I would recommend stepping up to the MP2000 90-210° and turn them down to the radius you need. They are adjustable from 13-21ft. I have some MP1000's (8-15ft) in one zone on my system and my experience has been that they are much more finicky than the MP2000's. I would only use the MP1000's in places where MP2000's will not work.

For proper head-to-head spacing in a 65x14ft rectangular area, I would arrange (12) MP2000 90-210° nozzles in a 6x2 grid - 13ft apart along the 65ft length, and 14ft apart the other way:


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## daviddsims (Apr 15, 2018)

Oh wow thanks @Ware . I didn't realize I would need to add sprays on both sides of the 14 foot pattern. I had planned to just butt the sprays against the new concrete and spray out 14 feet. Do you think I would not get coverage that way?


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## Ware (Jan 28, 2017)

daviddsims said:


> Oh wow thanks Ware . I didn't realize I would need to add sprays on both sides of the 14 foot pattern. I had planned to just butt the sprays against the new concrete and spray out 14 feet. Do you think I would not get coverage that way?


You would get uneven coverage everywhere, and no coverage in the yellow shaded areas.

Here is a good read on the importance of head-to-head spacing.


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## corneliani (Apr 2, 2019)

I have a similar layout along my driveway and, because of some large tree roots making the job difficult I chose to keep only one side of rotors and overshot them into the landscaped area across the lawn. The coverage isn't perfect but it suffices. I ended up with 15' spacing of the heads, shooting approx 18-20'. I'm in a wooded acreage neighborhood so it allowed me that slight 'imperfection' in layout, albeit not ideal.


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## daviddsims (Apr 15, 2018)

@corneliani you used MP2000 heads?


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## corneliani (Apr 2, 2019)

daviddsims said:


> @corneliani you used MP2000 heads?


Yessir. The MP1000s would be hard pressed to hit those distances, no matter the pressure. Not to mention the spray pattern gets all out of whack at higher pressures. But Ware brings up a great point in his linked reference: the precipitation rate is NOT linear. Here's some graphical examples of that, and why the head-to-head coverage is important for efficient coverage.


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## daviddsims (Apr 15, 2018)

@Ware do you think 1 inch pipe with the 12 MP2000 rotators and 70 psi incoming water pressure would be ok on one zone?


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## Ware (Jan 28, 2017)

daviddsims said:


> Ware do you think 1 inch pipe with the 12 MP2000 rotators and 70 psi incoming water pressure would be ok on one zone?


Yes, that would work fine. With 12 nozzles - 4 at 90° and 8 at 180°, you would be somewhere around 7gpm for that zone. At that flow using 1" Schedule 40 PVC your velocity would only be around 2.7 ft/sec, and friction loss would be around 1.4 psi per 100ft of pipe.


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## daviddsims (Apr 15, 2018)

@Ware are the mp rotators worth it over the normal rotors?


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## Ware (Jan 28, 2017)

daviddsims said:


> Ware are the mp rotators worth it over the normal rotors?


I would say it really depends on the location. There are some places where rotors are a better fit (e.g. covering large open areas). For a long narrow rectangular area like that 65x14ft, I would say MP Rotators or fixed sprays are probably the best fit. At 14ft width, you would be at the very bottom end of what something like a Hunter PGJ rotor could be turned down to. The number of nozzles to achieve head-to-head spacing would be the same no matter which type you use.


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