# Help with Design - Head's and GPM and Validation



## Thick n Dense (May 7, 2019)

I'm redesigning an existing system that is was done terribly, this problem seems all too common. 
I determined that I can use the existing zone that add 1-2 additional zones to complete the coverage so it's a partial rebuild/new design.

I measured PSI at on irrigation line before BFP and it was 78's however the line to my meter was 3/4" and my meter is a 5/8".
So I have a lot of questions about rotor head selection and distance throw. I have a bunch of rainbird maxi-paws that I would like to re-use in 1 zone then find a solution for the new ones, luckily my yard is rather square and I think that I can take advantage of longer throwing heads but still have concerns about the math.

This equates to working PSI of 55 and 13 GPM per hunter industries chart... 11 if I subtract 2 for being copper - *is this correct, did I do this math right? *

I'm having problems loading an image but basically my yard is L shaped with a 30x30 ft square and a 45x45 foot square.

*Can I run 4x Maxi paws in the 30x30 zone with one at each corner based off my System Stats? *
https://www.rainbird.com/sites/default/files/media/documents/2018-02/chart_2045MaxiPaw.pdf
According to this link, at 55 PSI and 06 nozzle, I can throw 38 ft with 2.5 GPM.... x4 = 10 which is less than 11, so I think that's good.

4x PGP Ultra's in the 45X45 zone with one at each corner based off my System Stats? 
I'm guessing no, it looks like to get any rotor to throw 40-45' would eat up my entire GPM with a single head solo on a zone. *Am I right with this analysis? * 
*If not, what would you'll recommend for 45x45 square? *

*Also, does the inlet to the sprinkler reduce overall pressure ? *These Maxi Paws have a 1/2" and 3/4" inlet, I'm assuming that using the smaller one will limit the GPM


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## Thick n Dense (May 7, 2019)

As a test today, I removed and capped 1 head and played around with the nozzles on the other 4 and the results of the chart and my measurements seemed accurate. with the heads running the beige nozzle, the impacts were significantly short and having problems returning for the next cycle all while spewing out a ton of water.

This gives me far more confidence in the design for the 45' x 45' area because my analysis seemed correct based off the design principles.

Should I buy the Pro spray body that regulates to 40 PSI ? IS that standard practice or good practice?


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