# Nozzle Sizing



## coreystooks (Aug 6, 2019)

Alright so I've been putting off a full irrigation audit and I'm finally starting to work on it now and have some questions on nozzles. So I've got a 6 zone system running rainbird 5000's with exception to the landscape zone. Checking the rotors this morning I noticed they all have the 3.0 gpm nozzles. Now most of them are 180 arcs but there are some 90 as well as a couple 360. Based on rainbird's recommendation the 90's should have a 2.0, 180's should have 3.0, and 360's should have a 4.0. Is this where you guys would start? I ran a catch cup test last night on my side yard which is made up of two zones that shoot towards each other and got between 0.1"-0.2" running each zone for 25 min. the area with the 360 head is where the lower measurement was recorded.
I still need to run the test on my front and back but just want to make sure I'm going in the right direction.


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## Grizzly Adam (May 5, 2017)

90 = 1x
180 = 2x
270 = 3x
360= 4x

Figure each zone as it's own animal. Solve for x using the highest numbers you have available.

ie: 2, 4, 6, 8

If you are putting water down too fast and seeing run off, try to reduce x.

ie: 1, 2,3,4

360s cover 4 times as much area as 90s, so they need 4 times as much flow to put down the same amount of water over the same amount of time.


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## g-man (Jun 15, 2017)

Try to draw your zones when you do this. Yes, you need the 4,2,1 ratio as Adam described above, but also, you can't exceed the design gpm for the zone.

It is amazing the amount of post we get for systems that have all the nozzles the same from install.


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## coreystooks (Aug 6, 2019)

@Grizzly Adam Thank your for the response, this was my understanding I just thought that a 6 gpm for the 360 sounded really high. I was worried about being able to push that much water. I guess I need to pull a head and check running pressure. Or just throw in the 6 gpm and see what happens.


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## pp6000v2 (Mar 8, 2021)

I'll link to Hunter's doc on matched precipitation rates. It was helpful as I went through auditing my system. I know that how the zones were laid out at install didn't keep up with changes to the property over time (fences added, landscape and shrubbery changes, the shed in the back yard, etc.). I had to do a bunch of math and catch cups to get things even. Many nozzles were swapped for fewer GPMs, not more. It takes one of my rotor zones 23 minutes to put down 1/4", while another rotor zone needs 34 minutes to do the same. The math and catch cups are critical.


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