# MFG Radius Specs VS Actual Throw Radius



## RowdyBrad (Jun 10, 2021)

Hello. First post here so thanks for this great resource.

Secondly, I searched and did read through other posts and threads that touched upon the subject but didn't fully explain or go in to detail.

I have a large section of my property that I am going to add an underground sprinkler to. Approximately 37,000 square feet. I have rectangles, long sections and odd shaped areas so to plan and plumb it correctly I want the radius and overlap to be as accurate as possible.

The question, how accurate are the manufacturer specs (say Rainbird) for distance thrown or radius when the GPM and pressure is accurate. Is it generally within 10% or more accurate when wind isn't a factor?. Looking for input from experienced people that can help me with this.

Brad


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## bernstem (Jan 16, 2018)

I would design for 10% less than the advertised radius.


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## RowdyBrad (Jun 10, 2021)

Thanks. Is that the general consensus?


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## MasterMech (Sep 24, 2017)

RowdyBrad said:


> Thanks. Is that the general consensus?


Most heads have a min/max radius in their spec sheets. Assuming you can supply the required pressure, they will make their max throw. But staying on the upper end of that throw will minimize the amount of reduction you need to make with the radius adjustment. On some heads, this adjustment has detrimental effects on the distribution and efficiency of the head.


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## RowdyBrad (Jun 10, 2021)

Thank you for the input.

I am being very careful to have the gpm, pipe size, friction loss and pressure at the heads be correct so they can run optimally. I am going a fair distance and increasing the main pipe size to decrease friction loss and am using the math from irrigation tutorial to keep the gpm the same to all heads.

I am going to have 2 boxes with 37k sq feet to water. One strip is along the road and the rest will be head to head coverage so I want to be sure I get the distance right first try.


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