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Hunter I20 Heads (are my calculations correct?)

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reboot_this

New Member

Posts: 3

1

Tuesday, July 29th 2003, 9:29am

Hunter I20 Heads (are my calculations correct?)

I'm designing a system for my yard and calculating which nozzles would be used on each head and how long I would need to water each week. I don't want to list each zone specifically by writing a novel on this post so I have broken it down to single heads and then combining overlap parameters, two heads at a time, to get a little more specific...

System layout (approx) 60 psi, 18 gpm, all heads here are I20 4" heads.

This first series of calculations does not include the fact that each head overlaps the next so the numbers reflect each head's performance by itself:

90 deg. arc, w/ #1 nozzle: water 60 min 2x/wk nets aprox. 1"/wk

180 deg. arc, w/ #4 nozzle: water 60 min 2x/wk nets aprox. 1"/wk

270 deg. arc, w/ #6 nozzle: water 60 min 2x/wk nets aprox. 1"/wk

360 deg. arc, w/ #8 nozzle: water 60 min 2x/wk nets aprox. 1"/wk


Now with each of my calculations (below), I tried to consider that each head is spraying the next one for proper overlap and in doing so combined the precipitation rate between each head and its overlapping neighbor head (only doing so between two heads at a time for a bit simpler calculation):

90 deg. arc, w/ #1 nozzle: water 30 min 2x/wk nets aprox. 1"/wk

180 deg. arc, w/ #4 nozzle: water 30 min 2x/wk nets aprox. 1"/wk

270 deg. arc, w/ #6 nozzle: water 30 min 2x/wk nets aprox. 1"/wk

360 deg. arc, w/ #8 nozzle: water 30 min 2x/wk nets aprox. 1"/wk

It may be paltry, but did I pass the test on the mystery behind all those pesky different nozzles provided by manufacturers?

Thanks in advance to all!

reboot_this

RVLI

Supreme Member

Posts: 462

Location: USA

2

Tuesday, July 29th 2003, 4:12pm

Yes! You may want to use a bigger nozzle than # 1 for your 90 degree though.

<img src="http://www.rainbird.com/about/imagelibrary/logos/rblogo_black.gif" border=0>

Rock Valley Lawn & Irrigation

Rays Sprinklers

Supreme Member

Posts: 493

Location: USA

3

Wednesday, July 30th 2003, 1:17pm

Sounds great to me!! Like RVLI said you can up the 90 deg...to a 2, because a #1 really doesnt product large water droplets.....

Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers

brochild

New Member

Posts: 3

Location: USA

4

Wednesday, September 21st 2005, 4:51pm

As a new member to this post, I am not 100% about how to calculate precipitatin rate when mixing different heads (1/4, 1/2, full circles ets) so I was wondering
How did your original calculations work out?
Did you change the #1 nozzle to a #2 as suggested?
If so how is the overall design working?

Tom

Supreme Member

Posts: 306

5

Thursday, September 22nd 2005, 1:02pm

a simply precip formula is

Precip= (96.3 x gpm)/A gpm = gallons per minute, A= area in square feet

jcruce13

Active Member

Posts: 13

Location: USA

6

Tuesday, October 11th 2005, 10:48pm

I think you are ok... I assume you are using city water for your sprinkler system and not a pump right?

If you are using a pump then you might want to make sure that each zone has the capability to let out a little less than your pump will put out.

If you are using city water then you dont have to worry about that...

But my rule of thumb for my system is that I start at the beginning of the zone by installing smaller nozzles and gradually get bigger as the zone moves away from the start of the zone. I test the system and make sure all sprinklers are putting out the same water... If the first ones aren't putting out enough I install bigger nozzles in them and keep playing around with it...

Just my 2 cents and Im not a profesional so take it as it lies.

Thanks
-John
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