# lawn sprinkler math problem

• posted on April 23, 2006, 1:01 am
I have 100 foot by 100 foot with equals 10,000 square feet. I want to water this area without putting any sprinklers in the middle. All sprinklers will be on the outside perimeter. Now I will put a sprinkler shooting 50 feet in the middle of all 4 sides. This will work. The only problem is half my lawn is getting twice as much as the other half. I can put a 10 foot diameter in the middle and put a sprinkler network there. But I'm not sure which the best way is. Any ideas?
Richard

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• posted on April 23, 2006, 1:20 am

If you're running 400 feet of line on one valve you might need to increase pipe size. Alternately, you could run two valves with 200 feet of pipe each. Reduce frictional loss. I would put a couple of 360 pop ups on the center line.
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elizabeth, Baton Rouge, LA
http://community.webshots.com/user/elott63

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• posted on April 23, 2006, 7:00 am

The other thing that you didn't think of is that impact sprinklers and gear driven sprinklers that can throw water 50 feet out also do a horrible job of watering directly infront of the sprinkler. So there will be a 5-10' radius of under watered as well. The way to over come this is to put 1 sprinkler in the 4 corners, and in the middle of each side as well.
Like this: o o o o o o o o
As someone else pointed out, you probably don't want to run 3/4" pipe down the entire run, the pressure loss and flow rate will be too low for the desired results. Use 1 1/2" pipe for your main runs.
-S

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• posted on April 23, 2006, 5:24 pm
Andy writes:
I assume the reason for the "overwatering" is the fact that the 180 degree sprinklers in each side OVERLAP, and NOT because of pipe size or pressure drop...
Why not consider four 90 degree heads, all in the center, facing each side.?"??? That should get rid of the overlap and use the same amount of water......
Just an idea...
Andy in Eureka, Texas

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• posted on April 23, 2006, 6:09 pm
Thanks Andy, 90 degrees is the answer, I will do that and make up for any lawn not being watered with pop ups and set them to whatever degrees I need.
Richard

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• posted on April 24, 2006, 3:18 am
Richard Miller wrote:

You will not have much luck with your 100% overlap which you need on windy days. Run your 4 sprinklers down the middle and do it right. It is too difficult to reinstall the center line after you have installed your system
Derryl snipped-for-privacy@shaw.ca