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new nickname:Quaker State
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Discussion Starter #1
Does anyone here know how to size a lawn or garden sprinkler system?
I really don't know how to figure this out unless I install system temporarily on top of ground but don't want to waste the time, materials, and money.
I don't know what my gpm is or how to arrive at this figure, but the sprinkler heads I chose will direct a good spray in a 72 ft radius with 45-65 psi, fed from a 3/4 line and run through a garden hose.
I need to water a huge garden area, 75 ft x 125 ft, or 9375 sq. ft. if that matters.
Have 1" feed directly from well available.
Would like to run at least 3 heads at once. Will reduce 1" line from each individual ball valve down to 1/2 fip to accept the 1/2 mip ocillating sprinkler head.
I elect to turn on or off each ball valve manually to do one section at a time.
I don't even know how many gallons per minute these things put out either, sorry for the cluelessness.
How many heads do I need, and how far apart should they be spaced?
If someone could please help, I will dance at youir wedding.:yes:
Btw, this is not a test. I am for real. Thanks:eek:
 

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new nickname:Quaker State
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Discussion Starter #4
God, I thought you changed your name from Ron. lol
 

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Seriously though, do you have specs on the well and the heads you want to use? You did say this is going to be a manual system right? Do you have a lot plan you could show me? Are we just watering grass or are there a mixture of different plants in different areas?
 

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I do know how to do this stuff. And I know that if you don't have the figures to work with you got nothing. You have to know what pressure you can deliver to how many heads at what GPM. If it's a well, it has to run constantly while the system is on, and it has to maintain a good static pressure.

If I was unsure of what the well will actually produce, I make a guess, based upon what knowledge I have, then I run a test line. Figure your furthest zone from the well - the nearest and furthest heads. Run a main piece of pipe and then branches, saddles, whatever. Loop the line to match the actual distance of the last set. Put the heads on and try it. If you try to design the system without this knowledge, it will fail.

I once designed a system for a church based upon the information they gave me - 2" meter and 2" main line. I measured the distance of the main, which was copper, and figured the loss for the distance. I installed the system and it simply didn't work.

I used Toro spider sprinklers and it should have been fine.

Turns out, the meter was 1-1/4" not 2". The main was 2" but you can't get enough GPM through an 1-1/4" meter, regardless how large the main was. Additionally, the meters here are hooked to the main by the idiot city crews using about three pieces of soft copper into 1" taps and teed together.

Anyway, the church had to pay me to revise the system, since it was their info that was wrong. I had to add a zone and take heads off each other zone.
 

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Ok this is what you need. you do need the Gpm from the 1" line, you then need the Gpm that the head puts out. simple math from there. the manufacturer of the head will tell you the spacing of each head because you need over lap or you will have dry areas. run the 1" line right to the head then step down with the right size nipple. hope this helps. steve
 

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Time how long it takes to fill a 5 gallon bucket then just divide 5 by the time it take like 30 seconds would be .5 ( half minute ) so that would be 10 gallons a minute. also get a pressure gauge and your pressure. then you can look at the specs fr the heads you plan to use to see how many you can get on a zone. I would say don't push it. I would do like a head less than it says to account for loss later.
 

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In addition to the above information: the heads should be spaced in a triangle rather than a square, and in such a way as to work with the prevailing wind.

You must not overpressure the heads because it will result in misting, which ends up evaporating and wasting water.

The bucket trick is a good start. You also have to figure volume loss for distance based upon the type of pipe.

But setting up a worst-case test run like I mentioned in my first post eliminates a lot of the math work.

I always drew a blueprint-sized drawing of the system and had copies made on a blueprint copier. I haven't done any systems for about 20 years, but I still have all the books.
 
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