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Thread: sprinkler throw height

  1. #1

    Default sprinkler throw height

    I have a K-rain sprinkler that is not evenly watering my grass. Its range is 15-30' and I only need it to throw 15', so I have screwed down the diverting screw (the one that protrudes into the water stream). This makes the water come out almost horizontally in a fine mist. The lawn gradually slopes down away from the sprinkler head, which means that the grass 15' from the head is not getting watered. The water basically flies right over top of it without landing.

    Is there a way to to make this head throw the water in a higher arc (ballistic trajectory) so that the water will be distributed evenly? Would reducing the water pressure encourage the water to come out in a softer arc, rather than a horizontal mist?

  2. #2
    Plumber jimbo's Avatar
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    Default

    Almost all sprinklers need to overlap their spray patterns. That is, they tend to be dry in close, so the next sprinkler on the line needs to reach over.

    Another way of sayin this....if a sprinkler has a 30' radius, they should be spaced 30' apart.

    The Rainbird RainCurtain models are better than most about even spray distribution along the axis.

  3. #3

    Default

    Yeah, I've read that elsewhere. The problem is the location of the heads - if I do a full overlap it would mean I am watering my patio more than my lawn - no exaggeration. The current heads actually dump a ton of water in close - the problem is where two adjacent arcs don't quite overlap

    It looks like the Rain Curtain rotors throw from 15-30 feet, do they make a Rain Curtain for 10-15' so I don't have to use the set-screw that diverts the water?

  4. #4
    DIY Senior Member SteveW's Avatar
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    Default

    When you crank a sprinkler head down 50%, you completely destroy the intended trajectory. Most sprinkler manufacturers show a specification that you can turn down the radius up to 20% or so (off the top of my head).

    Check out a neat line of heads called "MP Rotators." They are like smaller versions of Toro's famous "Stream Rotors" but have smaller radii - down to as low as 8'.

    I replaced a number of spray heads on one of my zones with these, and they work really well. They are particularly good to fix problems like mine, where the original installer put impulse heads and spray heads on the same zone (a no-no) - if you replace the spray heads with MP Rotators, you now have relatively matched precipitation rates.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default head

    You need partial arc heads to keep the water off your patio.

  6. #6

    Default

    I do have partial arc heads

    However if I were to do 100% overlap as suggested it would throw water on the patio even with a partial arc

    I will try the MP Rotators to see if I can get the correct trajectory without cranking down the set screw

  7. #7
    Moderator & Master Plumber hj's Avatar
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    Default overlap

    You are confusing us. IF you have 100% overlap the water will only reach the adjacent head which is already spraying water somewhere. THAT HEAD is the one that should already be spraying onto your patio.

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