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Hunter I-20 - Nozzle question

Discussion in 'Irrigation' started by Summett, Jul 11, 2006.

  1. Summett

    Summett LawnSite Member
    Posts: 72

    I have Hunter I-20's and upon closer look, it seems like i have the same nozzles in all of my heads (whether they are 1/4, 1/2 or full arc).

    I am assuming this, but to get the same coverage, wouldn't you have a lower volume rated nozzle in a head that rotates a 1/4 arc, than the 1/2 verses the full arcing head?

    Seems to me the area by the 1/4 arc rotating heads would get 4 times the water than the area with the full arc rotators (that is if they all overlap correctly).

    I guess i'm assuming that they are all rotating at the same speed. Am i wrong in this thinking?
  2. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    No..you are spot-on in the diagnosis. Nozzle sizes allow you to match precipitation rate throughout the system.

    To simplify it, if the full circle heads are rated at 4.0 gpm then the half circles need to be nozzled for 2.0 gpm amd the quarter circles for 1.0 gpm

    Check a Hunter catalog or instruction sheet and select the nozzles that you need to provide the matched flow rates.
  3. Summett

    Summett LawnSite Member
    Posts: 72

    Thanks Jerry! Then one more question for you. By changing the nozzles in the 1/2 & full arc heads to a higher gpm (say if i have 1 or 2 fulls in a 5 head zone), would/could that drastically affect my water pressure for the entire zone?
  4. Keith

    Keith LawnSite Gold Member
    Posts: 3,977

    What nozzles are them now? You may want to start from scratch. Nozzle down the 90 degree arcs, stay the same on the 180's and nozzle up the 360's,
  5. Summett

    Summett LawnSite Member
    Posts: 72

    They all have 3.0 nozzles in them (all of them). i was thinking of doing as you suggested Kevin. thanks for the info.

    But now i think i have another problem. I was checking the nozzle and when i pulled up on one of the heads, the very top of the head (or rubber cap) popped off. I'm having troubles getting that back on without it popping off. Any suggestions on that? Hopefully i didn't ruin the head. :hammerhead:
  6. PurpHaze

    PurpHaze LawnSite Fanatic
    Posts: 5,496

    It's done for. Replace it. I had this same problem the other day with one that wouldn't adjust. When I unscrewed it from the body it fell apart.
  7. PurpHaze

    PurpHaze LawnSite Fanatic
    Posts: 5,496

    We use mostly #6 and #8 nozzles with our I-20 ultras but we deal with a lot more water and pressure than most. Take it from experience with these sprinklers... you might want to consider going up one nozzle size (than true matched precipitation) for the adjustable heads. Better coverage.
  8. Summett

    Summett LawnSite Member
    Posts: 72

    Purphaze, are you saying replace the cover or the entire head? On the Hunter website it says the covers are "permanant", but then i noticed you can by replacement covers as well? :confused: I guess i couldn't tell how it was attached to the head.

    As for water pressure, i think i have a decent amount. I'm running about 55 psi in each zone (5 heads per zone), so i think i have enough to play around with the different nozzles.
  9. PurpHaze

    PurpHaze LawnSite Fanatic
    Posts: 5,496

    Replace the whole sprinkler and return it.

    Pressure only equals distance. I'd increase the adjustable sprinkler nozzles one up to gain additional water in the corners and sides. Experience shows me that it is well worth it regardless what the technical info shows. We learned the hard way with I-40s when we were first converting from Toro 640s to them. Hunter said use the #40 for quarters, #41 for halves and #42 for full circles. We ended up bumping them all up one nozzle and it produced a much better growth/coverage at a lesser programmimng time.

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