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Low Head Drainage and Check Valves

Discussion in 'Irrigation' started by csmlawn, Aug 13, 2008.

  1. csmlawn

    csmlawn LawnSite Member
    Messages: 106

    When you have a hill type grade and the lowest head on the zone doesn't go down all the way when it shuts off and drains until there is no water left in the pipe, does that mean there is no check valve in the head?

    FYI... All other heads in the zone go down and no water comes out.

  2. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    What is the elevation change?

    If you want to know if the head has a check, then pull the head and "check". ;)
  3. Waterit

    Waterit LawnSite Silver Member
    Messages: 2,931

    A successful diagnosis. You are a sprinkler man!
  4. csmlawn

    csmlawn LawnSite Member
    Messages: 106

    LOL!!! I don't even know what one looks like... anyone have any pics? I've pulled two heads to examine, but the cap screw was on so tight on both I couldn't check them. According to WM, the T3 rotor comes with a check valve... However, my low heads piss like racing horses. The elevation change is about 6 feet (if that).
  5. BrandonV

    BrandonV LawnSite Platinum Member
    Messages: 4,613

    depends on the amount of head. I know that the pro sprays we use will only hold back 10' of head you might need to install an online check valve.
  6. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,150

    Beep beep..warning: the inline check valves eat pressure for breakfast.
    The more head you need to adjust for, the higher the psi loss.
  7. csmlawn

    csmlawn LawnSite Member
    Messages: 106

    Hi Mike,

    Can you explain more on this?
  8. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,150

    The Hunter low-drain check valve is adjustable from 4' to 32'. As the height
    increases, the friction loss does also. It is factory set for 12' with a friction
    loss of 7 psi. With 32' of height, the loss is 15 psi, so you can see the need
    to be very careful adjusting it just enough to prevent low drainage. The amount
    of loss is also tied to your gpm, and the loss can screw you.
  9. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,150

  10. irritation

    irritation LawnSite Gold Member
    Messages: 3,590

    Where's your friction loss data?

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