Actual spray volume vs calibrated spray

Discussion in 'Pesticide & Herbicide Application' started by grassmasterswilson, Dec 7, 2011.

  1. grassmasterswilson

    grassmasterswilson LawnSite Platinum Member
    from nc
    Messages: 4,988

    Got my z spray calibrated at the factory settings. I've been spraying for a few days an keeping a daily record of my measured lawn measurements and gallons of spray used. What I have calibrated vs what I actually spray is off. I know it will be different when u take overlap or small lawns at slower speeds. Heading to check and clean my nozzles now.

    What is an acceptable difference between the two? Trying to get them as close as possible or change my mix to fit. 10%? 20%? Difference?
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  2. Rayholio

    Rayholio LawnSite Bronze Member
    Messages: 1,461

    In my experience, you'll never get the Z very close.... due to variable speed issues.

    I think upto 30% is acceptable (although it makes me cringe a bit).. probably - 10% variation is ideal, but hard to achieve.

    Here's the trick.. NEVER go over, or under the calibrated speed while the sprayer is putting out product.

    Note that the machine moves at a drastically different speed in turns.. and that the boom section on the inside of the turn will apply more product than the outside... It's not a good idea unless the turn is minor, and sweeping.

    So.. I achieved pretty good results by simply NOT turning while spraying. Apply in straight lines, and make sure that your 1st passes around the property allow enough room for full acceloration before the spray is engaged.

    Anything you can't get while turning should be trimmed with the wand.

    Finally.. Calibrate during every fill.. Keep track of how many sq ft since the last fill, and adjust your pressure slightly to compensate.

    One last note... be careful with the spray wand. It puts out a hellofalot at the default PSI.. It really needs it's own regulator.

    Hope that helps!
  3. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    Factor like what you're spraying will make a big differences in the actuary of your calibration. When I blanket spray for Fire Ants with a Thrin calibration is not as big an issues as Herbicide might be. With the Fire Ant Blanket spray I can actually miss strips and still gain control or better yet prevention. But when dealing with Herbicides 10 % should be acceptable but I want to be in the + or - 5 % range.

  4. gregory

    gregory LawnSite Bronze Member
    Messages: 1,083

    i would say i stay within 10% but i spray the same lot everytime since its my house which in a effect gives me great practice. i have got it down to the gallon....
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,794

    Within 10 percent is excellent. But variations in lawn size measurment, terrain, going around round flower beds, curves in the borders all cause inaccuracies.
    Calibrate on a big square lawn with water. Carefully measuring your speed and swath width. Then you will be good. Try to get it between 100 and 110 percent. You never want to be too low.
  6. jad004

    jad004 LawnSite Senior Member
    Messages: 282

    I had the same problem with calibration. I always come out just right on large lawns and about 10% over on small lawns. I figured that was probably ok but now I turn my pressure down 5 psi on smaller lawns and come out pretty close on smaller lawns.

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