What pressure for spraying

Discussion in 'Pesticide & Herbicide Application' started by Casey, May 11, 2002.

  1. Casey

    Casey LawnSite Member
    Messages: 142

    I am new to the spraying business and not sure what types of pressure to use to spray a fertilizer/herbicide mix. The sprayer I purchased is built by turbo technologies has a 5.5hp Honda engine and a Hypro 30 diaphram pump (rated at up to 500psi and 9.5 gal per minute), the gun is a Viton. I want to spray at a rate of 2 gal per minute or per 1000 sq ft, to accomplish this I have to run the system at 100psi. It appears that the other people around here are spraying with about 20 to 30 psi, spray pattern looks coarser like something that would come out of a garden hose end type of sprayer.

    MATTHEW LawnSite Senior Member
    from NE OHIO
    Messages: 665

    All you need to do is do a "bucket check". If you want to spray at 2GPM, simply get a bucket that has a one gallon marker inside. Get a stopwatch and begin spraying at 00 seconds. Stop spraying at 30 seconds. You should have exactly one gallon inside. If not, adjust the regulator up/down until you get the one gallon level. Make sure your strainer is clean each day as the volume will decrease as gunk builds up. Good luck. (Did you get that licence yet?)
  3. Casey

    Casey LawnSite Member
    Messages: 142

    Yes I got the license, that was the first step I made. I have already performed the bucket check, and to get the volume per minute that I want the pressure has to be around 100psi, at that pressure the spray droplets seem to be extremely small and tend to have more problem with drift than I believe I would with a coarser spray pattern.
  4. dougaustreim

    dougaustreim LawnSite Senior Member
    Messages: 488

    Sounds like you have the wrong type of pump for lawn work. Your pump is probably more appropriate for tree spraying and root feeding. We have a diapraghm pump for our tree sprayer, but the lawn units all use centrifugal pumps.

    You could experience serious drift problems at 100 psi, which could lead to significant liablity issues.

    I think you should go back to your dealer and rediscuss your needs.

    2 gpm seems a little on the light side for lawn apps. I like to use between 3-4. The higher volume is a more dilute mix and therefor is not as potent if it does drift to a non target. This dilution means that you need direct hit to do damage. Much safer
  5. MOW ED

    MOW ED LawnSite Fanatic
    Messages: 5,028

    What are you spraying? Many labels will tell you the perferred pressure settings for the type of sprayiing that you are performing. Start there but like was said above, it sounds like you have a tree sprayer with those pressures.
    I spray Millennium Ultra, Drive 75 and Dissolve and I use no pressure higher than 40psi. This is out of a boom sprayer, I don't use a gun, small areas get the backpack. Good Luck

    MATTHEW LawnSite Senior Member
    from NE OHIO
    Messages: 665

    The nozzle on the gun is probably the wrong one. Pressure should not matter if you have the right size holes. I am usually at about 60 lbs and I spray at 2GPM. I disagree about the higher volume spray. It is somewhat true that a little mist of it on a rhodo leaf will not curl it like a low volume mix will, but when trying to get control of small-leaf weeds such as veronica and chickweed, a hotter mix will get better results provided you can move the gun fast enough to hit the tissue.
  7. danzig

    danzig LawnSite Member
    Messages: 103

    I have the same set up but i use a green garde gun. I use a 4 gal per minute nozzle. I think you need a larger nozzle. I had the same problem before so i went to a larger nozzle. Remember dont up the psi for more volume, use a larger nozzle.
  8. Go to lesco and get their Chem lawn gun with the yellow tip.

    You have the worst type of gun to use for lawn apps, it is a mist type.

    Then follow the calibration method posted by Matthew above but use 1 full minute to 2 gallons for the yellow tip.

    I have a lesco 200 gal with a honda and D30, they are all the same to calabrate.

    Now why do you want to spray at 2 gal per a mintue?

    I would shoot more for 1.5 gal per 1000 "Blue tip" from Lesco.

    200 gallons will treat 100,000 sq/ft and that is not a lot of area

    The pump is a great multi purpose pump. Yes lawn apps are done at low volume and CAN be done with the D30 as thousands have done for years.
  9. Tordonista

    Tordonista LawnSite Member
    Messages: 36

    What size hose are you using? How much hose do you have? What kind of spray pattern do you have out of the nozzle?2gal/1000ft is around 90 gal/ac, which is plenty of water. (And pretty close to what most people put out of a hose.) More water gives you a better chance at coverage.
    Low pressue=larger droplets=less drift.
    Take some time just to play with the equipment. Get an area, hard top, gravel someplace where you can see where you're hitting. Play with the regulator, play with the settings on the nozzle. practice until you can get real good coverage at the rates you want. Do this with clean water.
    No matter how light or heavy your mix, what you spray off-target will show a lot more than what you intend to spray.
    Your walking speed has as much to do with how much you're laying down as any other factor (Just as ground speed does in boom spraying) How much volume do you put out at 35-50 psi?
    Adjust your walking speed from there. Practice, measure, and it will become habit.
    If you are more comfortable thinking in terms of 1000sf blocks, measure out a few500sf blocks to practice in. (Give one time to dry while you work on another)If you want to measure by the acre, measure out an 18ft square. Spray it, getting the coverage you need to get. Time how many seconds it takes to spray it.
    Then, spray into a bucket for the same amount of time. The number of ounces in the bucket is the number of gallons you spray per acre. (This used to be on some Dow labels.)
    When spraying with a hose, the operator is calibrated as much as the equipment.
    If YOU put out 100 g/ac, and you want to apply Confront at 1qt/ac (just to make the math easy) you will add 1 pt to your 50 gal tank. 1/2 pt to your 25 gal tank, 3 qts to your 300 gal tank.
    The only important number is the amount of pesticide, or fertiliser, or whatever material it is you are putting down on a particular parcel of ground. You calibrate so you can do that accurately and consitently. If you can deliver coverage with 10 gal of water per acre, that's fine. If you do it with 100, that's fine, too.
  10. Casey

    Casey LawnSite Member
    Messages: 142

    Thanks for the information.......i didn't want to toss the gun out and purchase a new one so I tracked down a different supplier and he is sending me a couple of different tips to try......the company that built my sprayer (I had told them that I wanted to be able to spray at a 2 gal per minute rate with about 50 to 60 lbs of pressure) sent it out with a tip that is rated for .75 gal per minute at 100psi.......I found this out from the new supplier that I am now dealing with.....the hose that I am running is 300ft long and 1/2 inch diameter

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