{"id":32980,"date":"2025-04-28T12:23:56","date_gmt":"2025-04-28T16:23:56","guid":{"rendered":"https:\/\/extension.umaine.edu\/publications\/?page_id=32980"},"modified":"2025-05-20T08:35:32","modified_gmt":"2025-05-20T12:35:32","slug":"2097e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/publications\/2097e\/","title":{"rendered":"Bulletin #2097, Boom Sprayer Calibration"},"content":{"rendered":"\n

Bulletin #2097, Boom Sprayer Calibration (PDF for printing)<\/a><\/p>\n\n\n\n

By Lily Calderwood, PhD., Wild Blueberry Specialist and Associate Professor of Horticulture, University of Maine Cooperative Extension and Jordan Parks, Wild Blueberry Research Technician, University of Maine Cooperative Extension.<\/em><\/p>\n\n\n\n

For information about UMaine Extension programs and resources, visit extension.umaine.edu<\/a>.<\/strong>
Find more of our publications and books at extension.umaine.edu\/publications\/<\/a>.<\/strong><\/p>\n\n\n\n

Introduction<\/strong><\/h2>\n\n\n
\n
\"A
Image 1.<\/strong> A three-point hitch boom sprayer attachment on a tractor at Blueberry Hill Farm, Jonesboro, ME.<\/em><\/figcaption><\/figure><\/div>\n\n\n

A boom sprayer is a piece of equipment that attaches to a tractor (Image 1) or is a built-in part of a tractor for larger-scale pesticide applications. Boom sprayers have folding arms that vary in size with equally spaced nozzles used to deliver pesticides. Pesticide products are unique and require different application rates, conditions, and timing to control pests. For questions specific to a particular product, refer to the pesticide label. Ensuring that your equipment applies the correct amount of pesticide product to your crop is the law and critical for successful pest control. Learning to calibrate your equipment will make you confident in your applications and ensure you are not over-applying. This will save you money and reduce the amount of material released into the environment. Calibration will help you stay on top of sprayer maintenance, contributing to the longevity of your sprayer equipment. There are many different sprayers, tractors, and nozzles available, which is why you must calibrate according to your equipment and product.<\/p>\n\n\n\n

Getting Started<\/strong><\/h2>\n\n\n\n

<\/a>Cleaning<\/h3>\n\n\n\n

The first task to complete is a thorough cleaning of your equipment. This means performing a triple rinse to your boom sprayer. The list below is from the CORE Pesticide Manual<\/a> (Barry et al., 2015).<\/p>\n\n\n\n

    \n
  1. Hose down the inside of the tank and partially fill the tank with water. Then flush the water through the nozzles by operating the sprayer.<\/li>\n\n\n\n
  2. Repeat step 1.<\/li>\n\n\n\n
  3. Remove nozzle tips and screens. Then clean using a strong detergent and a soft brush. Do not use metal wire, knives, or hard objects that can damage the nozzles or screens.<\/li>\n\n\n\n
  4. Refer to the label for cleaning agents and use as directed. <\/li>\n\n\n\n
  5. Partially fill the tank with water and add the cleaning agent.<\/li>\n\n\n\n
  6. Now your sprayer has been properly cleaned for the next pesticide application or for calibration.<\/li>\n<\/ol>\n\n\n\n

    Do not create areas of standing water that are accessible to children, pets, farm animals, or wildlife (Barry et al., 2015). \u201cIdeally, all wash water should be collected and applied to a labeled site or disposed of as hazardous waste\u201d (Barry et al., 2015).<\/p>\n\n\n\n

    Calibrating Using the 1\/128th<\/sup> Method<\/strong><\/h2>\n\n\n\n

    <\/a>Supplies Needed<\/h3>\n\n\n\n
      \n
    • Proper PPE<\/li>\n\n\n\n
    • A field tape that can measure up to 250 ft<\/li>\n\n\n\n
    • Tape measure<\/li>\n\n\n\n
    • Field flags or markers<\/li>\n\n\n\n
    • A stopwatch<\/li>\n\n\n\n
    • Calibration containers<\/li>\n\n\n\n
    • Nozzle cleaning supplies<\/li>\n\n\n\n
    • A clipboard with scratch paper and a calibration record sheet to record all settings for next time<\/li>\n<\/ul>\n\n\n\n

      Finding Nozzle Spacing<\/h3>\n\n\n\n
        \n
      1. Fill your boom sprayer with a half tank of water.<\/li>\n\n\n\n
      2. Measure your nozzle distance from the center of one nozzle to the center of the next nozzle and make sure all nozzles are spaced the same distance apart. If they are not, fix the spacing.<\/li>\n<\/ol>\n\n\n\n

        Evaluating Nozzles<\/h3>\n\n\n\n
          \n
        1. Run the sprayer. Look at all the nozzles and see if there are any visual problems with the spray pattern from each nozzle.\n
            \n
          1. If there is a nozzle clogged, stop the sprayer, take off the nozzle and clean the tip and strainer with a soft brush and\/or compressed air (Hamilton, 2023).<\/li>\n\n\n\n
          2. Do not use metal brushes, wires, or knives to clean debris from the nozzle. You will damage the components, which will result in improper application rates and inadequate pest control (Barry et al., 2015; Whitford et al., 2024).<\/li>\n<\/ol>\n<\/li>\n\n\n\n
          3. Do not use your mouth to blow into the nozzle tip. The residue will blow back into your face which exposes you to chemicals. Instead, bring a can of compressed air with you to clean out nozzle components safely (Hamilton, 2023).<\/li>\n<\/ol>\n\n\n\n

            Checking Application Pressure<\/h3>\n\n\n\n
              \n
            1. Make sure to check your master pressure gauge to make sure it is functioning correctly and note the rpm you need to maintain your desired pressure.\n
                \n
              1. Look at your gauge as you do your speed tests, described in the next section, so you can compensate for any pressure drops while traveling with the tractor.<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n\n\n\n

                Timing Tractor Speed<\/h3>\n\n\n\n
                  \n
                1. Use the nozzle spacing you measured earlier to find the distance you need to travel for calibration (Table 1).<\/li>\n<\/ol>\n\n\n\n

                  Table 1. <\/strong>Calibration distances for different nozzle spacings to spray 1\/128 of an acre.<\/p>\n\n\n\n

                  Nozzle Spacing (in)<\/strong><\/td>Travel Distance (ft)<\/strong><\/td><\/tr><\/thead>
                  18<\/td>227<\/td><\/tr>
                  20<\/td>204<\/td><\/tr>
                  22<\/td>185<\/td><\/tr>
                  24<\/td>170<\/td><\/tr>
                  26<\/td>157<\/td><\/tr>
                  28<\/td>146<\/td><\/tr>
                  30<\/td>136<\/td><\/tr>
                  32<\/td>127<\/td><\/tr>
                  34<\/td>120<\/td><\/tr>
                  36<\/td>113<\/td><\/tr>
                  38<\/td>107<\/td><\/tr>
                  40<\/td>102<\/td><\/tr><\/tbody><\/table>
                  *If spacing is not listed use: 340 ft\/nozzle space ft = distance (ft).<\/figcaption><\/figure>\n\n\n\n

                  Once you find your travel distance, use the field tape and flags to mark out your needed distance.<\/p>\n\n\n\n

                    \n
                  1. The best place to set the markers for timing speed is in similar field conditions to those you will be spraying.<\/li>\n\n\n\n
                  2. A safe travel speed should be chosen for timing between flags.\n
                      \n
                    1. If your field has a lot of terrain such as hills, bumps, and rocks, then pick a speed that can be safely and comfortably used by the operator.<\/li>\n<\/ol>\n<\/li>\n\n\n\n
                    2. Start with a minimum of one tractor length from the start marker. This will allow the tractor to accelerate to the set speed before using the stopwatch. Set the speed and rpm you will be using for spraying.\n
                        \n
                      1. Have someone outside with a stopwatch start timing as the boom crosses the starting marker, then stop it as the tractor boom crosses the end marker.<\/li>\n\n\n\n
                      2. If you are alone, put part of the boom down and use a stopwatch when the boom crosses over the flag at the start and finish. If you have tall, malleable markers, you can start the stopwatch as the front of the tractor hits the marker and stop the timer when it hits the end marker.<\/li>\n<\/ol>\n<\/li>\n\n\n\n
                      3. Turn around and repeat the timing process until you have three timed measurements to average.\n
                          \n
                        1. Add your three times together and divide them by three to record your average.<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n\n\n\n

                          Collecting Nozzle Output      <\/h3>\n\n\n\n
                            \n
                          1. Next, collect the output of all your nozzles.\n
                              \n
                            1. Take the calibration container and catch all the water coming from one nozzle while using the stopwatch. Stop collecting water once you have reached your average tractor time found earlier.<\/li>\n\n\n\n
                            2. Record, in ounces, what you collected from the nozzle by bringing up the container to eye level to get an accurate measurement.<\/li>\n\n\n\n
                            3. Repeat this process for every nozzle on the boom.<\/li>\n\n\n\n
                            4. Now, add your measurements together and divide by the number of nozzles on the boom to get an average application rate.<\/li>\n<\/ol>\n<\/li>\n\n\n\n
                            5. Check to make sure each nozzle is applying within the allowed range. Each nozzle is allowed a 10% difference above or below the average application rate that you found earlier (Bell et al., 2015; Hamilton, 2024).<\/li>\n<\/ol>\n\n\n