Skip to Content

Sprayer Calibration

I hope everyone learned a little something at our calibration workshop held in Alma on February 27. I think it became clear as the day went on that we really need to spend more time going through examples and doing some hands-on calibration for everyone to get a good feel for what it means. One farmer mentioned to me a method he has used to calibrate his sprayer and I would like to share it as a no equations or calculations way for determining how much you are applying per acre. You simply need to mark off an acre in your field and apply water at the settings of tractor speed and nozzle pressure you will be operating at during an actual crop spraying. Measure the number of gallons of water you used and that is the gallons per acre you are applying. Another suggestion I received for checking individual nozzles on an airblast sprayer is to turn off all nozzles but one of the lowest ones and use that location to test nozzles from the other ports and check for flow rate. You can then insert each nozzle into the port, collect water for a minute to get the GPM for that nozzle. Then, take that nozzle out, put in another one and repeat until you have checked the GPM for each nozzle on the sprayer. This makes it possible to check nozzle output without getting wet from the other nozzles and makes it easier to collect water from nozzles that are normally in the upper part of the sprayer. When using this method, you may need to readjust the pressure after you close off all the nozzle ports but the one you are collecting from.

Please remember that cheap nozzles wear very quickly (up to 15% increase in flow rate after 40 hours of operation). Ceramic nozzles offer the best wear resistance.

There were a couple of questions asked during the workshop that I also wanted to address. First, the worksheet for the BOOM SPRAYER determines the gallons per minute required PER NOZZLE to obtain the desired GPA. The worksheet equation for the AIRBLAST SPRAYER provides the GPM for THE WHOLE SPRAYER (ALL NOZZLES) to obtain the desired GPA. Secondly, there was some question on where to obtain the water sensitive cards Dr. Brennan discussed during his presentation. Any retailer that sells nozzles may carry them. I suggest the 1” x 3” cards which are about $50.00 for a pack of 50. The cards are manufactured by TeeJet and sold by distributors. You may need to contact Teejet to find a distributor that sells them near you. You can reach Teejet at 630-665-5000. Thirdly, there was a question on where to get a water flow meter for easily measuring the amount of water to refill the tank when measuring the gallons used by the sprayer. Grainger is a good source for a wide selection of water meters. Grainger has a website at or you can call them at 1-800-GRAINGER. Another source may be your local hardware and supply store. Do not forget fittings to connect your hose to the meter or a hose clamp if that will work. DO NOT use a fuel meter. They are calibrated for gasoline or diesel and will not work correctly with water.



Typical Flow Meter

Be Safe!
Glen Rains, PhD, PE

Posted in Spray Technology. Bookmark the permalink.
Avatar photo

About Ash Sial

Dr. Ash Sial is Associate Professor in Department of Entomology at the University of Georgia. He has had extensive training in agricultural entomology from various institutions. He earned his Ph.D. in Entomology from Washington State University where he worked with apple growers to develop sustainable IPM programs for major pests of tree fruits. After graduation, he accepted a Post-Doctoral Research Scientist position at University of California, Berkeley and worked with winegrape growers to develop sustainable IPM programs aimed at managing exotic and emerging arthropod pests such as vine mealybug, and the diseases transmitted by mealybugs such as grapevine leafroll disease. He then joined Cornell University to investigate various aspects of biology and ecology of an invasive insect pest – spotted wing drosophila, which has recently emerged as a major threat to fruit production in the United States. Currently, he serves as the blueberry entomologist and IPM Coordinator for Georgia. At the University of Georgia, the goals of his research program are to investigate biology and ecology of major arthropod pests of blueberries in order to develop sustainable IPM programs, and disseminate that information to all stakeholders including commercial blueberry producers in a timely and convenient manner. He has published numerous peer-reviewed papers, delivered research and Extension presentations including invited guest lectures and a keynote address. He has also served professional societies including Entomological Society of America (ESA) in a leadership role at the regional and national levels. He has been recognized for excellence in research productivity and professional leadership at the regional and national level with several prestigious awards including the John Henry Comstock Award.