Submitted to: Atomization and Sprays
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 15, 2013
Publication Date: January 15, 2014
Citation: Fritz, B.K., Hoffmann, W.C., Kruger, G., Henry, R., Hewitt, A., Czaczyk, Z. 2014. Comparison of drop size data from ground and aerial application nozzles at three testing laboratories. Atomization and Sprays. 24(2): 181-192. Interpretive Summary: Spray drop size is a critical factor in the performance of any agrochemical solution, but the use of different measurement systems and methods often produce conflicting data for the same tested nozzles and spray solutions. Extensive tests were conducted to establish the repeatability and accuracy of spray drop size measurements from an established set of reference spray nozzles at two application technology research laboratories in the USA and one in Australia. Using a previously-developed set of standardized test methods, drop size measurements for the reference spray nozzles varied by less than 5% between days at the same laboratory and among the three laboratories. This work has greatly enhanced the validity of data generated by these three cooperating laboratories, each of which contributes data to agrochemical manufacturers and to the U.S. EPA for product evaluations and registrations.
Technical Abstract: Spray drop size is a critical factor in the performance of any agrochemical solution and is a function of spray solution, nozzle selection, and nozzle operation. Applicators generally base their selection of a particular nozzle based on the drop size reported by manufacturers and researchers. Like most population sampling methods, the accurate measurement of spray drop size is a function of sampling methodology, accuracy of the measurement, and inferences about a total population from subset. Studies were conducted to determine the repeatability and accuracy of spray drop size from a standardized set of spray nozzles at three different application technology research laboratories (USDA-ARS in College Station, Texas, University of Nebraska-Lincoln in North Platte, NE, and the University of Queensland, Gatton campus, Australia). In an effort to minimize differences in drop size measurements between laboratories, the same set of nozzles was used at each location. The three laboratory measurements of drop size varied by less than 5% except for the measurement of the very largest drops in a spray plume. Day to day variation in drop size measurements within each lab was also found to be around 5%. This work shows that through careful monitoring of spray pressure, air speed, and measurement distance, very close agreement in drop size measurements can be obtained between different research laboratories.