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Droplet Size Classification of Aerial Application Nozzles

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

ASAE  ANSI/ASABE S641   May  2018

Keywords: Droplet size classification, Aerial sprays, Reference nozzles

1 Purpose and scope

1.1 This Standard defines droplet size categories for the classification of aerial application spray atomizers, relative to specified reference flat fan nozzles discharging into a high-speed air stream, which enhances atomization simulating aerial application conditions. The purpose of classification is to provide the nozzle user with droplet size information for use in making application decisions to meet pesticide product label and other regulatory requirements related to pesticide spraying by aircraft.

1.2 This Standard defines a means for relative nozzle comparisons only based on droplet size. Other spray factors related to drift or efficacy such as droplet velocities, droplet densities, discharge height, evaporation and target impaction are not addressed by this Standard.

1.3 This Standard is based on ASAE/ANSI S572, but accommodates narrower, high speed wind tunnels used to reflect aerial application factors. Primarily, this relates to the requirement for an active air stream/high-speed wind tunnel (rather than “static air or so that no stream of air enhances atomization”) and the selection of reference nozzles. Differences in measurement setups, methods and systems may impact numerical results from lab to lab, like ASAE/ANSI S572. The reference nozzles provide relative classification references that can be evaluated under airspeeds associated with aerial application conditions that cause secondary breakup. The drop size reference curves provided by this standard are equivalent to those in ASAE/ANSI S572, but allow for evaluation in aerial application airspeeds.

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