Submitted to: Journal of Plant Protection Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 2012
Publication Date: December 3, 2012
Citation: Fritz, B.K., Hoffmann, W.C., Czaczyk, Z., Bagley, W., Kruger, G., Henry, R. 2012. Measurement and classification methods using the ASAE S572-1 reference nozzles. Journal of Plant Protection Research. 52:447-457. Interpretive Summary: With an increasing number of spray nozzle and agrochemical manufacturers incorporating droplet size measurements into both research and development, the need for incorporating reference nozzle droplet size data is critical for comparing results between testing locations. Differences in both measurement distance from the nozzle and concurrent airflow velocities significantly impact the results from the laser diffraction instruments typically used. To compare the relative nozzle size classifications that would potentially result from multiple measurement locations, sets of references nozzles that define specific size classification categories were evaluated for droplet size under three concurrent air flow velocities. While absolute droplet size values were significantly different between measurement air velocities, nozzle size classifications agreed for all airspeeds. It is critical that testing facilities involved in the testing and evaluation of agricultural spray nozzles use reference nozzle droplet sizes, measured following the labs testing protocol, as standards for classification of relative droplet size to insure that the applicators select and use nozzle appropriate for a given application.
Technical Abstract: An increasing number of spray nozzle and agrochemical manufacturers are incorporating droplet size measurements into both research and development with each laboratory invariably having their own sampling setup and procedures, particularly with regard to both measurement distance from the nozzle and concurrent airflow velocities. Both have been shown to significantly impact results from laser diffraction instruments. These differences can be overcome through the use of standardized reference nozzles and relative spray classification categories. Sets of references nozzles, which defined a set of classification category thresholds, were evaluated for droplet size under three concurrent air flow velocities (0.7, 3.1 and 6.7 m/s). There were significant, through numerical small, differences in the droplet size data between identical reference nozzles. The resulting droplet size data were used to categorize a number of additional spray nozzles at multiple pressure and air flow velocities to determine if similar classifications were given across the different airspeeds. Generally, droplet size classifications agreed for all airspeeds, with the few that did not only differing by one category. When reporting droplet size data, it is critical that data generated from a set of reference nozzles also be presented as a means of providing a relative frame of reference.