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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of Droplet Spectra and Downwind Deposits from Venturi and Pre-Orifice Nozzles

Authors
item Derksen, Richard
item Ozkan, H - OSU/OARDC
item Fox, Robert
item Brazee, Ross

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 1999
Publication Date: N/A

Interpretive Summary: Spray drift is becoming an increasingly important factor for pesticide applicators to consider and it is believed to be one of the most challenging problems facing applicators and pesticide manufacturers. Equipment manufacturers are responding to these concerns by introducing different methods for reducing drift including drift reduction nozzles. The new equipment is designed to produce fewer drift prone droplets. Laser droplet sizing equipment and wind tunnel tests validate the potential improvement in spray drift management of new drift reduction nozzles compared to standard nozzles. The drift nozzles performed differently from each other but tests confirmed that the new venture type of nozzle did produce fewer downwind deposits and fewer drift prone droplets than standard nozzles. Tests also showed that plugging the air intake of venturi type nozzles, as would be expected to occur in dusty field conditions, would not significantly reduce the performance of the nozzles. The traditional method of reducing spray drift, bu reducing nozzle pressure and using larger orifices, was also shown to significantly reduce downwind drift. This research will help growers, extension educators and chemical manufacturers make better decisions related to use of or recommendation of spray nozzles that will reduce the environmental impact of spraying operations and make more efficient use of chemicals.

Technical Abstract: Spray drift is becoming an increasingly important factor for pesticide applicators to consider and it is considered to be one of the most challenging problems facing applicators and pesticide manufacturers. Computer simulations have shown that drift is less likely to be a problem when spraying with droplets 200 microns and larger in size. Equipment manufacturers are responding to these concerns and introducing different methods for reducing drift including drift reduction nozzles. USDA-ARS and Ohio State University engineers conducted tests to validate the effectiveness of two of the new drift reduction nozzles. Laser droplet sizing equipment was used to characterize the droplet size distributions produced by these nozzles. Wind tunnel experiments were conducted to evaluate downwind spray deposits in a 10 mph wind. The new drift reduction nozzles produced much fewer drift-prone droplets. They also produced fewer downwind ground deposits and statistically significant reductions in airborne deposits than standard nozzles. The various drift reduction nozzles provided different levels of drift minimization. However, reducing nozzle pressure and using larger orifices was shown to also significantly reduce downwind drift potential. Tests also showed operating in a dusty field environment which could plug the air intake on the venturi nozzle body, would not interfere with the performance of this particular type of nozzle and would not significantly increase the risk of spray drift.

Last Modified: 10/1/2014
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