Characterization of hydraulic nozzles for droplet size and spray coverage

Authors: GULER, H - Ege University; Zhu, Heping; OZKAN, H - The Ohio State University; LING, P - The Ohio State University

Submitted to: Atomization and Sprays
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2013
Publication Date: 3/29/2013
Publication URL: https://handle.nal.usda.gov/10113/58151
Citation: Guler, H., Zhu, H., Ozkan, H.E., Ling, P. 2013. Characterization of hydraulic nozzles for droplet size and spray coverage. Atomization and Sprays. 22(8):627-645.

Interpretive Summary: Spray application is a complicated undertaking and the many types of nozzles in use have unnecessarily confused applicators. Guidelines are lacking for applicators to select the optimal nozzles for the control of specific pests because of inadequate factual information on the performance of these nozzles in terms of spray coverage, spray deposition, and drift reduction potential. In this study, characteristics of popular spray nozzles based on their spray coverage and deposit density were evaluated under controlled-environmental conditions. The use of controlled-environmental conditions to test nozzles allowed us to determine how best to maximize the performance of the controllable variables of nozzles to improve spray application efficiency and mitigate the constraints of the uncontrollable variables in field tests. Test results demonstrated that the numerous types of nozzles and costs could be reduced and still achieved comparable spray coverage and droplet size. Air induction nozzles, for example, use higher pressures and larger orifices than conventional nozzles and cost nearly twice as much but their spray performances are no better than conventional nozzles of selective orifice sizes operated at proper pressures. This study also provided base-line data to help spray applicators select the most appropriate nozzles for efficient, effective and economical spray applications for pest control.

Technical Abstract: Spray coverage specifications for commercially available nozzles could help applicators determine the optimal nozzles for effective control of insects, diseases and weeds. Spray coverage and deposit density from seven types of nozzles at three different flow rates (0.76, 1.14 and 2.27 l min-1) and two target positions (0.50 and 0.70 m below the nozzle) were evaluated with water sensitive papers (WSP) as targets under controlled environmental conditions. These nozzles included 80° and 110° conventional flat-fan nozzles, air induction flat-fan nozzles with the air intake hole either opened or sealed, hollow-cone nozzles, turbo jet nozzles, and twin jet fan pattern nozzles. Spray coverage on WSPs increased as flow rate increased for all nozzles. The hollow-cone nozzles had the highest coverage at both target positions while air induction nozzles had the lowest coverage. With the same flow rate, the 80° nozzles had higher spray coverage than 110° nozzles. Nozzles producing coarse spray had the lower spray coverage than nozzles producing fine and medium sprays. The 80° and 110° flat-fan nozzles at lower than the specified operating pressures produced spray as coarse as that from the air induction nozzles with similar coverage. There was no significant difference in spray coverage between the same air induction nozzles whether the two air intake holes were opened or sealed. Spray coverage on targets at the 0.50 m position was greater than that at the 0.70 m position. Therefore, careful selection of nozzles could provide comparable performance for economical and effective spray coverage with optimal flow rates and operating pressures.