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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Publications at this Location » Publication #315643
Title: Evaluation of spray droplet spectrum of sprayers used for vector control

Author
item FAROOQ, MUHAMMAD - Us Navy
item Hoffmann, Wesley
item Fritz, Bradley - Brad
item COTE, NOEL - Us Navy
item WALKER, TODD - Us Navy
item SMITH, VINCENT - Us Navy

Submitted to: Atomization and Sprays
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2016
Publication Date: 5/11/2016
Citation: Farooq, M., Hoffmann, W.C., Fritz, B.K., Cote, N., Walker, T., Smith, V. 2016. Evaluation of spray droplet spectrum of sprayers used for vector control. Atomization and Sprays. 26(8):739-754.

Interpretive Summary: Numerous spray machines are used to apply products for the control of human disease vectors, such as mosquitoes and flies; the selection and setup of these machines significantly affects the level of control achieved during an application. The droplet spectra produced by 26 different machines were evaluated to help users select the best sprayer for their application. Generally, droplet size increased with increased flow rate, resulting in some of the sprayers generating droplets that were too large (greater than 50 microns) to be considered ULV sprays at the higher flow rates. Also, decreases in engine, blower, fan, or rotary atomizer rpm resulted in increased droplet size. The data generated in this study should assist operators of vector control equipment to select the appropriate spray solution and sprayer that generates the droplet size spectra needed to meet their specific application requirements. This work supplements other data sets reported on many other sprayers.

Technical Abstract: Droplet spectra data were collected from spray equipment intended for use in vector control by the US Department of Defense pest management programs to determine if they produce droplets in the ultra-low volume (ULV) spectrum. Droplets generated by 26 sprayers utilizing water + non-ionic surfactant (NIS) and/or BVA-13 mineral oil were measured at various operating conditions resulting in a total of 360 replicated tests. The volume median diameter (DV0.5) of the application equipment ranged from 3.5 - 215.3 µm. Ten of all the sprayers tested with water + NIS and fifteen of all those tested with BVA-13 mineral oil produced ULV sprays. All thermal foggers tested met the criteria for space sprays when applying mineral oil but not when applying water. Generally, droplet size increased with increased flow rate, resulting in some of the sprayers generating droplets that were too large (> 50 um) to be considered ULV sprayer at the higher flow rates. Also, decreases in engine, blower, fan, or rotary atomizer rpm resulted in increased droplet size. Therefore, careful attention should be given to the application parameters during selection and operation of a sprayer. As a rule of thumb, if the reported data is close to the Dv0.5 and Dv0.9 thresholds for ULV (25 and 50 um, respectively), changing any of the operational parameters from those listed here could result in an ineffective application. The data presented serves as a guide for users in selection of sprayers and corresponding operational parameters to meet the specific application requirements.