Droplet Characteristics and Near Nozzle Dispersion of Cold and Thermal Fog

ABSTRACT: In an effort to improve application methods for controlling sand flies in desert environments, a hand-held ultra-low volume (ULV) aerosol gener-ator, a truck-mounted ULV aerosol generator, and a hand-held thermal fogger were evaluated. The velocity and temperature of the air and characteristics of droplets generated by these aerosol generators were measured at various dis-tances from the nozzle. The droplet size characteristics were measured for three flow rates each of BVA-13 mineral oil and a mixture of water and non-ionic surfactant with a phase Doppler particle analyzer. Moving 0.9 m away from the nozzle, the velocity of air produced by the two hand-held sprayers decreased to <5 m/s, whereas the truck-mounted sprayer still had an air veloc-ity of 15 m/s. The air produced by truck-mounted cold fogger, thermal fogger, and hand-held ULV applicator was 38, 49.2, and 8.5C above ambient tempera-ture, respectively. Increases in flow rate, generally, did not affect the droplet size for the two hand-held units; however the droplet size increased as the flow Manuscript received August 15, 2011; accepted for publication May 3, 2012; published onlin