Study of a droplet electrification system in a backpack sprayer in a Faraday cage

ABSTRACT This study evaluated the factors affecting the charge/mass ratio (Q/M) generated by a droplet electrification system in a backpack sprayer with an electrostatic kit, using a Faraday cage. Two experiments were conducted in completely randomized design to determine the effect of application rate, the distance between the nozzle and the target, and spraying mixtures on performance of the droplet electrification system. The first study evaluated four distances (0, 0.5, 1.0, and 2.0 m) between the nozzle and the Faraday cage; the second study was conducted in a factorial design, with five tank mixtures and five flow rates (0.25, 0.76, 1.00, 1.45, and 1.58 L min-1). The Q/M ratio was determined using a multimeter by measuring the electric current from the volume of mixture sprayed in the Faraday cage, which was divided by the respective liquid mass. Droplet spectrum was analyzed by a particle analyzer using laser diffraction. The Q/M ratio became smaller as the spraying flow rate increased, similarly as observed with increasing distances of the electrostatic nozzle from the cage entrance. The Q/M ratio increased with the addition of mineral oil, vegetable oil, and insecticide to the spraying mixture. Flow rate, distance between the nozzle and the target, and the spraying mixture affected the electrostatic spraying efficiency.