EFFICIENCY OF DEPOSITION OF PESTICIDE DROPLETS ON FLAT CARDS AND SPHERES

The mass fur of a cloud of droplets heading towards a collector can be decomposed into its horizontal and vertical components. While only th e vertical mass flux contributes to droplet deposition on a flat card by the mechanism of sedimentation, both flux components contribute to deposition on a sphere by both mechanisms of inertial impaction and se dimentation. Calculated collection efficiencies decrease as wind speed increases for cards but as wind speed increases for spheres, a minimu m collection efficiency is reached at a certain wind speed. The averag e collection efficiencies, as measured in the field trial portion of t his study, are highly linearly correlated with wind speed for cards. F or spheres, however, no correlation was found between the average coll ection efficiency and wind speed.