Development of a Spray Droplet Size Test Rig for Knapsack Sprayers

The determination of spray droplet sizes is an essential aspect of selecting spraying equipment. It influences the efficacy and safety of spraying operations. This study focuses on developing a spray droplet size test rig for agricultural sprayers. The design focuses on emulating the method of test for spray droplet measurement as per the Philippine National Standards (PNS/BAFS 332:2022). The rig consists of a linear positioning system with a carriage, timing belts, spray barriers, and a water-sensitive paper platform. A stepper motor and Arduino-based software were used for the control system. The highest coefficient of variation recorded in all trials was 1.09%. The analysis for the spray droplet sizes showed a low coefficient of variation of 5.91%. All of the tests yielded the same droplet size classification of "VERY COARSE". This is the same classification in the official test report. This indicates that the developed test rig can precisely determine spray droplet sizes. It is recommended to test the rig further using other types of sprayers.