Interaction between pressure and drop size under electronic instrumentation on a pressurized CO2 sprayer

Abstract

The most popular agricultural sprayer used to determine the effectiveness and dosage of pesticides is the backpack sprayer pressurized by CO₂, which allows the application of small volumes of pesticides, on the exact amount needed in experimental plots with small areas. However, these sprayers cannot keep the working pressure for a long application time, affecting the application rate and drop size. This study aimed at evaluating the pressure changes on the hydraulic circuit of a backpack sprayer pressurized by CO₂ and the influence of the tank spraying volume over the drop size and application rate. Pressure transducers were mounted on the hydraulic pressure circuit, the electrical signals were recorded by a data monitor and the drop size was measured with the aid of water sensitive paper. There was a reduction on the hydraulic circuit pressure of the sprayer, during the spraying, despite the volume used in the tank. The highest pressure variation occurred with the application rate of 100.0 L ha^-1, followed by 150.0 L ha^-1 and 200.0 L ha^-1. Thus, the lowest application rate, the highest was the pressure variation, independently of the tank volume. The drop size increased according to the pressure reduction on the hydraulic circuit.