Effect of the nozzle adaptor of sprayer calibrator on flow rate measurements

To ensure the proper use of plant protection products, the European Directive 2009/128/CE requires sprayer inspection throughout Europe. The required tests and methods for inspection of agricultural sprayers are outlined in the European Standard EN 13790: 2003 in which nozzle flow rate measurement is one of the main requirements. Currently, most of the sprayer inspection workshops are equipped with a nozzle flow rate measurement device which consists of air-tight nozzle adaptors connected to 2-3 m hoses which discharge to a bank of graduated cylinders. However, these adaptors block the air holes of the air-induction nozzles, disrupt the spray atomization and change nozzle output. The main objective of this study was to investigate the variation of nozzle flow rate due to the use of air-tight adaptors. A series of nozzle flow rate measurements were made using different kinds of nozzle adaptors with various sizes of air induction, extended range and Turbo TeeJet^® nozzles.The use of air-tight nozzle adaptors increased the flow rates of air induction and extended range nozzles. Plugging the air holes of air-induction nozzles increased the flow rate. The increase in flow rate decreased with nozzle pressure. Overall, the magnitude of the flow rate increase depended on the nozzle type but remained constant for all of the same type. These differences should be accounted for in sprayer calibration.