Effect of working pressure and spacing of nozzles on the quality of spraying distribution

Abstract

The correct placement of the crop protection product on the target depends on the adequate distribution provided by the spray nozzles. In this research, the objective was to verify the influence of the working pressure and spacing between nozzles on the quality of the spray distribution. It was analyzed the nozzles jets concerning symmetry, opening angle and flow rate. Two methodologies for determining the volumetric distribution were used, considering (1) the simultaneous collection of a set of nozzles arranged in a spray boom and (2) the volumetric distribution of each discrete sample of nozzle. Overlapping between spray jets was used to calculate the coefficient of variation (CV) due the nozzles spacing. Nine models of flat fan nozzles were used, at two nominal flow rates and four working pressures. The working pressure achieved a big effect on the quality of volumetric distribution. The pressure of 100 kPa produced the worse results of volumetric distribution, with CVs higher than 10% along the boom for all nozzle models, in both flow rates. Continuous improvements in the quality of distribution were observed with the increase in pressure until reaching 300 kPa, followed by a slight decrease in quality when reaching 400 kPa pressure. The spray nozzle model has also a big effect on the quality of distribution and there are no implied design characteristics that can turn easier a better choice of nozzles. Both methodologies for the determination of spray distribution achieved similar results and can be used for the nozzles spray distribution quality determination.