Performance of an Agricultural Impact Sprinkler Fitted with Plastic Nozzles

The radial water distribution and irrigation performance of an agricultural sprinkler with plastic nozzles were analysed. Twenty-six tests with an isolated sprinkler corresponding to different combinations of three working pressure (p, 200, 300 and 400 kPa) and three nozzle diameters of the main nozzle (4.0, 4.5 and 5.0 mm) were performed to evaluate the radial water distribution curves, All the tests were performed under calm wind (≤ 1 m s) under open air conditions. Fifty tests corresponding to six combinations of nozzle diameter and pressure with the same sprinkler model were performed under a wide range of meteorological conditions in a rectangular solid-set system at 18 m X 18 m sprinkler spacing to evaluate the Christiansen's Uniformity Coefficient (CUC) and wind drift and evaporation losses (WDEL). The resulting radial water distribution curves were compared with those from impact sprinklers with brass nozzles. Sprinkler model had an important effect on the radial water distribution, even under similar operational conditions, and these differences were shown in the first 2.5 to 6 m from the sprinkler. The CUC and WDEL of a solid-set sprinkler system were compared with simulated values from the “Ador-Sprinkler” model. The results of this analysis showed that the type of sprinkler had a moderate influence on sprinkler irrigation uniformity. The analysis presented in this study may serve to develop a decision tool to choose the most suitable combinations of sprinkler model, nozzle diameter and working pressure to optimise the uniformity and efficiency of sprinkler irrigation.