Measured drop size distributions for the two sprinkler types used in the study are shown in Fig. 1. The drop size distribution of the R3000 red-plate sprinkler had smaller range in drop size and smaller maximum drop size (approximately 4.0 mm) than those of the R3000 orange-plate sprinkler. Approximately 90% of the applied water volume (d90) was from drops less than 2.5 mm in diameter. The d30 through d80 drop sizes of the R3000 red-plate sprinkler was smaller than those of R3000 orange-plate sprinkler (Table 3). This could be ascribed to the trajectory angles and width design of the multi-grooved moving spray-plate, which allows the drop size distribution to be manipulated by design of the individual grooves on the plate.