MEASUREMENT VARIATIONS IN REFERENCE SPRAYS FOR NOZZLE CLASSIFICATION

摘要

Variations in spray droplet measurements were identified for reference nozzles serving as category thresholds defined for the standardized classification of agricultural spray nozzles. Spraying Systems, Delavan, and Lurmark manufactured brands of reference nozzles produced mean volume median diameters (Dv0.5) that varied from 0.5 to 34 µm within a given nozzle size, as measured with a laser diffraction instrument. Similarly, mean Dv0.1 and Dv0.9 values differed from 0.1 to 14 µm and from 0.9 to 74.2 µm, respectively. Coefficients of variation (CV) in Dv0.1, Dv0.5, or Dv0.9 within a nozzle brand and size ranged from 0.19 to 3.62% across the test. Two additional laser instruments that were tested included an imaging probe and a phase Doppler instrument. Relative droplet size differences between nozzle brands were noted when using different types of laser instruments compared with number density weighted values. Similarly, droplet size differences were observed between instruments compared with number flux weighted values. Results indicate that dedicated reference nozzle sets may be preferred to increase the overall uniformity of classification thresholds; any of the tested brands of nozzles would be suitable; and laser instrument differences may contribute to relative shifts among thresholds for nozzle classification, thereby reducing the precision of uniform nozzle classification.