Contact: Drift from boom sprayers 1. PDPA laser based droplet characterisation To measure and compare droplet size and velocity characteristics of different nozzle-pressure combinations including the BCPC reference nozzles D NUYTTENS 1, K BAETENS 2, M DE SCHAMPHELEIRE 3, D DEKEYSER 1 & B SONCK 1 1 Institute for Agricultural and Fisheries Research (ILVO), Technology & Food, Agricultural Engineering, Belgium 2 MeBioS, Department Biosystems, Catholic University of Leuven, Belgium 3 Department of Crop Protection, University Ghent, Belgium Measuring set-up  Climate room  3-D positioning system  Spay unit  Aerometrics Phase Doppler Particle Analyser Objective Materials and Methods Results Nuyttens D, De Schampheleire M, Baetens K, Sonck B PDPA Laser-Based Characterisation of Agricultural Spray Nozzles. Agricultural Engineering International: the CIGR Ejournal. Manuscript PM Vol. VIII. December, Nuyttens D, Baetens K, De Schampheleire M, Sonck B Effect of Nozzle Type, Size and Pressure on Spray Droplet Characteristics. Biosystems Engineering. 97(3): Nuyttens D Drift from field crop sprayers: The influence of spray application technology determined using indirect and direct drift assessment means. PhD thesis nr. 772, Katholieke Universiteit Leuven. 293 pp. ISBN available at: Droplet size characteristics Spray application techniques Measuring protocol  Measuring conditions Spray liquid: water; T = 20 °C Environmental conditions: RH: 60-70%; T= 20 °C Nozzle positioned 0.5 m above measuring point 9 measurements for each nozzle-pressure combination (3 nozzles x 3 repetitions )  Selection of test nozzles based on flow rate (BELAC accredited Spray Tech Laboratory)  BCPC reference nozzle F/M (Lurmark F bar) to check for the repeatability  Scan trajectory depending on the type of nozzle at a constant speed Droplet velocity characteristics Cumulative volumetric droplet size distributions Proportion of total volume in % of droplets smaller than 200 µm (V 200 ) for the different Hardi nozzle types at 3.0 bar (+ 95% confidence intervals) Cumulative volumetric droplet velocity distributions Average volumetric droplet velocities (v vol50 ) for the different Hardi nozzles at 3.0 bar (+95% confidence intervals) Relation between droplet size and droplet velocity characteristics Average droplet velocities for the different droplet size classes at a pressure of 3.0 bar Average volumetric droplet velocities (v vol50 ) in relation to volume median diameters (D v0.5 ) for the different Hardi nozzles at 3.0 bar Comparison with other studies Variability of D v0.1, D v0.5 and D v0.9 values from 17 different studies on four BCPC reference nozzle-pressure combinations Comparison of BCPC nozzle classification of different nozzle-pressure combinations from this study with the results from other studies Important effect of nozzle type and size on droplet sizes and velocities Clear relation between droplet velocities and sizes Reference nozzles are useful due to considerable variations in absolute results Conclusions References