ASTM E2872, Guide for Determining Cross-Section Averaged Characteristics of a Spray Using Laser-Diffraction Instruments in a Wind Tunnel Apparatus, will help characterize nozzles and atomizers using laser diffraction instruments. Applicable to aerial agricultural spraying, aerial forest sprays, and airblast spraying, standard describes tests relating to use of laser diffraction instrumentation to estimate droplet size distribution for liquid sprays released into moving air streams.