A comparison of the drift potential of a novel twin fluid nozzle with conventional low volume flat fan nozzles when using a range of adjuvants

Spray drift from a novel twin fluid nozzle and low volume hydraulic pressure flat-fan nozzles has been measured in a wind tunnel. At a wind speed of 4.2 m s(-1), drift from the twin fluid nozzle, spraying a range of adjuvants increased with decreasing flow rate. Emulsifiable oil adjuvants produced less drift than an ethoxylated alcohol surfactant, in general agreement with data on in-flight droplet spectra. Comparing drift between the twin fluid nozzle and the flat fan nozzles at a constant flow rate of 600 ml min(-1) showed that drift from the former was intermediate between standard and low-drift nozzles. Drift increased with increasing spray release height, but for the twin fluid nozzle at 400 ml min(-1) at 50 cm was smaller than that from the same nozzle atomising 150 ml min(-1) at a height of 35 cm. Air inclusions in droplets from the twin fluid nozzles did not influence drift. The need for a technique to measure the mass of droplets containing air inclusions is highlighted and the method of plotting drift at variable wind speeds is discussed.