Fig.7. Spray nozzles produce a wide range of droplet sizes.
Most current agricultural sprayers use hydraulic nozzles to meter and atomize the liquid into drops. Hydraulic nozzles produce a wide spectrum of droplet sizes ranging from under 10 to over 1,000 microns (Fig. 7).
Drift can be minimized with nozzles that produce relatively large droplets, but still give sufficient penetration and coverage of the target (Fig. 8).
For example, flood-fan and wide-angle full-cone nozzles produce much fewer drift-prone droplets than hollow-cone nozzles and flat-fan nozzles. However, flood-fan and full-cone nozzles do not provide adequate control when applying contact herbicides, insecticides and fungicides. We are likely to continue using other nozzles for application of these types of pesticides even though they increase the risk of drift. Fortunately, nozzle manufacturers have recently developed a new family of "low-drift" nozzles that are capable of producing relatively large droplets with adequate spray coverage.
As the size of the nozzle opening increases, droplet size generally increases while the percentage of spray volume in small droplets decreases. However, smaller-capacity nozzles are often preferred because they require less volume of spray per acre