Fan low drift nozzles - insights
Drift is usually caused by wind action, which introduces a certain amount of pesticide into the environment causing pollution. Today this is a significant problem due to increased environmental awareness. Therefore many nozzle manufacturers are searching a solution to limit this problem.
Some experiments made by DISAFA in Torino in vineyards and orchards have shown that drift plays a major role. Experiments evidenced a 16% drift percentage when spraying a chemical product just three meters away from the target area. A controlled drift helps reducing air pollution, safeguarding water resources and health and safety of human beings, livestock and birds, and improving spraying quality, resulting in increased crop growth and lowered production costs.
Consequences of drift
Main factors causing drift
- drop size
- weather conditions
- operating height
- working speed
- pesticide specifications
Reduction of percentage volume of
drops <103μm at a pressure of 3 bar.
*Reference nozzle.
Drop size
Factor with a major impact on drift. Drop size is expressed in micron (μm), that is a thousandth of millimeter. As a reference a human hair can be used as it measures about 100 μm.
Generally speaking, the longer drops fly in the air the higher the possibility they are driven off the target by the wind. Small droplets offer a good coverage but are prone to drift as they are very light. As a matter of fact, they fly much longer and can be driven for long distances by the wind. Theoretically a drop released from three meters under breezy conditions (wind 1.3 m/s, 20 °C and RH 80%) is driven for 3 m if it has a diameter of 200 μm and 130 km if it has a diameter of 1 μm!
Drops under 50 μm are therefore not recommended as they fly for a longer time, even until evaporated, losing any control. Generally speaking, drops should never be under 200 μm. The use of drops with an average diameter of 200-300 μm is recommended.
Drift value according to drop size
Flight time of a drop according to its diameter
