Nozzles are used only on air-blast or hydraulic equipment, i.e. initial treatment boom sprayers and some face-by-face sprayers (air-blast, collector panels). Nozzles are positioned at different locations and heights on the sprayer and can be of different sizes and colours. Nozzles differ in terms of the size of the droplet formation. Accordingly, each nozzle is assigned a colour based on the droplet size formed. There are several criteria when choosing and correctly adapting a nozzle to a specific treatment:
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The type of nozzle: the nozzle can be either "swirl" and form a conical jet, or slotted (or brush) forming a flat jet. While the swirl nozzle is recommended for dense vines because it allows better penetration of the foliage, flat jet nozzles are more suitable for young vines.
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Nozzle technology: the nozzle can be a classic single-slot nozzle that simply sprays the product, a drift-controlled nozzle (adding a flow regulator to reduce drift) or an air-injection (or anti-drift) nozzle. This means that one or more orifices allow air to be absorbed and mixed with the product just before spraying. This results in the formation of larger droplets that are then less susceptible to drift. Note, however, that larger droplets are more susceptible to runoff due to their weight once on the plant. Nozzles with air injectors are necessary to reduce the NTA (Non-Treated Area).
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Size: this will depend on the size of the nozzle orifice and the size of the droplets formed measured in microns. The average droplet size is given by the VMD (Volumetric Median Diameter), the smaller the VMD in microns, the finer the droplets, the optimal size of droplets is between 250 and 300 microns. When drops have a VMD greater than 300 microns, the risk of runoff increases.
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Ideal pressure or pressure range: each nozzle type has an optimal pressure range for its size. Slot nozzles generally operate at a lower pressure than air injection nozzles.
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Projection angle: this determines droplet distribution over a given angle, thereby ensuring good coverage of the target zone.
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The type of material: nozzles can be plastic (polymer), stainless steel or ceramic. Depending on the material, the nozzles wear out at different rates, for example, polymer nozzles are less expensive but not as durable. Only stainless steel or ceramic flow regulator orifice plates are available.