Choosing a nozzle type
Choose the right type of nozzle that will produce the best spread of spray drops in the best shaped swath with the best sized spray drops for your spraying task. Understand how nozzle spacing affects the quality of your spraying. Check your pesticide label for advice.
Types of nozzle
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The types of nozzles shown above are even fan, standard flat fan, deflector (x2), hollow cone and solid cone nozzles.
Nozzles are designed to create and direct drops of spray, which land and form a shape or swath. Different types of nozzles create swaths (footprints) of different shapes.
These swaths are from even fan, standard flat fan, deflector, hollow cone and solid cone nozzles. The first row shows the downward spray patterns of each of the nozzles. The second row shows the 'footprint' on the ground of each nozzle. The third row shows the volume of spray deposited across the swath.
Some swaths are better for some spraying tasks than others. Choose the nozzle that is best for your spraying need.
How nozzles work: Design and size
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As the pressurised spray mix comes out of the nozzle it forms a sheet of liquid. This sheet gets thinner and thinner as it widens out, before breaking up into drops. The width of the footprint of these drops on the ground and the spread of the drops within the footprint, are controlled by the design of the nozzle.
The size of, and pressure of the liquid at, the nozzle opening, control the flow rate (L/minute). The speed at which you spray then determines the spray mix volume rate that you apply.
The design of the nozzle and the pressure at the nozzle opening also combine to produce smaller or larger drops of spray. For example at the same pressure, hollow cone nozzles produce smaller drops than deflector nozzles. This means that for nozzles producing larger drops there will be fewer drops to cover the target surface and for nozzle producing smaller drops there will be more drops to cover the target surface.
Each single nozzle can produce a range of flow rates and hence volume rates. The nozzle size (e.g. 03 Blue, 02E) that will produce the combination of drop size and volume rate that you need is a function of:
- the size of the nozzle orifice
- the pressure at the nozzle orifice
- the operator's walking speed.
Drop sizes
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Drop size can affect both how well the drop reaches and remains on a target surface and the cover of pesticide drops over the target surface. It can also affect your safety and that of your enviroment.
Terms used for drop size
The terms often used for drop size are:
Code | Category | VMD range (microns) |
|---|---|---|
XF | Extremely Fine | Up to 60 |
VF | Very Fine | 61-144 |
F | Fine | 145-235 |
M | Medium | 236-340 |
C | Coarse | 341-403 |
VC | Very Coarse | 404-502 |
XC | Extremely Coarse | 503-665 |
UC | Ultra Coarse | More than 665 |
Nozzle spacing
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Make sure that you space your nozzle correctly so that you:
- apply the right amount of spray mix
- get a uniform spread of spray drops.