The nozzle is one of the most important, least expensive and often the most neglected components of a spraying system.
Nozzle design and spray distribution patterns
Various types of nozzles for pesticide application are available but most nozzles for plant application are usually of three types. The table below details the most common use, the typical operating pressure and expected droplet size of these three nozzle types.
|
Type of nozzle |
Most common use |
Operating pressure in kilopascals (kPa) |
Remarks |
|
Hollow cone |
Low volume insecticides and fungicides. Special herbicide application. |
400-800 |
Moderate pressure. Small droplets. Good penetration of foliage |
|
Solid cone |
High volume insecticides and fungicides |
400-2500 |
High pressure. Small droplets. Good penetration of foliage |
|
Fan |
Herbicides |
200-200 |
Low pressure. Large droplets. Less drift. |
Summary of the main types of spray nozzles, their usage and characteristics.
[Note: 1 psi = 6.89 k Pa or 1 kPa = 0.145 psi]
Nozzles and strainers should be cleaned regularly and nozzles checked for both evenness of output as well as total output. Nozzles which deviate by more than 5% from the average should be replaced and all nozzles discarded when either their output or fan angle differs by more than 15% from new.
When water volumes are decreased, the fan angle of the nozzle needs to be increased to produce sufficient droplets in the working range. For water volumes greater than 50 l/ha, either 80 or 110 degree nozzles will produce enough droplets to give sufficient coverage. However, at volumes less than 50 l/ha, or where drift may cause problems, 110 degree nozzles are preferable.
Nozzles are made from a wide variety of material including brass, plastic, stainless steel, ceramic and sintered aluminum. Whilst there is a difference in the initial price, the added life attained by selecting material such as sintered aluminum far outweighs the initial cost. Sintered aluminum nozzles are approximately three times the cost of brass, but will possibly give ten times the life.
|
Type of material |
Durability |
Cost per tip* ($) |
|
Sintered alumina |
Most durable |
7.90 |
|
Tungsten carbide |
|
35.00 |
|
Hardened stainless steel |
|
7.75 |
|
Ceramic |
|
7.90 |
|
Plastic/nylon |
|
3.65 |
|
Stainless steel |
|
7.75 |
|
Brass |
Least durable |
3.15 |
Relative durability and cost of nozzle tips made from different materials.
*Cost as at October 1990
Nozzle identification
Nozzle tips come in many different shapes, sizes and colors and carry different markings
Most nozzles will have markings that indicate the manufacturer, spray angle, spray volume, the material that is made from. Some manufactures use different color coding to indicate different capacities within their range.
A typical nozzle may have the following markings
TEEJET 110-01-FF-HS
Where:
TEEJET= manufacturer
110 = spray angle
01 = spray volume
FF = flat fan
HS = hardened stainless steel