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The crop sprayer is equipped with a spraying computer as standard. The chapter entitled "Operation of the spraying computer" describes the settings of the nozzle output.
In the case of manual spraying, the spraying pressure must be adjusted as follows in order to spray a specific quantity in liters/hectare:
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Select the required application rate in liters/hectare (e.g. 300 l/ha)
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Select the required driving speed (e.g. 6 km/h) at an ideal combination of engine speed and transmission ratio. Make allowances for the fact that an increase in driving speed may negatively affect penetration, transverse distribution and increase spray drift.
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Always check the driving speed! This may be done as follows:
1.
Mark out a distance of 100 m in the field
2.
With the tank half full of water, drive to the field
3.
Measure the time required for driving 100 m.
4.
Determine the driving speed on the basis of the table below:
Time required to drive 100 m in relation to the driving speed
| Time (s) |
120 |
90 |
72 |
60 |
51 |
45 |
40 |
36 |
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| Km/h |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
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The speed can also be calculated as follows:
Driving speed (km/h) = 360 : time (sec)
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Next read the output per nozzle from the spray volume table (in this example 1.5 l/min). If you wish to set a value different from the one given in the table, calculate this value as follows:
Nozzle output (l/min) = (l/ha x km/h x nozzle spacing):600
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Now read in the nozzle output table which nozzle to select in combination with the spraying pressure. According to the example, set the nozzle output to 1.5 l/min. This can for instance be achieved with a 04 nozzle (e.g. XR-11004) at a spraying pressure of 3 bar.
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Always calibrate the machine because of loss of pressure and nozzle wear!
The pressure indicated by pressure gauge or pressure sensor is higher than the spraying pressure on the nozzles, because of pressure loss in the spray line and the presence of diaphragm valves in the nozzle holders. Therefore check the nozzle output with clean water. Set the pressure gauge to the spraying pressure found (e.g. 3 bar) and collect the nozzle output in a measuring jug during 1 minute. Measure several nozzles and calculate the average. If the output is different from the table value (1.5 l/min), adjust the spraying pressure until the correct output per nozzle is achieved.
In this way, determine the pressure loss on the machine for various outputs and nozzles.
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