GrowNotes

Spray application manual

Module 13: Rate-controller functions and settings

13.5: Functions the operator should consider using

Published 24 January 2025 | Last updated 20 January 2025

It is important to spend time going through the controller manual before operating the sprayer and highlight important functions and features. Each controller will have a

range of useful functions that the operator, may not be aware of.

Two particularly useful functions that are common to many rate controllers are the simulated speed or test speed function and the automatic adjust function.

Simulated or test speed function

The simulated speed, function allows the operator to simulate various spraying speeds while the sprayer is stationary. This is very useful for calibration and pre- operational checks.

There are various ways different manufacturers identify the minimum hold function in their controllers, including in the following.

Hardi 5500 speed simulation function

HC 5500 E4.6 speed simulation
Having a simulated speed or test speed function allows the operator to complete stationary tests of the spray system. Photo: Graham Betts. (1.6 MB JPG)
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Bravo 1805 speed simulation function

Bravo 180S speed simulation
Simulated speeds are useful for calibration and checking spray plans. Photo: Graham Betts. (2.0 MB JPG)
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Checking controller inputs and settings

24 January 2025

Checking spray controller inputs & settings is one of the many aspects of a spray operator's routine. GRDC's Spray Application GROWNOTES™ covers this ...

Finding simulated test speed function by model

Table 3 where to find the simulated speed test
Where to find the simulated (test) speed function for selected rate controller models (always consult the rate controller manual where newer models have been released). (103.3 KB JPG)
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‘Automatic adjust’ function for application volume

Another useful function of controllers is the ‘automatic adjust function’, which allows the operator to program a predetermined adjust figure into the controller to increase the application rate by a certain amount, either by a known L/ha or by a percentage increase of the L/ha.

For example, if the automatic adjust figure is set at 10L/ha and the spray operator decides to increase the application rate because of a heavy patch of weeds, the operator can push a switch or button to adjust the application rate (e.g. go from 70L/ha to 80L/ha). Then after passing the heavy patch of weeds, push a switch or button to resume the rate originally programmed into the controller.

Using this function should only be considered in situations where the applied rate is less than the maximum rate permitted on the product label, and the increased rate will not exceed the maximum label rate.

Pressure adjust in pulse-width modulation systems

With many pulse-width modulation systems, the operator has the ability to set more than one pressure while still being able to achieve the target application rate. This function allows the operator to change droplet size without changing nozzles, provided the selected duty cycle remains within the useful range.

Find out more

For more information on pulse-width modulation systems, go to Module 17: Pulse width modulation