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Calibration
Any sprayer should be calibrated regularly
to ensure minimal error in the application
rate. A nozzle selection chart indicates what
application rates are to be expected but
variations due to nozzle wear and pressure
irregularities can result in large application rate
errors.
Application Rate
The application rate depends on the following:
Spray pressure
- increasing pressure
increases application rate and reducing
pressure reduces application rate
Speed of travel
- increasing speed reduces
application rate and reducing speed increases
application rate
Nozzle size
- increasing the nozzle size
increases the application rate.
Nozzle Selection
Refer to the chemical manufacturer’s
information to determine the recommended
application rate in litres per hectare (l/ha) for
your particular situation. Then determine the
speed in kilometres per hour (km/hr) at which
you intend to spray, taking into consideration
the ground conditions of the area to be
sprayed. Using the appropriate chart for your
boom select the most suitable nozzle to use.
Nozzle Calibration
As part of your daily sprayer calibration,
Goldacres suggests that you carry out a jug
test to ensure the spray nozzles you are using
are delivering the correct amount of chemical,
as stated in your nozzle supplier’s rate chart.
The method of carrying out the jug test is as
follows:
You will need:
• A calibrated measuring container that can
measure the medium in litres, in 10 ml
increments. e.g. 0.45 Lt.
• A timing device showing seconds.
• A pressure gauge mounted at the nozzle
tip to verify the system pressure being
delivered at the nozzle. Goldacres part
number QJ4676-1/4-NYR will mount a
suitable gauge to the nozzle body bayonet
fitting. (Not including gauge).
NOTE:
There may be a noticeable difference
between pressure shown on main spray
pressure gauge on sprayer and the gauge
installed on the boom. This is due to pressure
loss through the circuit.
1. Check the plumbing system for kinked or
obstructed hoses and repair or replace any
hoses that restrict the normal flow of the
liquid.
2. Start your sprayer
a. For sprayers not fitted with a spray
application controller, set the boom
operating pressure to the pressure at
which you expect to spray.
b. For sprayers fitted with a spray application
controller, initiate a ‘self test’ procedure
and set the application rate and speed to
the settings depicted in your “Rate Chart”
at which you expect to spray.
3. Then place the jug under one of the
nozzles, for 60 seconds (exactly) and then
record the volume of liquid collected.
4. Repeat the test over a representative
sample of the jets in each boom section
5. Compare the volume collected from each
nozzle to the stated volume in your rate
chart. It should be no more than plus or
minus 10% of the volume stated in your
Nozzle Supplier’s rate chart
6. In the event that any of your nozzles do
not deliver the required volume, a further
investigation is required which may
include, but not be limited to:
a. Cleaning the nozzles, using the method
recommended by the nozzle supplier.
b. Replacing the nozzles.
c. TeeJet advise that nozzles that flow
greater than +10% of their stated volume
are ‘worn out’ and should be replaced.
d. Cleaning nozzle filters.
e. Replacing filters.
f. Replacing pump diaphragms.
g. Replacing the pump.
h. Ensuring that the application rate
required does not exceed the maximum
fl
ow and pressure parameters of the
sprayer.
