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Calibration of hand held spraying equipment - summary
• Always follow high hygiene standards when working with crop
protection products
• Spraying equipment must be calibrated at least once in every season
of use
• Keep calibration records
• Product labels often contain recommendations on optimum
application volumes, timing and the choice of nozzles
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Calibration of hand held spraying equipment
• There are many different ways to calibrate spraying equipment
• This module contains several examples of calibration procedures
for the following spraying equipment:-
– Single nozzle knapsack and lance sprayers
– Multi nozzle boom sprayers
– Hand held mist blowers
– Compression sprayers
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Calibration of hand held spraying equipment
Factors affecting application volume -
• Forward speed
• Nozzle size, type and condition
• Sprayer pressure
• Operator accuracy
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Calibration of hand held spraying equipment
Forward speed
• Forward speed will vary between spray operators
• Always calibrate in the actual spraying situation
Crop density and growing conditions will have an effect on
walking speed (flood/irrigated crops)
• It is very difficult to maintain an even forward speed when trying to
walk at an unnatural forced pace
• Do not use adjusted forward speed to vary the output of hand held
equipment unless there are no other alternatives to achieve the
desired application volume
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Calibration of hand held spraying equipment
Pressure
• Built in control systems
Pressure regulators
• External control sytems
Control flow valves
Several manufacturers make control flow valves that can be
fitted behind the spray nozzle to keep constant pressure.
Valves are available with a working pressure of 1 (yellow),
1.5 (red), 2 (blue) and 3 bar (green).
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Calibration of hand held spraying equipment
Nozzles - fans, hollow cones
• Changing nozzles gives the greatest flexibility in spray liquid
sprayer output
• Many different types of nozzles are available which can generate
contrasting application volumes and spray qualities. Nozzles are
colour coded according to emission rates
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Calibration of hand held spraying equipment
Operator accuracy
• Even with a full, calibrated and checked sprayer operator accuracy
can have a major impact on the final results achieved.
• It is important to -
1. Maintain a constant forward speed
2. Keep the nozzle at a uniform height above/from the target
3. If using a lever operated knapsack maintain a uniform
pumping action
4. If spraying in a Zig Zig pattern ensure forward speed is
suited to the width of the spray area to ensure even cover
5. Ensure accuracy in mixing the correct dose of product to
the spray tank
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Calibration of hand held spraying equipment
Before carrying out any calibration:
• Fill the sprayer with water and test that the sprayer is working well
and has no leaks.
• Check that the nozzle is functioning correctly. Change the nozzle if
needed.
Why calibrate?
• Enables the accurate calculation of how much product to add per
tank and that product‘s optimal safe use. Under-dosing can lead to
product failure, over dosing can lead to un-acceptable crop
residues and other risks.
• Both under-dosing and over-dosing lead to wasted product and
wasted money.
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Easy calibration method
• This method allows the calibration of single and multi nozzle
sprayers without the use of calculations.
• Items required -
1. A clean non-leaking knapsack with appropriate working nozzle
2. A means of measuring swath width and area to spray
3. Graduated measuring jug
4. Clean water
5. Stopwatch or watch with a second hand
6. Calibration disc/chart
7. Calibration record sheet
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Easy calibration method
Calibration process
1. Fill the knapsacks spray tank to maximum rated capacity with clean
water.
2. Set the correct operating pressure.
3. Spray holding the nozzle at the required height and measure the
swath width.
4. Using the calibration chart find out how far you must walk to cover
100m2
Continued over…….
Most nozzles have an optimum height of
50cms above the first intercepting surface
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Easy calibration method cont.
5. Measure out the required distance to enable you to spray 100m2
(this should preferably be done in the intended spray area to
provide a reliable walking speed).
6. Prime the sprayer and fill the tank to the maximum rated graduation
line or if there is no line fill to the top.
7. Walking at an even speed spray the 100m2, recording the amount
of time taken to complete the task (if you spray more than one row
do not record the time taken turning at the end of each row).
8. Refill the sprayer to the same level as in step 6 recording the
amount of water required.
9. Using the calibration chart find out the application volume per ha.
10. Record all the results on the calibration form.
11. Repeat steps 7 to 10 three times to ensure accuracy.
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15. Calibration records - easy calibration
The following items should be recorded during a calibration -
Date Name or Sprayer
number
Nozzle type and
number
Name of sprayer
operator
Sprayer pressure
Time taken to
cover 100m2 (secs)
Nozzle height (cm) Swath width (m)
Sprayer output per 100m2 (mls) Calculated volume (Litres) per
hectare
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‚Kalibottle‘ calibration method
This method allows the calibration of sprayers using the Kalibottle.
Items required -
1. A clean non-leaking knapsack with working nozzle
2. A means of measuring swath width and area to spray
3. Kalibottle
4. Clean water
5. Stopwatch or watch with a second hand
6. Calibration disc/chart
7. Calibration record sheet
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Calibration using the Kalibottle
Kalibottles are designed to fit over the sprayer nozzle to collect its emitted spray
during a calibration. The Kalibottle has a graduated scale which allows the user to
determine the application volume per hectare.
Follow the steps to achieve an accurate calibration -
Caution: When full the Kalibottle is heavy and could damage the sprayer lance
and trigger assembly.
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18. Calibration records using Kalibottle
The following items should be recorded during a calibration -
Date Name or Sprayer
number
Nozzle type
Name of sprayer
operator
Sprayer pressure
Time taken to
cover 25m2
(secs)
Nozzle height (cm) Swath width (m)
Sprayer output per 25m2 (mls) Calculated volume (Litres)
per hectare
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19. Static calibration
This calibration process works best with multi-nozzle sprayers because
it not only gives an overal measurement of sprayer output but also
allows the indentification in variation of flow from each nozzle to be
measured.
Items required -
Sprayer Clean water
Watch with second hand Means to measure 100m
Measuring jugs Calculator
Calibration sheet Spare nozzles
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Static calibration cont.
Calibration process
1. Measure out 100m in intended spray area.
2. Record the amount of time taken to walk the 100m, this should be
done with the sprayer as it would be used by operator.
3. On a level surface place a jug under each nozzle.
4. Prime the sprayer with clean water.
5. Place the nozzles over the jugs and spray for 1 minute.
6. Record the output of each nozzle
7. If any nozzles are more than 10% from the mean output then they
should be changed.
8. Repeat steps 5 to 6 three times to ensure accuracy.
9. Use the collected measurements to obtain the output per hectare.
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21. Static calibration calculation
Static calibration calculation -
Information required Example
1. Nozzle spacing (m)
2. Nozzle output per minute
3. Number of nozzles
4. Forward speed (m/sec)
1. 0.50m
2. 650mls
3. 4
4. 0.9m/sec
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22. Static calibration records
Sprayer name Date Operator Nozzle
type
Number of
Nozzles
Sprayer pressure Time to walk 100m
Nozzle output Run 1 Run 2 Run 3
Nozzle 1
Nozzle 2
Nozzle 3
Nozzle 4
Nozzle 5
Total output per minute
Mean output (divide total by no. nozzles)
% variance (difference between nozzles)
Output/nozzle/sec (mean / by 60)
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Calibrating mist blowers
• A mist blower can be calibrated using the easy calibration method.
• When calibrating a mist blower it is important to hold the nozzle at the
same angle as will be used when spraying.
Water to the nozzle is often gravity fed so altering the nozzle
height will increase or decrease the flow rate.
You do not need to have the fan running when calibrating mist
blowers.
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Calibrating compression sprayers
• To enable accurate calibration of controlled outputs of spray liquid
from a compression sprayer the sprayer must be fitted with a
constant flow value to enable constant pressure to be achieved.
• A compression sprayer can be calibrated using any of the calibration
methods mentioned in this Power Point.
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Calibration for band application
Width of band sprayed
18 cm
50 cm
Space between rows
Factor
0.36
=
From within a 1 hectare field only 0.36 x 10‘000 m2 = 3600 m2 are is to
be treated. Less product is required but localised dose rates
maintained.
Width of band sprayed Space between rows
Calculation & example:
How to calculate the lower required amount of product necessary
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Efficient knapsack use
If the calibrated output is too high or too low changes can be made to
ensure the application is made to suit the label recommendations and
the crop geography.
1. Increasing or decreasing walking speed will reduce or increase
application volume per ha.
Difficult to maintain an un-natural walking speed.
2. Increasing or decreasing sprayer pressure (if possible) will increase
or decrease spray volume.
Will alter spray coverage and may increase spray drift.
3. Changing the nozzle to one that has the correct output.
This is the best solution.
More information available in the nozzle selection training module.
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Calculating product rate using dosage wheel for
knapsacks
If available use the calibration disc to
work out how much product to add to
each knapsack.
• Select product rate (B)
• Select calibrated application
volume (A)
• Identify knapsack volume (C)
• Result is the amount of product
required for each knapsack (D)
If you do not have a dosage wheel then use the following
formula to calculate doses per knapsack -
n vol(lt)
applicatio
Calibrated
(lt)
size
tank
rate/ha
Product
per tank
Quantity
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Trainer notes
1. Ensure that there is sufficient space to enable participants to
calibrate sprayers.
2. Have sufficient spraying equipment to ensure that there are no
more than 3 people per sprayer.
3. Calibration equipment and sheets.
4. If using the Kalibottle have sufficient bottles and calibration discs.
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