Spray equipment calibration methods

Item of equipment to be calibrated.

Spray tank capacity (litres).

L ➎

Area to be sprayed.

ha ➐

Chemical used.

Actual ground speed*

(       ) x3.6
________
(       )

=_____ km/h ➌

‘3.6’ in the calculation is a conversion factor to convert metres to kilometres (metres ÷ 1000) and seconds to hours (seconds ÷ 3600): D/1000 ÷ S/3600 = D/1000 × 3600/S = D/S × 3600/1000 = D/S × 3.6.

* To calculate your actual ground speed:

• Measure a set distance, for example 100 metres.
• Make sure that the spraying conditions are like those in the area that you will be spraying.
• Record how long it takes using the appropriate gears and revs.

Now you can calculate the water application rate, how much chemical you will need to mix in each tank and how many tank loads you will need to do the whole job. Follow the step below:

1.  Copy the answers you worked out on the previous page into the boxes below. You will need these numbers to do the calculations on this page. (The numbers in black circles (e.g. ➋) tell you the step where the answer is on the previous page.

Total spray output

________ L/min ➊

Actual ground speed

________ km/h ➌Ž

2. Work out the water application rate by using the numbers you have recorded above. Put these numbers in the correct place in the calculation below.

Water application rate

➊ × 600
________
➋ × ➌Ž

(     ) × 600
________
(     ) × (     )

= (       )
________
(        )

________ L/ha ➏

‘600’ in the calculation is a conversion factor to convert litres per minute to litres per hour (minutes × 60), and kilometres to metres (km × 1000), then square metres (m × km × 1000 = m²) to hectares (m² ÷ 10000):
60 ÷ 1000/10000 = 60 ÷ 1/10 = 60 × 10 = 600.

Chemical rate

________ L/ha ➍

Spray tank capacity

________ L ➎

How much chemical to mix in each tank?

➍( L/ha ) × ➎( L )
________
➏ ( L/ha )

(    ) × (    )
________
(    )

= _____ L

➐ (ha) × ➏(L/ha)
_______
(   ) × (   )

= _______ L ➑

➑ (L)                       (       )
_______                 _______
➎ ( L )                     (       )

= ______ tanks

Part A

Part B

Select appropriate chemical rate (from the label).

mL ______  /  ______

Part C

Record the nozzle type and size (from the equipment).

Type

Size

Part D

Is there a required operating pressure? If so, what is it?

Yes                  No

kPa or Bar  ______

Part E

Tank size of equipment.

______ L

Part F

Hand-held height above target should be recorded.

______ cm above target

Part G

Measure out an area 10 m × 1 m (this is 10 m²). This is an area of 1/1000th of a hectare (1 ha = 100 m × 100 m).

Part H

Using the required pressure (or a constant pressure), time how long it takes to spray this area. (Walk at a comfortable pace, ensuring complete coverage.)

Time in seconds

Part I

Spray into a measuring jug for the same time it took to cover the 10 m × 1 m area. Record this output.

________ L

Part J

You can now multiply this figure by 10, which will give a water application rate per 100 m².

10 × ________ L

=______ / 100 m²

Part K

OR you can now multiply this figure by 1000 to give a water application rate/ha.

1000 × ______ /L

= ______ /ha