Hardi MARRO TWIN FORCE 1000 Instruction Book Download

Page: 28 / 64

GB 09 01

Air Technique

A Setting of air speed, rules of thumb

Step 1

: Find the range of air speeds that can control

drift:

1.Start with the air setting at zero and keep increasing

the air speed just to the point where you can see that
the drift cloud is minimised - note minimum setting.

2.Then increase the air speed until you see drift again -

note maximum setting.

3.Now you know the range of air speeds that can be

used with minimum drift.

Bare ground / low crop

The range of air speeds is usually very small.

Taller crop

The taller the crop the wider the range of air speeds that
can reduce drift.

At higher wind speeds

More air is needed on the sprayer and it is advisable
to drive more slowly and use minimum boom height
(40 cm)/(16 in).

NOTE!

Too high air speed over bare ground/low crop

can cause reflection of the spray liquid and leave dust
on the leaves, which can again reduce the effect of the
plant protection product.

Step 2

: Set the optimal air speed within possible the

range mentions above.

Conditions

Air speed recommen-

dations

Bare ground / low crop:

Use maximum air

within the

possi-

ble range

Taller crop:

Deeper crop penetra-

tion

re-

quires more air on the

sprayer (if you are in doubt

check with water sensitive

paper).

Forward speed:

Higher forward speeds

require

more air on the

sprayer.

Volume rate:

Lower volume rates require

more air assistance to

avard

drift.

B Angling of air and liquid, rules of thumb

To control wind drift the influence of wind speed and
wind direction as well as the horizontal air current
around the boom due to forward speed must be mini-

mised. Because it is a sum of two forces with variable
direction and size that we have to counteract for, the
following can only be very rough guidelines.

NOTE!

Often it will be necessary to drive with two

different anglings, so the angling is changed when
changing driving direction after turning at the headland.

Wind direction Angle / air speed

Head wind:

Angle forward

Down wind:

Angle back (if the forward

speed is

higher than the

wind speed: angle

for-

ward)

Side wind /
No wind:

Angle vertical or back. Only

high

forward speeds may

require forward

angling.

Crop condition Angle / air speed

Bare ground/
low vegetation:

Low air speed and angling back

will

often be the best

setting to avoid

reflection of

spray liquid.

Dense crop:

The angling feature is ideal to

help opening the canopy and im

prove

penetration. If

you follow the

crop movement

as you are varying

the

angling you will find that at certain

settings the crop will open more for

penetration.

If wind speed, wind direction or for some reason forward
speed changes during spraying the optimum angling is
likely to change too. Be aware that with certain combina-
tions of air speed and angling you can “close” or flatten
the crop and make penetration impossible - follow the
crop movement intensively especially when setting the
air assistance and keep an eye on the crop all through
the application.

NOTE!

• It is most important that the sprayer operator is familiar
with the above rules of thumb before using the TWIN
sprayer

• All volume rates, pressures and air adjustments stated
in the following tables are, of course, guiding. Special
conditions regarding climate, crop quality, spraying time
and applied chemical can change the procedure. The
tables are showing practice in northern Europe, and
conditions may be very different in other countries. If you
want some local advice you are very welcome to contact
the TWIN application expert at the HARDI importer or
daughter company in your country

• The volume rate can generally be reduced to half of
what is applied with a conventional sprayer, but with a