9
THEORY OF OPERATION
Spray fluid is placed in the tank where it is drawn through a suction filter and pumped to a control valve. The
excess flow from the valve is returned to the tank via the bypass hose. Fluid at a nominal pressure is pumped to
the spray outlet via the spray hose.
If a boom is fitted, when the pressure in the spray lines reaches 0.7 Bar (10 psi), the diaphragm check valves at
each nozzle body open allowing fluid to reach the spray tips.
If a hose reel is fitted fluid will pressurise the reel until the spray gun is operated.
The control unit has a pressure adjustment valve to regulate the spraying pressure with a maximum pressure
relief valve.
When the dump valve on the control unit is operated, the pump output is allowed to return to the tank with
reduced restriction. The resulting drop in pressure allows the DCVs in the boom to close and spraying will stop.
The CD7C compensating control unit also has individually adjustable metered bypass outlets fitted to each
controller outlet to return the unused flow from each valve. This allows the operator to turn individual boom
sections on or off without affecting the spraying pressure.
The CD7V Volumetric control unit also has a pressure regulating proportional flow control valve, and individually
adjustable metered bypass outlets fitted to each controller outlet. This allows the operator to vary speed within the
pressure range and maintain a set flow to the spray boom as well as being able to turn individual boom sections
on or off without affecting the spraying pressure.
At the spray tip, fluid is atomized at the spraying pressure and the fluid is propelled toward the target at the tip
angle (80
or 110
nominally).
The spraying pressure controls droplet size.
Application rate is controlled by tip size, and vehicle speed.
CALIBRATING YOUR PRESSURE NOZZLE BOOM KIT
Metric Version (litres, metres, kph)
(*Standard nozzle spacing 0.5 metres)
You will need to calibrate your sprayer to ensure the accurate application of chemical or liquid fertilizer. If too
much chemical or liquid fertilizer is applied you will be wasting money! If too little is applied you may need to
repeat the spraying, which will be wasting your money and time!
Chemicals are expensive. Repeat calibration frequently during the seasons to avoid disappointment.
To calibrate your sprayer you will need:
a) Nozzle calibrator or an accurate measuring flask
b) Watch or clock with seconds, or a stopwatch
c) Tape-measure
d) Calculator
NOTE: “Chemical “ also refers to liquid fertilizers.
1.
Measure time taken to travel 100m at the speed used for spraying
NOTE
Maximum Recommended Spraying Speed is 12 Kph.
2.
Run Sprayer and record output from each nozzle (in mls) for the same time it took to travel 100m.
Calculate average flow per nozzle.
I.e. Add individual nozzle output and divide by number of nozzles.
NOTE
Check any nozzle tip that is out by ± 5%
Discard any nozzle tip that is out by ± 10%
3.
Litres/ha = Average Nozzle output (ml/nozzle) x 100
500 nozzle spacing mm)
4.
Chemical to add to tank
Litres of Chemical = Water in Tank (L) x Label chemical rate/ha
L/ha (application Rate)
