Constant factor 600 = 28 litres per min for boom6 - Calculate 5% of the volume of your tank capacity for agitation:
e.g. 1000 litre tank = 50 litres7 - Add the two answers: e.g. 28 +50 = Minimum pump size = 78 litres per min.
A hand gun sprayer normally requires up to12 litres per minute per gun.
Knowing your real tractor speed is an essential part of accurate spraying. Speedometer readings can be inaccurate because of wheel slippage. The most accurate method is to half fill your sprayer tank with water the measure out a suitable distance in a field with a tape measure. e.g.100 metres.
Select a suitable gear and time your vehicle over this measured distance.
The formula to calculate your speed is:-
Distance in metres multiplied by 3.6 and divide this figure by the time in seconds taken to cover the distance.
Example: 100 (metres) x 3.6 = 360
36 (seconds) = 10 kph
To determine the flow rate per nozzle required, the following formula is used:
The desired litre per ha rate is multiplied by speed in kph and this figure is multiplied by the nozzle spacing in cm. The figure is divided by 60,000
Example: 200 (Lit/ha) x 10 (kph) x 50 (cm) = 100,000
60,000 = 1.66 lit/min
Go to a nozzle chart and select a nozzle that will give an application rate of 1.66 lit/min at between 2 and 3 bar. A Teejet XR11005 will give this rate at about 2.2 bar.
Adjust the pressure until a catch test of a number of nozzles gives the correct flow rate.
Your sprayer is now calibrated.