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Calibration of knapsack sprayers
The label of the pesticide should be examined to see if a volume application
rate, spray quality, nozzle or spray concentration is recommended. The
desired nozzle is selected and its output measured during 1 minute. When
using lever-operated sprayers, a control flow valve, or alternatively a pressure
gauge, should be fitted as close to the nozzle as possible, and the lever operated evenly with a full stroke to maintain as uniform a pressure as possible.
The operator will need to practise before achieving an even pumping rate.
Having determined the output from the nozzle in litreslmin, the rate per unit
area treated can be calculated, knowing the swath width and walking speed.
Volume application rate (Litres/m2=Output( litres/m2/Swath(M)xSpeed(M/min
Thus with a swath of 1m, walking at 60m/min and a flow rate of 0.6 litres/min,
the volume of spray per square metre is
0.6 litres/min/1m x60m/min=0.01litres/m2 OR 0.01 litres/m2 x10000=100litres/ha
If the application rate is incorrect, other nozzles should be tried. When the
most suitable nozzle has been selected, the volume applied can be rechecked
by measuring the distance walked and time taken to spray a known quantity.
Frederick paul answered the question on March 21, 2019 at 08:16
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