Step 2 of 6 - calibrating your knapsack sprayer for pesticide dose and spray mix/water volume
This video will show you how to maintain the pressure at the knapsack sprayer's nozzle. Click the play button to view the video now or to view the video off-line, click the link from the 'download' tab.
We must train ourselves to reach the pressure for which the sprayer emits the correct flow at the nozzle.
High quality backpack sprayers are equipped with a pressure regulator. This means that they can be set to spray under different pressures and thus be used with different types of nozzles.
The pressure on this knapsack sprayer is being set to the high, 3 bar pressure setting.
Next half fill the spray tank with clean water. Pour the water through the mesh filter in the tank’s opening to ensure that any debris is filtered out.
Make sure the sprayer is safe and comfortable-in-use on your back.
Pump steadily and carefully and increase the pumping rate until you get enough pressure to spray out some water.
Spray for the few seconds it takes to expel all air in the supply pipes. If necessary, raise the nozzle to spray upwards to help the removal of any trapped air.
Find the best rhythm of pumping that holds that pressure with the least effort and most comfort. When you have found the right pumping speed to maintain the pressure, count the rhythm. The amount of spray coming out of the nozzle depends on this pressure, so you must keep the pressure constant or you will not apply the pesticide evenly, so practice until you are confident that you have got it right.