Step 4 of 6 - calibrating your knapsack sprayer for pesticide dose and spray mix/water volume
This video will demonstrate keeping the nozzle at the right distance from the target surface whilst maintaining the right knapsack sprayer pressure. Click the play button to view the video now or to view the video off-line, click the link from the 'download' tab.
Now practice maintaining the nozzle height (distance) and sprayer pressure so that you achieve the right swath width and drop size.
Position the nozzle to spray at a distance of 50 cm away from your practice target surface. When you are spraying downward with a single nozzle use a flat dry area like this concrete. If you are not certain of the nozzle height when spraying downward try using a weighted string tied to the lance to help maintain that distance.
If the nozzle height is too low, the spray is less likely to be sprayed evenly.
If you spray too high then you risk the spray drops being blown away contaminating you, any bystanders, and your environment; wasting money and risking the quality of pest control as your spray distribution will not be as even as it should be.
So hold the nozzle at the right distance from the target surface, spray the water at the correct pressure over a dry surface like this concrete. Spray for a few seconds until you can see where the spray is being applied. Check that the spray pattern is even. In this example, the water is being sprayed out in a fine spray and is forming a circular, hollow cone, pattern.
Measure the swath width, which is the spread of drops. This swath is correct at 0.75 metres across.
Now you have the right nozzle fitted, know the pressure to use and have checked the width of the swath produced.