Calibration of Application Equipment

The calibration of application equipment is a process to determine the amount of spray applied per time interval. For calibration to be accurate, the pressure must remain constant. Changing the pressure or application equipment, especially the nozzle, will change the rate of spray applied. Thus calibration needs to be carried out for each set of equipment at a given working pressure. A pressure gauge is an essential part of most application equipment.

The process of calibration is simply a matter of measuring the volume of pesticide applied over a chosen time interval. One minute is sufficient time in most cases, except where volumes applied are very high or very low.

After operating the spray equipment for the time interval, the volume of collected spray is measured. The application can now be expressed in volume by time terms (usually litres per minute). Therefore, field applications can be determined by recording time of application. This is particularly important when application directions are given in volume per area or site.

For example, the application of termiticide at 5L/m2 is most accurately applied when the technician knows the calibrated rate of application for the equipment being used, and thus measures time to determine volume applied to measured areas.

Calibrations, where possible should be done without the pesticide mixed with the carrier. In most cases, water only will be used. The addition of pesticide to the water will not significantly change the application rate in most cases.

Calibrations are essential for the application of pesticide to comply with label direction.