Application Equipment and Calibration
Equipment and the calibration mindset
Calibration is the process of measuring and adjusting equipment so it delivers the intended rate uniformly. The exam tests your grasp of nozzles (flat-fan, hollow-cone, flood, etc.), spray pressure, flow rate, speed, and swath width - and how each affects application rate. Know that rate = flow ÷ (speed × swath) in concept: faster travel or wider swath lowers the per-area rate unless flow increases to compensate.
Concepts to master
Understand nozzle wear - worn nozzles over-apply and pattern-test unevenly; replace worn tips. Know the difference between calibration and simple adjustment, and how to check output. Recognize drift causes: droplet size, wind, boom height, pressure, and nozzle type - and drift-reduction practices like lower pressure, larger droplets, and shielded booms. Know sprayer components (tank, pump, agitation, regulator, boom, nozzles) and the importance of agitation for suspensions. For granular/other equipment, know pattern checks and rate verification.
Traps to watch
A common trap is assuming higher pressure improves coverage without consequence - it also creates finer droplets and more drift. Another is confusing gallons per acre (GPA) with total tank mix. Watch questions where a nozzle is worn: the answer is usually to replace, not recalibrate around the wear. Also remember agitation keeps suspensions uniform; without it, concentration varies.
Worked example / rule of thumb
Rule of thumb: Calibrate before you spray, and recheck after changes. Example: a sprayer is calibrated to apply 20 GPA at 4 mph. The applicator speeds up to 5 mph with no nozzle change. Since rate falls as speed rises, the per-acre output drops (roughly 20 × 4/5 = 16 GPA) - under-applying. To restore 20 GPA, the applicator must increase flow (pressure/nozzle) or slow down. Always recheck calibration after changing speed, pressure, or nozzles.