Pesticide Application Equipment and Calibration
What this domain tests
Calibration math, nozzle selection, speed and output measurement, and spotting equipment faults before they cause an off-rate application.
Nozzle and spray-quality basics
- Flow through an orifice increases with the square root of pressure: quadrupling pressure doubles flow, and doubling pressure raises flow about 41%. Change tips to change rate; do not simply raise pressure.
- Replace a nozzle when its output is more than 10% above its rated flow or when the pattern is visibly streaked.
- Finer droplets drift farther. Air-induction and pre-orifice tips produce coarser droplets; boom height, wind, and pressure all affect drift.
Core formulas
- GPA = 5,940 × GPM ÷ (MPH × nozzle spacing in inches)
- MPH = distance (ft) × 60 ÷ (seconds × 88)
- 1/128 acre = 340 sq ft; travel distance = 4,080 ÷ row width in inches (feet).
Worked example
Nozzles on 20-inch spacing, target 15 GPA at 5 mph. Required flow = (15 × 5 × 20) ÷ 5,940 = 0.25 gpm per nozzle, about 32 fl oz/min. Verify in the field: 4,080 ÷ 20 = 204 ft of travel; at 5 mph (440 ft/min) that takes 204 ÷ 440 = 0.46 min; 0.25 gpm × 0.46 min = 0.117 gal, or 15 fl oz per nozzle. A 500-gallon tank then covers 500 ÷ 15 ≈ 33 acres.
Traps
Trusting the tractor speedometer instead of timing a measured 100-ft pass; catching from one nozzle and ignoring plugged or worn neighbors; forgetting that banded output must be scaled by band width ÷ row spacing; failing to recheck the pattern after changing tips or adding a drift retardant.