Application Equipment, Calibration, and Techniques
Equipment and nozzle selection
Match the nozzle to the job: flat-fan for broadcast boom spraying (operate at the pressure and height giving 30–50 percent overlap), even flat-fan for banding over the row, hollow cone for penetration and directed insecticide/fungicide work, full cone for coarse, high-volume work, flooding/flood tips for low-pressure, coarse droplets, and air-induction/twin-fluid tips for drift reduction. Finer droplets give better coverage but drift more; pressure changes both flow rate and droplet size.
Calibration essentials
You must know three numbers: nozzle flow rate, swath width (nozzle spacing), and ground speed. Measure speed over a measured course - 88 feet in 10 seconds equals 8.8 ft/sec, and multiplying by roughly 0.68 gives about 6 mph. Speed errors are the most common calibration failure: driving faster than calibrated lowers the GPA proportionally.
The 5940 formula: GPM per nozzle = (GPA × MPH × nozzle spacing in inches) ÷ 5940. Worked example: target 20 GPA, 5 mph, 20-inch spacing → (20 × 5 × 20) ÷ 5940 = 2000 ÷ 5940 ≈ 0.34 GPM per nozzle. Select a tip rated near that flow at your operating pressure, then verify by catching output from several nozzles for a timed minute.
Techniques and traps
Replace nozzles when flow exceeds the rated output by about 10 percent, and check the pattern with a spray card. Calibrate with the actual product or a tracer, at the actual speed and pressure. Keep agitation running, follow label mix order, and screen tank mixes. In chemigation, use backflow prevention - a check valve and vacuum relief are legal requirements, not accessories.