Performance of a Pulse Width Modulated (PWM) Single to Multifold Outlet System for Variable-Rate Anhydrous Ammonia Application
A pulse-width modulation (PWM) metering system for anhydrous ammonia with two valves and single-outlet feeding to a vertical dam manifold was developed and tested for variable rate, lateral distribution, and flow characteristics. The single-point system was designed to lower the cost of PWM metering for applicators with narrow knife spacing, which are common for wheat. The system ensured that liquid ammonia was fed to the valves for correct metering. The distribution test was simulated using the dynamic water absorption technique applied to individual knives. The flow tests were conducted for valve duty cycles ranging from 10% to 90% with recorded average flow rates of 39 kg h-1 at 10% to 112 kg h-1 at 90% duty cycle. The lateral coefficient of variation was in the range of 5% to 9%.