<i>Boom pressure and droplet size uniformity of a pulse width modulation (PWM) spray technology</i>

Abstract

Abstract. Pulse width modulation (PWM) technology manages the flowrate by varying the duty cycle. However, application errors might still occur while the system manages to maintain the target pressure resulting in pesticide resistance and product loss. Field tests were performed to assess the pressure and droplet size uniformity of the PWM technology. Boom pressure and duty cycle data from selected nozzles across the sprayer boom were recorded using a custom data acquisition system when applying product at a rate of 140.3 l L ha-1 at 275.8 kPa application pressure (field 1) and 112.2 L ha-1 application rate at 413.7 kPa application pressure ( field 2). Results showed that the pressure was within ±10% of the target for 84.4% on field 1 and 89.8% on field 2 when using a PWM system. Pressure coefficient of variations were less than 10.0% for 98.0% of the time in both fields. In a flow-based system, the pressure was below ±10.0% of the target for the majority of the time in both fields. The droplet size varies from coarse (73.0%) to medium (27.0%) for field 1 while medium (65.9%) to fine (34.1%) on field 2 when using a PWM system. In a flow-based system, the droplet size was at the coarse category for field 1, while it varies from coarse (24.0%), medium (60.8%) to fine (1.6%) for field 2. The PWM technology may provide an application pressure within the acceptable range thereby providing a better droplet size and application uniformity than a flow-based system.