Evaluation of spray pattern uniformity using three unique analyses as impacted by nozzle, pressure, and pulse‐width modulation duty cycle

Abstract

BACKGROUND: The increasing popularity of pulse-width modulation (PWM) sprayers requires that application interaction effects on spray pattern uniformity be completely understood to maintain a uniform overlap of spray, thereby reducing crop injury potential and maximizing coverage on target pests. The objective of this research was to determine the impacts of nozzle type (venturi vs. non-venturi), boom pressure, and PWM duty cycle on spray pattern uniformity. Research was conducted using an indoor spray patternator located at the University of Nebraska-Lincoln in Lincoln, NE, USA. Coefficient of variation (CV), root mean square error (RMSE), and average percent error (APE) were used to characterize spray pattern uniformity. RESULTS: Generally, across nozzles and pressures, the duty cycle minimally impacted the CV of spray patterns. However, across nozzles and duty cycles, increasing pressure decreased CV values, resulting in more uniform spray patterns. The RMSE values typically increased as pressure and duty cycle increased across nozzles. This may be the result of a correlation between RMSE values and flow rate as RMSE values also increased as nozzle orifice size increased. Generally, APE increased as the duty cycle decreased across nozzles and pressures with significant increases (40%) caused by the 20% duty cycle. Within non-venturi nozzles, increasing pressure reduced APE across duty cycles, while venturi nozzles followed no such trend. CONCLUSION: Overall, results suggest PWM duty cycles at or above 40% minimally impact spray pattern uniformity. Further, increased application pressures and the use of non-venturi nozzles on PWM sprayers increase the precision and uniformity of spray applications.

Optimum Droplet Size Using a Pulse‐Width Modulation Sprayer for Applications of 2,4‐D Choline Plus Glyphosate

“…Therefore, the application process was simplified and standardized for operators across a range of spray environments. Second, because previous research highlighted PWM duty cycle had a minimal effect on droplet characteristics (Butts et al, 2018a, 2019a) and spray pattern (Butts et al, 2019b), a nozzle type, orifice size, and application pressure combination could be selected to provide a consistent droplet size for each treatment while maintaining the appropriate spray output (94 L ha –1 ) throughout an application.…”

“…In contrast, research has shown that the PWM duty cycle has little to no effect on droplet size when using non‐venturi nozzles (Butts et al, 2019a; Giles et al, 1996). Additionally, when PWM sprayers were operated at or above a 40% duty cycle, minimal to no negative impacts were observed on spray pattern and coverage (Butts et al, 2019b; Mangus et al, 2017; Womac et al, 2016, 2017). Therefore, it is feasible with a PWM sprayer to sustain an optimum herbicide droplet size and spray pattern throughout an application in which efficacy could be maximized and particle drift minimized.…”

Modeling and Prediction of the Uniformity of Spray Liquid Coverage from Flat Fan Spray Nozzles

“…Increasing the signal means increasing the value of this factor [31]. In the same technique when for various kinds of nozzles the fixed pressure is equal to 207, 276, or 476 kPa, the values of the coefficient of variation range from 5.3% to 20.1% [32].…”

Application of Non-Parametric Bootstrap Confidence Intervals for Evaluation of the Expected Value of the Droplet Stain Diameter Following the Spraying Process

“…Currently produced atomizers and in particular Venturi nozzles, are designed to produce larger diameter droplets. These designs were created because droplets with a smaller diameter (<200 µm) are more likely to drift [45]. The quality of the plant protection treatment is influenced by the height of the boom position above the sprayed surface [45].…”