Full TGIF Record # 98744
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Web URL(s):http://www.wsweedscience.org//wp-content/uploads/proceedings-archive/2004.pdf#page=81
    Last checked: 12/10/2013
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Publication Type:
Content Type:Abstract or Summary only
Author(s):Wolf, Robert E.
Author Affiliation:Kansas State University, Manhattan, Kansas
Title:Pulse width modulation to control spray droplet size for increased efficacy and spray drift minimization
Section:Teaching and technology transfer
Other records with the "Teaching and technology transfer" Section
Meeting Info.:Colorado Springs, Colorado: March 9-11, 2004
Source:Proceedings of the Western Society of Weed Science. Vol. 57, 2004, p. 79-80.
# of Pages:2
Publishing Information:Newark, CA: Western Society of Weed Science
Keywords:TIC Keywords: Application rates; Spray drift; Spraying methods; Sprayer calibration
Abstract/Contents:"For normal agricultural spray operations the flow rate and consequent volume to a application (GPA) are typically regulated through adjustments in pressure, speed, or by changing different nozzle orifice size. As pressures are adjusted through a given orifice size the spray droplet size will also change. With today's abundance of spray machines with electronically controlled applications systems, pressure variations can occur rapidly as application speeds change, thus changing the quality of the spray equally as often. Even though the pressure changes are beneficial to maintaining calibrated spray rates, a dramatic change in the spray droplet size emitted from the spray system occurs. For instance, to double the flow from a given orifice, a four-fold pressure increase is required. Thus, in field spraying situations with electronic controllers, doubling the speed of application requires doubling the flow to maintain the calibrated rate, increasing the pressure four-fold, resulting in dramatic changes in spray droplet size. Technology is available to alleviate the problems associated with this scenario. A system utilizing pulse width modulation (PWM) for controlling droplet size while varying application volumes, speeds, and pressure is currently available commercially (Capstan Ag Systems Inc., Topeka, KS). By maintaining the application volume while adjusting spray pressure, operators are able to manipulate droplet size to meet changing wind and weather conditions or protect sensitive downwind areas. It is also possible to adjust application volumes without changing nozzles or adjusting pressure. This technology can also help maintain pattern uniformity when slowing in turns, for corners, and on hills preventing over-application at lower speeds and reducing under-application during acceleration. PWM utilizes a valve system which consists of an electronically actuated solenoid valve coupled to the inlet of the spray nozzle to provide a variable-duration, pulse spray emission. PWM could modulate flow without distorting droplet size or spray pattern uniformity over a 10:1 flow adjustment while maintaining a constant pressure. With the inclusion of PWM for flow control, the speed and pressure affects are minimized, eliminating major variations in droplet size. Thus, high-pressure scenarios normally producing smaller spray droplets with higher drift potential are minimized. Providing a more uniform droplet spectrum should increase field growing of agronomic crops in our countries [country's] economy. A better understanding of PWM should provide the application industry, which includes growers, commercial applicators, agrochemical companies, scientists, and extension personnel with the information necessary to make the best choices regarding this technology for the application of crop protection products. Future EPA label directives will require applicators to adhere to spray droplet standards (ASAE-572) during application as a means to improve efficacy and minimize drift into sensitive areas. Management of spray droplet size is a critical issue in the search of accurate and efficient crop protection application systems."
Note:"This article appears as abstract only."
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Wolf, R. E. 2004. Pulse width modulation to control spray droplet size for increased efficacy and spray drift minimization. Proc. West. Soc. Weed Sci. 57:p. 79-80.
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    Last checked: 12/10/2013
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    Notes: Item is within a single large file
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MSU catalog number: SB 610 .W43 v.49
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