Precision Spray Technology: How Modulation Spray Systems Improve Application
December 2, 2013 
CropLife Media Group’s recent Webinar “How Pulse Width Modulation Spray Systems Improve Accuracy and Quality of Chemical Application” is available on demand.
Achieving consistent coverage across a field can be challenging with conventional spray technology. Certain field conditions can lead to over-application, causing potential crop damage as well as wasting product.
That was the topic of CropLife Media Group’s recent Webinar, “Precision Spray Technology: How Pulse Width Modulation Spray Systems Improve Accuracy and Quality of Chemical Application.” The hour-long presentation was highlighted by insight from experts at Capstan Ag Systems, Case IH and Wilger Inc., on how Pulse Width Modulation (PWM) spray systems can improve an applicator’s bottom line by addressing the overall quality of application and drift management issues.
Evolution Of Spray Technology
Case IH Application Equipment Marketing Manager Mark Burns described the evolution of spraying from simply managing application with speed and pressure, to using rate controllers, to today’s PWM systems, which “address the constraints found in conventional application practices.”
According to Burns, the PWM system works via a solenoid valve in each nozzle body that opens and closes at a variable rate (pulses) depending on a variety of factors such as variable field speeds and differing product rates.
“With the pulse width modulation technology we have individual control of application rate and pressure,” said Burns. “So you’re holding a constant pressure as you speed up and slow down across the varying terrain of the field, all while knowing you are getting good, consistent coverage. Secondly, we’re able to provide selective drift control.”
Next Level Spraying
Gordon Hooper, field engineer at Capstan Ag Systems, discussed Capstan’s evolving individual nozzle control capabilities during the Webinar. The company currently offers solutions that allow for individual nozzle swath control, turn compensation and programmable “soft” boom sections, and features nozzle valve diagnostic tools such as a key-fob control for nozzle calibration and tip status checks.
“Individual nozzle control, the ability to turn each individual tip on and off as needed to eliminate over application, was the first step,” said Hooper. “Individual nozzle swath control capabilities were the next step; that’s what a lot of applicators have wanted for a long time.
“With individual nozzle swath control each tip turns on and off individually, based on the GPS coverage map that we make internal to our controller,” he continued. “We intentionally make this so that it works in conjunction with the rate controllers; with this system we are reducing the over-application of chemical.”
Turn compensation was the next piece of the puzzle within PWM application, according to Hooper. “If you watch a 120-foot spray boom, or even shorter ones, and you’ll notice compensation as the operator goes around a corner or around the border of a field,” he said. “You’ll see each nozzle is running at a different duty cycle and each nozzle is able to individually adjust to the turn.”
Capstan also has the ability to set up four “soft boom” presets, on the go, in the event of an over- or under-application scenario, such as what can typically occur with nozzles directly behind the sprayer’s wheel tracks or with fence row nozzles.
Just The Spray Tip
Wilger’s Craig Bartel began his presentation with a warning: “Whether you choose to spray conventionally or purchase every piece of technology on the market, your application is only as good as … the spray tip.”
According to Bartel, there are several factors to consider when choosing a tip, and he presented several of the “basics of tip selection” with attendees. “Step one is picking the size of the tip for the speed range you desire,” he said. “And step two is to pick the tip that provides the best droplet size range spectrum for application.”
Bartel also advised on selecting a tip for a standard (non-PWM) spray system, noting that “setting ones’ operating pressure near the middle of the nozzle’s range will give a better pattern and allow for pressure adjustments based on speed variations” and using an auto-rate controller “can increase or decrease the rate of product to compensate for changes in speed.”
Wilger’s Website features the Tip Wizard Computerized Spray Tip Finder, a tool applicators can use to get customized nozzle recommendations.
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