Using%20Pulse%20Width%20Modulation%20to%20Control%20Spray%20Droplet%20Size - PowerPoint PPT Presentation

Title: Using%20Pulse%20Width%20Modulation%20to%20Control%20Spray%20Droplet%20Size


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Using Pulse Width Modulation to Control Spray
Droplet Size

• Robert E. Wolf
• Extension Specialist Application Technology

Biological and Agricultural Engineering
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Efficacy and Drift Potential is Influenced by

• Size of the Spray Droplets -
• Volume Median Diameter (VMD)
• Droplet Spectrum (Range - big to small)

Volume in droplets less than 200 microns in
size
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Drop Size
One micron (?m) 1/25,000 inch
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1/2 of spray volume smaller droplets
VMD
1/2 of spray volume larger droplets
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Important Droplet Statistics
VMD (50)
Operational Area
VD0.9 (90)
VD0.1 (10)
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EPA Requested Changes Coming!?!?

• Guidance to Chemical Manufacturers
• Match the crop protection product to the target
• Adhere to label guidelines based on an industry
  standard
• ASAE S-572
• Buffer Zones or No Spray Zones
• Maximize Efficacy
• Minimize Drift

VMD
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Pulse Width Modulation - PWM
Pulsed Emissions from Nozzles
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SYNCHRO - Nozzle System

• Capstan Ag Systems
• Topeka, KS
• Developed by the
• Precision Spray Laboratory
• U of CA - Davis

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Synchro Nozzles

• Blended Pulse Technology
• Independent Flow Control (1-8X)
• Independent Drop Size Control
• Independent Band Width Control (Fan Nozzles)
• Separate boom section controls
• GPS - program management control

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Synchro Controller Components
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How it Works

• Uses high speed solenoid valves to regulate flow
• Varies application rate with duty cycle
  independently of pressure

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Pulse compared to conventional
PWM
Conventional
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What is Pulse Width?

• Type of control system
• Modulates a DC square wave signal

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Synchro Blended Pulse
Each Synchro nozzle emits 10 pulses per second,
with adjacent nozzles having alternating timing.
The alternating pulses, combined with overlapping
spray patterns and the natural dispersion of
droplets traveling in air, blend together to
provide consistent coverage.
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Spray pattern quality not sacrificed
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Electronics/Rate Controllers

• How does your system work when speed changes?
• Is it pressure based?
• What is the effect of going slower?
• What is the effect of going faster?

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Procedures

• Treatment 1
• Conventional, 20 psi, 5 mph, tt11002, 8 GPA
• Treatment 2
• Conventional, 75 psi, 10 mph, tt11002, 8 GPA
• Treatment 3
• PWM, 40 psi, 5 mph, tt11004, 8 GPA
• Treatment 4
• PWM, 40 psi, 10 mph, tt11004, 8 GPA

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Drift
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Sharp Shooter/Synchro Controller

• Pulse generator
• On/Off
• Select volume
• Valve Driver
• Power from battery
• Nozzle valve
• Creates spray pulse

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For more information contact
rewolf_at_ksu.edu
www.capstanag.com/
www.caseih.com/
www.bae.ksu.edu/faculty/wolf