Drift

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Drift
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Why Interest in Drift?

• Spotty Pest Control
• Wasted chemicals
• Off-target damage
• Higher costs -
• Environmental impact
• Water and Air Quality
• Public more aware of pesticide concerns!
  (Negative)
• Spraying in more populated areas? (Suburbs)

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Misapplication Facts
Source Farmland Insurance 1996
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Contributions to Drift
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WHAT IS DRIFT?

• Movement of ..
• spray particles
• vapors off-target
• Less effective control
• Possible injury to susceptible vegetation and
  wildlife.

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Spray Characteristics Affecting Drift
Equipment Application Factors Affecting Drift

• - Nozzle type
• Nozzle size
• Nozzle orientation
• Nozzle pressure
• Height of release

• Chemical Properties
• Formulation
• Evaporation
• Drop size
• Volume

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Reducing Pesticide Drift
Nozzles, Nozzles and More Nozzles!!
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Low Drift Nozzles

• 87 reduction in drift prone droplets
• lt 150 microns
• Low drift nozzle _at_ 0.2 gal/min flow rate - 40
  psi
• Compared to 8002 Standard Flat-fan nozzle

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8003 tip
80 means 80o fan
03 means 0.3 gallons per minute at 40 psi(38 ½
ounces per minute)
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Low Drift Nozzles

• Larger droplets
• At the same flow rate
• Same operating pressure than standard flat-fan
  (SFF) nozzles.

PRE-ORIFICE
REDUCES LIQUID VELOCITY
Reduces small droplets (200 microns) by 50 to 80
percent
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Drift Potential is Influenced by

• Droplet Spectrum (Range - big to small)

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Comparison of Micron Sizes(approximate)

• 2000 ?m
• 850 ?m
• 420 ?m
• 300 ?m
• 150 ?m
• 100 ?m

• 2 Pencil lead
• paper clip
• staple
• toothbrush bristle
• sewing thread
• human hair

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Driftability of Spray Droplets of Varying Sizes
Crosswind _at_ 3 mph

• 20 m
• 50 m
• 100 m
• 150 m
• m
• 8 ft 22 ft.
  48 ft. 178 ft. 1065 ft.

10 feet
\
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Nozzle Drop Size Classes
Very Fine to Fine lt 200 um
Medium to Coarse 200 to 450 um
Very Coarse gt 450 um
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Tip Spray Selection by Drop Size
Turbo TeeJet Flat-fan
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Secondary Break-Up
Droplet elongation and fracture produces small
droplets
\
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Sources of Spray Mist or Fines
Secondary
Break-Up
Droplet elongation and fracture
produces small droplets
\
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Sources of Spray Mist or Fines Aerodynamic
Effects Air
friction due to speed of the application vehicle
causes additional production of small droplets
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Sources of Spray Mist or Fines Aerodynamic
Effects Air
friction due to speed of the application vehicle
is dependent upon the nozzle orientation angle.
90o produces the greatest number of small
droplets
Movement
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Hypro Ultra Low Drift

• 15 100 psi range
• 120o pattern
• 4.00 - 5.00
• Fits Standard fan tip caps

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Spraying Systems DG TeeJet

• Removable Pre-orifice
• 4.50 - 5.00

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Turbo Tee Jet

• Spraying Systems
• Flat Fan pattern
• wider range of pressures 15 to 90 psi
• produce fewer drift-prone droplets compared to
  SFF.
• Fits standard TeeJet Nozzle caps

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Turbo Flood Nozzles

• Spraying Systems
• Clog resistant
• Wide angle

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Conventional SSF
Turbo Tee Jet
25 psi at 30 spacings. 20 height
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Turbo Drop Nozzle

• Greenleaf Technologies
• Air Induction (AI)
• Venturi pressure reduction chamber
• Droplets are filled with air and expand when
  leaving tip
• Better coverage
• 10.00

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Tee Jet Air Induction

• Operates at higher psi to work efficiently
• Needs special caps

6.00
TeeJet Banding Tip 7 - 8.00
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CP Nozzle

• Dial-an-orifice
• Pattern similar to flood jet
• Mainly used by aerial sprayers

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Weather and Other Factors Affecting Drift

• Temperature humidity
• Air movement (direction and velocity)
• Air stability/inversions
• Topography

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Evaporation of Droplets
High Relative Humidity Low Temperature
Low Relative Humidity High Temperature
Fall Distance
Wind
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Evaporation and Deceleration of Various Size
Droplets
Droplet
Terminal
Final Drop
Time to
Deceleration
Diameter
Velocity
diameter
evaporate
distance
(microns)
(ft/sec)
(microns)
(sec)
(in)
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.04
7
0.3
lt1
50
.25
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1.8
3
100
.91
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7
9
150
1.7
50
16
16
200
2.4
67
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Conditions assumed 90 F, 36 R.H., 25 psi.,
3.75 pesticide solution
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Strategies to Reduce Drift

• Increase drop size

• Increase flow rates - higher application volumes

• Use lower pressures

• Use lower spray (boom) heights

• Avoid adverse weather conditions
• Consider using buffer zones
• Consider using new technologies
• drift reduction nozzles
• drift reduction additives
• shields, electrostatics, air-assist

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Adjuvant Influence on Spray Pattern (Note Fan
Angle)
Polymer Drift Supressants produce larger droplets
across the spectrum, but will decrease the fan
angle. Nozzles on the Left have the polymer
supressant.
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Adjuvant Influence on Spray Pattern (Note
Uniformity of Pattern)
LI 700
R-11
Tallow Amine
Water
Source FRI New Zealand
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Shielded Sprayers
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Shrouded Sprayers
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