Drift

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)

33% 8% 2% 24% 33% Source: Farmland Insurance 1996 Equipment Drift Tank Mix Wrong Field Off Label

23% 13% 26% 38% Nozzle Applicator Physical Other

WHAT IS DRIFT?

• Movement of ..

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

Spray Characteristics Affecting Drift • Chemical Properties • Formulation • Evaporation • Drop size • Volume Equipment & Application Factors Affecting Drift - Nozzle type – Nozzle size – Nozzle orientation – Nozzle pressure – Height of release

Low Drift Nozzles 87% reduction in drift prone droplets < 150 microns Low drift nozzle @ 0.2 gal/min flow rate - 40 psi Compared to 8002 Standard Flat-fan nozzle

8003 tip

80 means 80 o fan 03 means 0.3 gallons per minute at 40 psi (38 ½ ounces per minute)

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

Drift Potential is Influenced by: Droplet Spectrum (Range - big to small)

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

\ Driftability of Spray Droplets of Varying Sizes Crosswind @ 3 mph 20



50



100



150

 400 

8 ft 22 ft. 48 ft. 178 ft. 1065 ft.

Nozzle Drop Size Classes

Very Fine to Fine < 200 um Medium to Coarse – 200 to 450 um Very Coarse > 450 um

Tip Spray Selection by Drop Size Turbo TeeJet Flat-fan

\ Secondary Break-Up Droplet elongation and fracture produces small droplets

Sources of Spray Mist or Fines Secondary Break-Up \ Droplet elongation and fracture produces small droplets

Sources of Spray Mist or Fines Aerodynamic Effects Air friction due to speed of the application vehicle causes additional production of small droplets

Sources of Spray Mist or Fines Aerodynamic Effects

Movement

Air friction due to speed of the application vehicle is dependent upon the nozzle orientation angle. 90 o produces the greatest number of small droplets

Hypro Ultra Low Drift • 15 – 100 psi range • 120 o pattern • $4.00 - $5.00

• Fits Standard fan tip caps

Spraying Systems DG TeeJet

• Removable Pre-orifice • $4.50 - $5.00

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

Turbo Flood Nozzles • Spraying Systems • Clog resistant • Wide angle

Conventional SSF Turbo Tee Jet

25 psi at 30” spacings. 20” height

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

Tee Jet Air Induction • Operates at higher psi to work efficiently • Needs special caps $6.00

TeeJet Banding Tip $7 - $8.00

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

Weather and Other Factors Affecting Drift 

Temperature & humidity



Air movement (direction and velocity)



Air stability/inversions



Topography

Evaporation of Droplets High Relative Humidity Low Temperature Low Relative Humidity High Temperature Wind

Evaporation and Deceleration of Various Size Droplets*

Droplet Diameter (microns)

20 50 100

Terminal Velocity (ft/sec)

.04

.25

.91

Final Drop diameter (microns)

7

Time to evaporate (sec)

0.3

17 33 1.8

7

Deceleration distance (in)

<1 3 9 150 1.7

50 16 16 200 2.4

67 29 * Conditions assumed: 90 F, 36% R.H., 25 psi., 3.75% pesticide solution 25

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

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.

Adjuvant Influence on Spray Pattern (Note Uniformity of Pattern) LI 700 R-11 Tallow Amine Water Source: FRI New Zealand

Shielded Sprayers

Shrouded Sprayers