Influence of Nozzle Type and Spray
Pressure on Droplet Size
Robert Wolf
Biological and Agricultural Engineering Dept.
Cathy Minihan and Dallas Peterson
Department of Agronomy
Kansas State University Biological and Agricultural Engineering Department
Nozzles Types?
Nozzles designed to reduce drift
 Improved ‘Droplet Spectrum’
 Emphasis on ‘Spray Quality’

How should each be used????
Kansas State University Biological and Agricultural Engineering Department
EPA Requested Changes Coming!!!!


New Label languageEPA ‘PR Notice’ Out
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
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Kansas State University Biological and Agricultural Engineering Department
EPA Pesticide Registration Notice:

PR Notice issued in the Federal
Register on August 22, 2001
– Pages 44141-44143
– www.epa.gov/fedrgstr/
» Click on date – look for document
– 90-day public comment period
» Original date - Nov. 20, 2001
» Extended until Jan. 19, 2002
Kansas State University Biological and Agricultural Engineering Department
Objective of this study:
Field measure the spray droplet
characteristics of venturi flat-fan
nozzles at 345 kPa (50 PSI)
compared to extended range flatfan nozzles at 173 kPa (25 PSI), and
turbo flat-fan and DR flat-fan
nozzles at 242 kPa (35 PSI).
Kansas State University Biological and Agricultural Engineering Department
Materials and Methods:
Experiments:
Exp. 1 and 2 - Early and Late Postemergence Grass
Location: Ashland Bottoms, Manhattan, KS
Exp. Design:
2 x 2 x 4 split-split plot with 4 reps
Drop Collectors: Placed in 2 reps with 3 cards per rep (192 cards)
Plot Size:
3 x 9 m with 1.5 m buffer
Crop
Oats ‘Don’
Visual Ratings: 1, 2, and 4 weeks after treatment
Herbicides (2):
Paraquat, 878 ml/ha, NIS @ .25%
Glyphosate, 878 ml/ha
Application Conditions:
Exp. 1
Date:
April 25, 2001
Oat Size:
15 cm
Temperature: 26 C
R. H.:
20%
Wind:
S-SW@ 4-5 km/h
Exp. 2
May 2, 2001
51 cm
23 C
65%
SE 3-6 km/h
Kansas State University Biological and Agricultural Engineering Department
Materials and Methods cont.:
Spray Tips (4):Extended Range Flat-fan (XR)
Turbo Flat-fan (TT)
Combo-Jet DR
Air Induction Flat-fan (AI)
Spray Volumes (2):
47 L/ha (110015 orifice tips)
94 L/ha (110025 orifice tips)
94 L/ha (11003 orifice tips)
Application Ground Speed: 7.6 – 8.8 km/h
Spray Pressure:
173, 242, 345 kPa
Spray Tip Spacing:
76 cm
Canopy Boom Height:
51 cm
Kansas State University Biological and Agricultural Engineering Department
DropletScan used to analyze droplets:
System Components
Kansas State University Biological and Agricultural Engineering Department
What is DropletScan ?
A software program that will allow
accurate and rapid measure of
spray droplet impressions on
water-sensitive paper.
 Developed at K-State by Devore
Systems - modeled after
‘Crumbscan’, a software program to
determine hole sizes in slices of
bread.

Kansas State University Biological and Agricultural Engineering Department
Important Droplet Statistics:
Dv0.1 (µm) - 10% of the spray volume in
drops < number reported
 Dv0.5 (µm) - 50% of the spray volume in
drops < number reported
(also is VMD- volume median diameter)
 Dv0.9 (µm) - 90% of the spray volume in
drops < number reported
 Number of droplets under 200 microns

Kansas State University Biological and Agricultural Engineering Department
Important Droplet Statistics:
Operational
Area
Kansas State University Biological and Agricultural Engineering Department
Collection Procedure:
Kansas State University Biological and Agricultural Engineering Department
Results and Discussion
Kansas State University Biological and Agricultural Engineering Department
Sample cards:
XR
TT
DR
47 L/ha
AI
XR
TT
DR
AI
94 L/ha
Kansas State University Biological and Agricultural Engineering Department
Spray Droplet Size – Tip * Volume
47 L/ha
VMD Means - by Tip and Volume
591 595
700
523
Microns
600
370 440
500
400
483 531
328
300
XR
TT
DR
AI
200
100
47 L/ha
173 kPa XR
94 L/ha
242 kPa TT
242 kPa DR
345 kPa AI
94 L/ha
Kansas State University Biological and Agricultural Engineering Department
Drift Potential – Tip * Volume
47 L/ha
Droplets <200 by Tip and Volume
1000
900
773
720
800
Microns
700
600
500
422
374
XR
400
300
152
105
200
TT
DR
AI
139
68
100
0
47 L/ha
173 kPa XR
94 L/ha
242 kPa TT
242 kPa DR
345 kPa AI
94 L/ha
Kansas State University Biological and Agricultural Engineering Department
Efficacy – Tip * Volume
47 L/ha
Percent Control
Tip by Volume - Early (2 WAT)
100
90
80
70
89
87
81
84
79
80
78
74
60
50
40
30
XR
TT
DR
AI
20
10
0
47 L/ha
LSD=2
173 kPa XR
94 L/ha
242 kPa TT
242 kPa DR
345 kPa AI
94 L/ha
Kansas State University Biological and Agricultural Engineering Department
Summary of findings Dv0.5 (µm) (VMD):



As the spray volume increased the Dv0.5 (µm)
(VMD) also increased.
The venturi flat-fan tips produced the
largest droplets (VMD) with the Combo-Jet
next smallest in size. The turbo flat-fans
produced the next smallest droplets and the
extended range flat-fan tips produced the
smallest droplets.
This trend was present for both application
volumes.
Kansas State University Biological and Agricultural Engineering Department
Summary of Findings – Drift Potential:


At 47 L/ha the extended range flat-fan
produced approximately 70% more droplets
under 200 microns than the turbo flat-fan,
580% more than the Combo-Jet and 960%
more than the venturi flat-fan.
At 94 L/ha the extended range flat-fan
produced approximately 100% more
droplets under 200 microns than the turbo
flat-fan, 400% more than the Combo-Jet
and 450% more than the venturi flat-fan.
Kansas State University Biological and Agricultural Engineering Department
Summary of findings for the Efficacy:


At 47 L/ha efficacy data collected
indicates that the extended range flat-fan
tips slightly out performed the turbo flatfan tips which slightly out performed the
Combo-jet tips, which slightly outperformed
the venturi flat-fan tips.
At 94 L/ha a similar trend was shown with
each nozzle while overall performance for
each nozzle was less than at 47 L/ha.
Kansas State University Biological and Agricultural Engineering Department
Take Away Message:
Even though the extended range
tips slightly outperformed the
other nozzles for oat control, these
other nozzles had significantly less
drift potential and should be
considered when conditions for
drift are present.
Kansas State University Biological and Agricultural Engineering Department
Thanks
Kansas State University Biological and Agricultural Engineering Department