Transcript Spray Droplet Size Standard - Pesticide Safety Education

Spray Droplet Size Standard
S-572
Robert E. Wolf
Extension Specialist Application
Technology
Biological and Agricultural Engineering
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
Relationship of Drift to Drop Size
One micron (m) =1/25,000 inch
Comparison of Micron Sizes for Various
Items: (approximate values)
2000 (m)
pencil lead
paper clip
150
staple
850 (m)
420 (m)
toothbrush bristle
sewing thread
300 (m)
150 (m)
human hair
100 (m)
1/2 of spray volume = smaller droplets
VMD
1/2 of spray volume = larger droplets
Cutting Droplet Size in Half
Results in Eight Times the Number of Droplets
250
Microns
250
Microns
500
Microns
250
Microns
250
Microns
250
250
250
250
Microns Microns Microns Microns
Important Droplet Statistics
Operational
Area
Evaporation of Droplets
High Relative Humidity
Low Temperature
Wind
Low Relative Humidity
High Temperature
EPA Requested Changes Coming!?!?
 Buffer Zones or No
Spray Zones
 Maximize Efficacy
 Minimize Drift
8
0
0
800
7
0
0
700
v
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very fine/ fine
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fine/medium
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medium/
coarse
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coarse/
very
coarse
very coarse/ extremely coarse
6
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600
5
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500
4
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400
Drop Size (microns)
• ASAE S-572
9
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900
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Example Reference Graph
X
C
XC
M
3
0
0
300
M
2
0
0
200
F
1
0
0
100
C
C
V
C
VC
DropSize(microns)
 Guidance to Chemical
Manufacturers
 Match the crop
protection product to
the target
 Adhere to label
guidelines based on
an industry standard
F
V
F
VF
0
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0
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1
0.1
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5
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9
0.5
0.9
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Cumulative Volume Fraction
ASAE S-572 Droplet
Size Standard
Origin Of Standardized Spray
Droplet Size Categories
 1985 -- British Crop Protection Council (BCPC)
• Droplet size classifications, primarily
designed to enhance efficacy.
• Uses the term SPRAY QUALITY for droplet
size categories.
2000 -- ASAE Standard S572
• Droplet size classifications, primarily
designed to control spray drift.
• Uses the term DROPLET SPECTRA
CLASSIFICATION for droplet size
categories.
Specifics of the Standard
 Based on spraying water through reference
nozzles.
 Nozzle manufacturers can conduct the tests.
 Must use a set of reference tips and a laserbased instrument.
 Droplet Spectra measurements must be with
the same:
• Instrument, measuring method, sampling technique,
scanning technique, operator, and in a similar
environmental condition.
Coverage
Need knowledge of the product being used.
• Systemic
• Contact
What is the target?
•
•
•
•
Soil
Grass
Broadleaf (smooth, hairy, waxy)
Leaf orientation – time of day
ASAE DSC and Volume Median Diameter
(DV0.5) From PMS* Laser Spectrometer
Droplet Spectra
Classification (DSC)






Very Fine (VF)
Fine (F)
Medium (M)
Coarse (C)
Very Coarse (VC)
Extremely Coarse (XC)
Droplet Size
Range
< 182µm
183-280µm
281-429µm
430-531µm
532-655µm
>656µm
*USDA ARS
College Station, TX
Nozzle Technology? How to use??
 Nozzles designed to reduce drift
 Improved drop size control
 Emphasis on ‘Spray Quality’
Spray Characteristics are Important
to Understand:
Demonstrates Turbo Flat vs TurboDrop-5 MPH Wind
Nozzles Types?
Extended Range Flat-fan:
 Tapered edge pattern
 80 and 110 degree fan
 Requires overlap - 50 to 60%
 15-60 psi range
Extended Range Flat-fan:
 Tapered edge pattern
 80 and 110 degree fan
 Requires overlap - 50 to 60%
 15-60 psi range
80°
110°
Demo
Nozzles Types?
Turbo Flat-fan:







Turbulence chamber as in the Turbo Flood
Tapered edge, wide angle flat pattern
Designed to work in flat-fan nozzle holder
Uniform spray distribution, 50-60% overlap
Wide pressure range, 15 – 90 psi
Large, drift resistant droplets
Plastic with superior wear characteristics
Turbo Flat-fan:







Turbulence chamber as in the Turbo Flood
Tapered edge, wide angle flat pattern
Designed to work in flat-fan nozzle holder
Uniform spray distribution, 50-60% overlap
Wide pressure range, 15 – 90 psi
Large, drift resistant droplets
Plastic with superior wear characteristics
TT
Demo
Nozzles Types?
Air-Induction/Venturi Nozzles
Where air is drawn into the nozzle
cavity and exits with the fluid.
Air/Induction – Venturi Nozzle:
 Spraying Systems AI TeeJet
 Air intake venturi section
 Mixing Chamber - air and
spray solution blended
 Exit orifice - Pattern tip forms large air-bubble drops





Better Penetration?
Reduced run-off?
Improved coverage?
Adequate efficacy?
Reduced drift? YES!!!
XR Flat-fan and Turbo Flat-fan
compared to Venturi Style
5.0 MPH wind at 40 psi
XR vs TurboDrop
Turbo Flat vs Turbo Drop
Demo
Driftable Droplets:
Nozzle Type
(0.5 GPM Flow)
Spraying Systems-2000
Approximate % of Spray
Volume < 200 Microns
15 PSI
40 PSI
XR 11005
14%
22%
XR 8005
6%
12%
DG 11005
N/A
11%
DG 8005
N/A
7%
TT 11005
<1%
<6%
TF-2.5
<1%
<1%
AI 11005
N/A
<1%
Page 4
Computer Models:
AgDRIFT® Program Map
Example of Model Use –
Aerial Applicators Standard Operation
CP STRAIGHT STREAM NOZZLE
FOR USE ON FIXED-WING AIRCRAFT
AERIAL APPLICATORS SPRAY NOZZLE HANDBOOK
USDA ARS AGRICULTURAL HANDBOOK NO. XXX
The author is I. W. Kirk, Agricultural Engineer, Areawide Pest M anagement Research Unit,
F
I X E D - W I N G
Southern Plains Agricultural Research Center, Agricultural Research Service, U. S. Department of Agriculture, 2771 F&B Road, College Station, TX 77845-4966, USA.
Directions: Enter CP STRAIGHT STREAM nozzle settings, pressure, and airspeed in the cells highlighted below.
(Atomization parameters are valid only with nozzle and operational settings specified in the Acceptable Range.)
Orifice Size,
Deflector Angle,
Pressure,
Airspeed,
inches
degrees
psi
mph
Acceptable Range: .061 to .171
0 to 30
20 to 60
100 to 160
0.125
5
30
130
Application parameters are displayed in the box below.
CAUTION: Do not enter or clear data in the cells in this box!
DV0.5 =
330 µm
= Volume median diameter
RS =
1.33
= Relative Span
%V<100µm =
4.26 %
= Percentage of spray volume in droplets smaller than 100 µm diameter.
%V<200µm = 13.52 %
= Percentage of spray volume in droplets smaller than 200 µm diameter.
DSC = MEDIUM
= ASAE S572 AUG99 Droplet Spectra Classification
Values and classifications reported here are least-squares best-estimate predictions from experimental data collected in a w ind tunnel.
Values reported from other laboratories may not yield the exact same values, but similar trends w ould be expected.
The droplet spectra classification category is based on droplet sizes in the mid-80% of the spectrum and not a single data point.
Trade names are mentioned solely for the purpose of providing specific information. M ention of a trade name does not constitute a guarantee or warranty of the product by the
U. S. Department of Agriculture, and does not imply endorsement of the product over other products not mentioned.
For more information contact:
[email protected]
www.bae.ksu.edu/rewolf/