spray droplet size standard s-572 robert e. wolf extension specialist application technology...
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Spray Droplet Size StandardS-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
One micron (m) =1/25,000 inch
Relationship of Drift to Drop Size
Comparison of Micron Sizes for Various Items: (approximate values)
pencil lead 2000 (m)paper clip 850 (m) staple 420 (m) toothbrush bristle 300 (m)sewing thread 150 (m)human hair 100 (m)
150
1/2 of spray volume = larger droplets
VMDVMD
1/2 of spray volume = smaller droplets
Cutting Droplet Size in HalfResults in Eight Times the Number of Droplets
500Microns
250Microns
250Microns
250Microns
250Microns
250Microns
250Microns
250Microns
250Microns
Important Droplet Statistics
Operational Area
Evaporation of Droplets
Wind
High Relative HumidityLow Temperature
Low Relative HumidityHigh Temperature
Fal
l Dis
tanc
e
Example Reference Graph
Cumulative Volume Fraction
0.1 0.5 0.9
Drop S
ize (microns) 0
100
200
300
400
500
600
700
800
900
very fine/ fine fine/mediummedium/ coarsecoarse/ very coarsevery coarse/ extremely coarse
VF
F
M
CVC
XC
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
EPA Requested Changes Coming!?!?Example Reference Graph
Cumulative Volume Fraction
0.1 0.5 0.9
Dro
p S
ize
(mic
rons
)
0
100
200
300
400
500
600
700
800
900
very fine/ fine fine/mediummedium/ coarsecoarse/ very coarsevery coarse/ extremely coarse
VF
F
M
CVC
XC
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 laser-
based 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
Very Fine (VF) < 182µm Fine (F) 183-280µm Medium (M) 281-429µm Coarse (C) 430-531µm Very Coarse (VC) 532-655µm Extremely Coarse (XC) >656µm
*USDA ARS College Station, TX
Droplet Spectra Classification (DSC)
Droplet SizeRange
Nozzle Technology? How to use??
Nozzles designed to reduce drift Improved drop size controlEmphasis 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 pattern80 and 110 degree fanRequires overlap - 50 to
60%15-60 psi range
Extended Range Flat-fan:Tapered edge pattern80 and 110 degree fanRequires overlap - 50 to 60%15-60 psi range
110°
80°
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
XR
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: Spraying Systems-2000
Nozzle Type(0.5 GPM Flow)
Approximate % of SprayVolume < 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 NOZZLEFOR USE ON FIXED-WING AIRCRAFT
AERIAL APPLICATORS SPRAY NOZZLE HANDBOOKUSDA ARS AGRICULTURAL HANDBOOK NO. XXX
The author is I. W. Kirk, Agricultural Engineer, Areawide Pest M anagement Research Unit,
Southern Plains Agricultural Research Center, Agricultural Research Service, U. S. Department of Agriculture, 2771 F&B Road, College Station, TX 77845-4966, USA.
G Directions: Enter CP STRAIGHT STREAM nozzle settings, pressure, and airspeed in the cells highlighted below.
N (Atomization parameters are valid only with nozzle and operational settings specified in the Acceptable Range.)
I Orifice Size, Deflector Angle, Pressure, Airspeed,
W inches degrees psi mph
- Acceptable Range: .061 to .171 0 to 30 20 to 60 100 to 160
D 0.125 5 30 130
E Application parameters are displayed in the box below.
X CAUTION: Do not enter or clear data in the cells in this box!
I DV0.5 = 330 µm = Volume median diameter
F 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 classif ications reported here are least-squares best-estimate predictions f rom experimental data collected in a w ind tunnel.
Values reported f rom other laboratories may not yield the exact same values, but similar trends w ould be expected.The droplet spectra classif ication 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 theU. S. Department of Agriculture, and does not imply endorsement of the product over other products not mentioned.
