United States Prevention, Pesticides EPA712-C-98-055
Environmental Protection and Toxic Substances March 1998
Agency (7101)
&EPA Spray Drift Test
Guidelines
OPPTS840.1100
Spray Droplet Size
Spectrum
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INTRODUCTION
This guideline is one of a series of test guidelines that have been
developed by the Office of Prevention, Pesticides and Toxic Substances,
United States Environmental Protection Agency for use in the testing of
pesticides and toxic substances, and the development of test data that must
be submitted to the Agency for review under Federal regulations.
The Office of Prevention, Pesticides and Toxic Substances (OPPTS)
has developed this guideline through a process of harmonization that
blended the testing guidance and requirements that existed in the Office
of Pollution Prevention and Toxics (OPPT) and appeared in Title 40,
Chapter I, Subchapter R of the Code of Federal Regulations (CFR), the
Office of Pesticide Programs (OPP) which appeared in publications of the
National Technical Information Service (NTIS) and the guidelines pub-
lished by the Organization for Economic Cooperation and Development
(OECD).
The purpose of harmonizing these guidelines into a single set of
OPPTS guidelines is to minimize variations among the testing procedures
that must be performed to meet the data requirements of the U. S. Environ-
mental Protection Agency under the Toxic Substances Control Act (15
U.S.C. 2601) and the Federal Insecticide, Fungicide and Rodenticide Act
(7U.S.C. I36,etseq.).
Final Guideline Release: This guideline is available from the U.S.
Government Printing Office, Washington, DC 20402 on The Federal Bul-
letin Board. By modem dial 202-512-1387, telnet and ftp:
fedbbs.access.gpo.gov (IP 162.140.64.19), or call 202-512-0132 for disks
or paper copies. This guideline is also available electronically in ASCII
and PDF (portable document format) from the EPA's World Wide Web
site (http://www.epa.gov/epahome/research.htm) under the heading "Re-
searchers and Scientists/Test Methods and Guidelines/OPPTS Harmonized
Test Guidelines."
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OPPTS 840.1100 Spray droplet size spectrum.
(a) Scope—(1) Applicability. This guideline is intended to meet test-
ing requirements of both the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA)(7 U.S.C. 136, et seq.) and the Toxic Substances
Control Act(TSCA)(15 U.S.C. 2601).
(2) Background. The source material used in developing this har-
monized OPPTS test guideline is the OPP guideline 201-1—Droplet size
spectrum testing (Pesticide Assessment Guideline, Subdivision R: Pesticide
Spray Drift Evaluation, EPA Report 540/9-84-002, April 1984).
(b) General—(1) Purpose. Droplet size spectrum studies are per-
formed to determine the influence of a number of equipment and formula-
tion parameters and initial environmental factors on the formation of the
droplets as they leave the pesticide dispersal equipment. The major param-
eters that will be tested are type of nozzle, orientation to the wind shear,
and formulations. By studying this part of the application process in detail,
the more expensive field evaluations will have to be performed less fre-
quently. Droplet size studies indicate which of the conventionally used
nozzle types, orifice sizes, operating conditions, adjuvants, formulations,
and discharge orientations would produce the greatest volume of droplets
less than 100 microns in diameter. Droplet size spectrum studies may be
carried out in wind tunnels or during the field evaluation of drift using
commercial equipment.
(2) Test standards. In addition to those test standards set forth in
OPPTS guideline 840.1000, the following standards apply:
(i) Test substance. A formulated end-use product of the same formu-
lation category as the end-use product to be registered, i.e. wettable pow-
ders, emulsifiable concentrates, etc., and use, i.e. herbicide, insecticide,
etc., will be tested.
(ii) Equipment. The label-recommended or commonly-used nozzles
and associated parts, nozzle pressures, and nozzle discharge orientation
that would produce droplets that would be most conducive to spray drift
should be tested.
(iii) Meteorological conditions. (A) For wind tunnel studies, the fol-
lowing conditions should be tested:
(7) The product should be tested at various temperature levels from
10 to 35 °C.
(2) The air flow (velocity) in the wind tunnel may be adjusted to
relate to the type of equipment used (e.g. 130 to 225 kmph (80 to 140
mph)) for fixed-winged aircraft and air carriers, 65 to 110 kmph (40 to
70 mph) for helicopter (rotary-winged aircraft), and 5 to 40 kmph (3 to
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25 mph) for ground applications (including sprinkler irrigation) other than
air carriers (mist blowers).
(B) For field determination studies, the meteorological conditions
should be those most conducive to spray drift (relatively high temperature,
low relative humidity, and inversion). Field studies with the elevated tem-
peratures are conducted to determine the effect of a higher evaporation
rate on the droplets.
(iv) Collection devices. The collection devices should be either laser
particle measuring systems, collection cards (both horizontal or vertical
surfaces), air samplers, or other devices by which droplet size distribution
can be determined.
(c) Data reporting. The registrant's report on droplet size spectrum
studies should include all information necessary to provide: A complete
and accurate description of the treatments and procedures; sampling data;
data on storage of the samples until analysis (if performed); any chemical
analysis of the collection surfaces as to chemical content (if performed);
recovery efficiency; reporting of the data, rating system and statistical
analysis; and quality control measures/precautions taken to ensure the fi-
delity of the operations. Specifically, each report should include the fol-
lowing information:
(1) General, (i) Cooperator or researcher (name and address), test
location (county and state; country, if outside of the U.S.A.), and date
of study;
(ii) Name (and signature), title, organization, address and telephone
number of persons responsible for planning/supervising/monitoring.
(iii) Trial identification number.
(iv) Quality assurance indicating: control measures/precautions fol-
lowed to ensure the fidelity of the droplet size; record-keeping procedures
and availability of logbooks; skill of the laboratory personnel; equipment
status of the laboratory; degree of adherence to good laboratory practices;
and degree of adherence to good agricultural practices for application of
pesticides.
(v) Other information the registrant considers appropriate and relevant
to provide a complete and thorough description of the test procedure and
results.
(2) Control data. Control values for the test should be reported. Due
to the wide diversity of pesticide properties, use patterns, and organisms
exposed in the field environment, specific reporting requirements for con-
trol values (as to source, sampling regime, and total number of sample
data submitted) will depend upon the complexity and variability of the
environment in which the test is to be conducted.
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(3) Test substance and physical properties, (i) Identification of the
pesticide active ingredient including chemical name, common name
(ANSI, BSI, ISO, WSSA), and company developmental/experimental
name.
(ii) Active ingredient percentage by weight in the formulated end-
use product used or substituted (with reasons for substitution of end-use
product).
(iii) Type of formulation (e.g., emulsifiable concentrate, flowable
powder, liquid, etc.). Product formulation used, diluent and manner of dilu-
tion, mixtures, adjuvants, and their physical properties (surface tension,
viscosity, density, vapor pressure, etc.).
(iv) Dosage of active ingredients or acid equivalent per unit area of
land or gallons-per-minute (gpm) or liters-per-minute (1pm). The con-
centration of the final diluted spray mixture (in the spray tank) should
be sampled, chemically analyzed, and reported.
(v) If droplet size distribution is determined during the field evalua-
tion, physical property data, including droplet size, viscosity, density,
vapor pressure, visco-elasticity, and surface tension, should be determined
and reported.
(4) Test method. Each report should contain a statement regarding
the method of droplet testing used (wind tunnel, aircraft, mist blower) in-
cluding a full description of the experimental design and procedure. In
lieu of the wind tunnel study required for this test, droplet size distribution
may be determined under field conditions during the spray drift evaluation
test as provided in OPPTS 840.1200.
(5) Collection surfaces, (i) Identification of the collection surfaces.
The collection surfaces may include laser particle measuring systems
(PMS), collection cards (flat horizontal or vertical surfaces), air samplers
or other devices by which droplet size distribution can be measured;
(ii) Identification of the number of replicates.
(iii) Distance between nozzles and collection surface/detection device.
(6) Site of the test, (i) Type of site of the droplet size spectrum study
as to whether the study was performed in or out of a wind tunnel or in
the field during the drift field evaluation study.
(ii) Climatological data (records of applicable conditions for the type
of site, i.e, temperature, air flow or velocity, wind direction [field study],
relative humidity).
(7) Application equipment, (i) The nozzle type, orifice size, and core
identification.
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(ii) The nozzle pressure and flow rate.
(iii) The nozzle discharge orientation to the airstream. Nozzle dis-
charge orientation should be designated in degrees related to the direction
of travel of the spray equipment. Zero degrees indicates a horizontal nozzle
discharge pointing rearward (opposite to the equipment direction of travel),
90* indicates a vertical nozzle discharge pointing downward, and 180* in-
dicates a horizontal nozzle discharge pointing forward (with the equipment
direction of travel).
(iv) The estimated minimum and maximum nozzle-to-target height.
(v) Air velocity past the nozzle.
(vi) Descriptions of techniques and size determination devices.
(vii) Particle size distribution vs. cumulative percent volume and par-
ticle size distribution vs. droplet number (frequency) (an attempt should
be made to determine the droplet size distribution where droplet formation
is finalized).
(8) Additional information. If droplet size distribution is determined
during the field evaluation, the following information should also be sub-
mitted:
(i) A diagram of the plot indicating north, swath width, and orienta-
tion, and location and spacing of the collection stations.
(ii) Temperature at two levels, wind velocity and direction, variations
in velocity and direction during the application, relative humidity, atmos-
pheric pressure, and air stability. The latter is expressed as Barad's stability
ratio:
SR =[(T3 meters - TI meters)/(ave. wind velocity)] x 105
Temperature should be determined just above the canopy (Ti) and at least
2 m above that (Ts) for all applications. A standard vertical separation
should be 2 m. Wind velocity should be determined at least 1 to 2 m
above the canopy height.
(iii) Spray volume (liters per hectare or gallons per acre) and
carrier(s). The maximum and minimum carrier volumes recommended on
the label should be reported.
(iv) The ground speed of application equipment, the number of swaths
sprayed during exposure of collecting surfaces, and swath width.
(v) The quantity of active ingredients(s) or acid equivalent collected
or detected at each sampling point in terms of kilograms per hectare
(pounds per acre).
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(9) Results, (i) The particle size distribution versus cumulative per-
cent volume and versus droplet number (frequency) should be reported.
(ii) The 10th, 50th and 90th percentile of the size distributions with
respect to droplet volume and number and standard deviations, where pos-
sible, should be reported.
(d) In lieu of the wind tunnel study required by this section, droplet
size distribution may be determined under field conditions during the spray
drift evaluation test as provided in OPPTS 840.1200.
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