Draft Generic Verification Protocol for Pesticide Spray DRT Version 1.5 September 2012

U.S. EPA Generic Verification Protocol

for Testing Pesticide Application Spray Drift Reduction Technologies 

for Row and Field Crops

This protocol has been reviewed and approved by:
Draft Generic Verification Protocol for Pesticide Spray DRT Version 1.5

September 2012 Page ii

A2: Table of Contents

List of Figures................................................................................................................................. v

List of Tables .................................................................................................................................. v

List of Acronyms and Abbreviations............................................................................................. vi

Preface.......................................................................................................................................... viii

Acknowledgments........................................................................................................................... x

Group A: Project Management ....................................................................................................... 1

A4: Project or Task Organization .......................................................................................... 1

A5: Project Definition and Background ................................................................................ 2

A6: Project or Task Description ............................................................................................ 4

A6.1 Description.................................................................................................................. 4

A6.2 Test Facility Description............................................................................................. 5

A6.3 Schedule...................................................................................................................... 9

A7: Quality Objectives and Criteria ...................................................................................... 9

A7.1 Spray Droplet Size Measurements............................................................................ 10

A7.2 Low Speed Wind Tunnel Tests.................................................................................... 11

A7.3 High Speed Wind Tunnel Tests................................................................................... 11

A7.4 Field Tests.................................................................................................................... 12

A7.5 Standards Cited ............................................................................................................ 12

A8: Special Training and Certifications .............................................................................. 12

A9: Documentation and Records......................................................................................... 13

Group B: Data Generation and Acquisition for Low Speed Wind Tunnel.................................. 14

B1: Sampling Process Design (Experimental Design)........................................................ 14

B2: DQIGs and DQOs for Low Speed Wind Tunnel Measurements.................................. 15

B3: Sampling Methods for Measurement of Droplet Size, Deposition, and Test Conditions

17

B3.1 Sampling Locations .................................................................................................. 17

B3.2 Process and Application Data Collection ................................................................. 17

B3.3 Measurement of Droplet Size Spectrum near the Nozzle......................................... 19

B3.4 Wind Tunnel Measurement of Spray Drift Potential................................................ 20

B4: Sample Handling and Custody Requirements .............................................................. 22

B5: Analytical Methods....................................................................................................... 22

B7: Instrument and Equipment Testing, Inspection, Maintenance, and Calibration 

Frequency.............................................................................................................................. 22
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B8: Inspection and Acceptance of Supplies and Consumables....................................... 22

B9: Non-Direct Measurements............................................................................................ 23

B10: Data Management ......................................................................................................... 23

B10.1 Data Flow.............................................................................................................. 23

B10.2 Data Reduction...................................................................................................... 24

B10.3 Analysis of Verification Data ............................................................................... 25

Group C: Data Generation and Acquisition for High Speed Wind Tunnel Tests......................... 26

C1: Sample Process Design (Experimental Design) ........................................................... 26

C2: DQIGs and DQOs for High Speed Wind Tunnel Measurements................................. 27

C3. Sampling Methods for Measurement of Droplet Size and Test Conditions................. 28

C3.1 Sampling Locations .................................................................................................. 28

C3.2 Process and Application Data Collection ................................................................. 29

C3.3 Wind Tunnel Measurement of Droplet Size Distribution at Aerial Application Air 

Speeds at the Nozzle ............................................................................................................. 29

C4: Sample Handling and Custody Requirements .............................................................. 31

C5: Analytical Methods....................................................................................................... 31

C6: Quality Control ............................................................................................................. 31

C7: Instrument and Equipment Testing, Inspection, and Maintenance............................... 31

C8: Instrument and Equipment Calibration and Frequency ................................................ 31

C9: Inspection and Acceptance of Supplies and Consumables........................................... 31

C10: Non-Direct Measurements............................................................................................ 32

C11: Data Management ......................................................................................................... 32

C11.1 Data Flow.............................................................................................................. 32

C11.2 Data Reduction: .................................................................................................... 32

C11.3 Analysis of Verification Data: .............................................................................. 32

Group D: Data Generation and Acquisition for Field Studies...................................................... 33

D1: Sampling Process Design (Experimental Design)........................................................ 33

D2: DQIGs and DQOs for Field Test Measurements.......................................................... 33

D3: Sampling Methods for Measurement of Droplet Size, Deposition, and Test Conditions

33

D3.1 Sampling Locations .................................................................................................. 35

D3.2 Process and Application Data Collection ................................................................. 35

D3.3 Ambient Data Collection .......................................................................................... 35

D4: Sample Handling and Custody Requirements .............................................................. 36

D5: Analytical Methods....................................................................................................... 37
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D6: Quality Control ............................................................................................................. 37

D7: Instrument and Equipment Testing, Inspection, and Maintenance............................... 38

D8: Instrument and Equipment Calibration and Frequency ................................................ 38

D9: Inspection and Acceptance of Supplies and Consumables........................................... 38

D10: Non-Direct Measurements............................................................................................ 38

D11: Data Management ......................................................................................................... 38

D11.1 Data Flow.............................................................................................................. 39

D11.2 Data Reduction...................................................................................................... 39

D11.3 Analysis of Verification Data ............................................................................... 39

Group E: Data Reporting .............................................................................................................. 40

E1: Outline of the Verification Test Report ........................................................................ 40

E2: Draft Report Preparation............................................................................................... 41

E3: Data Storage and Retrieval ........................................................................................... 41

F1: Assessments and Response Actions.............................................................................. 42

F1.1 Internal Audits .......................................................................................................... 42

F1.2 Audits of Data Quality.............................................................................................. 42

F1.3 External Audits......................................................................................................... 42

F1.4 Corrective Action...................................................................................................... 42

F2: Reports to Management ................................................................................................ 42

Group G: Data Validation and Usability Elements....................................................................... 43

G1: Data Review, Verification, and Validation................................................................... 43

G2: Verification and Validation Methods........................................................................... 43

G3: Reconciliation with Data Quality Objectives ............................................................... 43

Appendix A: Applicable Documents and Procedures .................................................................. 45

1. EPA Documents................................................................................................................ 45

2. Verification Organization Documents.............................................................................. 45

3. Other Literature................................................................................................................. 46

Appendix B: Example Format for Test Data ................................................................................ 47
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List of Figures

Figure 1. Example of a low speed wind tunnel................................................................................7

Figure 2. Example of a high speed wind tunnel.............................................................................. 8

Figure 3. Example verification schedule for testing organization with approved T/QAP.............. 9

Figure 4. Data management system.............................................................................................. 24

Figure 5. Sampling locations for field testing................................................................................37

List of Tables

Table 1. DRT versus Testing Approach ......................................................................................... 6

Table 2. DQIGs for Spray Droplet Size Measurements ............................................................... 10

Table 3. DQIGs for Low Speed Wind Tunnel Testing................................................................. 15

Table 4. Summary of Spray and Test Condition Measurements.................................................. 18

Table 5. Quality Control Samples for Low Speed Wind Tunnels................................................ 23

Table 6. DQIGs for High Speed Wind Tunnel Testing ................................................................ 27

Table 7. Summary of Spray and Test Condition Measurements.................................................. 28

Table 8. DQIGs for Field Testing................................................................................................. 34

Table 9. Summary of Spray and Test Condition Measurements for Field Testing ...................... 36

Table B-1. Example of Test Data Report Format..........................................................................47
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List of Acronyms and Abbreviations

ADQ audit of data quality

ANSI American National Standards Institute

APCT Center Air Pollution Control Technology Center

ASABE American Society of Agricultural and Biological Engineers

ASAE American Society of Agricultural Engineers (precursor to ASABE)

ASHRAE American Society of Heating, Refrigerating, and Air Conditioning Engineers

ASME American Society of Mechanical Engineers

ASTM American Society for Testing and Materials

BBA Biologische Bundesanstalt für Land- und Forstwirtschaft (Germany’s Federal 

Biological Research Center for Agriculture and Forestry)

oC degrees Celsius

cfm cubic feet per minute

cm centimeter

CV coefficient of variance

DQIG data quality indicator goal

DQO data quality objective

DRT drift reduction technology

Dv0.x droplet diameter (μm) at which 0.x fraction of the spray volume is contained in 

smaller droplets

dyne/cm dynes per centimeter

EC emulsifiable concentrates

EPA United States Environmental Protection Agency

ESTE Environmental and Sustainable Technology Evaluations

ETV Environmental Technology Verification

fpm feet per minute

ft foot

gal/acre gallons per acre

Hz hertz

ISO International Standards Organization

kPa kilopascal

L liter

LERAP Local Environmental Risk Assessment for Pesticides (UK scheme)

m meters

mph miles per hour

min minute

mg milligram

mL milliliter

mm millimeter

ms millisecond

m/s meters per second

μL microliter

μm microns

OPP Office of Pesticide Programs

ORD Office of Research and Development

PE performance evaluation
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PES performance evaluation system

PMT photo multiplier transistor 

psi pounds per square inch

QA quality assurance

QC quality control

QM quality manager

QMP quality management plan

QSM quality system manual

RH relative humidity

RTI Research Triangle Institute S second

SNR signal to noise ratio

SOP standard operating procedure

STPstakeholder technical panel

T/QAP test and quality assurance plan

TSA technical systems audit

VMD volume median diameter

v/v volume/volume
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Preface

This generic verification protocol, Verification of Pesticide Application Spray Drift Reduction 

Technologies for Row and Field Crops, provides a detailed method for conducting and reporting 

results from a verification test of pesticide application technologies that can be used to evaluate 

these technologies for their potential to reduce spray drift, hence the term “drift reduction 

technologies” (DRTs). EPA, through its Environmental and Sustainable Technology Evaluations 

(ESTE) program, developed this protocol with input by external experts to provide the pesticide 

application technology industry with a standard method to voluntarily test their technologies for 

potential reductions in spray drift. This protocol describes the testing approach used to generate 

high-quality, peer-reviewed data for DRTs, including test design and quality assurance aspects. 

Evaluation of this protocol has been limited to spray nozzles in low and high speed wind tunnels.

(EPA, 2012) Methods for field testing methods have been documented by others. (ISO Standard 

22866, 2005) The effect of tank mixes, including adjuvants, was not evaluated as part of this 

effort.

EPA intends to use this test protocol as part of a program to accelerate acceptance and use of 

improved and cost-effective application technologies which can significantly reduce spray drift 

and thereby provide benefits to applicators, the public, and the environment. Applications of 

most if not all sprays result in some amount of drift from the application site and can cause 

adverse effects and other undesirable consequences. For this reason, the agricultural sector, 

government, and the general public seek ways to significantly reduce spray drift. 

EPA expects the use of verified DRTs to significantly reduce pesticide spray drift and loss from 

the application site, thereby keeping more of the applied pesticide on the treated field and 

reducing risks to the surrounding environment, nearby humans, and property, including crops. 

Pesticide product labels with DRTs may also increase applicators’ flexibility in applying those 

pesticides by reducing the need for more restrictive application measures as compared to those 

required for the use of standard application equipment.

The pesticide industry and government have conducted considerable research to determine the 

underlying factors that affect spray drift, including different types of application equipment

(spray nozzles for ground boom, air blast, and aerial applications). A number of underutilized 

commercial technologies exist for managing drift; however, little information exists on their 

effectiveness in reducing spray drift levels. Verification of the effectiveness of pesticide spray

drift reduction technologies is the focus of this protocol document.

EPA will encourage equipment manufacturers to voluntarily participate in this program and to 

test their equipment using this protocol. EPA will also encourage pesticide registrants to 

recommend or require the use of verified DRTs for the application of their products. When 

product labels include the use of DRTs, EPA will include this in its scientific review and risk 

management decision-making.

EPA’s Office of Research and Development partnered with EPA’s Office of Pesticide Programs 

to complete this project under the ESTE program. The ESTE program is part of EPA’s

Environmental Technology Verification Program (ETV) which was created in 1995 to facilitate 
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September 2012 Page ix

the commercialization of innovative or improved environmental technologies through 

performance verification and dissemination of information. In 2005, ETV established the ESTE 

program to focus these verifications on specific Agency needs. Consistent with other ESTE 

efforts, a technical panel of knowledgeable and interested stakeholders representing application 

equipment and pesticide manufacturers and academic and government research scientists assisted 

by offering technical advice in developing this test protocol.

This protocol is the final product of the ESTE effort and reflects the 2006 input of the 

Stakeholder Technical Panel (STP). Technology has improved since 2006 and there are 

emerging/alternative methods to measure and model spray drift from ground boom spray

equipment using data generated in low speed wind tunnels. Potential alternatives are included as 

footnotes in Group B of this document. The protocol will evolve as the science of measurement 

and modeling advances. The EPA Office of Pesticide Program’s DRT program will be 

responsible for any changes to the protocol and will post the current version at 

http://www.epa.gov/DRT.
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Acknowledgments

Much of this effort was completed by RTI International under Contact EP-C-05-060, Work 

Assignment 52. EPA thanks RTI for its diligent efforts to develop a coherent test protocol for a 

complicated and difficult area of testing.

Stakeholder Technical Panel (STP)

The individuals selected to participate on the Drift Reduction Technology Stakeholder Technical 

Panel are listed below. We want to thank the panel members for contributing their technical 

expertise to this protocol document.

Carolyn Baecker, CP Products Co., Inc.

Tom Bals, Micron Inc.

Aldos Barefoot, Ph.D., DuPont Crop Protection, CropLife America

Terrell Barry, Ph.D., California Department of Pesticide Regulation

Sandra Bird, Ph.D., Retired, EPA/Office of Research and Development

Clare Butler-Ellis, Ph.D., Silsoe Spray Application Unit, TAG, Silsoe, UK

Dennis Gardisser, Ph.D., WRK of Arkansas, LLC (Retired, University of Arkansas)

Ken Giles, Ph.D., University of California, Davis

W. Clint Hoffmann, Ph.D., USDA-Agricultural Research Service

Ted Kuchnicki, Pesticide Management Regulatory Agency, Canada

Stephen Pearson, Ph.D., Spraying Systems Company

Carmine Sesa, AgMarketResults (Retired, Rhodia)

Harold Thistle, Ph.D., USDA Forest Service

David Valcore, Valcore Consulting, LLC (Retired, Dow AgroSciences, Spray Drift Task Force)

Jan Van de Zande, WageningenUR-Plant Research International, The Netherlands

Tom Wolf, Agriculture & Agri-Food, Canada

Alvin R. Womac, Ph.D., University of Tennessee

Other Contributors

In addition to the STP members listed above, several other individuals provided technical input 

and resources to develop this protocol. We would like to thank the following individuals for 

their contributions to this protocol document.

Norman Birchfield, Ph.D., EPA/Office of Research and Development

Kerry Bullock, Ph.D., Formerly with EPA/Office of Research and Development

Jay Ellenberger, EPA/Office of Pesticide Programs

Bradley Fritz, Ph.D., USDA-Agricultural Research Service

Christine Hartless, EPA/Office of Pesticide Programs

Andrew Hewitt, Ph.D., Lincoln Ventures, Ltd., New Zealand

Faruque Khan, Ph.D., EPA/Office of Pesticide Programs

Michael Kosusko, EPA/Office of Research and Development

Steven Perry, Ph.D., EPA/Office of Research and Development

Mohammed Ruhman, EPA/Office of Pesticide Programs

Karen Schaffner, RTI International

Dee Ann Staats, Retired, CropLife America
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Bill Taylor, Hardi International 

Jonathan Thornburg, Ph.D., RTI International

Drew Trenholm, Retired, RTI International

Jenia Tufts, Formerly with RTI International

Robert S. Wright, EPA/Office of Research and Development
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Group A: Project Management

A4: Project or Task Organization

The U.S. Environmental Protection Agency’s (EPA’s) Office of Pesticide Programs (OPP) has 

responsibility for the DRT Program. It intends to employ this test protocol in the DRT Program. 

EPA’s Office of Research and Development (ORD) has overall responsibility for the 

Environmental Technology Verification (ETV) Program and for the Verification of Pesticide 

Drift Reduction Technologies project under the Environmental and Sustainable Technology

Evaluations (ESTE) Program. The ESTE Program operates as part of the Agency’s larger ETV 

Program. ETV develops testing protocols and verifies the performance of innovative 

technologies that have the potential to improve protection of human health and the environment. 

Both OPP and ORD were involved in this protocol development effort.

In 2005, the EPA created a new program element, ESTE, under its current ETV. This program 

was designed to support specific priority Agency issues to support program and regional efforts 

to address important environmental issues (and environmental sustainability) and to protect 

human health. As part of ESTE, innovative, commercial-ready technologies showing potential 

to significantly reduce risks are selected for verification testing. Testing—conducted with the 

same commitment to quality assurance, cost-sharing, and stakeholder involvement fundamental 

to the larger ETV program—provides credible performance data needed for accurate assessment 

of the effectiveness of these technologies. 

Future DRT verification testing programs will be conducted under the sponsorship of EPA with 

the participation of DRT manufacturers and vendors. Test site-specific test and quality assurance 

plans (T/QAPs) will be prepared by each testing organization to meet the requirements of the 

generic verification protocol (this document) and must be approved by EPA.

This protocol developed the procedures to test pesticide DRTs in accordance with quality

management documents used by the ETV Program’s Air Pollution Control Technology Center 

(APCT Center). The primary source for this quality system is EPA’s Policy and Program 

Requirements for the Mandatory Agency-wide Quality System, EPA Order CIO2105.0 (May

2000). The quality system that was used to govern testing under this plan is consistent with the 

following:

 EPA Requirements for Quality Management Plans (EPA QA/R-2)

 EPA Environmental Technology Verification Program, Quality Management Plan (EPA 

ETV QMP), for the overall ETV program

 APCT Center’s Verification Testing of Air Pollution Control Technology - Quality

Management Plan (APCT Center QMP)

 Each Testing Organization’s Standard Operating Procedures (SOP)

 This protocol. 

EPA’s ETV QMP provides the definitions, procedures, processes, organizational relationships, 

and outputs that will ensure the quality of the data and the programmatic elements of ETV. Part 

A of the EPA ETV QMP includes the specifications and guidelines that are applicable to 

common or routine quality management functions and activities necessary to support the ETV 
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program. Part B of the EPA ETV QMP includes the specifications and guidelines that apply to 

test-specific environmental activities involving the generation, collection, analysis, evaluation, 

and reporting of test data.

APCT Center QMP describes the quality systems in place for the overall APCT Center 

program. It was prepared by RTI and approved by EPA. Among other quality management 

items, it defines what must be covered in the generic verification protocols and T/QAPs for 

technologies undergoing verification testing.

Generic verification protocols are prepared for each technology to be verified. These 

documents describe the overall procedures to be used for testing a type of technology and define 

the critical data quality objectives (DQOs). The document herein is the generic verification 

protocol for pesticide spray DRTs. It was written with input from the technical panel and 

approved by EPA.

Test and quality assurance (QA) plans are prepared by the testing organization. The T/QAP

describes in detail how the testing organization will implement and meet the testing requirements 

of the generic verification protocol. The T/QAP also sets data quality objectives (DQOs) for 

supplemental non-critical measurements that are specific to the site of the test. The T/QAP

addresses issues such as the test organization’s management organization, test schedule, 

documentation, analytical methods, data collection requirements, calibration, and traceability. It 

also specifies the QA and quality control (QC) requirements for obtaining verification data of 

sufficient quantity and quality to satisfy the DQOs of the generic verification protocol. A test 

plan addendum will also be developed that describes the specific DRT. For pesticide spray

DRT, the critical measurements include the droplet size distribution, the spray flux (low speed 

wind tunnels only), and deposition (field testing). Other supplemental, non-critical 

measurements may also be conducted (e.g., application rate, application pressure, air or wind 

speed, relative humidity, and ambient temperature). EPA provides guidance for writing test/QA 

plans in Guidance on Environmental Data Verification and Data Validation, EPA QA/G-8.

Appendix A lists full citations for these documents. This protocol is in conformance with EPA

Requirements for Quality Assurance Project Plans (EPA QA/R-5), EPA Guidance for Quality 

Assurance Project Plans (EPA QA/G-5), and the documents listed above.

A testing organization with a quality system as described in Element A8 of this document and 

with the capability to carry out the methods and procedures contained in this plan will conduct 

the testing. The testing organization will verify the emissions reductions of drift reduction 

technologies. The testing organization will perform the testing, evaluate the data, and submit a 

report documenting the results. The various QA and management responsibilities are divided 

among the testing organization and key EPA project personnel.

A5: Project Definition and Background

For the purpose of this document and associated testing projects, pesticide spray drift is defined 

as the movement of spray droplets through the air at the time of application or soon thereafter 

from the target site to any non- or off-target site, excluding pesticide movements by erosion, 

migration, volatility, or windblown soil particles after application. Spray drift management is of 
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interest to pesticide and other chemical manufacturers, application equipment manufacturers, 

pesticide applicators, government agencies, advocacy groups, and the public. Spray drift risks 

are correlated to deposition in EPA risk assessment. To reduce exposure, DRTs that can reduce 

drift downwind are beneficial; the results of testing conducted under the DRT Program using this 

protocol are to be used by EPA to estimate downwind deposition. For example, the testing 

results from wind tunnel testing (droplet size distribution and spray flux) will be used as inputs to 

models that will estimate deposition downwind. Any modeling results will be determined 

outside of this protocol, the T/QAP and verification test report. Information about the use of 

wind tunnel data and an example calculation are provided at (http://www.epa.gov/DRT).

Industry, including pesticide applicators, and government researchers have developed and 

employed a variety of pesticide application strategies and technologies to reduce spray drift. 

Examples include low drift spray nozzles and sprayers, drift control chemical adjuvants, barrier 

structures, and vegetation. Although these and other technologies have the potential to provide 

drift reduction, there is often uncertainty about their effectiveness or performance. Verification 

testing of DRTs provides objective, quality-assured data that can be used to evaluate the 

effectiveness of the tested technologies to reduce spray drift. Use of these test results by EPA 

and pesticide and equipment manufacturers will enable pesticide applicators to make more 

informed and confident DRT selection. Use of these DRTs in the application of pesticides has 

the potential for significant benefits: reduced spray drift and the associated risks to humans and 

the environment; greater on-target deposition of pesticides applications; increased efficacy; and 

applications under a wider range of environmental conditions.

Testing will be performed on application technologies with one or more of the following test 

methods: low speed wind tunnel testing, high speed wind tunnel testing, and field testing. Field 

testing is an acceptable method of testing all DRTs. Low speed would be the speed of the air in 

the wind tunnel crossing the spray nozzle for ground application, and high speed would be the 

speed of the air in the wind tunnel crossing the nozzle for aerial application. For certain DRTs, 

wind tunnel testing may be an appropriate test method. The verification tests will gather 

information and data for evaluating the performance of the strategies and technologies versus a 

reference application system and the technologies’ associated environmental impacts and 

resource requirements. The scope will, in most cases, cover two principal study questions:

1. What is the performance of the technology in terms of the manufacturer or vendor’s 

statement of capabilities for reducing downwind deposition? Answering this question 

is critical to determining the performance of the technology and thus the measurements 

made to address this question are critical. The specific DQOs for these measurements 

are included in Element A7. 

2. What are the test conditions over which the performance is measured (e.g., spray

pressure, formulation type, release height, crop canopy, ambient temperature, wind 

speed, relative humidity)? The range of conditions under which the technology is 

evaluated will be used to determine the conditions required for performance in the 

field. The DQOs for the measurement of the test conditions are described in Element 

A7. 
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Two additional study questions are of interest, but not quantified during the verification. The 

information gathered will be general observations of test conditions to be recorded by the testing 

organization. The DRT tested will determine specific observations to be made. These details 

will be specified in the test and quality assurance plan (T/QAP). 

3. What are the associated environmental impacts, if any, of operating the technology

within this range other than drift reduction (e.g., effects on application rate and 

material usage, dose, other sources of environmental exposure, worker exposure)? 

Evaluation of the associated environmental impacts is a supplemental non-critical 

product of this test plan and as a result available instrumentation may be used to make 

measurements for this purpose. No DQOs are defined for this question. 

4. What are the resources associated with operating the technology within this range 

relative to standard pesticide application equipment (e.g., energy, waste disposal, and 

product usage, as well as sprayer handling – for example, some technologies may

affect the safety of operation of aircraft or other sprayers)? Measurement of 

consumption of resources is a supplemental non-critical measurement of this test plan 

and as a result, available instrumentation may be used to make measurements for this 

purpose. No DQOs are defined for this question.

This protocol describes the overall procedures to be used. The T/QAP for a pesticide drift 

reduction technology will describe how test procedures will be specifically implemented for 

verifying the technology performance. In addition to the procedures described in this protocol, 

the test procedures to be used can be derived from standard methods (e.g., ISO, ASTM, ASABE, 

etc.). Each test site or testing organization will need to develop a T/QAP for its test facility

detailing its test procedures. Deviations from described protocols must be described by the 

testing organization in its T/QAP. 

A6: Project or Task Description

A6.1 Description

This protocol describes the test and QA procedures that will conform to all specifications of EPA 

Requirements for Quality Assurance Project Plans, EPA QA/R-5, the current EPA ETV QMP, 

and the current ETV APCT Center QMP. The T/QAP will specifically describe the quality 

system required of the testing organization and the procedures applicable to meeting EPA quality 

requirements. T/QAPs, developed for each test site, and test plan addenda, developed for each 

technology, will be reviewed and approved by EPA prior to testing. The low speed wind tunnel 

(Group B) and high speed wind tunnel (Group C) portions of this protocol were tested, evaluated 

and revised during the ESTE project. 

The verification tests will gather information and data to evaluate the extent to which the DRT

reduces downwind deposition. Also, any other positive or adverse environmental impacts of 

operating the DRT will be noted as informal observations. The specific operating conditions 

used during the testing will be documented as part of the verification process. Table 3 in 

Element B2, Table 6 in Element C2, and Table 9 in Element D3 of this protocol present a 
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summary of all measurements that will be made to evaluate the performance of the DRT and 

document the test conditions.

A description of a specific technology, the test procedures to be used and test-specific details will 

be documented as an applicant-specific addendum to the T/QAP that will be prepared and 

submitted for EPA review and approval prior to the start of testing. The applicant-specific 

addendum will provide additional information needed to conform to required Elements A5 

(Problem Definition/Background) and A6 (Project/Task Description) of EPA QA/R-5.

Categories of DRTs include:

1. Spray nozzles (e.g., atomizers with fewer fines);

2. Sprayer (passive delivery assistance) modifications (e.g., shields and shrouds, wingtip 

devices);

3. Spray (active) delivery assistance (e.g., air assisted spraying);

4. Spray property modifiers (e.g., formulation and tank mix ingredients that modify spray

solution physical properties);

5. Landscape modifications (e.g., artificial or natural hedges and shelterbelts).

The draft version of this protocol (EPA, 2007) was evaluated as described in Evaluation of the 

Verification Protocol for Low and High Speed Wind Tunnel Testing (EPA, 2012, 

http://www.epa.gov/nrmrl/std/etv/pubs/600etv12010.pdf). The evaluation was limited to testing 

spray nozzles in low and high speed wind tunnels. Test methods for evaluating the drift 

reduction impact of spray property modifiers (adjuvants) will be incorporated into this protocol 

as they become available.

A6.2 Test Facility Description

A description of the test facility will be included in the T/QAP for each test site.

A6.2.1 Test Site Description

Three potential testing sites or approaches are covered in this protocol: low speed wind tunnel, 

high speed wind tunnel, and field testing. EPA OPP will use the low speed wind tunnel and the 

high speed wind tunnel test results in conjunction with modeling to determine downwind drift 

deposition reduction. Low speed wind tunnel testing is appropriate for certain types of DRTs 

intended for use on or with some ground boom sprayers while high speed wind tunnel testing is 

for certain DRTs, such as nozzles and devices intended to reduce air shear, on aerial application 

equipment. Field testing is acceptable for testing all types of DRTs.

In Table 1, the DRT categories are matched to the potential testing approaches and a map to the 

testing procedures laid out in this document is provided.
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Table 1. DRT versus Testing Approach

Test Method

Type of Drift Reduction Technology

Spray Nozzle

Spray Material 

Property 

Modifiers

Sprayer 

Modification

Spray Delivery 

Assistance

Landscape 

Modification

Low speed wind 

tunnel1

Acceptable Acceptable Questionable4

and 

Supplemental5

Not Acceptable Supplemental5

High speed 

wind tunnel2

Acceptable Acceptable Not Acceptable Not Acceptable Not Acceptable

Field testing3 Acceptable Acceptable Acceptable Acceptable Acceptable

1

For DRTs intended for use on or with ground boom spray equipment

2

For DRTs intended for use on or with aerial spray equipment

3

For DRTs intended for use with either ground boom or aerial spray equipment

4

It is advisable to confirm with EPA that the test methods will be adequate for verification of these types of 

DRTs.

5 Low speed wind tunnel testing may provide information that can reduce the extent of field testing required for 

validation, or supplement field data; however, field testing is also required.

Low speed wind tunnel testing

A wind tunnel with the following characteristics will be used:

1. The tunnel must be of sufficient width so that the spray pattern does not impinge on the 

walls of the tunnel. (Wall effects would affect characteristics of spray size distribution 

and should be discernible in the data.) A wind tunnel with working section dimensions 

at least 1.75 meter (m) wide x 1.75 m high x 7 m long shall be used for measurement 

of the spray distribution vertically (“airborne drift potential”) and horizontally 

(“deposition drift potential”) and droplet size distribution for a spray. [NOTE: For 

nozzles including boom sprayer nozzles, ISO 22856 specifies a minimum size 

requirement of 1 m minimum height and 2 m minimum width with a length at least 2 

m (1 m at each end) greater than the length over which spray generators and samplers 

are mounted.]

2. An example of a suitable wind tunnel setup is shown on Figure 1.

3. The airflow characteristics of the wind tunnel shall be known and documented. The air 

speed at different horizontal and vertical locations in the wind tunnel must be 

documented in order to identify the distance from the tunnel’s surface that edge effects 

occur and document the space where air flows uniformly in the working section. The 

wind tunnel working section used for sampling shall have less than 8% turbulence and 

local variability of air velocity below 5%.

4. Temperature and relative humidity within the wind tunnel shall be monitored to ensure 

operation within desired specifications.
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September 2012 Page 7

High speed wind tunnel testing

For high speed wind tunnel testing, a wind tunnel of the following characteristics will be used:

1. The tunnel must be of sufficient width so that the spray pattern does not impinge on the 

walls of the tunnel. (Wall effects would affect characteristics of spray size distribution 

and should be discernible in the data.) For nozzles including boom sprayer nozzles, 

ISO 22856 specifies a minimum size requirement of 1 m minimum height and 2 m 

minimum width with a length at least 2 m (1 m at each end) greater than the length 

over which spray generators and samplers are mounted.

2. An example of a suitable high speed wind tunnel setup is shown on Figure 2. The 

testing organization should beware of tunnel blockage with the nozzle and fan.

3. The airflow characteristics of the wind tunnel should be known and documented

according to ISO 22856. Generally, detailed characteristics are not needed for the high 

speed tunnel test since there are no downwind measurements. As always, data 

requirements will be documented in the T/QAP used for testing. 

Thermohygrometer →

← Anemometer

 Spray Nozzle →

 ↑ Monofilament Collectors (2 mm diameter) ↓

Figure 1. Example of a low speed wind tunnel.
Generic Verification Protocol for Pesticide Spray DRT 

September 2012

Figure 2. Example of a h

Field testing

For field testing, the designated trial

that could influence the air flow in the areas of application or measurement

bare ground (or stubble less than 

for sampling stations. The measurement area should be downwind of the treatment area

length of the spray track should be at least twic

and should be approximately symmetrical about the axis of the sampling array

distances should be measured from the downwind edge of the directly sprayed treatment area

The requirements for the field test site are consistent with requirements 

Local Environmental Risk Assessments for Pesticides (LERAP), Germany’s Biologische 

Bundesanstalt für Land- und Forstwirtschaft 

and Forestry (BBA)], the International Standards Organization (ISO), and the American Society 

of Agricultural and Biological Engineers (ASABE) 

Agricultural Engineers (ASAE)]. 

data generation and acquisition have not been 

A6.2.2 Application and Process Equipment Description

The description of the application and process equipment including photographs will be included 

in the applicant-specific addendum.

Generic Verification Protocol for Pesticide Spray DRT 

. Example of a high speed wind tunnel.

For field testing, the designated trial or spray site should be an exposed area with no obstructions 

that could influence the air flow in the areas of application or measurement. There should be a 

bare ground (or stubble less than 7.5 cm high) treatment area and a similarly bare downwind area 

for sampling stations. The measurement area should be downwind of the treatment area

length of the spray track should be at least twice that of the largest downwind sampling distance 

symmetrical about the axis of the sampling array. All downwind 

distances should be measured from the downwind edge of the directly sprayed treatment area

he field test site are consistent with requirements from United Kingdom’s 

Local Environmental Risk Assessments for Pesticides (LERAP), Germany’s Biologische 

und Forstwirtschaft [Federal Biological Research Center for Agriculture 

, the International Standards Organization (ISO), and the American Society 

of Agricultural and Biological Engineers (ASABE) [formerly known as the American Society of 

. Note, the applicability of the site characteristics to verification 

data generation and acquisition have not been evaluated. 

Process Equipment Description

The description of the application and process equipment including photographs will be included 

ific addendum.

Version 1.5

Page 8

spray site should be an exposed area with no obstructions 

There should be a 

high) treatment area and a similarly bare downwind area 

for sampling stations. The measurement area should be downwind of the treatment area. The 

e that of the largest downwind sampling distance 

All downwind 

distances should be measured from the downwind edge of the directly sprayed treatment area . 

from United Kingdom’s 

Local Environmental Risk Assessments for Pesticides (LERAP), Germany’s Biologische 

Federal Biological Research Center for Agriculture 

, the International Standards Organization (ISO), and the American Society 

formerly known as the American Society of 

acteristics to verification 

The description of the application and process equipment including photographs will be included 
Generic Verification Protocol for Pesticide Spray DRT Version 1.5

September 2012 Page 9

A6.2.3 Control Technology (i.e., DRT) Description

The technology to be verified must be described fully and concisely. The description, provided 

by the technology manufacturer or vendor, must include: technology name, model number, the 

DRT principle, key specifications, manufacturer’s name and address, serial number or other 

unique identification, warning and caution statements, capacity or output rate, and other 

information necessary to describe the specific DRT. The performance guarantee coupled with 

operating conditions and instructions will be provided. EPA OPP verification reports and 

statements will be modeled on ETV documents. Examples of ETV verification reports and 

statements are presented on the ETV Website (http://www.epa.gov/etv/). If combinations of 

independent technologies are being submitted, the description of the combined technology

should completely identify and describe those technologies being combined.

A6.3 Schedule

Figure 3 shows an example schedule for completion of a first draft verification report and 

statement. The test-specific schedule is expected to vary from technology to technology based 

on the scheduling needs of the applicant and the testing organization.

MONTH

TASK 1 2 3 4 5 6

Testing organization develops applicant-specific 

T/QAP addendum

X

Applicant accepts addendum, signs Terms & 

Conditions

X

EPA approves applicant-specific T/QAP addendum X

Testing organization receives test items from applicant X

Testing organization conducts testing

Testing organization delivers draft verification report 

and statement to EPA

X

EPA approves verification report and statement X

Figure 3. Example verification schedule for testing organization with approved T/QAP.

A7: Quality Objectives and Criteria

The DQOs of this testing focus on the direct or indirect measurements of spray drift deposition 

using wind tunnel or field testing. For wind tunnel testing, the testing organization will measure 

droplet size and spray volume data. EPA OPP will use these data with spray drift models such as 

the dispersion models to translate droplet size and spray volume measurements made using this 

protocol to downwind deposition. For field tests, measurements of spray drift on horizontal 

collectors are collected to directly measure spray drift deposition in the area downwind. Test 

requirements for low speed wind tunnels, high speed wind tunnels, and field testing are found in 

Groups B, C, and D, respectively.

The rationale for the number of test runs will be included in the site-specific T/QAPs and the 

applicant-specific addenda, which will conform to required Element B1 of EPA QA/R-5. In 

general, the number of test runs would include: (1) a minimum of three test runs, (2) additional 
Generic Verification Protocol for Pesticide Spray DRT Version 1.5

September 2012 Page 10

test runs indicated to meet certain statistical criteria, and (3) additional test runs desired by the 

applicant vendor or manufacturer. A replicate may only be discarded if proven an outlier by an 

appropriate statistical test or if the tester can document a human or mechanical error during a 

particular measurement.

A7.1 Spray Droplet Size Measurements

The data quality objectives (DQOs) and data quality indicator goals (DQIGs) for measurement of 

spray droplet size distribution are summarized in Table 2. Size distribution data will consist of 

30 or more droplet size bins. The standard deviation around volume median diameter (VMD) 

should be less than 10% as should the standard deviations for the droplet diameter (μm) 

measurements at which 0.1 fraction of the spray volume is contained in smaller droplets (Dv0.1) 

and droplet diameter (μm) measurements at which 0.9 fraction of the spray volume is contained 

in smaller droplets (Dv0.9).

For droplet size distribution at the nozzle, the continuous traverse method is usually the optimal 

technique for sampling the spray plume, and data should be expressed as mass-balanced average 

droplet size data across the traverse. Multiple chordal measurements or (for phase-Doppler 

measurement systems), two- or three-dimensional mapping of droplet size and velocity 

throughout the spray plume, may also be used. Sampling should occur across a representative 

cross-sectional sample of the spray. Sampling should occur far enough from the atomizer to

allow for both atomization of ligaments and secondary break up of droplets in the air stream to 

be complete. However, the sampling distance must be close enough to the atomizer that spray is 

not contacting the wind tunnel’s surfaces. The sampling distance may need to be adjusted for 

different atomizers, flow rates, and test substances, but in general, the optimal sampling distance 

is between 20 and 60 cm from a nozzle. 

Table 2. DQIGs for Spray Droplet Size Measurements

Parameter

Standard 

Operating 

Procedure 

(if applicable) Acceptance Criteria

Standard deviation around volume 

median diameter (VMD, Dv0.5), Dv0.1

and Dv0.9 for three (minimum) 

replicate droplet size measurements

Vary by less than 10%.

Spray nozzle and sampling height 

measurement 

Within 5 mm (without airflow)

Sample size per replicate 

measurement 

> 10,000 droplets for particle counting instruments 

or > 5 s for laser diffraction instruments

Replicate measurements Measurements to be carried out with an atomizer or 

nozzle with a maximum deviation of output rate of ± 

2.5% from the value specified by the manufacturer 

at the nominal rated recommended spray operating 

conditions. A randomly selected representative 

nozzle must be used. 
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Parameter

Standard 

Operating 

Procedure 

(if applicable) Acceptance Criteria

Number of size class bands for 

reported data

≥ 30 bins regardless of the presence of particles. 

Spray volume in largest and smallest 

droplet size class bands in laser 

diffraction measurements

< 1% of total volume in each case (i.e., < 2% total 

of the spray volume). To be achieved through 

selection of appropriate lens and instrument 

configuration for the dynamic size range of the 

spray being sampled. Also select air speed to 

transport sufficient quantity of spray material 2 m 

from nozzle. 

Obscuration for spray measurements 

across a spray diameter (for laser 

diffraction systems)

< 60% unless corrected for multiple scattering, 

whereupon the report shall include the measured 

obscuration, the algorithm used to correct for 

multiple scattering, and the manufacturer-stated 

limits of applicability for that algorithm.

Minimum obscuration for sampling to 

achieve cross-section average spray 

(e.g., start or end trigger using traverse 

with laser diffraction systems) 

2%

Diode suppression (laser diffraction 

systems)

Diodes may not be suppressed (no channels may be 

killed) in sampling. Correct selection of focal 

length lens, system alignment, avoidance of 

vibrations, and cleanliness of optical surfaces 

should prevent the need for diode suppression (data 

loss). (If the laser is displaced during sampling, all 

diodes will measure incorrect scattering angles, and 

diode suppression is not an appropriate solution to 

such sampling problems.)

Distance of farthest edge of spray from 

collecting lens (Malvern instruments)

< 1 lens focal length to avoid vignetting sampling 

errors

A7.2 Low Speed Wind Tunnel Tests

For low speed wind tunnel testing, the product of this test design will be the measurement of a 

spray droplet size distribution at the nozzle, spray droplet size distribution and spray flux 

measurements at multiple heights at the 2 m flux plane. Flux measurements will be used to 

assess pesticide drift potential. The DQIGs and DQOs for individual low speed wind tunnel 

measurements are provided in Element B2. Test-specific DQIGs will be documented in each 

site-specific T/QAP and applicant-specific addenda.

A7.3 High Speed Wind Tunnel Tests

For high speed wind tunnel testing, the product of this test design will be the measurement of a 

spray droplet size distribution at the nozzle. The DQIGs and DQOs for individual high speed 

wind tunnel measurements are provided in Element C2. Test-specific DQIGs will be 

documented in each site-specific T/QAP and applicant-specific addenda.
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September 2012 Page 12

A7.4 Field Tests

The measure of performance for the DRT in field studies will be directly determined by

deposition measured on horizontal fallout collectors according to either ASABE 561.1 APR04 or 

ISO/DIS 22866:2005(E) standard methods with modifications specified in Element D below. 

The DQIGs and DQOs for field testing measurements are provided in Element D2. Test-specific 

DQIGs will be documented in each site-specific T/QAP and applicant-specific addenda.

A7.5 Standards Cited

ANSI/ASHRAE 41.1 (1986) Standard Method for Temperature Measurement, American Society 

of Heating, Refrigerating and Air Conditioning Engineers, Inc. 1791 Tullie Circle, NE, Atlanta, 

GA 30329.

ASABE S561.1 (2009) Procedure for Measuring Drift Deposits from Ground, Orchard and 

Aerial Sprayers. American Society of Agricultural and Biological Engineers, St. Joseph, MI.

ASABE S572.1 (2009) [revised from ASAE S572 (1999)] Spray Nozzle Classification by 

Droplet Spectra. Standard No. S572.1, American Society of Agricultural and Biological 

Engineers, St. Joseph, MI.

ASTM E337-02 (2007) Standard Test Method for Measuring Humidity with a Psychrometer (the 

Measurement of Wet- and Dry-Bulb Temperatures), ASTM International, 100 Barr Harbor 

Drive, PO Box C700, West Conshohocken, PA, 19428-2959.

ASTM E2798-11 (2011) Standard Test Method for Characterization of Performance of Pesticide 

Spray Drift Reduction Adjuvants for Ground Application. ASTM International, 100 Barr Harbor 

Drive, PO Box C700, West Conshohocken, PA, 19428-2959.

ASTM WK24544 (2011) New Test Method for Determining Cross-Section Averaged Liquid 

Droplet Size Characteristics in a Spray Using Laser Diffraction Instruments, ASTM Committee 

E29, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 

19428-2959.

ISO Standard 22866 (2005): Equipment for Crop Protection—Methods for Field Measurement of 

Spray Drift. ISO.

ISO Standard 22856 (2008): Equipment for Crop Protection—Methods for the Laboratory 

Measurement of Spray Drift –Wind Tunnels. ISO.

A8: Special Training and Certifications

The DRT Program is open to multiple test laboratories. All participating laboratories, domestic 

and international, must register their laboratories with the DRT Program, meet the program’s QA 

requirements, and accept on-site audits by EPA or its representatives. The audits may include 

technical system audits, performance evaluations, assessments of the test laboratory’s quality

system, and audits of data quality. In order to qualify, a test laboratory must take the following 

actions: 
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September 2012 Page 13

 Have American National Standards Institute / American Society for Quality Control 

(ANSI/ASQC) E4 or International Organization for Standardization (ISO) 9000 quality

management systems in place; 

 Possess the equipment and facilities required to perform tests identified in this protocol; 

 Be an independent organization (e.g., not be a manufacturer’s or end user’s in-house 

laboratory or subsidiary); 

 Have an EPA-compliant QA system1; 

 Allow on-site audits by EPA or its representatives; 

 Have an EPA approved test/QA plan as described in this protocol; 

 Provide written health and safety procedures for verification testing; and 

 Comply with EPA reporting requirements.

The testing organization may include any registrations, accreditations, qualifications, 

independently-assessed quality systems of the testing organization in the test site-specific 

test/QA plan.

A9: Documentation and Records

Test-specific documentation and records will be processed as specified in the testing 

organization’s SOPs, protocols, etc. See Element B10 for details of test data acquisition and 

management.

Procedures to manage documents and records of the ETV program are taken from the EPA 

Records Management Policy 2161; Records Management Manual (including specified records 

schedules); and the ORD Policy and Procedures Manual, Section 13.2. Accordingly, the testing 

organization will retain all test-specific documentation and records for 7 years after the final 

payment of the funding agreement. These requirements will be updated to conform to any future 

changes in the EPA Records Management Policy.

 

1 The best place to start for information about EPA-compliant QA systems is "Doing Business with EPA: Quality 

Specifications for non-EPA Organizations" (see http://www.epa.gov/quality/exmural.html). More generally, the 

EPA Quality System website (see http://www.epa.gov/quality/) has a wealth of information on the topic.
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Group B: Data Generation and Acquisition 

for Low Speed Wind Tunnel

B1: Sampling Process Design (Experimental Design)

The measure of performance for the DRT for low speed wind tunnels will be derived from 

airborne droplet size distribution and spray flux measurements. The resulting data will be used 

by EPA OPP to model deposition from 0 to 61 m downwind from the nozzle. The effectiveness 

of the DRT will be quantified by comparison of the DRT’s drift to the drift of the reference test. 

Information about the use of wind tunnel data and an example calculation are provided at 

(http://www.epa.gov/DRT). The low speed wind tunnel verification data generation and 

acquisition procedures were evaluated as described in Evaluation of the Verification Protocol for 

Low and High Speed Wind Tunnel Testing (EPA, 2012, 

http://www.epa.gov/nrmrl/std/etv/pubs/600etv12010.pdf). The evaluation was limited to spray

nozzles with a simple tank mix (i.e., water with surfactant). Procedures for spray modifiers and 

other adjuvants have not been considered in any detail. It is anticipated that ASTM and ISO 

standard test methods will be developed, such as ASTM E2798-11, to address this issue.

For nozzles, the basic experimental design will be to measure the droplet size spectrum of a 

candidate DRT and a reference application system operating under targeted spray pressure, air

speed, boom height, and “ambient” conditions. The measurement of droplet size spectrum and 

flux volume at 2 m distance downwind of the spray nozzle are the critical measurements for this 

verification test2. Wind tunnel and application conditions establish the bounds of the verification 

test design.

In order to meet the DQOs, a minimum of three replications will be used for each set of 

application conditions, such as each combination of release height and nozzle pressure, intended 

for actual use in the field. As required by the DQOs in Element B2, the product of this test 

design will be the measurement of a droplet size distribution at the nozzle and 2 m flux plane, 

and measurement of the spray drift potential (flux and deposition) at the 2 m flux plane.

Measurements for candidate test systems are compared to a reference spray system based on the 

ASAE S572 standard for droplet size. For nozzles with a simple tank mix, the reference system 

is the method ASABE S572.1 fine/medium boundary reference nozzle [Flat fan 110° at 300 kPa 

(43.5 psi)]. For adjuvants and other complex tank mixes, the reference system should use the 

ASAE S572 nozzle model associated with the lower (coarser) boundary of the droplet size 

category (very fine, fine, medium, coarse, very coarse, and extremely coarse) in which the test 

system falls. During drift potential measurements, the height of the reference nozzle (and nozzle 

spacing, if multiple nozzles are used) should be identical to the candidate test system. The 

 

2 Measurements at the two-meter flux plane were included by the STP in this protocol in 

anticipation of their use in proposed ground spray drift models. Newer drift models may be able 

to use spray droplet size data taken near the nozzle with the sprayer flow rate as the flux value. 

In order to confirm that a fully developed spray pattern has been captured, measurements should 

be taken at several distances (e.g. between 10 to 50cm) downwind of the nozzle.
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September 2012 Page 15

reference nozzle should be directed straight down. The vendor may select the spray angle for the 

candidate test system nozzle. 

In addition to the procedures described in this protocol, the test procedures to be used can be 

derived from standard methods (e.g., ISO, ASTM, ASABE, etc.). Each test site or testing 

organization will need to develop a T/QAP for its test facility detailing its test procedures. 

Deviations from described protocols must be described by the testing organization in its T/QAP. 

B2: DQIGs and DQOs for Low Speed Wind Tunnel Measurements

The DQIGs for individual low speed wind tunnel measurements will conform to those specified 

in relevant sections of the test protocols and referenced procedures, as shown in Table 3. The 

DQOs for this testing are the Table 3 DQIGs. Test-specific DQIGs will be documented in each 

site-specific T/QAP and applicant-specific addenda. 

Table 3. DQIGs for Low Speed Wind Tunnel Testing

Parameter

Standard Operating 

Procedure 

(if applicable) Acceptance Criteria

Low Speed Wind Tunnel Operating Conditions

Wind tunnel working section width ISO 22856 Minimum to avoid boundary layer and blockage 

effects 

Spray measurement chamber or wind 

tunnel cross-section diameter

Cross section at least three diameters larger than 

plume of nozzle (at measurement location) 

Wind tunnel turbulence ISO 22856 < 8% 

Air speed Between 2 m/s and 10 m/s, and measured to 

within 0.1 m/s accuracy, close to nozzle 

location (with nozzle absent).

Sampling rate for air speed ASABE S561.1 Sampling should occur over a measuring period 

of 10 s or less.

Consistency of air speed in wind 

tunnel working section

ISO 22856 < 5%

Ambient air temperature (dry bulb air 

temperature)

ASHRAE Standard 

41.1

Measured to an accuracy within 0.1 oC

10 to 30 oC with less than 5 oC variation during 

test

Wet bulb and dew point temperature 

or 

Percent relative humidity

Thermohygrometer 

equivalent to ASTM 

E337-02(2007); or 

ASHRAE Standard 

41.1

Temperature measured to an accuracy within 

0.1 oC 

% Relative humidity measured within 3%

LSWT relative humidity ISO 22856 20 to 80% with maximum variation of 5% 

during test
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Parameter

Standard Operating 

Procedure 

(if applicable) Acceptance Criteria

Dynamic surface tension of spray 

liquid (not for use with drift retardant 

adjuvants)

40 ± 4 dynes/cm at surface lifetime age of 10 to 

20 ms

Spray material flow rate ASABE S572.1 ± 0.04 L/min of values specified in the ASABE 

standard for reference nozzles and 

manufacturer recommended values for the test 

nozzles.

Spray pressure (nozzle operating 

pressure)

ASABE S572.1 ± 3.4 kPa of values specified in the ASABE 

standard for reference and manufacturer 

recommended values for the test nozzles. 

Spray material temperature ASHRAE Standard 

41.1

Measured within 0.1 oC

Relative spray material and air 

temperatures

Spray material temperature must be within 5 oC 

of the air temperature to avoid atomization 

anomalies

Spray Droplet Size Measurements for Low Speed Wind Tunnels

Spray nozzle and sampling height 

measurement 

Within 5 mm (without airflow)

Standard deviation around volume 

median diameter (VMD, Dv0.5), Dv0.1

and Dv0.9 for three (minimum) 

replicate droplet size measurements

Vary by less than 10%.

Spray Flux Measurements for Low Speed Wind Tunnels

Sampling height measurement Within 5 mm (without airflow)

Spray duration for similar nozzle 

types

Similar nozzle types from different vendors or 

manufacturers should be tested for similar time 

duration, within ± 5%.

Spray duration for replicate 

measurements

Minimum spray time of 5 s for each replicate 

measurement should be used, to allow stability 

of spray formation and to avoid under- or overdosing of samplers or collectors. (Appropriate 

spray duration should be verified prior to 

measurement). Replicate measurements for a 

nozzle type should be within ± 5% of mean time 

duration for a given setup. 

Solvent volume for extraction of 

tracer, if using collectors

Within 5% of volume required for analytical 

recovery and assessments (i.e., all samples 

should be washed with the same volume of 

solvent within 5% of the target volume)
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For low speed wind tunnel testing, the product of this test design will be the measurement of a 

spray droplet size distribution at the nozzle, spray droplet size distribution and spray flux 

measurements at multiple heights at the 2 m flux plane. Flux measurements via deposition on 

monofilament lines will be used to assess pesticide drift potential3.

B3: Sampling Methods for Measurement of Droplet Size, Deposition, and Test 

Conditions

Table 4 lists all the measurements required for this verification test. Measurements are 

categorized in the table as performance factors and test conditions. Performance factors are 

critical to verifying the performance of the DRT. Test conditions are important to understand the 

conditions of performance. Further detail is provided in Elements B3.1 through B3.4.

B3.1 Sampling Locations

Spray droplet size shall be sampled using one of several laser measurement systems: laser 

diffraction, phase- Doppler (excluding multi-phase droplets, e.g., air inclusion or emulsions), or 

laser imaging. Spray flux can be measured with monofilament lines. 

For droplet size distribution and spray flux for drift potential, sampling will occur at the same 

locations for both [i.e., at 2 m downwind of the atomizer and at a minimum of six positions (or 

heights)].

Measurement of air temperature and humidity should occur upwind and as close as possible to 

the atomizer without affecting its performance or the air speed at that location.

B3.2 Process and Application Data Collection

1. Droplet size distribution sampling

 Droplet size at the atomizer: Near the nozzles, see Element B3.3, Measurement of 

Droplet Size Spectrum Near the Nozzle 

 Spray flux 2 m downwind from the atomizer and droplet size 2 m downwind from 

the atomizer: For all measurements, the downwind sampling distance will be 2 m 

from the nozzle orifice. The spray droplet size distribution and volume per unit 

time (i.e., spray flux) will be sampled at a minimum of six heights evenly

distributed from the 0.1 m above the wind tunnel floor to a height equal to the 

nozzle height. The flux at the highest measurement height must be less than 1% 

of the cumulative flux measurements from lower heights. If amount of spray

measured at the highest height exceeds 1% of the total volume measured at the 

lower heights, additional measurements at increments consistent with the lower 

measurement heights must be made. Alternatively, a continuous traverse

 

3 Monofilament lines were selected by the STP in 2006 to measure flux at the two-meter flux 

plane. Laser-based techniques, such as phase Doppler interferometry (PDI), have since evolved 

to reliably take this measurement and should be considered as an alternative.
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Table 4. Summary of Spray and Test Condition Measurements

for Low Speed Wind Tunnels

Factors to Be Verified

Parameter to be 

Measured

Sampling and 

Measurement Method Comments

Performance Factors

Spray flux 2 m downwind 

from the atomizer

Tracer flux (L or 

mg/cm2/min) at the six (or 

more) measurement heights 

used in the downwind 

droplet size distribution 

measurement.

Multiple horizontal 

monofilament lines (or 

non-intrusive sampling 

methods appropriate for 

the spray material may be 

used).

If a method other than 

monofilament line is 

used, less than 2% total 

of the spray volume 

should be contained at 

the uppermost height.

Droplet size 2 m 

downwind from the 

atomizer 

At least six measurements 

of droplet size distribution 

corresponding to six or 

more heights. 

Non-intrusive sampling 

methods appropriate for 

the spray material such as 

laser diffraction, phaseDoppler, laser imaging 

instruments.

Less than 2% total of the 

spray volume should be 

contained in the 

uppermost or lowermost 

size classes.

Test Conditions Documentation

Droplet size at the 

atomizer 

Droplet size distribution 

produced by the atomizer

Non-intrusive sampling 

methods appropriate for 

the spray material such as 

laser diffraction, phaseDoppler, laser imaging 

instruments. 

Less than 2% total of the 

spray volume should be 

contained in the 

uppermost or lowermost 

size classes.

Spray pressure Pressure of spray mix at the 

atomizer

See ASABE S572.1, 

section 3.

Spray materials 

temperature

Temperature of the spray 

mixture

Calibrated thermometers 

accurate within 0.1 oC.

Temperature of the 

ambient air and spray 

mixture should be within 

5 oC.

Spray nozzle height or 

boom height

Height of the atomizer 

above the floor of the wind 

tunnel

Calibrated tape measure 

accurate within 0.5 cm. 

Nozzle height should be 

within 1 cm of specified 

height.

Wind tunnel conditions Air speed An appropriate and 

calibrated anemometer 

such as hot wire or pitotstatic tubes. Measurement 

should occur as close as 

possible to the atomizer 

without affecting its 

performance.

The air speed measured 

in the wind tunnel will be 

used to define acceptable 

field conditions of use.

Testing organization 

conducts air speed, 

temperature, and 

humidity measurements 

simultaneously. Ambient air temperature Calibrated thermometers 

accurate within 0.1 oC.

Air humidity Thermohygrometer 

equivalent to ASTM 

E337-02(2007); ASHRAE 

Standard 41.1; or other 

similar approach.
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September 2012 Page 19

spanning the specified height range may be used if the data droplet size 

distribution and spray volume data for specific heights can be recovered and it can

be demonstrated that flux above the measured range accounts for less than 1% of 

the cumulative flux below.

2. Wind tunnel conditions

 The following conditions shall be measured at the same height as the nozzle, 

upwind of the nozzle in the wind tunnel working section at the time of spray 

release: ambient air temperature, air speed, relative humidity. 

3. Sprayer conditions

 Spray pressure shall be measured consistent with ASABE S572.1, section 3. 

 The spray flow shall be measured following the method in Table 3 or described in 

the testing organization’s SOP.

 Spray fluid temperature shall be measured with a calibrated thermometer that 

meets the specifications in Table 3. The measurement method will follow the 

reference in Table 3 or the testing organization’s SOP.

B3.3 Measurement of Droplet Size Spectrum near the Nozzle 

The droplet size spectrum of the test system near the nozzle is used to classify its ASABE S572.1 

the spray characteristics. The candidate test system is categorized into droplet size category for 

very fine, fine, medium, coarse, very coarse, and extremely coarse.

1. Droplet size spectra for spray drift tests shall be made under the same conditions (e.g., 

spray material, spray pressure, nozzle settings) and following the same procedures 

outlined in Element B3.4 except the measurements do not need to be made within a 

wind tunnel.

2. Droplet size may be measured using one of several laser measurement systems: laser 

diffraction, phase-Doppler (excluding multi-phase droplets, e.g., air inclusion or 

emulsion) or laser imaging. The instruments and apparatus used in the test shall be 

listed. Names, model numbers, serial numbers, scale ranges, software version number, 

and calibration verification shall be recorded. 

3. A representative cross-section average sample must be obtained, using a massweighted traverse or multiple chordal measurements of the full spray (or half spray for 

axi-symmetric spray plumes). 

4. The sampling distance from the nozzle must be sufficient to ensure that the spray has 

atomized into droplets, for example through completion of breakup of sheets or 

ligaments of liquid following discharge from the nozzle.

5. The sampling system must be configured to measure the entire dynamic size range of 

the instrument with less than 2% total of the spray volume contained in the uppermost 

and lowermost size classes. 
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6. If a number-density weighted (“spatial”) sampling system is used, the setup should 

minimize the development of a size-velocity profile within the spray (e.g., by using a 

concurrent airflow if spray discharge is in the horizontal plane) to avoid data bias 

toward slower-moving (usually smaller) droplets. 

7. The droplet size measurements should include assessment and confirmation of the 

droplet size category of the candidate test system and reference system according to 

ASABE S572.1, respectively.

B3.4 Wind Tunnel Measurement of Spray Drift Potential

All sampling will follow the requirements of the specific test method being used unless 

otherwise stated in this document or approved as part of the site-specific T/QAP prior to the 

verification test. Laser-based measurement devices are used to measure droplet size distribution 

at 2 m and monofilament line is used to measure flux in the wind tunnel at 2 m at the heights as 

specified in B3.2 part 1.

1. The spraying system shall be mounted to minimize effects on airflow.

2. The orientation of the nozzle (predominant spray direction or axis of rotation) that the 

fan sprays discharge relative to the air flow direction must be measured with a 

protractor and recorded.

3. Droplet size shall be measured using one of several laser or optical measurement 

systems: laser diffraction, phase-Doppler (excluding multi-phase droplets, e.g., air 

inclusion or emulsion) or laser imaging. The instruments and apparatus used in the test 

shall be listed. Names, model numbers, serial numbers, scale ranges, software version 

number, and calibration verification shall be recorded.

4. The test spray nozzle(s) shall be mounted at the height defined by the manufacturer’s 

operating conditions and at least 100 mm below the wind tunnel ceiling. Nozzles must 

be positioned in a place free from edge effects. 

5. A representative cross-section average sample must be obtained, using a massweighted traverse or multiple chordal measurements of the full spray (or half spray for 

axi-symmetric spray plumes).

6. For each height, the sampling system must be configured to measure the entire 

dynamic size range of the instrument with less than 2% total of the spray volume 

contained in the uppermost or lowermost size classes.

7. The wind tunnel floor shall be covered with an artificial turf surface to minimize 

droplet bounce and mimic stubble vegetation for field conditions.

8. For monofilament spray flux measurements, approximately 2 mm in diameter 

monofilament sampling lines should be used, extended horizontally across the wind 

tunnel, and cause minimal disruption to air flow in the wind tunnel.
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9. For testing atomizers without using adjuvants, water containing surfactant may be 

used. Acceptable surfactants and surfactant concentrations are those that will provide 

a Newtonian tank mix with dynamic surface tension of 40 dyne/cm at surface lifetime 

age of 10 to 20 ms. 

 Use of other surfactants or concentrations should be approved as part of the sitespecific T/QAP prior to testing.

10. When an adjuvant is included as the DRT in the test spray material, a pesticide 

formulation and spray equipment reflecting the adjuvant’s proposed end use should be 

evaluated during testing. (See ASTM E2798-11 for further details).

11. The spraying system shall be primed with spray prior to measurements to ensure that 

rinsing liquid is removed from the line and the liquid discharging from the nozzle is 

the actual intended tank mix. In addition, sprayer systems should be “run-in” for 5 min 

to ensure removal of machining burrs or plastic mold residue.

12. Spray material flow rate shall be measured at the operating pressure for the tests. The 

liquid flow rate measurement may include techniques using liquid collected for a 

known duration, using Coriolis mass flow sensors, calibrated flow turbine, oval 

displacement meter, weighing system for the spray mix tank, or other method. Nozzle 

output should remain constant with a maximum deviation of ± 2.5%. These liquid 

flow rate measurements are consistent with ISO 5682 part 1.

13. The wind tunnel shall be operated during sampling to provide an air speed between 2 

m/s and 10 m/s at the nozzle height with a default value of 2 m/s.

14. To minimize evaporation effects on results, the relative humidity in the working 

section at the time of measurements shall be 20 to 80% with a maximum variation of 

5% during each test.

15. The type of nozzle being tested must be documented as follows:

 Flat fan, cone (hollow or full), impingement (deflector), and solid stream nozzles: 

manufacturer, fan angle at reference operating pressure, orifice size, material of 

manufacture.

 Other types of atomizers (e.g., rotary, electrostatic, and ultrasonic): the type of 

nozzle must be described in the T/QAP provided to EPA prior to testing in order 

to identify the appropriate parameters to be recorded. 

 Include a close-up photograph of the nozzle and manifold and a cross-sectional 

drawing.

 Include the manufacturer nozzle part number.

 Document the type of nozzle body and cap used in the tests.

 Manufacturer-recommended nozzle settings including spray height and angle.
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B4: Sample Handling and Custody Requirements

The media for collecting samples shall be monofilament line. Analysis of these samples will be 

conducted using spectrofluorometers, as described in Element B5. Each test lab will document 

its approach to collecting, storing, and analyzing monofilament samples in its site specific 

test/QA plan. Immediate analysis of wind tunnel samples is strongly encouraged. If data 

collection and analysis will not be done on-site, sample custody requirements are a required part 

of the test/QA plan. 

B5: Analytical Methods

Measurement of deposited material will occur by extracting tracer from the monofilament 

lines followed by measurement of the amount of tracer in the extract. Tracer 

measurements should be expressed as the amount of material per unit area. 

Instruments used to measure tracer (e.g., spectrofluorometers) should be of adequate 

sensitivity to measure deposition at the most distant sampler. The type and mixing rate 

(mass per volume) of the spray tracer material must be reported to allow for post 

processing of collected data.

B6: Quality Control

Data quality will be assessed with a series of multiple test nozzles, blank samples, spiked 

samples, collocated duplicate samples, and duplicate analyses as described in Table 5. 

B7: Instrument and Equipment Testing, Inspection, Maintenance, and Calibration 

Frequency

The site-specific T/QAP resulting from this protocol will reference the testing organization’s 

SOP for testing, inspection, and maintenance of instruments and equipment. Equipment to be 

included in the T/QAP are the laser diffraction or phase Doppler particle sizing instrument, 

anemometers, pressure gauges, rotometers, viscometers, and tensiometers used. Standard 

calibration methods (e.g., ASTM or equivalent methods) will be followed. 

Calibration verification of some laser diffraction particle size analyzers can be achieved using 

ASTM Standard Test Method E 1458 “Test Method for Calibration Verification of Laser 

Diffraction Particle Sizing Instruments using Photomask Reticles.” All analyzers will be 

calibrated against appropriate NIST-traceable standard reference materials.

Alternative techniques include reference particles and sprays of known size distribution. 

B8: Inspection and Acceptance of Supplies and Consumables

The primary supplies and consumables for this exercise consist of monofilament lines, tracer 

materials, adjuvants, water, hoses, tubing, and tank. Prior to use, each sampler is visually

inspected and is discarded for use if any damage is found. The tracer selected should allow for

adequate sensitivity to measure deposition at all test distances. The tracer should be stable and 

nonvolatile in the test frame for testing and analysis. Background measurement samples from
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Table 5. Quality Control Samples for Low Speed Wind Tunnels

Sample Description Acceptance Criteria

Multiple nozzles For evaluating nozzles as DRTs, conduct size 

distribution measurements at the nozzle and 2 

meters with three randomly selected nozzles 

from a batch of ten.

< 10% variation in Dv0.5, Dv0.1, and 

Dv0.9

Spiked monofilament line A monofilament line will be spiked with a 

known quantity of fluorescent tracer to 

quantify the extraction efficiency of the 30 

mL 0.01N NaOH wash.

> 93% recovery of fluorescent tracer

Blank monofilament line New monofilament line will be handled as 

experiment blanks to monitor for background 

fluorescence. 5% of the samples collected 

will be monofilament line blanks.

Acceptable fluorescence will be less 

than three times the minimum 

detection limit of the fluorometer, 

which will be determined during 

analysis. Otherwise, a correction 

factor will be applied to the 

fluorescence data.

Blank spray liquid Three samples of the spray liquid without 

tracer will be analyzed fluorometrically to 

determine any background fluorescence. 

Acceptable fluorescence will be less 

than three times the minimum 

detection limit of the fluorometer.

Replicate fluorometric 

analyses

Multiple aliquots of extraction fluid will be 

analyzed to quantify analytical error. 

< ± 5% variation in fluorometry 

results

the testing site should demonstrate negligible levels of tracer or other interfering compounds. 

The hardness of water used in spray tanks should be documented. Adjuvants should be in 

original manufacturer’s packaging.

B9: Non-Direct Measurements

If applicable, data that are not gathered directly by the testing organization may be used, 

however, the testing organization must describe these measurements in the T/QAP or the 

applicant-specific addendum. 

B10: Data Management

It is expected data will be collected on paper datasheets and in electronic format. The data 

collection format will depend on the testing organization’s data acquisition systems. Paper 

datasheets will be signed by the technician responsible for collecting the data. The datasheet will 

be reviewed for completeness and approved by the testing organization technical leader 

immediately after an experiment. The testing organization technical leader will review 

electronic data for compliance with DQIGs immediately after an experiment. Data from paper 

datasheets and electronic data will be consolidated into a single database with reference to the 

DRT tested and all experimental conditions. 

B10.1 Data Flow

Data measurement and collection activities are shown in Figure 4. This flow chart includes all 

data activities from the initial pretest QA steps to the passing of the data to EPA.
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Figure 4. Data management system.

B10.2 Data Reduction

Data from each measurement for droplet size from the verification test will be reported as the 

incremental and cumulative volumes of 30 appropriately spaced and described bins of droplet 

diameter (microns). The Dv0.1, Dv0.5, Dv0.9, and relative span will also be presented. An example 

of a presentation of the output data is shown in Table B-1 in Appendix B. Raw data of droplet 

sizing instrument output should be provided as an appendix. 

Data from measurements for flux (i.e., volume/unit area/unit time) from the verification test will 

be reported as “mL/cm2/min” and labeled with the height at which the flux measurement was 

taken. Annex D of ISO 22856 (2008): Equipment for Crop Protection—Methods for the 

Laboratory Measurement of Spray Drift –Wind Tunnels] provides an example calculation.

Testing Organization Technical Leader: Test Oversight and Data Production

Testing Organization Quality Manager: Quality System and Data Integrity

DRT Information from 

Manufacturer/Vendor

Instrument Data and 

Sampling Data

QC Data

Assemble Data

Calculations & Data Analysis

QA Review

Report

Data Flow

Data Flow

Oversight
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B10.3 Analysis of Verification Data

Measurements should be presented separately (raw data) and as an average across repetitions for 

the following types of measurements.

1. Downwind measurements:

 Flux at each height

 Volume per droplet size category (i.e., each of the 30 or more droplet size 

categories) at each height

2. Droplet size at the nozzle: Volume per droplet size category and reference spray type.
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Group C: Data Generation and Acquisition for High Speed Wind Tunnel Tests

C1: Sample Process Design (Experimental Design)

The measure of performance for the DRT for high speed wind tunnels will be derived from 

droplet size distribution measurements. The high speed wind tunnel verification data generation 

and acquisition procedures were evaluated as part of an ESTE project. These values will be used 

by EPA to model deposition from 0 to 61 m downwind. Information about the use of wind 

tunnel data and an example calculation are provided at (http://www.epa.gov/DRT). The high 

speed wind tunnel verification data generation and acquisition procedures for spray nozzles with 

a simple tank mix (i.e., water with surfactant) were evaluated as part of the ESTE project. 

Procedures for spray modifiers and other adjuvants have not been considered in any detail. It is 

anticipated that ASTM and ISO standard test methods will be developed, such as ASTM E2798-

11. 

The basic experimental design will be to measure the droplet size spectrum under targeted test 

conditions with the DRT operating at specified spray pressure, air speed, and the “ambient” 

conditions. Droplet size spectrum is the critical measurement for this verification test. Wind 

tunnel conditions and application conditions are important measurements for establishing the 

bounds of the verification test design. Unlike the low speed wind tunnel testing, no deposition 

measurements are made with high speed wind tunnel testing. 

In order to meet the DQOs, at least three replications will be used for each set of application 

conditions intended for actual use in the field. For instance, at least three replications will be 

conducted for each combination of air speed and nozzle pressure. The product of this test design 

will be the measurement of a droplet size distribution consisting of 30 or more droplet size bins 

for the specified operating range. The DQIGs for appropriate parameters identified in Table 6 

must be met. Measurements for candidate test systems are compared to a reference spray system 

based on the ASAE S572 standard for droplet size. For nozzles with a simple tank mix, the 

reference system is the method ASABE S572.1 fine/medium boundary reference nozzle [Flat fan 

110° at 300 kPa (43.5 psi)]. For adjuvants and other complex tank mixes, the reference system 

should use the ASAE S572 nozzle model associated with the lower (coarser) boundary of the 

droplet size category (very fine, fine, medium, coarse, very coarse, and extremely coarse) in 

which the test system falls. See ASTM E2798-11.

During drift potential measurements, the angle of the candidate test system does not need to be 

identical to that of the reference spray system. The vendor may select the spray angle for the 

candidate test system nozzle. Acceptable nozzles, associated wind tunnel air speeds, and nozzle 

angles relative to air direction are identified below.

In addition to the procedures described in this protocol, the test procedures to be used can be 

derived from standard methods (e.g., ISO, ASTM, ASABE, etc.). Each test site or testing 

organization will need to develop a T/QAP for its test facility detailing its test procedures. 

Deviations from described protocols must be described by the testing organization in its T/QAP. 
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C2: DQIGs and DQOs for High Speed Wind Tunnel Measurements

The DQIGs for individual high speed wind tunnel measurements will conform to those specified 

in relevant sections of the test protocols and referenced procedures, as shown in Table 6. The 

DQOs for this testing are the Table 6 DQIGs. Test-specific DQIGs will be documented in the 

site-specific T/QAPs and its applicant-specific addenda.

Table 6. DQIGs for High Speed Wind Tunnel Testing

Parameter

Standard Operating 

Procedure 

(if applicable) Acceptance Criteria

High Speed Wind Tunnel Operating Conditions

Spray measurement chamber or 

wind tunnel cross-section diameter

Cross section at least three diameters larger than 

plume of nozzle (at measurement location) 

Air speed Between 50 mph (22 m/s) and 165 mph (73 m/s), 

and measured to an accuracy within 5 mph (2 m/s), 

close to nozzle location (with nozzle absent)

Ambient air temperature ASHRAE Standard 

41.1

Measured within 0.1 oC

10 to 30 oC with less than 5 oC variation during test

Ambient relative humidity ASHRAE Standard 

41.1

Measured within 3%

Spray material temperature ASHRAE Standard 

41.1

Measured within 0.1 oC

Relative spray material and air 

temperatures

Spray material temperature must be within 5 oC of 

the air temperature to avoid atomization anomalies

Spray material flow rate ASABE S572.1 ± 0.04 L/min of values specified in the ASABE 

standard for reference nozzles and manufacturer 

recommended values for the test nozzles.

Spray pressure (nozzle operating 

pressure)

ASABE S572.1 ± 3.4 kPa of values specified in the ASABE 

standard for reference and manufacturer 

recommended values for the test nozzles.

Dynamic surface tension of spray 

liquid (not for use with drift 

retardant adjuvants)

40 ± 4 dynes/cm at surface lifetime age of 10 to 20 

ms

Replicate measurements Measurements to be carried out with an atomizer or 

nozzle with a maximum deviation of output rate of 

± 2.5% from the value specified by the 

manufacturer at the nominal rated recommended 

spray operating conditions. A randomly selected 

representative nozzle must be used. 

Spray Droplet Size Measurements for High Speed Wind Tunnels

Standard deviation around volume 

median diameter (VMD, Dv0.5), Dv0.1

and Dv0.9 for three replicate droplet 

size measurements

< 10% for measurements with the same nozzle in 

HSWT tests. 
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C3. Sampling Methods for Measurement of Droplet Size and Test Conditions

Table 7 lists all the measurements required for this verification test. Measurements are 

categorized in the table as performance factors and test conditions. Performance factors are 

critical to verifying the performance of the DRT. Test conditions are important to understand the 

conditions of performance. Further detail is provided in Elements C3.1 through C3.3.

Table 7. Summary of Spray and Test Condition Measurements

for High Speed Wind Tunnels

Factors to Be 

Verified

Parameter to Be 

Measured

Sampling and Measurement 

Method Comments

Performance Factors

Droplet size at the 

atomizer

Droplet size 

distribution produced 

by the atomizer

Non-intrusive sampling 

methods appropriate for the 

spray material such as laser 

diffraction, phase-Doppler, 

laser imaging instruments. 

The range of droplet size 

categories measured must 

account for at least 99% of 

the spray volume. 

Test Conditions Documentation

Spray pressure Pressure of spray mix 

at the atomizer

See ASABE S572.1, section 

3.

Spray materials 

temperature

Temperature of the 

spray mixture

Calibrated thermometers 

accurate within 0.1 oC

Temperature of the ambient 

air and spray mixture should 

be within 5 oC.

Wind tunnel 

conditions

Air speed An appropriate and calibrated 

anemometer such as hot wire 

or pitot-static tubes. 

Measurement should occur as 

close as possible to the 

atomizer without affecting its 

performance. 

The air speed measured in the 

wind tunnel will be used to 

define acceptable field 

conditions of use and should 

reflect the proposed 

application of the DRT (e.g.

rotary wing vs. fixed wing 

aircraft).

Testing organization conducts 

air speed, temperature, and 

humidity measurements 

concurrently. 

Ambient air 

temperature

Calibrated thermometers 

accurate within 0.1 oC

Air humidity Thermohygrometer 

equivalent to ASTM E337-

02(2007); ASHRAE Standard 

41.1; or other similar 

approach

C3.1 Sampling Locations

Spray shall be sampled using one of several laser measurement systems: laser diffraction, phaseDoppler (excluding multi-phase droplets, e.g., air inclusion or emulsions) or laser imaging.

Measurement of air temperature and humidity should occur upwind of the atomizer and as close 

as possible to the atomizer without affecting its performance or the air speed at the atomizer. 
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C3.2 Process and Application Data Collection

1. Droplet size distribution sampling

 Droplet size at the atomizer: Near the nozzles, see Element C3.3, Wind Tunnel 

Measurement of Spray Drift Potential (Droplet Size Distribution at Aerial 

Application Air Speeds at the Nozzle).

2. Wind tunnel conditions

 The following conditions shall be measured at the same height as the nozzle, 

upwind of the nozzle in the wind tunnel working section at the time of spray 

release: ambient air temperature, air speed, relative humidity. 

3. Sprayer conditions

 The spray pressure shall be measured at the nozzle tip using a capillary connected 

to a pressure gauge.

 The spray flow shall be measured following the method in Table 6 or described in 

the testing organization’s SOP.

 Spray fluid temperature shall be measured with a calibrated thermometer that 

meets the specifications in Tables 6 and 7. The measurement method will follow 

the reference in Table 6 or the testing organization’s SOP.

C3.3 Wind Tunnel Measurement of Droplet Size Distribution at Aerial Application Air 

Speeds at the Nozzle

All sampling will follow the requirements of the specific test method being used unless 

otherwise stated in this document or approved by EPA prior to the verification test. Laser-based 

measurement devices are used to measure droplet size distribution at the nozzle in the wind 

tunnel.

1. The spraying system shall be mounted to minimize effects on airflow.

2. The orientation of the nozzle (predominant spray direction or axis of rotation) that the 

fan sprays discharge relative to the air flow direction must be measured with a 

protractor and recorded.

3. Droplet size shall be measured using one of several laser or optical measurement 

systems: laser diffraction, phase-Doppler (excluding multi-phase droplets, e.g., air 

inclusion or emulsion) or laser imaging. The instruments and apparatus used in the test 

shall be listed. Names, model numbers, serial numbers, scale ranges, software version 

number, and calibration verification shall be recorded.

4. Nozzles must be positioned in a place free from edge effects.

5. A representative cross-section average sample must be obtained, using a massweighted traverse or multiple chordal measurements of the full spray (or half spray for 

axi-symmetric spray plumes).
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6. The sampling system must be configured to measure the entire dynamic size range of 

the instrument with less than 2% total of the spray volume contained in the uppermost 

or lowermost size classes. 

7. If a number-density weighted (“spatial”) sampling system is used, the setup should 

minimize the development of a size-velocity profile within the spray (e.g., by using a 

concurrent airflow if spray discharge is in the horizontal plane) to avoid data bias 

toward slower-moving (usually smaller) droplets. 

8. For testing atomizers without using adjuvants, water containing surfactant may be 

used. Acceptable surfactants and surfactant concentrations are those that will provide 

a Newtonian tank mix with dynamic surface tension of 40 dyne/cm at surface lifetime 

age of 10 to 20 ms. Use of other surfactants or concentrations should be approved as 

part of the site-specific test plan prior to testing.

9. When an adjuvant is included as the DRT in the test spray material, a pesticide 

formulation and spray equipment reflecting the adjuvant’s proposed end use should be 

evaluated during testing. (See ASTM E2798-11 for further details).

10. The spraying system shall be primed with spray prior to measurements to ensure that 

rinsing liquid is removed from the line and the liquid discharging from the nozzle is 

the actual intended tank mix. In addition, sprayer systems should be “run-in” for 5 min 

to ensure removal of machining burrs or plastic mold residue.

11. Spray material flow rate shall be measured at the operating pressure for the tests. The 

liquid flow rate measurement may include techniques using liquid collected for a 

known duration, using Coriolis mass flow sensors, calibrated flow turbine, oval 

displacement meter, weighing system for the spray mix tank, or other method. Nozzle 

output should remain constant with a maximum deviation of ± 2.5%. These liquid 

flow rate measurements are consistent with ISO 5682 part 1.

12. The air speed in the working section of the wind tunnel must be measured as close as 

possible to the nozzle without affecting nozzle performance or allowing the atomizer to 

influence the air speed measurement. Air speed must be maintained between 50 and 

165 mph.

13. The type of nozzle being tested must be documented as follows:

 Flat fan, cone (hollow or full), impingement (deflector), and solid stream nozzles: 

manufacturer, fan angle at reference operating pressure, orifice size, material of 

manufacture.

 Other types of atomizers (e.g., rotary, electrostatic, and ultrasonic): the type of 

nozzle must be described in the T/QAP provided to EPA prior to testing in order 

to identify the appropriate parameters to be recorded. 

 Include a close-up photograph of the nozzle and manifold and a cross-sectional 

drawing.

 Include the manufacturer nozzle part number.
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 Document the type of nozzle body and cap used in the tests.

 Manufacturer-recommended nozzle settings including spray height and angle.

C4: Sample Handling and Custody Requirements

No physical samples are collected.

C5: Analytical Methods

No analytical methods are used.

C6: Quality Control

At least three replicates for each set of test conditions should be conducted. Measured volume 

median diameter (VMD) should vary by less than 10%. Dv0.1 and Dv0.9 (the droplet diameter 

bounding the upper and lower 10% fractions of the spray) should vary by less than 10%. 

Air speed should vary by less than 5% within a trial and less than 5% across replicates. Air 

speed is anticipated to be maintained between 50 and 165 mph.

C7: Instrument and Equipment Testing, Inspection, and Maintenance

The site-specific T/QAP resulting from this protocol needs to reference the testing organization’s 

SOP for testing, inspection, and maintenance of instruments and equipment.

C8: Instrument and Equipment Calibration and Frequency

The site-specific T/QAP resulting from this protocol will reference the testing organization’s 

SOP for testing, inspection, and maintenance of instruments and equipment. Equipment to be 

included in the T/QAP are the laser diffraction or phase Doppler particle sizing instrument, 

anemometers, pressure gauges, rotometers, viscometers, and tensiometers used. Standard 

calibration methods (e.g., ASTM or equivalent methods) will be followed. 

Calibration verification of some laser diffraction particle size analyzers can be achieved using 

ASTM Standard Test Method E 1458 “Test Method for Calibration Verification of Laser 

Diffraction Particle Sizing Instruments using Photomask Reticles.” Alternative techniques 

include reference particles and sprays of known size distribution. 

C9: Inspection and Acceptance of Supplies and Consumables

The hardness of water used in spray tanks should be documented. Adjuvants should be in 

original manufacturer’s packaging. 

As there are no other supplies and consumables, additional inspection and acceptance 

requirements are not a required part of this verification test protocol.
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C10: Non-Direct Measurements

If applicable, data that are not gathered directly by the testing organization may be used, 

however, the testing organization must describe these measurements in the T/QAP or the 

applicant-specific addendum. 

C11: Data Management

It is expected data will be collected on paper datasheets and in electronic format. The data 

collection format will depend on the testing organization’s data acquisition systems. Paper 

datasheets will be signed by the technician responsible for collecting the data. The datasheet will 

be reviewed for completeness and approved by the testing organization technical leader 

immediately after an experiment. The testing organization technical leader will review 

electronic data for compliance with DQIGs immediately after an experiment. Data from paper 

datasheets and electronic data will be consolidated into a single database with reference to the 

DRT tested and all experimental conditions. 

C11.1 Data Flow

Data measurement and collection activities are shown in Figure 4 in Element B10. This flow 

chart includes all data activities from the initial pretest QA steps to the passing of the data to 

EPA. 

C11.2 Data Reduction:

Data from each measurement for droplet size from the verification test will be reported as the 

incremental and cumulative volumes of 30 appropriately spaced and described bins of droplet 

diameter (micrometers). The Dv0.1, Dv0.5, Dv0.9, and relative span will also be presented. An 

example presentation of the output data is shown in Table B-1 of Appendix B. Raw data of 

droplet sizing instrument output should be provided in an appendix.

C11.3 Analysis of Verification Data:

Size distribution measurements for each size bin will be presented as raw data and as descriptive 

statistics across repetitions. The descriptive statistics include the average, standard deviation and 

coefficient of variation. Descriptive statistics for the Dv0.1, Dv0.5, and Dv0.9 will also be presented.

Two tables of supplementary data will also be presented. One table will document the wind 

tunnel operating conditions, spray nozzle conditions (type, pressure, flow) and test fluid 

conditions (temperature, surface tension, viscosity, etc.) for the experimental parameters 

described in Table 7. The second table will describe the pass or fail status of non-critical 

measurements to indicate whether DQIGs in Table 6 were achieved. If a DQIG is not achieved, 

an explanation of the cause for failure and the impact on verification test data will be provided. 
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Group D: Data Generation and Acquisition for Field Studies

D1: Sampling Process Design (Experimental Design)

The measure of performance for the DRT in field studies will be directly determined by 

deposition measured on horizontal fallout collectors according to either ASABE 561.1 APR04 or 

ISO/DIS 22866:2005(E) standard methods with modifications specified in Element D below. 

The modifications discussed below have not been evaluated during field testing. The specific 

placement of collectors will allow for an estimate of the integrated deposition from 0 to 61 m 

(200 ft) and the point deposition at 30.5 m (100 ft) downwind of the application site. 

The treatment area and spray track must be at least 100 m long and perpendicular to wind 

direction. This arrangement allows for the outermost samplers to be downwind of the treatment 

area when the wind direction approaches ± 30 degrees relative to the length of the treatment area.

The conditions of the study will be selected to allow for the measurement of the DRT and the 

reference spray systems under identical or similar conditions (e.g., wind speed, wind direction, 

temperature, relative humidity, release height). The measurements of deposition are the critical 

measurements for this verification test. Measurements of field and application conditions are 

important for establishing the limitations of the verification test design. As required by the DQO 

in Element A7, the DQIGs for the parameters identified in Table 8 must be met.

Measurements of candidate test systems are compared to a reference spray system based on the 

ASABE S572.1 standard for droplet size. For nozzles, the reference system is the method 

ASABE S572.1 fine/medium boundary reference nozzle. The spacing of the reference nozzles

should be appropriate for the spray angle produced with the height equal to the candidate test 

system. The reference nozzles should be directed straight down.

D2: DQIGs and DQOs for Field Test Measurements

The DQIGs data and measurements collected during field tests will conform to those specified in 

relevant sections of the test protocols and referenced procedures, as shown in Table 8. The 

DQOs for this testing are the Table 8 DQIGs. Test-specific DQIGs will be documented in the 

site-specific T/QAPs and its applicant-specific addenda.

D3: Sampling Methods for Measurement of Droplet Size, Deposition, and Test 

Conditions

Table 9 lists all the measurements required for this verification test. Measurements are 

categorized in the table as performance factors and test conditions. Performance factors are 

critical to verifying the performance of the DRT. Test conditions are important to understand the 

conditions of performance. Further detail is provided in Elements D3.1 through D3.3.
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Table 8. DQIGs for Field Testing

Parameter

Standard Operating 

Procedure 

(if applicable) Acceptance Criteria

Dry bulb air temperature ISO 22866 Between 5 and 35 C, measured to an accuracy 

within 0.5 C

Wet bulb and dew point temperature 

or 

Percent relative humidity

ASABE S561.1 Measured to an accuracy within 0.5 oC or within 

5% 

[3% from ASHRAE Standard 41.1] 

Horizontal wind speed ISO 22866 At least 1 m/s for all applications, measured at 

an accuracy within 0.2 m/s at nozzle height 

Horizontal wind direction ASABE S561.1 90°  30° to the spray track or the downwind 

edge of the sprayed area during the spray 

application

Nozzle flow rate ASABE S561.1 Repeat measurements for individual nozzles 

within ± 2.5%

Horizontal wind angle relative to 

sample line

ASABE S561.1 Mean angle between the sample line and the 

horizontal wind direction should not exceed 30o

Frequency of meteorological 

measurement sampling

ASABE S561.1 ≥ 1.0 Hz sampling rate

Dynamic surface tension of spray liquid Measured to within ± 5% at surface lifetime age 

of 10 to 20 ms

Surface vegetation height ASABE S561.1 < 7.5 cm absolute height for all vegetation 

surface heights in drift sampling areas with 

typical uniformity not to exceed  10% standard 

deviation.

Sample line and collection station 

locations

± 2.5% of required location distances (at a 

minimum 2 m downwind of nozzle)

Sampling media area for individual 

collectors

ASABE S561.1 ≥ 1000 cm2 for deposition cards

Collector orientation for flat card or 

plate or cylindrical collectors

Horizontal ± 15o relative to spirit level 

instrument or for vertical towers (optional 

additional collector), vertical ± 15o

Diameter of cylindrical collectors (if 

used)

ASABE S561.1 2 mm ± 5%

Number of samples at each sampling 

location

Determined from tests for the specific setup to 

produce confidence interval of ± 10%

Boom length (swath width) and boom 

height above ground

Measured with accuracy within 1.0 cm when 

stationary

Application rate of tank mix in treated 

area

Within 2.5% of intended application rate

Forward speed of sprayer Within 10% of target speed throughout entire 

application period. For aerial, at least 140 mph, 

and measured to an accuracy within 5 mph.
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Parameter

Standard Operating 

Procedure 

(if applicable) Acceptance Criteria

Solvent volume for extraction of tracer 

if using collectors

5% of volume required for analytical recovery 

and assessments (i.e., all samples should be 

washed with the same volume of solvent within 

5% of the target volume)

Stability of tracer under conditions of 

study (light intensity, relative humidity, 

temperature, sampling media, storage 

conditions and duration, etc.) measured 

as the amount recovered relative to the 

amount mixed for control samples

Tracer must exhibit adequate photostability 

(documented or published) allowing within 10% 

of the initial mixture detection values for all 

samples (note: samples should be collected in 

minimum possible time after exposure to drift 

sampling, stored in dark containers, and 

analyzed as soon as possible after collection) 

D3.1 Sampling Locations

Three parallel lines of horizontal collectors within the sampling array should be used. Collector 

lines in the sampling array should be spaced at least 15 m apart. The center collector line in the 

sampling array should be in the center of the application area. Horizontal deposition samplers 

should be placed at a minimum of 4 m, 8 m, 16 m, 30.5 m, and 61 m from the downwind edge of 

the treated area. At least one collector should be placed in the swath and upwind of the treatment 

area. 

The placement of the station(s) for measuring meteorological conditions should be located in the 

open within 30 m of the treatment area and away from any obstruction or topographical 

irregularities. 

A map should be provided showing the treatment area, sampler placements, position of the 

meteorological station(s), and any obstructions or identifying features of the test area. 

D3.2 Process and Application Data Collection

All sampling will follow the requirements of the specific test method being used, either ASABE 

561.1 APR04 or ISO/DIS 22866:2005(E) standard methods, unless otherwise stated in this 

document or approved by EPA prior to the verification test. Example sampling locations for 

field testing are shown in Figure 5.

D3.3 Ambient Data Collection

Meteorological conditions will be measured with at least one weather station during applications. 

The sampling rate for wind speed and direction should be at least four samples per minute. The 

wind speed must be at least 1 m/s for all applications.
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Table 9. Summary of Spray and Test Condition Measurements for Field Testing

Factors to Be 

Verified

Parameter to Be 

Measured

Sampling and Measurement 

Method Comments

Performance Factors

Deposition Tracer deposit at 

multiple locations 

downwind of the 

treatment area

Sampled using smooth horizontal 

surface collectors such as filter 

paper.

Deposition should be 

described in terms of 

mass of nonvolatile 

tracer per unit area

Test Conditions Documentation

Spray pressure Pressure of spray mix

at the atomizer

See ASABE S572.1, section 3.

Spray materials 

temperature

Temperature of the 

spray mixture

Calibrated thermometers accurate 

within 0.1 oC

Temperature of the air 

and spray mixture should 

be within 5 oC

Flow rate Volume per unit time 

produced by the 

nozzle under test 

conditions.

See ASABE S561.1 Repeat measurements for 

individual nozzles within 

± 2.5%

Release height Height above the 

ground the spray 

materials are released

Travel speed Rate of speed for the 

equipment used to 

apply the spray 

material

Meteorological 

conditions

Wind speed See ASABE S561.1, section 3.2.3 Ambient air temperature 

of 10 to 30 oC with less 

than 5 oC variation 

during test

Wind direction See ASABE S561.1, section 3.2.4

Ambient air 

temperature

See ASABE S561.1, section 3.2

Ambient pressure See ASABE S561.1, section 3.2

Relative humidity See ASABE S561.1, section 3.2.2

D4: Sample Handling and Custody Requirements

The date and time of sample collection and analysis must be recorded. Sample holding 

conditions (e.g., temperature, containers, light) must be noted for the period between sample 

collection and analysis. 

The samples collected during the test program will consist of horizontal samplers (for example, 

filter paper). Tracer materials and sample processing techniques should be selected to meet the 

specified DQIGs. Analysis of these samples will be conducted as described in Element D5. 

The media for collecting samples shall be horizontal sample collectors. Each test lab will 

document its approach to collecting, storing, and analyzing horizontal sample collectors in its 

site specific test/QA plan. Immediate analysis of samples is strongly encouraged. If data 

collection and analysis will not be done on-site, sample custody requirements are a required part 

of the test/QA plan. 
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Figure 5. Sampling locations for field testing.

D5: Analytical Methods

Measurement of deposited material will occur by extracting tracer from the horizontal sample 

collectors followed by measurement of the amount of tracer in the extract. Tracer measurements 

should be expressed as the amount of material per unit area of sampler. Instruments used to 

measure tracer (e.g., gas chromatographs) should be of adequate sensitivity to measure 

deposition at the most distant sampler.

D6: Quality Control

The boom width, intended swath width, nozzle placement, and nozzle orientation of the 

application equipment will be reported. Wind direction during and for 2 minutes after 

application should be ± 30 degrees perpendicular to the swath. Drive speed for ground 

equipment is anticipated to be between 4 and 24 km/h (2.5 to 15 mph). Aerial application 

equipment speed is anticipated to be maintained between 50 and 165 mph.

Treatment Site Horizontal Sampling Area

4m 8m 16m 30.5m 61m

100 m
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Randomly selected, unused horizontal sample collectors should be spiked with tracer at 2 and 

200 times the level of quantitation for the analytical equipment to be used for measuring tracer. 

Tracer recovery should be within 80 to 120% of the spiked amount. Stock solutions used in 

testing should also be tested. Linearity of deposition relative to measurement instrumentation 

response should be demonstrated in the deposition range measured.

Tracer concentration in the spray material tank will be measured and reported before and after 

testing on each test day and for each tank mix used.

D7: Instrument and Equipment Testing, Inspection, and Maintenance

The site-specific T/QAP needs to reference the testing organization’s SOP for testing, inspection, 

and maintenance of instruments and equipment.

D8: Instrument and Equipment Calibration and Frequency

Analytical instruments used to measure tracer extracts from collectors will be calibrated on the 

same day of analysis. Calibration will use a standard curve consisting of at least three points 

spanning the level of quantitation and the highest measured concentration level. The standard 

curve should be linear (r2greater than 0.95).

D9: Inspection and Acceptance of Supplies and Consumables

The primary supplies and consumables for this exercise consist of the horizontal samplers and 

tracer materials. Prior to labeling, each sampler is visually inspected and is discarded for use if 

any damage is found. The tracer selected should allow for adequate sensitivity to measure 

deposition at all test distances. The tracer should be stable and nonvolatile in the test frame for 

testing and analysis. Background measurement samples from the testing site should demonstrate 

negligible levels of tracer or other interfering compounds.

The hardness of water used in spray tanks should be documented.

D10: Non-Direct Measurements

If applicable, data that are not gathered directly by the testing organization may be used, 

however, the testing organization must describe these measurements in the T/QAP or the 

applicant-specific addendum.

D11: Data Management

Results will be calculated as deposition for each set of sampling conditions at downwind 

positions at 4 m, 8 m, 16 m, 30.5 m, and 61 m, including a summary of meteorological 

conditions and application conditions. Requirements for the verification test report, verification 

statement, and data storage and retrieval are provided in Group E, Data Reporting.
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D11.1 Data Flow

Data measurement and collection activities for deposition are shown in Figure 4 of Element B10. 

This flow chart includes all data activities from the initial pretest QA steps to the passing of the 

data to EPA. 

D11.2 Data Reduction

Data from each measurement for deposition from the verification test will be reported in units of 

mass/area for each downwind distance and the meteorological and application conditions will 

clearly be reported.

D11.3 Analysis of Verification Data

Measurements should be presented separately (raw data) and as an average across repetitions for 

each downwind measurements for the deposition on horizontal samplers at each downwind 

distance.
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Group E: Data Reporting

E1: Outline of the Verification Test Report

 Verification statement

 DRT manufacturer or vendor information

 Summary of verification test program including testing location and type (LSWT, 

HSWT, or Field)

 Results of the verification test

 Droplet size classification, using ASABE S572.1 and the reference system used

 Any limitations of the verification results

 Brief QA statement

 Introduction

 Description and identification of the DRT

 Procedures and methods used in testing

 The instruments and measurement apparatus used for droplet size measurement 

(including name and type, model number, serial number, scale ranges, software 

version number, and date of most recent calibration verification)

 Spray flux and deposition sampling (including description of monofilament lines, 

placement of monofilament lines, and photograph of lines in place for collection)

 Tracer types and concentration in test spray materials, if used.

 Statement of operating range and testing conditions over which the test was conducted 

including:

 Nozzle orifice height

 Spray pressure at nozzle

 Volume/unit time produced by nozzle 

 Test spray material composition

 Source of spray materials (including water)

 Sampling locations

 Temperature

 Humidity

 Air speed – wind tunnel testing only

 Flight speed or ground equipment speed – field testing only

 Wind speed and direction – field testing only
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 Atmospheric stability – field testing only

 Results of the ASABE S572.1 droplet size measurement

 Summary and discussion of results

 Results supporting verification statement

 Deviations and explanations from test plan

 Discussion of QA and QA statement

 References

 Appendices

 QA/QC activities and results

 Raw test data

 Equipment calibration results

 Sample handling

 Description of the use of the data to determine drift reduction and a link to an 

example calculation on OPP’s DRT website.

E2: Draft Report Preparation

The testing organization will develop a verification report that verifies and summarizes the DRT 

test results. EPA will review the draft report and provide comments to the testing organization. 

The draft report will be edited by the testing organization to address EPA comments. The final 

report will be submitted to EPA for approval, distribution, and publication.

E3: Data Storage and Retrieval

This section describes the handling and storage of the data. After the completion of a 

verification test, labeled three-ring binders containing manually recorded information and data 

output generated from instrumentation will be stored with a copy retained by the testing 

organization. This is called the ‘data notebook’ in the ETV and APCT Center QMPs. After 

completion of a verification test, a CD-ROM or other storage media containing the T/QAP, 

spreadsheet data files and the report will be generated by the testing organization for distribution. 

The testing organization and the EPA will retain copies of the electronic data on a system with at 

least monthly back-up in perpetuity.
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Group F: Assessment and Oversight

F1: Assessments and Response Actions

F1.1 Internal Audits

Internal audits by the testing organization are conducted as specified in the testing organization’s 

SOP, which must conform to required Element C1 (Assessments and Response Actions) and C2 

(Reports to Management) of EPA QA/R-5. The testing organization SOP documents must be 

identified in the site-specific T/QAP.

F1.2 Audits of Data Quality

The testing organization QM will conduct an ADQ of at least 10% of all of the verification data. 

The ADQ will be conducted in accordance with EPA’s Guidance on Technical Audits and 

Related Assessments for Environmental Data Operations, EPA QA/G-7, including:

 a written report detailing the results of custody tracing, 

 a study of data transfer and intermediate calculations, 

 a review of QA and QC data, including reconciliation to user requirements, e.g., DQOs

and DQIGs, and 

 a study of project incidents that resulted in lost data, and a review of study statistics.

The ADQ report ends with conclusions about the quality of the data from the project and their 

fitness for their intended use.

F1.3 External Audits

The testing organization will cooperate with any external assessments by the EPA. EPA 

assessors will conduct a single mandatory quality and technical systems assessment of the testing 

organization before the start of the first test for each test facility. They may conduct optional 

witness assessments during the first test or any subsequent test. The external assessments will be 

conducted as described in EPA QA/G-7.

F1.4 Corrective Action

Corrective action to any audit or assessment is performed according to the testing organization’s 

SOPs, which must conform to required Elements B5 (Quality Control) and C1 (Assessments and 

Response Actions) of EPA QA/R-5.

F2: Reports to Management

Internal assessment reports will be reviewed by the testing organization QM, who will respond 

as noted in Element C1 of EPA QA/R-5. The written report of the ADQ will be submitted for 

review as noted in Element F1.2 of this protocol.
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Group G: Data Validation and Usability Elements

G1: Data Review, Verification, and Validation

Data review and validation will primarily occur at the following stages:

 On site following each test run – by the test technician

 On site following completion of the test program – by the testing organization technical 

leader

 Before writing the draft verification test report – by the testing organization QM

 During QA review of the draft report and audit of the data – The criteria used to review 

and evaluate the data will be the QA/QC criteria specified in each test procedure, 

protocol, guideline, or method (e.g., see Tables 3 and 4 for low speed wind tunnel testing) 

and the DQIG analysis of the parameter test data. Those individuals responsible for 

onsite data review and validation are noted in Figure 4, Element B10, and above. The 

testing organization technical leader is responsible for verification of data with all written 

procedures. Finally the testing organization QM reviews and evaluates the data and the 

draft report using the site-specific T/QAP, test methods, general SOPs, and projectspecific SOPs.

The data review and data audit will be conducted in accordance with the testing organization’s 

SOP.

G2: Verification and Validation Methods

Data are verified by the data collector. The goal of data verification is to ensure and document 

that the data are what they purport to be (i.e., the reported results reflect what actually was done). 

When deficiencies in the data are identified, then those deficiencies should be documented for 

the data user’s review and, where possible, resolved by corrective action. Data verification 

applies to activities in the field as well as in the laboratory. Validated data are reported in 

verification reports and statements along with any limitations on the data and recommendations 

for limitations on data usability. All validated data arising from testing under the DRT Program 

are disclosed in verification reports, even if the technology did not perform to the expectations of 

the technology provider. Results of the testing are conveyed to the data users through verification 

statements and verification reports. 

G3: Reconciliation with Data Quality Objectives

DQO requirements have been defined (in Tables 2, 3, 6, and 8). This reconciliation step is an 

integral part of the test program and will be done at the test site. Attainment of the DQO is 

confirmed by analyzing the test data as described in Element A7 and will be completed by the 

testing organization test technician and testing organization technical leader at the conclusion of 

the scheduled test runs. The DQO is defined as meeting the DQIG in Tables 2, 3, 6, and 8.

The reconciliation of the results with the DQO will be evaluated using the data quality

assessment process. This process started with the review of the DQO and the sampling design to 

assure that the sampling design and data collection documentation are consistent with those 

needed for the DQO. When the preliminary data is collected, the data will be reviewed to ensure 
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that the data are consistent with what was expected and to identify patterns, relationships, and 

potential anomalies. The data will be summarized and analyzed using appropriate statistical 

procedures to identify the key assumptions. The assumptions will be evaluated and verified with 

all deviations from procedures assessed as to their impact on the data quality and the DQO. 

Finally, the quality of the data will be assessed in terms of precision, bias, and statistical 

significance as they relate to the measurement objectives and the DQO.

Results from verification testing of the DRT will be presented in a verification statement and a 

verification report as described in Element E.
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Appendix A: Applicable Documents and Procedures

1. EPA Documents

EPA. Policy and Program Requirements for the Mandatory Agency-wide Quality System. EPA 

Order CIO2105.0. http://www.epa.gov/irmpoli8/policies/21050.pdf, U.S. Environmental 

Protection Agency. May 2000.

EPA. EPA Requirements for Quality Management Plans. EPA QA/R-2, EPA Publication No. 

EPA/240/B-01/002. http://www.epa.gov/quality/qs-docs/r2-final.pdf, U.S. Environmental 

Protection Agency, Office of Environmental Information. Washington, DC. March 2001.

EPA. Environmental Technology Verification Program, Quality Management Plan. EPA 

Publication No. EPA/600/R-08/009. http://www.epa.gov/etv/pubs/600r08009.pdf, Office of 

Research and Development, U.S. Environmental Protection Agency. Cincinnati, OH. January

2008.

EPA. Guidance on Environmental Data Verification and Data Validation, EPA QA/G-8. EPA 

Publication No. EPA/240/R02/004. http://www.epa.gov/quality/qs-docs/g8-final.pdf, Office of 

Environmental Information, U.S. Environmental Protection Agency. 2002.

EPA. EPA Requirements for Quality Assurance Project Plans. EPA QA/R-5, EPA Publication 

No. EPA/240/B-01/003. http://www.epa.gov/quality/qs-docs/r5-final.pdf, Office of 

Environmental Information, U.S. Environmental Protection Agency. March 2001.

EPA. Guidance for Quality Assurance Project Plans. EPA QA/G-5, EPA Publication No. 

EPA/240/R-02/009. http://www.epa.gov/quality/qs-docs/g5-final.pdf, Office of Environmental 

Information, U.S. Environmental Protection Agency. December 2002.

EPA. Records Management. EPA Classification No. 2161. 

http://www.epa.gov/records/policy/2161/rm_policy_2161_archive.htm, Office of Environmental 

Information, U.S. Environmental Protection Agency. May 2009.

EPA. Guidance on Technical Audits and Related Assessments for Environmental Data 

Operations. EPA QA/G-7, EPA Publication No. EPA/600/R-99/080. 

http://www.epa.gov/quality/qs-docs/g7-final.pdf, Office of Environmental Information, U.S. 

Environmental Protection Agency. January 2000.

EPA. Evaluation of the Verification Protocol for Low and High Speed Wind Tunnel Testing. 

EPA Publication No. TBD. http://www.epa.gov/nrmrl/std/etv/pubs/600etv12010.pdf, Office of 

Research and Development, U.S. Environmental Protection Agency. Cincinnati, OH. April 

2012.

2. Verification Organization Documents

RTI International. Verification Testing of Air Pollution Control Technology - Quality 

Management Plan, Revision 2.3. RTI International. Research Triangle Park, NC. 

http://www.epa.gov/nrmrl/std/etv/pubs/600etv10011.pdf, March 2010. 
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3. Other Literature

Fritz, B.K., Hoffmann, W.C., Jank, P. 2011. A Fluorescent Tracer Method for Evaluating Spray 

Transport and Rate of Field and Laboratory Spray Applications. J. of ASTM Int. 8(3):1-9.

American National Standard Specifications and Guidelines for Quality Systems for 

Environmental Data Collection and Environmental Technology Programs (ANSI/ASQ E4-1994)
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Appendix B: Example Format for Test Data

Table B-1. Example of Test Data Report Format

Droplet Size

Bin No.

Measures of droplet size categories (m) Mass Fraction

Largest Arithmetic Mean Smallest Incremental Cumulative

1 1504 1400.5 1297 0 0

2 1297 1208.5 1120 0 0

3 1120 1042.5 965 0 0

4 965 899 833 0 0

5 833 776 719 0 0

6 719 669.5 620 0.01 0.01

7 620 577.5 535 0.01 0.02

8 535 498 461 0.02 0.04

9 461 430 399 0.03 0.07

10 399 371.5 344 0.01 0.08

11 344 320 296 0.06 0.14

12 296 276 256 0.05 0.19

13 256 238 220 0.06 0.25

14 220 205.5 191 0.09 0.34

15 191 177.5 164 0.09 0.43

16 164 152.5 141 0.08 0.51

17 141 131.5 122 0.12 0.63

18 122 113.5 105 0.11 0.74

19 105 97.95 90.9 0.08 0.82

20 90.9 84.7 78.5 0.06 0.88

21 78.5 73.1 67.7 0.03 0.91

22 67.7 63.05 58.4 0.02 0.93

23 58.4 54.4 50.4 0.03 0.96

24 50.4 46.95 43.5 0.01 0.97

25 43.5 40.5 37.5 0.01 0.98

26 37.5 34.95 32.4 0.01 0.99

27 32.4 30.15 27.9 0.01 1.0

28 27.9 26 24.1 0.0 1.0

29 24.1 22.45 20.8 0.0 1.0

30 20.8 19.35 17.9 0.0 1.0

31 17.9 16.7 15.5 0.0 1.0

32 15.5 9.75 4.0 0.0 1.0

Dv 0.1 (m) 74 

Dv 0.5 (m) 160

Dv 0.9 (m) 335

Relative Span 0.82