ASTM D7520-16(2023)
(Test Method)Standard Test Method for Determining the Opacity of a Plume in the Outdoor Ambient Atmosphere
Standard Test Method for Determining the Opacity of a Plume in the Outdoor Ambient Atmosphere
SIGNIFICANCE AND USE
5.1 Air permits from regulatory agencies often require measurements of opacity from stationary air pollution point sources in the outdoor ambient environment. Opacity has been visually measured by certified smoke readers in accordance with USEPA (USEPA Method 9). DCOT is also a method to determine plume opacity in the outdoor ambient environment.
5.2 The concept of DCOT was based on previous method development using Digital Still Cameras and field testing of those methods.7,8 The purpose of this standard is to set a minimum level of performance for products that use DCOT to determine plume opacity in ambient environments.
SCOPE
1.1 This test method describes the procedures to determine the opacity of a plume, using digital imagery and associated hardware and software. The aforementioned plume is caused by particulate matter emitted from a stationary point source in the outdoor ambient environment.
1.2 The opacity of emissions is determined by the application of a Digital Camera Opacity Technique (DCOT) that consists of a Digital Still Camera, Analysis Software, and the Output Function’s content to obtain and interpret digital images to determine and report plume opacity.
1.3 This method is suitable to determine the opacity of plumes from zero (0) percent to one hundred (100) percent.
1.4 Conditions that shall be considered when using this method to obtain the digital image of the plume include the plume’s background, the existence of condensed water in the plume, orientation of the Digital Still Camera to the plume and the sun (see Section 8).
1.5 This standard describes the procedures to certify the DCOT, hardware, software, and method to determine the opacity of the plumes.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7520 − 16 (Reapproved 2023)
Standard Test Method for
Determining the Opacity of a Plume in the Outdoor Ambient
Atmosphere
This standard is issued under the fixed designation D7520; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method describes the procedures to determine 2.1 ASTM Standards:
the opacity of a plume, using digital imagery and associated D1356 Terminology Relating to Sampling and Analysis of
hardware and software. The aforementioned plume is caused Atmospheres
E691 Practice for Conducting an Interlaboratory Study to
by particulate matter emitted from a stationary point source in
the outdoor ambient environment. Determine the Precision of a Test Method
2.2 U.S. Environmental Protection Agency (USEPA) Docu-
1.2 The opacity of emissions is determined by the applica-
ment:
tion of a Digital Camera Opacity Technique (DCOT) that
USEPA Method 9 Visual Determination of the Opacity of
consists of a Digital Still Camera, Analysis Software, and the
Emissions from Stationary Sources, 40 CFR, Part 60,
Output Function’s content to obtain and interpret digital images
Appendix A-4
to determine and report plume opacity.
2.3 Institute of Electrical and Electronics Engineers (IEEE)
1.3 This method is suitable to determine the opacity of
Document:
plumes from zero (0) percent to one hundred (100) percent.
IEEE 12207-2008 Systems and Software Engineering—
Software Life Cycle Processes (ISO/IEC 12207:2008(E)),
1.4 Conditions that shall be considered when using this
method to obtain the digital image of the plume include the Edition: 2nd, Institute of Electrical and Electronics
Engineers, 01-Feb-2008, 138 pages, ISBN:
plume’s background, the existence of condensed water in the
plume, orientation of the Digital Still Camera to the plume and
the sun (see Section 8).
2.4 Japanese Electronic and Information Technology Indus-
tries Association (JEITA) Document:
1.5 This standard describes the procedures to certify the
Exchangeable Image File Format (EXIF) for Digital Still
DCOT, hardware, software, and method to determine the
Cameras Joint Photographic Experts Group: JPEG file
opacity of the plumes.
format version 2.21, JEITA CP-3451-1 (English version)
1.6 This standard does not purport to address all of the
dated 2003-09
safety concerns, if any, associated with its use. It is the
2.5 International Organization for Standardization (ISO)
responsibility of the user of this standard to establish appro-
Standard:
priate safety, health, and environmental practices and deter-
ISO 9001:2000(s) Quality Management Systems – Require-
mine the applicability of regulatory limitations prior to use.
ments
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Development of International Standards, Guides and Recom-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mendations issued by the World Trade Organization Technical
Standards volume information, refer to the standard’s Document Summary page on
Barriers to Trade (TBT) Committee.
the ASTM website.
Available from United State Environmental Protection Agency (USEPA), Ariel
Rios Bldg, 1200 Pennsylvania Ave., NW, Washington, DC 20460, http://
www.epa.org.
1 4
This test method is under the jurisdiction of ASTM Committee D22 on Air Available from Institute of Electrical and Electronics Engineers, Inc., (IEEE),
Quality and is the direct responsibility of Subcommittee D22.03 on Ambient 1828 L St., NW, Suite 1202, Washington, DC 20036-5104, http://www.ieee.org.
Atmospheres and Source Emissions. Available from http://www.jeita.or.jp/english/standard/list/
Current edition approved March 1, 2023. Published March 2023. Originally list.asp?cateid=1&subcateid=4.
approved in 2009. Last previous edition approved in 2016 as D7520 – 16. Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
DOI:10.1520/D7520-16R23. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7520 − 16 (2023)
3. Terminology certification between numbered runs (that is, black smoke from
Run 1, and white smoke from Run 2.)
3.1 Definitions—For definitions of terms used in this test
method, refer to Terminology D1356.
4. Summary of Test Method
3.2 Definitions of Terms Specific to This Standard:
4.1 A Digital Still Camera is used to capture a set of digital
3.2.1 analysis software—software that when combined with
images of a plume against a contrasting background. Each
a defined operating environment: (a) inputs images captured by
image is analyzed with software that determines plume opacity
the Digital Still Camera image capture devices; (b) produces
by comparing a user defined portion of the plume image where
opacity measurements from the combination of human
opacity is being measured in comparison to the background
interaction, open or proprietary calculations and algorithms,
providing the contrasting values. The Analysis Software is
and image content viewing; (c) and then outputs said opacity
used to average the opacities from the series of digital images
measurement along with Analysis Software’s configuration,
taken of the plume over a fixed period of time. The software is
image source documentation and other environmental param-
also used to archive the image set utilized for each opacity
eters.
determination including the portion of each image selected by
3.2.2 certified—for the purpose of this standard, certified
the operator.
refers to achieving or excelling the requirements described in
4.2 The following conditions must be followed to make a
this method.
valid opacity determination:
3.2.3 DCOT certification package—for the purpose of this
4.2.1 The image must be captured in a JPEG format that
standard, certification package refers to 300 images (150 white
adheres to the EXIF 2.1 (or higher) standard.
smoke and 150 black smoke) captured against at least two
4.2.2 The image must be captured with the sun located
different backgrounds.
behind the Digital Still Camera and within a 140° sector
3.2.4 DCOT operator—refers to the human operating the
directly behind the Digital Still Camera (see Table 1 for
DCOT system who records the digital still images with the
schematic).
Digital Still Camera and then determines plume opacity with
4.2.3 The image must be captured perpendicular to the
the Analysis Software.
direction of plume travel.
4.2.4 The ambient light must be sufficient to show a clear
3.2.5 Digital Still Camera—an image capture device used to
contrast between the plume and its background.
collect store and forward digital still images to the Analysis
4.2.5 The portion of the plume selected for opacity deter-
Software for analysis as defined by the DCOT vendor’s
certification documentation. mination shall not contain condensed water vapor.
4.2.6 The selected portions of each image representing the
3.2.6 image transfer file—an electronic file that contains the
visible plume and the uniform background must contrast
image captured by the Digital Still Camera and its associated
sufficiently for the software to differentiate between the plume
environment documentation that is consistent with EXIF 2.1
and its background.
JPG (or higher) format and is input to the Analysis Software;
4.2.7 The portion of the plume selected for opacity deter-
all of the digital images obtained by a DCOT system shall be
mination shall represent the part of the plume with the highest
reviewed by a qualified human DCOT operator to assess if the
apparent opacity, excluding water vapor, as determined by the
digital images are acceptable (for example, no obvious errors
DCOT operator.
in the digital images).
4.2.8 The area of the digital image to be analyzed for
3.2.7 opacity—measurement of the degree to which particu-
opacity shall be centered in the digital image when taking the
late emissions reduce the intensity of transmitted photopic light
photograph.
and obscure the view of an object through an effluent gas
4.2.9 Each DCOT vendor shall provide training for opera-
stream of a given path length in ambient air.
tors of their DCOT system. The training shall include the
3.2.8 opacity source—any source that produces emissions
content of the “Principles of Visual Emissions Measurements
that are visible to the human eye.
and Procedures to Evaluate those Emissions Using the Digital
Camera Optical Technique (DCOT)” (Annex A1) and a de-
3.2.9 output function—human readable information docu-
scription of how to operate that specific DCOT system that
menting the image being analyzed and configuration of the
passed smoke school.
Analysis Software used, the opacity measurement and the other
required environment variables defined (for example, view
5. Significance and Use
angle, wind direction).
5.1 Air permits from regulatory agencies often require
3.2.10 run—for the purpose of this standard, run or smoke
school run refers to 50 consecutive images (25 white and 25 measurements of opacity from stationary air pollution point
black); smoke schools identify Runs with a number (normally sources in the outdoor ambient environment. Opacity has been
1–10), a date, and a location; smoke schools may allow visually measured by certified smoke readers in accordance
D7520 − 16 (2023)
TABLE 1 Example of Field Data Record when Determining Plume Opacity with DCOT
Company name:
Company location:
Test Identification No.:
Date:
Type of facility:
Process unit:
Operating capacity or mode for process:
Control device:
Operational status of control device:
Height of emission point and estimation method:
Operator name:
Operator affiliation:
DCOT certification date:
DCOT certified by:
Camera’s manufacturer, model, and serial number:
Initial Final
CLOCK TIME
CAMERA LOCATION
Distance to discharge
Vertical angle of emission point
to camera
Angle of sun to back of camera
Height of emission point relative
to camera
ENVIRONMENTAL CONDITIONS
Background of plume
Wind direction
Wind speed
Ambient temperature
Relative humidity
Sky condition (for example,
clear, partially cloudy, overcast)
PLUME DESCRIPTION
Color
Distance between discharge and
location where opacity
is determined
NUMBER CAPTURED IMAGES
ADDITIONAL INFORMATION
Operator signature: Date:
with USEPA (USEPA Method 9). DCOT is also a method to minimum level of performance for products that use DCOT to
determine plume opacity in the outdoor ambient environment. determine plume opacity in ambient environments.
5.2 The concept of DCOT was based on previous method
6. Interferences
development using Digital Still Cameras and field testing of
7,8
those methods. The purpose of this standard is to set a
6.1 Contrast—As the contrast between the color of the
plume and the background decreases, the observed opacity
decreases. To achieve maximum opacity, the opacity shall be
Du, K., Rood, M. J., Kim, B. J., Kemme, M. R., Franek, B. J., and Mattison,
measured at a point where the maximum contrast exists
K., Quantification of Plume Opacity by Digital Photography, Environmental Science
between the plume and the background.
and Technology, Vol 41, No. 3, DOI: 10.1021/es061277n, 2007a, pp. 928–935.
Du, K., Rood, M. J., Kim, B. J., Kemme, M. R., Franek, B. J., Mattison, K., and
6.2 Luminescence—Low light levels adversely impact the
Cook, J., Digital Optical Method to Quantify the Visual Opacity of Plumes in the
determination of plume opacity. Adequate natural light must be
Field, Journal of the Air and Waste Management Association, Vol 57, DOI:10.3155/
1047-3289.57.7.836, 2007b, pp. 836–844. available to illuminate the plume and background during the
D7520 − 16 (2023)
period the images are captured. This method shall only be used Digital Still Camera must be capable of generating EXIF 2.1
during daytime conditions. JPG (or higher) formatted output files (JEMA EXIF 2.1 JPG,
1995) and the Analysis Software shall stipulate the required
6.3 Steam Plumes—Steam plumes (or condensed water
values of the EXIF 2.1 JPG (or higher) file as defined in its
vapor) cause significant errors in measuring opacity, and occur
certification documentation as described in A2.1. The Digital
in two distinct modes as either attached plumes or detached
Still Camera performs the image acquisition function and thus
plumes. When either condition is noted to exist, the camera
images must be captured in accordance with the procedures
operator must record sufficient images to document the type of
described in Section 8 to ensure that interferences are reduced
plume observed and the relative position of the exhaust stack
as discussed in Section 6. Once the images have been captured
with relationship to the point the opacity measurement is made.
and stored into the resulting EXIF 2.1 JPG (or higher) file per
6.3.1 Attached Steam Plumes—When condensed water va-
the minimum EXIF 2.1 JPG (or higher) data requirements in
por is present within the plume as it emerges from the emission
Annex A2 of this standard the image capture component is
outlet, opacity images shall be made beyond the point in the
complete and the Analysis Software takes over. The Digital
plume at which condensed water vapor is no longer visible.
Still Camera is dependent on the minimum image requirements
The operator shall record the approximate distance from the
of the associated Analysis Software and thus must conform to
emission outlet to the point in the plume at which the images
the requirements for image capture as dictated by the Analysis
are made (Table 1).
Software component.
6.3.2 Detached Steam Plume—When water vapor in the
plume condenses and becomes visible at a distinct distance 7.1.2 The second component of the DCOT is the Analysis
from the emission outlet, the opacity of emissions shall be Software which reads the images captured by the Digital Still
evaluated at the emission outlet prior to the condensation of Camera, performs analysis of the image and calculates the
water vapor and the formation of the steam plume. opacity level of the pictorially repre
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.