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Document Number: 

75) ll-A-7 

Docket Number: 

A-84-22 

Printed 4/18/2008 10:52:08 AM Sheet 75 of 94 

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4-*¥*}*- U-A-7 

EPA-650/4-75-009 

January 1975 Environmental Monitoring Series 

EVALUATION AND COLLABORATIVE 

STUDY OF METHOD 

FOR VISUAL DETERMINATION 

OF OPACITY OF EMISSIONS 

FROM STATIONARY SOURCES 

Environme it 

Wa DC 20460 
P.3 

EPA-650/4-75^009 

by 

Henry F. Hamil, Richard E. Thomas, 

and Nollie F . Swynnerton 

Southwest Research Institute , 

8500 Culebr a Road 

San Antonio, Texa s 78284 

Contract No. 68-02-0626 

ROAP No. 26AAG 

Program Element No. 1HA327 

EPA Project Officer: M. Rodney Midgett 

Quality Assuranc e and Environmental Monitoring Laboratory 

National Environmental Research Center 

Research Triangl e Park , North Carolina 27711 

Prepare d for 

U.S . ENVIRONMENTAL PROTECTION AGENCY 

OFFICE OF RESEARCH AND DEVELOPMENT 

WASHINGTON, D.C. 20460 

Januar y 1975 
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EPA REVIEW NOTICE 

This report has been reviewed by the National Environmental Research 

Center - Research Triangle Park, Office of Research and Development, 

EPA, and approved for publication. Approval does not signify that the 

contents necessarily reflect the views and policies of the Environmental 

Protection Agency, nor does mention of trade names or commercial 

products constitute endorsement or recommendation for use. 

RESEARCH REPORTING SERIES 

Research reports of the Office of Research and Development, U.S . Environmental Protection Agency, have been grouped into series. These broad 

categories were established'to facilitate further development and application of environmental technology. Elimination of traditional grouping was 

consciously planned to foster technology transfer and maximum interface 

in related fields. These series are: 

1. ENVIRONMENTAL HEALTH EFFECTS RESEARCH 

2. ENVIRONMENTAL PROTECTION TECHNOLOGY 

3. ECOLOGICAL RESEARCH 

4. ENVIRONMENTAL MONITORING 

5. SOCIOECONOMIC ENVIRONMENTAL STUDIES 

6. SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS 

9. MISCELLANEOUS 

This report has been assigned to the ENVIRONMENTAL MONITORING 

series. This series describes research conducted to develop new or 

improved methods and instrumentation for the identification and quantification of environmental pollutants at the lowest conceivably significant 

concentrations. It also includes studies to determine the ambient concentrations of pollutants in the environment and/or the variance of 

pollutants as a function of time or meteorological factors. 

This document is available to the public for sale through the National 

Technical Information Service. Springfield, Virginia 22161. 

i i 
P.5 

SUMMARY AND CONCLUSIONS 

This report presents the results of statistical analyses on data obtained in the collaborative testing of 

EPA Method 9 (Visual Determination of Opacity). There were 5 separate tests of Method 9 at three different sites: a training smoke generator, a sulfuric acid plant and a fossil fuel-fired steam generator. I 

For these tests, the opacity measure used is the average opacity, defined as the average of 25 readings made at 15-second intervals. These determinations are analyzed for their accuracy and their precision. 

For this report, accuracy is measured by the deviation of the observer's determination from the true opacity 

as measured by the in-stack transmissometer. The precision of the method is measured in terms of withinobserver, observer bias and between-observer terms. 

Training Generator—Thirty-six runs were made over a two-day period using two training smoke 

jrs' 

nok 

arately. 

generators with 9 qualified observers participating. There were 20 runs using white smoke and 16'using 

black smoke with plume opacity ranging.from just above zero to 40 percent. The two cases are' treated sep-

• White Smoke-There were a total of 170 determinations made using a white plume. 

These values showed a low bias with respect to the transmissometer, and the deviation from the meter is • 

estimated by 

deviation = 3.46 — 0.33 (meter average). 

The within-observer standard deviation is estimated as 2.38 percent opacity with 133 degrees of freedom. 

The observer bias standard deviation is 0.95 percent opacity with 7 df. This gives a between-observer ] 

standard deviation of 2.56 percent opacity. 

o Black Smoke—There were 133 determinations of the average opacity of black smoke. The 

results from these values were similar to those of the white smoke. The predicted deviation from the transmissometer tor tins case ts ' 

deviation = 3.74 — 0.34 (meter average). 

The within-observer standard deviation is 1.84 percent opacity with 105 degrees of freedom. The observer 

bias standard deviation is 1.00 percent opacity with 7 df. This gives a between-observer standard deviation 

of 2.09 percent opacity. 

• Sulfuric Acid Plant—Thirty observation runs were made over two days at a sulfuric acid plant. 

There were 11 observers on the first day for 14 runs and 9 on the second day for the remaining 16 runs. The 

plume opacity was varied around the compliance limit for sulfuric acid plants, ranging from 2 to 15 percent 

average opacity. The observers were chosen from both a local enforcement agency and from private concerns to allow a comparison of the two groups. 

The predicted deviation for these data is -2.0 percent opacity for the entire range studied! The 

within-observer standard deviation is 2.12 percent opacity with 232 degrees of freedom. The observer bias 

standard deviation is 0.96 percent opacity with 8 degrees of freedom. This gives a between-observer standard deviation of 2.33 percent opacity. It is shown for this test that the enforcement observers read a 

higher, and more accurate, average opacity than did the private sector observers. 

• Steam Station—Three separate tests were conducted at a power plant with plume opacity [ranging up to 35 percent average opacity. On the first two days of testing, the weather conditions prevented 

the accurate determination of plume opacity. In the third test period, viewing conditions were ideal and 

the accuracy of the method is evaluated. ! 

IH' 
P.6 

• Test 1 -There were 10 runs using 10 observers at the first test. The determinations were 

well below the concurrent meter averages due to the sky and wind conditions. The deviation from the meter 

average is represented by 

deviation = —3.01 — 0.40 (meter average). 

A total of 60 determinations were used to obtain the precision estimates. The within-observer standard 

deviation is estimated as 1.82 percent opacity with 45 df. The observer bias standard deviation is estimated 

as 1.39 percent opacity with 8 df, which gives a between-observer standard deviation estimate of 2.29 percent opacity. 

• Test 2—Eighteen runs were made at the second test using 10 observers. The determinations 

made were more accurate than the previous test, but still were well below the meter average. The deviation 

from the true opacity is represented.by 

deviation = —1.02 — 0.19 (meter average). 

A total of 118 determinations are used to obtain the precision estimates. The within-observer standard 

deviation is 1.84 percent opacity with 88 degrees of freedom. The observer bias standard deviaton is estimated as 1.50 percent opacity with 8 degrees of freedom. The estimated between-observer standard deviation, then, is 2.37 percent opacity. 

• Test J-Twenty-four runs were made using eight observers over a two-day period. The 

resulting 192 determinations have a negative bias with respect to the metered opacity that can be represented by 

deviation = 2.27 — 0.24 (meter average). 

The within-observer standard deviation is estimated as 1.89 percent opacity with 90 degrees of freedom. 

Tlie observer bias standard deviation is 1.77 percent opacity with 6 degrees of freedom, which gives a 

between-observer standard deviation of 2.59 percent opacity. 

Also included for this test are evaluations of two variations to the method: reading to the 

nearest percent, and averaging two observers' results. 

• Composite Estimation—Using the results from the three test sites, it is possible to make composite estimates of the accuracy and precision that can be expected with field use of Method 9. The expected deviation from the average metered opacity is given by 

deviation = 3.13 — 0.31 (meter average) 

for the range from 5 to 35 percent average opacity. This equation is obtained from the training generator 

and steam station test data. 

The composite precision estimates are obtained using the estimates from all tests. The estimated 

within-observer standard deviation is 2.05 percent opacity with 693 df. The estimated observer bias standard 

deviation is 1.29 percent opacity with 44 df. This gives a composite between-observer standard deviation 

estimate of 2.42 percent opacity. 

For each case, estimates are made of the range of determinations that would be expected from a single 

observer, and ofthe maximum difference that would be expected between two observers when determining 

the average opacity of a plume. 

iv 
•••v r 

TABLE OF CONTENTS 

P.7 

Page 

LIST OF TABLES [vi i 

I. INTRODUCTION ; 1 

II. COLLABORATIVE TESTING 2 

A. Purpose 2 

B. Smoke Generator Test 2 

C. Stauffer Chemical Company Test 2 

D. Riverbend Steam Station 3 

E. Collaborators and Test Personnel 4 

III. DEFINITIONS AND STATISTICAL TERMINOLOGY 7 

A. Definitions 7 

B. Statistical Terminology 7 

IV. SMOKE GENERATOR TEST 9 

A. White Smoke 9 

B. Black Smoke 12 

V. STAUFFER CHEMICAL COMPANY TEST 16 

A. Accuracy 16 

B. Precision 16 

C. Predicted Results 18 

D. Comparision of Enforcement and Private Observers 19 

VI. RIVERBEND STEAM STATION TEST 20 

A. Test 1 20 

B. Test 2 23 

C. Test 3 '26 

VII. COMPOSITE ESTIMATION 34 

A. Accuracy 34 

B. Precision 34 

C. Predicted Results 35 

APPENDIX A-EPA METHOD 9 FOR VISUAL DETERMINATION OF OPACITY 37 

A.1 Federal Register, Vol 36, No. 247-Thursday, December 23, 1971 ,39 

A.2 Federal Register, Vol 39, No. 177-Wednesday, September 11, 1974 . 40 

APPENDIX B-STATISTICAL METHODS 45 

B.1 Linear Regression and Test for Significance '46 

B.2 Precision Estimation for Training Generator Test 47 

B.3 Precision Estimation for Sulfuric Acid Plant and Tests of Hypotheses 49 

B.4 Analysis of Variance and Tests of Hypotheses from Riverbend Steam Station Test 1 . 52 
P.8 

TABLE OF CONTENTS (Cont'd) 

Page 

B.5 Precision Estimation and Tests of Hypotheses for Riverbend Steam Station Test 2 54 

B.6 Precision Estimation and Tests of Hypotheses for Riverbend Steam Station Test 3 56 

B.7 Precision Estimation for Riverbend Steam Station Test 3, 1-Percent Increment 

Runs 59 

B.8 Significance of Reduction of Frequency of Large Deviations 61 

B.9 Multiple Comparison Tests and Composite Estimation 62 

LIST OF REFERENCES 63 

vi 
P.9 

LIST OF TABLES 

Table Page 

1 Certification Data on Collaborators, Riverbend Steam Station Tests | 4 

2 Test Log, Riverbend Steam Station, Test 1 j 4 

3 Test Log, Riverbend Steam Station, Test 2 I 4 

4 Test Log, Riverbend Steam Station, Test 3 5 

5 Determinations of Average Opacity of Training Generator, White Smoke 10 

6 Deviation From Training Generator, White Smoke 10 

7 Predicted Deviations, Training Generator, White Smoke jl 1 

8 Predicted Determinations, Training Generator—White Smoke 112 

9 Determinations of Average Opacity of Training Generator, Black Smoke '13 

10 Deviation From Training Generator, Black Smoke J13 

11 Predicted Deviation From Metered Opacity, Training Generator—Black 14 

12 Predicted Determinations of Average Opacity, Training Generator—Black 15 

13 Determinations of Average Opacity, Stauffer Chemical 17 

14 Deviations From Meter Average, Stauffer Chemical |18 

15 Predicted Determinations, Sulfuric Acid Plant 19 

16 Observer Means, Sulfuric Acid Plant [19 

17 Average Opacity Determinations, Steam Station Test 1 20 

18 Deviations From Metered Opacity, Steam Station Test 1 21 

j 

19 Predicted Deviation From Metered Opacity, Steam Station Test 1 21 

20 Predicted Determinations, Steam Station Test 1 23 

21 Observer Means For Steam Station Test 1 23 

22 Average Opacity Determinations, Steam Station Test 2 24 

23 Deviations From Metered Opacity, Steam Station Test 2 . 25 

24 Predicted Deviation From Metered Opacity, Steam Station Test 2 J25 

25 Predicted Determinations, Steam Station Test 2 26 

26 Observer Means For Steam Station Test 2 26 

vii 
P.10 

LIST OF TABLES (Cont'd) 

Table Page 

27 Average Opacity Determinations, Steam Station Test 3 27 

28 Deviations From Metered Opacity, Steam Station Test 3 27 

29 Predicted Deviation From Metered Opacity, Steam Station Test 3 28 

30 Predicted Determinations, Steam Station Test 3 29 

31 Observer Means For Steam Station Test 3 30 

32 Predicted Deviations, 1-Percent Increment Data 30 

33 1-Percent Data Summary 31 

34 Predicted Determinations, 1-Percent Data 32 

35 Opacity Determinations Using Paired Observers 32 

36 Deviations From Opacity, Paired Observers 33 

37 Predicted Deviation From Metered Opacity, Composite Estimate 34 

38 Predicted Determinations of Average Opacity, Composite Estimate 35 

Bl Analysis of Variance From Training Generator Test, White Smoke 47 

B2 Analysis of Variance From Training Generator Test, Black Smoke 48 

B3 Analysis of Variance From Sulfuric Acid Plant Test 50 

B4 Analysis of Variance From Steam Station Test 1 53 

B5 Analysis of Variance From Steam Station Test 2 55 

B6 Analysis of Variance From Steam Station Test 3 57 

B7 Analysis of Variance From Steam Station Test 3,1% Variation 60 

B8 Analysis of Variance From Steam Station Test 3, 1% Runs 61 

vm 
P.11 

' P I "•]) 

I. INTRODUCTION 

This report describes the work performed and results obtained on Southwest Research Institute 'Project 

01-3462-006, EPA Contract No. 68-02-0626, which includes collaborative testing of Method 9 for visual determination of the opacity of emissions from stationary sources as given in "Standards of Performance for New Stationary 

Sources' and "Stationary Sources, Proposed Emission Monitoring and Performance Testing Requirements."(2) 

This report describes the statistical analysis of the data from collaborative tests conducted on two EPA-type 

training smoke generators, and at a sulfuric acid plant and a coal-fired power plant. 

The results of the data analyses and the conclusions based on these analyses are given in this report. 

'Superscript numbers in parentheses refer to the List of References at the end of this report. 
P.12 

II. COLLABORATIVE TESTING 

A. Purpose 

Collaborative testing of the method for visual determination of opacity of emissions from stationary sources' ' > 

was conducted in order to obtain data using certified observers which would allow statistical evaluation of the method. 

Results from these tests are presented in this report. 

Three collaborative test sites were used: a training smoke generator, a sulfuric acid plant, and a fossil fuelfired steam generatoi. Tests at the first two sites mentioned above were designed to evaluate the determination of 

average opacity of emissions^), while the test at the third site was designed to allow evaluation of both the determination of minutes of noncompliance with a standard and determination of average opacity. 

(2) The results in 

this report are all based upon average opacity determinations. 

The initial test on the training smoke generator was conducted to provide background information on the use 

of the method. The tests at the sulfuric acid plant and the fossil fuel-fired steam generator were conducted to obtain 

information on the use ofthe method on applicable sources under field conditions. At no time during any 

of the test were warm-up or practice runs allowed prior to the test itself. 

B. Smoke Generator Test 

The smoke generator test was conducted on 19-20 November 1973 at the National Environmental Research 

Center. Research Triangle Park. North Carolina. Two training smoke generators were used, one belonging to the EPA 

and one belonging to the State of North Carolina. A total of nine collaborators from enforcement agencies in the 

State of North Carolina were available for the tests. All nine collaborators participated in the first fifteen runs—only 

eight participated in the remaining twenty-one runs, since one collaborator operated the State of North Carolina's 

smoke generator. Time since last certification for the collaborators varied from one to thirteen weeks. 

During the two-day test, a total of thirty-six runs were made, with a run consisting of twenty-five readings 

taken at the fifteen-second intervals by each collaborator. The collaborators read the plume on a time signal from 

the test supervisor in order to assure that the readings were as nearly simultaneous as possible. The opacity of the 

plume as indicated by the in-stack transmissometer of the smoke generator was recorded at the time signal to provide "true" opacity data. Twenty runs were made with white plumes, and sixteen runs were made with black plumes. 

The range of opacity studied was from just above 0 to 40 percent. During some of the runs, plume opacity was held 

essentially constant while on other runs the opacity ofthe plume was varied randomly to determine how 

well the observers could follow changing opacity during the course ofa set of observations. 

Due to the relatively short stack height on the smoke generators, in some runs the observers had objects in 

the background (buildings, trees, power lines, etc.), while on other runs only a sky background was available. 

Since use of background objects in evaluating plume opacity is permitted in most training courses, no differentiation 

was made in this test between runs with or without background objects. During both days of the test, viewing conditions were ideal, with blue sky and bright sunshine. On all runs, the observers were allowed to select the optimum viewing position with respect to sun and wind angles. 

C. Stauffer Chemical Company Test 

The sulfuric acid plant test was conducted on 29-30 January 1974 at Stauffer Chemical Company's facilities 

in Houston, Texas. The unit was equipped with a 300-foot-high stack. In-stack monitoring of opacity was accomplished by use ofa Lear Siegler Model 610A transmissometer*. 

A total of eleven collaborators were available for the first day of the test. Nine collaborators were available for 

the second day of the test. Four of the collaborators were from the City of Houston Department of Public Health, 

•Mention ol trade names or specific products docs not constitute endorsement by the Lnvironmental Protection Agency. 
P.13 

six were from area industries, and one was from a local health association. All collaborators' most recen't certification was on 24 August 1973 at the State of Texas Training Session conducted at Houston, Texas. 

• 

I 

During the two-day lest, a total of thirty runs were made, fourteen runs on the first day and sixteen runs on 

the second day. Each run consisted of twenty-five readings taken at 15-second time intervals by each observer. 

The collaborators began each run on a time signal from the test supervisor. The average opacity as indicated by 

the in-stack transmissometer was obtained from the instrument strip chart recorder for the time period corresponding to each run. 

Arrangements were made with plant personnel to change unit operating conditions during the test to provide 

plumes of varying opacity. The range of opacity studied was from slightly above 0 to 15 percent. Opacity of the 

plume was essentially constant during any single run. During both days of the test, good viewing conditions prevailed, with blue sky and a slight haze. Wind was light and variable throughout the test. Color of the plume was 

white. ! 

The observers were allowed to select the optimum viewing position with respect to wind directioniand sun 

angle. 

D. Riverbend Steam Station 

Three tests were conducted at the Duke Power Company's Riverbend Steam Station near Charlotte. N.C. 

Tests were conducted on 27 August, 5 September, and 30 September-1 October, 1974. The tests involved use of 

two units at the power plant, number 9 and number 10 boilers. Each boiler was equipped with two stacks (A&B). 

Readings for the first two tests and the first day of the third test were made on Stack B of boiler number 9. On 

1 October 1974, the number 9 boiler was shut down, and the third test was completed using Stack A! of .number 10 

boiler. Both stacks were fitted with Lear Siegler Model RM4 transmissometers*. 

The plan for the tests at the Riverbend Steam Station varied from the plans for the previously described tests 

This set of tests was designed to provide infonnation on some variations to the method as written.0 .-) The collaborators were divided into two equal groups with regard to size and experience. One group was used as a control 

and made their readings of opacity within the constraints of the published method, with the sun in the quadrant 

to their rear, assigning opacity to the plumes in 5-percent increments. The other was used as the experimental 

group. One variation under study by this group was reading at 45- and 90-deg angles with respect to 'the sun. 

Opacity was assigned in 5-percent increments during this portion ofthe experiment. The other variation was reading the plume in 1-percent increments from the same position as the control group. • 

From this test, the effect on a method test result induced by reading outside some of 

the constraints of the method may be estimated. By altering, the angle of view with respect 

to the sun, it may be determined whether this is an important consideration for the observer. 

By requiring that the plume be read in 1-percent increments, it may be determined if this i 

variation is more accurate or more precise. In addition to these, the relative performance of ; 

an inexperienced to an experienced observer may be assessed, and the possible improvement 

of the method by averaging two observers' results may be evaluated. 

In the first two tests, a run consisted of forty observations by each observer taken at 15-second intervals. This 

was done for the purpose of evaluating the method when used to determine minutes of noncompliance with a 

standard. The average opacity presented in the data tables represents the average of the first twenty-five readings 

by an observer in each run. In the third test, a run consisted of twenty-five observations by each observer taken at 

15-second intervals. In all three tests, the observers read the plume on a time signal from test.personnel. Transmissometer readings were recorded to the nearest percent on the time signal to provide "true" opacity readings. 

"Trade name. 
P.14 

TABLE 1. CERTIFICATION DATA ON COLLABORATORS, 

RIVERBEND STEAM STATION TESTS 

Collaborator 

Code Number 

1 

2 

3* 

4 

5 

6 

7 

8 

9t 

10 

1 1 

12 

13 

Date of 

Most Recent 

Certification 

7-16-74 

7-16-74 

4-5-74 

4-5-74 

4-5-74 

4-5-74 

4-5-74 

4-5-74 

3-19-74 

8-27-74 

9-11-74 

9-U-74 

9-11-74 

Average Deviation 

from True Opacity 

During Certification, % 

4.7 

5.7 

4.6 

5.4 

5.9 

6.2 

5.9 

4.4 

4.3 

3.8 

3.1 

2.9 

3.9 

*Not qualified. One reading during qualification deviated from the opacity by more than 15 percent. Not 

determined until after test due to clerical error. 

^Certification expired 9-19, recertified 10-22. 

TABLE 2. TEST LOG, RIVERBEND STEAM STATION, TEST 1 

27 August 1974 

Run 

No. 

1 

-> 

3 

4 

5' 

6 

7 

8 

9 

10 

Time Run 

Began 

1015 

1055 

1130 

1330 

1350 

1410 

1430 

1450 

1510 

1530 

Position 

Angle, deg 

45 

90 

90 

0 

0 

0 

45 

45 

90 

90 

Sky Conditions 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Mostly cloudy, low haze 

Wind 

NE, 0-5 mph 

Light, variable 

Light, variable 

SW, 5-10 mph 

SW, 5-10 mph 

Light, variable 

Light, variable 

Light, variable 

W, 3-5 mph 

W, 3-5 mph 

TABLE 3. TEST LOG, RIVERBEND STEAM STATION, TEST 2 

5 September 1974 

Run 

No. 

. 

2 

3 

4 

5 

6 

7 

8 

9 

10 

H 

'-

13 

14 

15 

16 

'-

IS 

Time Run 

Began 

0910 

0930 

0950 

1010 

I ti30 

1050 

1130 

1150 

1210 

1230 

1350 

1411) 

1430 

1450 

1530 

1550 

1610 

1'>.*(> 

Position 

Angle, deg 

0 

0 

45 

45 

90 

90 

45 

45 

90 

9U 

0 

0 

90 

90 

0 

n 

45 

45 

Sky 

Conditions 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Overcast 

Wind 

NE, 5-1 0 mph 

NE, 5-10 mph 

NE, 5-10 mph 

NE, 5-10 mph 

NE, 5-1 0 mph 

NE, 5-10 mph 

NE, 5- 10 mph 

NE.5-1 0 mph 

NE. 5-10 mph 

NE, 5-10 mph 

NE. 5 10 mph 

NE, 5- 10 mph 

NI. 5- 10 mph 

NE.5 10 mph 

NE. 5 It) mph 

NE.5 10 mph 

M . 5 10 mph 

NE.5 10 mph 

The range of opacity studied in all 

three tests was from just above 0 to "40 percent. Opacity of the plume was varied by 

cutting off one or more stages of the electrostatic precipitator prior to the run. 

With the exception of occasional shortduration transient high values, plume opacity was essentially constant during a given 

run for the low opacities. Variation in the 

"true" opacity within a run increased as 

the average plume opacity increased. 

The collaborators for each test came 

from State of North Carolina enforcement 

agencies, EPA offices, and private contractors. The first two tests utilized four state, 

four EPA, and two contractor personnel. 

The third test utilized four state, two EPA, 

and two contractor personnel. The date of 

the most recent certification of the collaborators is given in Table 1. Also included 

for each of the collaborators is the average 

deviation from the true plume opacity for 

the twenty-five white and twenty-five black 

plumes read during certification. 

The three tests consisted of ten, 

eighteen, and twenty-four runs, respectively. 

Viewing conditions during the first test were 

poor, mostly cloudy and low haze. There 

was also interference from another plume 

during portions of the test. Conditions 

for the second test were marginal, with a 

solid overcast, while for the third test conditions were ideal, with a cloudless sky and 

bright sunshine. The plume color was white. 

Test logs for the three tests are presented in Tables 2,3, and 4. In Tables 2 

and 3, the position of the experimental 

group is given relative to the control group. 

In Table 4, the positions of both the control and experimental groups are given 

relative to the sun, with the angles calculated as shown in Figure 1. 

E. Collaborators and Test Personnel 

The collaborators for the smoke generator test were Mr. Sammy L. Amerson, 

Mr. George Lawson. Mr. Dewey D. Johnson, 

Mr. Roy T. Gorman. Mr. J.R. Kirk, Mr. D.Y. 

Daniel, Jr., Mr. B.J. Foust and Mr. Bill 

Proctor from the State o

1

.' North Carolina 
P.15 

TABLE 4. TEST LOG. RIVERBEND STEAM STATION, TEST 3 

30 September - 1 October 1974 

Run 

No. 

j 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

Time Run 

Began 

1315 

1330 

1345 

1400 

1415 

1430 

1445 

1500 

1515 

1530 

0930 

0945 

1000 

1015 

1130 

1145 

1200 

L215 

1230 

1245 

1300 

1315 

1330 

1345 

Viewing Angle, i) (Fig. 1) 

Control 

Group. 

deg 

0 

0 

10 

10 

15 

15 

45 

45 

0 

0 

30 

30 

25 

25 

20 

20 

10 

10 

0 

0 

0 

0 

o 

0 

Experimental 

Group, 

deg 

0 

0 

45 

45 

60 

60 

45 

45 

0 

0 

30 

30 

75 

75 

90 

90 

45 

45 

0 

0 

45 

45 

90 

90 

Sky 

Conditions 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Clear 

Oear 

Clear 

Wind 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

N. 8-12 mph 

N.8-1 2 mph 

N, 5 10 mph 

N. 5-10 mph 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light, variable 

Light variable 

Light, variable 

Light, variable 

\ / 

\ 

SUN 

9 = Angle formed by line between sun and 

plume being observed and line between 

observing group and plume. { 

CONTROL GROUP 

EXPERIMENTAL 

GROUP 

o o oo o o oo 

POWER PLANT 

FIGURE I. SCHEMATIC OF OBSERVER POSITIONS. 

RIVERBEND STEAM STATION,TEST 3 
P.16 

Depai inient o\ Natural and Economic Resources; and Mr. William M. Edsel from the County of Forsyth Air Quality 

Control Division. Forsyth County, North Carolina. 

The collaborators for the sulfuric acid plant test, all from the Houston, Texas, area, were Mr. Charles L. Owen 

from Armco Steel; Mr. James S. Corbin, Mr. Robert J. Stahl, Mr. Ronald F. Stockunas and Mr. Wendell La Foe 

from the City ol Houston Department of Public Health; Mr. B. L. Bolton from Rollins Environmental Services; 

Mi. T. M. Walker and Mr. Klaus R. Gerlach of Stauffer Chemical Co.; Mr. Mel Remley from Jefferson Chemical Co.; 

Mr. William Mooie from the San Jacinto Lung Association; and Mr. Larry P. Stoltz from GAF Corporation. 

The collaborators for the power plant tests were Mr. Dewey D. Johnson, Mr. Ron Jernigan, Mr. John Leatherman and Mi. Don Shepherd from the State of North Carolina Department of Natural and Economic Resources; 

Mr. William M. Edsel from the County of Forsyth Air Quality Control Division; Mr. David Da Crema and 

Mr. John Yates, from Engineering Science Inc.; Mr. Alan Luther and Mr. Peter F. Burnette from Environmental Science and Engineering, Inc.; and Mr. Alfred Vervaert, Mr. J.W. Brown. Mr. Joseph Peoples, Mr. James 

E. Casey. Mr. Jack Siegel and Mr. John Hund from the Environmental Protection Agency.* 

The tests were conducted under the general supervision of Mr. Nollie F. Swynnerton. The collaborators from 

the Stntc o( North Carolina were provided through the assistance of Mr. James A. McColman, Chief, Air Quality 

Division, State of North Carolina Department of Natura! and Economic Resources. The collaborators for the sulfuric 

acid plant test were selected by Mr. Swynnerton from a list of people who had certified at the most recent State of 

Texas certification school in the Houston area. The list was provided by Mr. Thomas Jay McMickle, Environmental 

Health Specialist. Texas State Department of Health. The collaborators from EPA, Engineering Science, and 

Environmental Science and Engineering were provided by Mr. Roy Neulicht, Environmental Engineer, 

Emissions Standards and Engineering Division. Office of Air Quality Planning and Standards, EPA. Mr. Dennis 

Holzschuh. Pysical Science Technician. Engineering and Enforcement Section. Air Pollution Training Institute. 

Control Programs Development Division. Office of Air Quality Standards and Planning. EPA, assisted in the 

conduct of the smoke generator test at the National Environmental Research Center. Mr. William D. Conner, 

Research Physicist. Stationary Source Measurements Research Section. Emission Measurements Research 

Branch. Chemistry and Physics Laboratory, National Environmental Research Center. EPA. made the necessary arrangements with Duke Power Company personnel for the Riverbend Steam Station Tests. 

I n.-.iughniit the icmaindcr of this reporl. ihc observer- .ire refericd lo b> assigned code numbers. T he code numbers used do nol 

•.•.-respond M ihc .ihovc ordered listin. ol obscivcrs. 
P.17 

III. DEFINITIONS AND STATISTICAL TERMINOLOGY . 

To facilitate the understanding of this report and the utilization of its findings, this section explains the 

statistical terms used in this report and defines certain terms used in presenting the data and results. , 

A. Definitions 

1. Run-A 6-minute period during which the observers determined the opacity of the plume. 

2. Determination—The arithmetic mean of 25 consecutive opacity readings taken at 15-second 

intervals during a run. 

3. Meter Average—The average opacity of the plume as determined by the in-stack transmissometer. 

4. Deviation—The difference between a determination and the corresponding meter average; deviation = 

determination — meter average. 

B. Statistical Terminology 

n 1

 *•*"» 1. x = — 2^i X,- —the sample mean. This statistic estimates the mean, or center, of a given population. 

"i= l 

1 " 

2. x

2

 = V^ (_"_", —x)* "~^ie sampl6 variance. This statistic estimates the dispersion in a distribution around the mean value. 

3. s = y/P —the sample standard deviation. The standard deviation is an alternative estimate of 

dispersion. 

4. Analysis of Variance (ANOVA)—A statistical technique for testing whether different groups or 

factors perform in an equivalent manner, and for obtaining estimates of different variance terms. 

5. SS-sums of squares. The sum of squared deviations from the mean for a component. The SSj are 

used to estimate variability. 

6. df—degrees of freedom. The df are an indication of the amount of confidence in the estimate. A 

larger number of df implies a greater degree of confidence. 

7. MS-the mean square. The MS is the basis for hypothesis testing in the ANOVA and estimating a 

variance component. MS = SS/df 

8. EMS—the expected mean square. The EMS determines which mean squares are used to test which 

hypotheses, and to estimate the particular variance components. 

9. F-Ratio-the ratio of two mean squares. The F-ratio is the test statistic for determining the relative 

performance of two groups. 
P.18 

All precision components in this report are estimated using an ANOVA procedure. The statistical 

model is given separately for each data set, but, in general, consists of an observer term, a run term and an 

error term. The MS and EMS from these ANOVA tables are used to determine the significance of the various factors, and to estimate the following precision components. 

• Within-observer. The within-observer, or error, component measures the dispersion that would be 

expected in replicate determinations by the same observer at the same true opacity. The withinobserver variance is denoted by a

2

. 

• Observer bias. The observer bias component measures the dispersion that would be expected in 

replicate determinations due to the use of the method by independent observers. These differences can result from such factors as the training generator on which the observers qualified 

and the relative frequency with which they use the method. The observer bias variance is denoted 

A- by a? 

Between-observer. The between-observer component is estimated from the within-observer and 

observer bias terms. The between-observer term measures the variability associated with the difference between results by independent observers. The between-observer term is composed of 

within-observer and observer bias terms, and the between-observer variance, o\ is defined as 
P.19 

-• r |'-|ii 

IV. SMOKE GENERATOR TEST 

The initial test of Method 9 was conducted using two EPA-approved smoke generators to produce plumes, 

both white and black, covering tlie range of opacities that could be expected by observers seeking to detennine 

compliance with the new source performance standards. These included plumes from just above zero up, to | 

40 percent. On each run, the collaborators recorded their observations to the nearest 5 percent for 25 readings 

taken at 15-second intervals. The observers read on a signal given by test personnel, so that all determinations 

were comparable. The 25 readings were averaged by SwRI personnel after the test to insure that the deter- ! 

mination was correctly computed. 

To determine to what extent the observers were able to follow changes in the plume opacity, the generated 

opacity was subject to change during a run. During the runs, the opacity was either held constant, increased or 

decreased according to a test plan. In addition, the number of times the plume opacity was changed, the point 

at which it was changed and the amount it changed all were varied from run to run so that the observers would 

not be able to anticipate these changes. 

The observers were allowed to choose their position for observing the generated plume, consistent with 

the constraints of the method. On some runs, they had a background (e.g., trees, buildings) to read against, 

while on others, there was only blue sky. No record ofthe background was kept, so any differences in this 

regard cannot be determined. 

There were a total of 36 sampling runs, 20 with white smoke and 16 with black, made during the two 

day period. One observer participated in only the first 15 runs then operated the second training generator for 

the remainder of the test. This resulted in a total of 303 determinations, 170 with white smoke and 133 with 

I black. The analyses of the data will concern itself with two aspects: the accuracy, as measured by the deviation 

from the metered opacity, and the precision, expressed in terms of standard deviations. The results are presented below separately for the white and black plumes. 

A. White Smoke 

The 170 determinations are shown in Table 5, along with the concurrent meter averages. To evaluate the 

performance of the observers, the determinations will be looked at in two ways. First, they will be compared 

to the meter averages to determine how accurately the observers were able to read the opacity; and second, they 

will be compared to each other to determine how much variation can be expected both from a single observer, 

and between two independent observers when reading the same opacity plume. 

1. Accuracy 

The deviations from the plume opacity are shown in Table 6. As can be seen from the data, there 

is a tendency for the deviation to be greater and negative as the plume opacity increases. Because of this! a 

linear regression is used, with opacity as the independent variable and deviation as the dependent variable. 

The technique is presented in Appendix Bl. 

For these deviations, the slope of the least-squares fit to these points is significantly different 

from zero. This indicates that there is a linear relationship between the two variables. The equation of the 

line derived is 

Yj = 3.46 - 033*/ 

where 

Yj is the predicted deviation 

Xj is percent opacity 
P.20 

•""""""""* *wr» 

TABLE 5. DETERMINATIONS OF AVERAGE OPACITY OF TRAINING 

GENERATOR, WHITE SMOKE 

(Percent Opacity) 

Run 

No. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

1 

12.8 

10.6 

8.8 

27.0 

11.2 

5.6 

8.8 

31.2 

22.6 

9.4 

17.4 

8.6 

10.0 

13.0 

18.2 

32.2 

19.0 

9.0 

14.8 

12.4 

2 

12.0 

9.0 

5.8 

28.2 

9.6 

4.6 

8.4 

22.6 

15.4 

7.6 

17.4 

6.4 

8.8 

14;8 

20.8 

29.4 

18.8 

8.8 

17.0 

10.2 

3 

10.8 

11.2 

8.6 

23.8 

12.0 

5.0 

7.0 

2.4.6 

13.6 

8.4 

19.2 

8.6 

12.4 

15.8 

17.4 

30.8 

20.8 

13.6 

20.4 

9.8 

Observer 

4 

13.2 

11.0 

9.6 

22.6 

12.0 

6.6 

7.2 

24.4 

16.6 

7.8 

19.6 

7.4 

10.6 

19.4 

18.4 

28.6 

19.6 

9.6 

16.4 

10.0 

5 

10.6 

8.2 

6.0 

13.6 

11.4 

5.8 

7.6 

20.2 

19.6 

10.0 

18.8 

8.0 

11.4 

15.4 

19.6 

27.6 

16.6 

7.2 

17.0 

9.4 

6 

17.4 

10.6 

8.6 

22.2 

12.8 

5.8 

8.2 

21.0 

17.4 

7.8 

17.4 

6.2 

11.4 

12.0 

12.8 

18.2 

15.0 

7.2 

13.0 

7.4 

7 

11.0 

8.4 

6.6 

14.6 

11.8 

6.0 

7.2 

21.4 

20.6 

9.0 

16.4 

5.2 

8.7 

13.6 

13.8 

23.6 

18.8 

7.8 

15.8 

9.2 

8 

10.6 

12.8 

8.6 

25.0 

11.4 

5.0 

7.6 

27.4 

17.0 

7.2 

16.4 

5.2 

8.2 

12.6 

10.8 

23.2 

13.0 

7.0 

11.0 

8.0 

9 

13.0 

14.8 

10.0 

24.0 

11.2 

6.6 

7.4 

27.4 

16.0 

8.6 

Meter 

10.0 

13.6 

9.2 

23.8 

12.3 

4.7 

7.6 

34.0 

25.4 

12.4 

13.1 

8.6 

9.0 

11.2 

14.3 

31.3 

13.2 

16.8 

18.7 

14.6 

TABLE 6. DEVIATION FROM TRAINING GENERATOR, 

WHITE SMOKE 

(Percent Opacity) 

Run 

No. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

1 

2.8 

-3.0 

-0.4 

3.2 

-1.1 

0.9 

1.2 

-2.8 

-2.8 

-3.0 

4.3 

0.0 

1.0 

1.8 

3.9 

0.9 

5.8 

-7.8 

-3.9 

-2.2 

2 

2.0 

-4.6 

-3.4 

4.4 

-2.7 

-0.1 

0.8 

-11.4 

-10.0 

-4.8 

4.3 

-2. 2 

-0. 2 

3.6 

6.5 

-1.9 

5.6 

-8.0 

-1.7 

-4.4 

3 

0.8 

-2. 4 

-0. 6 

0.0 

-0. 3 

0.3 

-0.6 

-9.4 

-11.8 

-4.0 

6.1 

0.0 

3.4 

4.6 

3.1 

-0.5 

7.6 

-3. 2 

1.7 

-4.8 

4 

3.2 

-2.6 

-0.4 

-1.2 

-0.3 

1.9 

-0.4 

-9.6 

-8.8 

-4.6 

6.5 

-1.2 

1.6 

8.2 

4.1 

-2.7 

6.4 

-7.2 

-2.3 

-4.6 

Observer 

5 

0.6 

-5. 4 

-3. 2 

-10. 2 

-0. 9 

1.1 

0.0 

-13.8 

-5. 8 

-2.4 

5.7 

-0.6 

2.4 

4.2 

5.3 

-3. 7 

3.4 

-9. 6 

-1.7 

-5. 2 

6 

7.4 

-3.0 

-0.6 

-1.6 

0.5 

1.1 

0.6 

-13.0 

-8.0 

-4.6 

4.3 

-2.4 

2.4 

0.8 

-1.5 

-13.1 

1.8 

-9.6 

-5.7 

-7.2 

7 

1.0 

-5.2 

-2.6 

-9.2 

-0.5 

1.3 

-0.4 

-12.6 

-4.8 

-3.4 

3.3 

-3.4 

-0.3 

2.4 

-0.5 

-7.7 

5.6 

-9.0 

-2.9 

-5.4 

8 

0.6 

-0.8 

-0.6 

1.2 

-0.9 

0.3 

0.0 

-6.6 

-8.4 

-5.2 

3.3 

-3.4 

-0.8 

1.4 

-3.5 

-8.1 

-0.2 

-9.8 

-7.7 

-6.6 

9 

3.0 

1.2 

0.8 

0.2 

-1.1 

1.9 

-0.2 

-6.6 

-9.4" 

-3.8 

Meter 

10.0 

13.6 

9.2 

23.8 

12.3 

4.7 

7.6 

34.0 

25.4 

12.4 

13.1 

8.6 

9.0 

11.2 

14.3 

31.3 

13.2 

16.8 

18.7 

14.6 

10 
P.21 

and 

3.34 and -0.33 are the least-squares estimates of the intercept and slope; respectively. 

The /-statistic for these data is tc = —8.59 with 168 degrees of freedom, which is significant at the 5^percent 

level. This equation holds over the range of average opacities studied, from 5 to 30 percent. By substituting 

values into this equation, it is possible to predict what the deviation would be at a particular true average I 

opacity. This is done for selected opacities in Table 7. 

TABLE 7. PREDICTED DEVIATIONS, 

TRAINING GENERATOR, 

WHITE SMOKE 

2. Precision 

The precision of the determination of the average 

opacity of a white plume from a training generator is determine'd 

through use of an Analysis of Variance (ANOVA) technique. 

From this, it is possible to estimate both the within-observer and 

the observer bias components, and using these, to estimate the 

between-observer component. 

The precision estimates are obtained usihg onlyithe; 

determinations from the eight observers who completed all 20 j 

runs, which enables an estimate of the within-observer variance 

to be made without blocking the data. The details of the ANOVA are given and the estimate obtained inj 

Appendix B.2. I 

The within-observer variance, a2 , is estimated as 

r>2=5.67 

with 133 df. This gives an estimated within-observer standard deviation of 

0 = y/S£7 

Percent 

Opacity 

5 

10 

15 

20 

25 

30 

Estimated 

Deviation 

1.81 

0.16 

-1.49 

-3.14 

-4.79 

-6.44 

= 2.38 percent opacity. 

The F-ratio for observers is Fc = 4.16. This exceeds the tabled value of 2.75, approximately j 

from the F distribution with 7 and 133 df, at the 5-percent significance level. Thus, there is a significant 

observer bias variance, o\, and it is estimated by 

a\ = 0.90 

with 7 df. The estimated observer bias standard deviation, then, is 

aL=y/0S0 

= 0.95 percent opacity. 

The between-observer variance, o\, is estimated from the components above as 

d| = d2 + di \ 

= 5.67 + 0.90

 ! 

= 6.57. 

11 
P.22 

n i n i«i|iip^pfi 

This gives a between-observer standard deviation of 

a6=V637 

= 2.56 percent opacity. 

Predicted Results 

By combining the above results, it is possible to predict confidence limits for the average opacity 

determined by an observer. Let /tbe any true opacity level. Then the average opacity reported by the 

observer could be expected to be within 

expected range: k + (a + bk) ± (1.96) a percent opacity 

: k + (3,46 - 0.33/fc) + (1.96) (2.38) percent opacity 

: (0.67* + 3.46) ± 4.66 percent opacity 

at the 95-percent confidence level. The ranges for selected values of* are given in Table 8. 

TABLE 8. PREDICTED DETERMINATIONS, TRAINING 

GENERATOR-WHITE 

SMOKE 

Percent Opacity 

5 

10 

15 

20 

25 

30 

35 

Expected Range 

2.15-11.47 

5.50-14.82 

8.85-18.17 

12.20-21.52 

15.55-24.87 

18.90-28.22 

22.25-31.57 

Similarly, an estimate can be made of the difference 

expected between two determinations of the same average plume 

opacity made by independent observers. The difference between 

determinations has a variance of 2 o\. Thus, the maximum expected 

difference would be no more than 

maximum difference: ± (1.96) Jl bb 

: ± (2.77) ab 

: ±(2.77) (2.56) 

± 7.09 percent opacity 

at the 95 percent confidence level. 

B. Black Smoke 

The 133 determinations made using a black plume are shown in Table 9 along with the average of the 

transmissometer readings taken. These detexminations are examined for accuracy and precision in the same 

manner as were the white plume determinatSoias. 

1. Accuracy 

The deviations from the transmissometer average are shown in Table 10. As before, there is a 

tendency for the deviation to be greater as tbe true value increases. To obtain the best estimate of the deviation, a linear regression of the deviations on the true opacity is done. 

For these data, the line that best fits these points is 

y

i = 3.74-0.34Ar,' 

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H -< 

O -n 

> 

Z 

o 
P.24 

TABLE ll. PREDICTED DEVIATION Using this equation, deviations may be estimated for 

FROM METERED OPACITY, plumes within the applicable range. This is done in Table 11. 

TRAINING GENERATORBLACK 

Average 

Opacity 

10 

15 

20 

25 

30 

35 

Predicted 

Deviation 

0.44 

-1.21 

-2.86 

-4.51 

-6.16 

-7.81 

2. Precision 

The precision estimation for the black smoke determinations is similar to that done for the white smoke data. The results 

from the collaborator who did not complete all 16 runs are not included. The remaining 128 determinations of average opacity are 

used in an ANOVA to estimate the precision components. The details are presented in Appendix B.2. 

The within-observer variance, a

2

, is estimated as 

a

2

 = 3.38 

with 105 df. This gives an estimated within-observer standard deviation of 

o = \/338 

= 1.84. 

The F-ratio for observers is Fc = 5.73 which exceeds the critical value, F0-0 5 (7,105) *« 2.10 at ' 

the 5-percent level. Thus the observer bias variance, a\, is significantly different from zero, and is estimated 

by 

a

2

 = 1.00 

with 7df. Thus, the observer bias standard deviation is estimated by 

6L = 1.00. 

The between-observer variance is estimated from the above as 

al = a2 + a\ 

= 3.38 + 1.00 

= 4.38. 

The estimated between-observer standard deviation, then, is 

a6=V438 

= 2.09. 

3. Predicted Results 

Using the results above, it is possible to predict, at the 95-percent confidence level, the range of 

opacities that would occur in the use of the method at particular opacity levels. The predicted determination 

at fc-percent opacity would be 

fc + (a + bit) = * + (3.74 - 0.34*) 

= 0.66fc + 3.74. 

14 
P.25 

The variability in a reading would be measured by the within-observer standard deviation. For the 95-percent 

confidence level and 105 df, the factor 1.96 is used. This gives [ 

i 

expected range: (0.66* + 3.74) ± 1.96 6 . 

: (0.66*+3.74) ±1.96 (1.84) I 

: (0.66*+ 3.74) ±3.61.

 ! 

The expected range is given for selected values of * in Table 12. 

TABLE 12. PREDICTED DETERMINATIONS OF AVERAGE OPACITY, 

TRAINING GENERATORBLACK 

Percent Opacity 

5 

10 

15 

20 

25 

30 

35 

Expected Range 

3.43-10.65 

6.73-13.95 

10.03-17.25 

13.33-20.55 

16.63-23.85 

19.93-27.15 

23.23-30.45 

The maximum difference between two determinations i 

made by independent collaborators is determined from these data at 

the 95-percent confidence level. The factor 1.96 is again used, and 

this gives 

maximum difference: ± 1.96 Jl a\ 

±(2.77) a„ 

+ (2.77) (2.09) 

± 5.79 percent opacity, 

at the 95-percent confidence level. 

15 
P.26 

V. STAUFFER CHEMICAL COMPANY TEST 

The second test of the method was conducted at the Stauffer Chemical Company sulfuric acid plant. 

This test was specifically designed to test the ability of a qualified observer to accurately read the plume 

opacity near the compliance limit for that source. The standard for sulfuric acid plants is 10 percent, meaning that an opacity of 10 percent or greater is in violation. ' 

The observers were chosen both from government enforcement agencies and from the private sector. 

This was done to investigate whether the affiliation of the individual influenced his determination of opacity. 

There were 14 runs made on the first day of the test by 11 collaborators, and 16 runs on the second with 

9 collaborators for a total of 298 determinations. The average opacity during each run was determined from 

a strip chart readout of opacity as determined by an in-stack transmissometer. Because of this, the "true" 

opacity coujd only be determined to the nearest percent, and the observers' determinations were rounded to 

the nearest percent opacity for comparison. 

The observers made one deviation from the published method on the second day. Since the plume was 

light, they suggested that they read to the nearest 1 percent rather than the nearest 5 percent, and this was 

permitted. However, since the method specified that 5-percent increments be used, the individual readings 

subsequently were rounded to the nearest 5 percent prior to being averaged to obtain the determinations used. 

While there may be a difference between these and a Method 9 determination, it is felt that it would be slight. 

The determinations are shown in Table 13 along with the average meter opacity for that range. These 

values are investigated for both their accuracy and precision, as for the smoke generator test. 

A. Accuracy 

The deviations from the transmissometer average are shown in Table 14 for the sulfuric acid plant data. 

The deviations show a negative bias, falling generally 1 to 3 percent below the metered opacity. To determine 

if there is a linear relationship between the deviations and the meter average, a regression line is fit to these 

points. 

The equation of the best fit to these points is 

deviation = —2.36 + (0.05Xmeter average). 

From the slope of the line, it can be seen that there is a slightly positive trend to these deviations compared 

to the negative trend of the smoke generator test. 

To determine if the slope is significant, a f-statistic is calculated as described in Appendix B.l. The 

value of the statistic is tc = 0.68 with 296 df. This is not significant, which implies that the slope, 0.05, 

is not significantly different from zero. Thus, no linear relationship can be said to exist between deviation 

and opacity for these data. The best estimate of the deviation, then, is the mean deviation of —2.0 percent 

opacity. This is valid in the range studied, from 2 to 15 percent opacity. However, since the majority of the 

runs were made between 5 and 10 percent average opacity, it is possible that there is a relationship between 

the two variables that would be noticeable if a wider range of opacities was studied. 

B. Precision 

The determinations are submitted to an ANOVA procedure to estimate the precision of the method at 

a sulfuric acid plant. The ANOVA was performed using only the nine observers who completed all 30 runs. 

The remaining data set is large enough to obtain the desired estimates, and the necessity for blocking is 

eliminated by their exclusion. 

16 
,.,,-J . 

P.27 

TABLE 13. DETERMINATIONS OF AVERAGE OPACITY, 

STAUFFER CHEMICAL 

(Percent Opacity) 

Run 

No. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

1 

7 

5 

5 

5 

7 

5 

5 

5 

18 

7 

1 

5 

5 

5 

0 

0 

0 

0 

9 

6 

5 

5 

3 

3 

4 

5 

8 

6 

6 

7 

2 

3 

1 

0 

0 

2 

3 

3 

3 

10 

5 

0 

2 

2 

3 

0 

0 

0 

0 

8 

9 

9 

7 

4 

5 

6 

9 

9 

9 

10 

10 

3 

7 

7 

7 

6 

6 

6 

6 

6 

15 

8 

3 

5 

4 

5 

1 

1 

1 

0 

8 

7 

5 

5 

4 

3 

5 

7 

7 

6 

8 

5 

4 

6 

5 

4 

3 

5 

5 

5 

5 

15 

7 

1 

5 

5 

3 

0 

1 

2 

0 

10 

12 

6 

5 

5 

3 

6 

10 

13 

16 

15 

16. 

Observer 

5 

5 

5 

3 

1 

4 

2 

5 

5 

12 

10 

1 

4 

3 

5 

0 

3 

1 

0 

12 

13 

10 

5 

6 

5 

7 

13 

13 

17 

13 

15 

6 

5 

5 

5 

5 

5 

5 

5 

5 

14 

8 

4 

5 

5 

5 

0 

4 

3 

1 

14 

14 

10 

6 

7 

5 

7 • 

13 

16 

17 

16 

15 

7 

4 

4 

4 

4 

5 

5 

5 

5 

11 

9 

2 

6 

5 

7 

3 

4 

1 

1 

7 

6 

5 

5 

2 

2 

2 

4 

5 

4 

5 

5 

8 

5 

4 

4 

3 

5 

3 

3 

4 

9 

5 

0 

3 

4 

4 

0 

1 

0 

0 

9 

10 

6 

5 

5 

5 

9 

11 

8 

9 

14 

14 

9 

5 

4 

4 

4 

6 

6 

6 

6 

14 

8 

5 

5 

5 

5 

3 

5 

3 

4 

9 

8 

6 

5 

5 

5 

5 

6 

7 

5 

7 

6 

10 

7 

7 

3 

3 

6 

6 

6 

5 

12 

9 

4 

5 

5 

5 

11 

3 

2 

3 

2 

4 

3 

2 

2 

13 

8 

1 

2 

1 

3 

Meter 

9 

8 

8 

8 

8 

8 

8 

8 

14 

7 

5 

6 

6 

6 

2 

2 

5 

4 

10 

10 

10 

10 

7 

7 

7 

9 

9 

9 

9 

9 

The precision estimates are taken from the ANOVA table in Appendix B.3. The within-observer com-| 

ponent is estimated by: 

5

2

=4.51 

which has 232 df associated with it. This gives an estimated within-observer standard deviation of 

a=V43T 

= 2.12 percent opacity 

The observer term for these data is shown in Appendix B.3 to be significantly different from zero. The 

observer bias variance, a\, is estimated from the ANOVA table as 

al = 0.93 

with 8 df. This gives an estimated observer bias standard deviation of 

bL=J033 

= 0.96 percent opacity 

17 
P.28 

3 U P| I l| IR| 

TABLE 14. DEVIATIONS FROM METER AVERAGE, STAUFFER CHEMICAL 

(Percent Opacity) 

Run 

No. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

1 

- 2 

- 3 

- 3 

- 3 

- 1 

- 3 

- 3 

- 3 

4 

0 

- 4 

- 1 

- 1 

- 1 

_2 

- 2 

- 5 

- 4 

- 1 

- 4 

- 5 

- 5 

- 4 

- 4 

- 3 

- 4 

- 1 

- 3 

- 3 

- 2 

2 

- 6 

- 7 

- 8 

- 8 

- 6 

- 5 

- 5 

- 5 

- 4 

- 2 

- 5 

- 4 

- 4 

- 3 

- 2 

- 2 

- 5 

- 4 

- 2 

- 1 

- 1 

- 3 

- 3 

- 2 

- 1 

0 

0 

0 

1 

1 

3 

- 2 

- 1 

- 1 

- 2 

- 2 

- 2 

- 2 

- 2 

1 

1 

- 2 

- 1 

- 2 

- 1 

- 1 

- 1 

- 4 

- 4 

- 2 

- 3 

- 5 

- 5 

- 3 

- 4 

- 2 

- 2 

- 2 

- 3 

- 1 

- 4 

4 

- 3 

- 3 

- 4 

- 5 

- 3 

- 3 

- 3 

- 3 

1 

0 

- 4 

- 1 

- 1 

- 3 

- 2 

- 1 

- 3 

- 4 

0 

2 

- 4 

- 5 

- 2 

- 4 

- 1 

1 

4 

7 

6 

7 

Observer 

5 

- 4 

- 3 

- 5 

- 7 

- 4 

- 6 

- 3 

- 3 

- 2 

3 

- 1 

- 2 

- 3 

- 1 

- 2 

1 

- 4 

- 4 

2 

3 

0 

- 5 

- 1 

- 2 

0 

4 

4 

8 

4 

6 

6 

- 4 

- 3 

- 3 

- 3 

- 3 

- 3 

- 3 

- 3 

0 

1 

- 1 

- 1 

- 1 

- 1 

- 2 

2 

- 2 

- 3 

4 

4 

0 

- 4 

0 

- 2 

0 

4 

7 

8 

7 

6 

7 

- 5 

- 4 

- 4 

- 4 

- 3 

- 3 

- 3 

- 3 

- 3 

2 

- 3 

0 

- 1 

1 

- 1 

2 

- 4 

- 3 

- 3 

- 4 

- 5 

- 5 

- 5 

- 5 

- 5 

- 5 

- 4 

- 5 

- 4 

-A 

8 

- 4 

- 4 

- 4 

- 5 

- 3 

- 5 

- 5 

- 4 

- 5 

- 2 

- 5 

- 3 

-2 

-2 

- 2 

- 1 

- 5 

- 4 

- 1 

0 

- 4 

- 5 

- 2 

- 2 

2 

2 

- 1 

0 

5 

5 

9 

- 4 

- 4 

- 4 

- 4 

- 2 

- 2 

- 2 

- 2 

0 

1 

0 

- 1 

- 1 

- 1 

- 2 

0 

- 2 

- 2 

- 4 

- 5 

- 2 

- 2 

- 2 

- 3 

- 2 

- 4 

- 2 

- 3 

10 

- 2 

- 1 

- 5 

- 5 

- 2 

- 2 

- 2 

- 3 

- 2 

2 

- 1 

- 1 

- 1 

- 1 

11 

- 6 

- 6 

- 5 

- 6 

- 4 

- 4 

- 6 

- 6 

- 1 

1 

- 4 

- 4 

- 5 

- 3 

Meter 

9 

8 

8 

8 

8 

8 

8 

8 

14 

7 

5 

6 

6 

6 

2 

2 

5 

4 

10 

10 

10 

10 

7 

7 

7 

9 

9 

9 

9 

9 

The between-observer variance, al, is the sum of the within-observer and observer bias components. 

The estimated value is 

afc = ni + b2 

= 0.93+4.51 

= 5.44. 

This results in a between-observer standard deviation of 

ab=j5M 

= 2.33 percent opacity. 

C. Predicted Results 

The above results can be used to make statements concerning the results that would be obtained by an 

independent observer. The range of opacities that could be expected is calculated by using the best estimate 

of the deviation, along with the variation that could be expected. 
P.29 

At * percent opacity, the expected result would be ' 

i 

(*-2)%±(1.96)d 

i 

at the 95-percent confidence level. The factor 1.96 is used since with 232 df, the distribution of the t statistic 

is essentially a standard normal curve. Substituting in the value of ogives: 

expectedrange : (* - 2)%± (1.96)(2.12) 

(fc-2)±4.16 

* - 6.16 to * + 2.16 

for plumes of from 2 to 15 percent average opacity. For selected values, the expected range is calculated and 

shown in Table 15. 

TABLE 15. PREDICTED DETERMINATIONS, The maximum expected difference between deterSULFURIC ACID PLANT rninations by two independent observers is calculated using 

the between-observer variance term. As before, the difference 

is ' 

maximum difference = (2.306) Jib2, • 

= (3.26)S6 

at the 95-percent confidence level. The factor 2.306 comes 

from Student's t distribution with 8 df, due to the observer 

bias term. Substituting gives 

maximum difference = (3.26)(2.33) 

= 7.60 percent opacity 

D. Comparison of Enforcement and Private Observers 

The test personnel were chosen from both an enforcement 

agency and from private concerns to allow the determinations 

by each group to be compared. The nine collaborators who 

completed all 30 runs are used, and the mean over the 30 runs 

is computed. The observer means are shown in Table 16. 

Avg Opacity 

5 

10 

15 

"Truncated to ze 

Expected Range 

0*-7.16 

3.84-12.16 

8.84-17.16 

o. 

TABLE 16. OBSERVER MEANS, 

SULFURIC ACID PLANT 

Observer 

1 

2 

3 

*4 

*5 

*6 

7 

*8 

9 

Mean 

5.00 

4.40 

5.47 

6.47 

6.60 

7.63 

4.57 

5.40 

5.73 

'Observer from enforcement 

agency. 

largest overall means and the sixth largest, 

opacity than the private sector people. 

The observers from the enforcement agency were numbers 4, 5, 6 and 8. As can be seen, this group gives the three 

The indication, then, is that these people tend to read a higher 

The hypothesis that the two groups read the same average opacity is tested in Appendix B.3. The 

test is a contrast among the means, and the test statistic follows Student's t distribution. The statistic is 

tc = 5.69 with 232 df. This is a significant value and the conclusion is that the enforcement observers did j 

indeed determine higher average opacities overall than the other group. 

The average opacity for all 30 runs, however, was 7.6, so that the enforcement observers were closer 

to the true opacity than those from other agencies. 

19 
P.30 

VI. RIVERBEND STEAM STATION TEST 

The three tests at the Riverbend Steam Station are treated separately in the analysis since there were 

different groups of collaborators and varying sky conditions for the three tests. 

The original test plan was designed to allow the evaluation of the method as used for the determination 

of minutes of noncompliance with a particular standard/2^ A test run was set as 10 minutes of observation, 

and the reported variable was to be how many observations exceeded a certain standard. 

The experimental factors to be studied included the angle of observation and the relative experience 

of the observer. Variations to the method to be evaluated included reading in 1 percent rather than 5 percent 

increments and averaging the responses of two observers as opposed to a single observer's result. 

In the third testing period, the test personnel were advised that the average opacity, based on 25 readings, was the test variable of interest. The other factors for the test remained unchanged. For purposes of 

comparison, average opacities were calculated from the first two data sets using the first 25 observations of 

each run. 

Due to the adverse sky and wind conditions during tests 1 and 2, not all of the planned evaluations are 

useful. There was an inability to read the low opacity plumes against the type of background that existed, 

and as a result, the determinations were generally well below the concurrent meter average. The precision 

estimated, however, is independent of the accuracy of the determination. 

The observers at each test were divided into two groups for the test, a control and an experimental. 

The control group observed the plume at all times from a position consistent with the method as written and 

read in increments of 5 percent. The experimental group either read the plume from a more extreme angle, 

in increments of 5 percent or from the same angle as the control but in increments of 1 percent. Each group 

was composed both of observers who had considerable field experience with the method and of observers 

who had relatively little such experience. 

A. Test 1 

There were 10 runs made at the first test by 10 observers. The determinations of average opacity 

calculated from the observer record sheets are shown in Table 17. These determinations will be evaluated 

with respect to their accuracy and precision. There are six missing determinations in the data set. These 

TABLE 17. AVERAGE OPACITY DETERMINATIONS, STEAM 

STATION TEST 1 

Run 

1 

2 

3 

4 

5 CTV 

7 

8 

9 

10 

Control Group 

1 

6.4 

13.4 

11.6 

5.4 

8.4 

14.8 

17.6 

9.4 

1.2 

* 

2 

4.4 

8.2 

11.0 

4.4 

6.4 

7.6 

9.6 

3.2 

0.2 

* 

3 

6.2 

11.2 

10.6 

6.0 

7.8 

12.4 

12.4 

4.0 

2.4 

* 

•Incomplete.data sheet. 

4 

5.2 

9.6 

13.8 

6.8 

6.6 

14.6 

14.2 

9.6 

5.6 

* 

5 

5.8 

12.8 

12.6 

4.8 

11.4 

9.0 

11.4 

1.8 

0.6 

* 

Meter 

16.0 

23.5 

26.0 

11.6 

15.7 

26.1 

24.4 

14.2 

13.0 

13.4 

1 

1 

5.4 

6.6 

10.8 

5_2 

7.6 

12.2 

7.5 

4.4 

1.6 

2.0 

_xperimental Group 

2 

5.4 

6.2 

9.4 

5.5 

5.8 

8.5 

9.4 

6.0 

3.0 

3.0 

3 

1.8 

3.8 

7.8 

4.1 

5.9 

7.5 

4.6 

1.0 

0.2 

0.0 

4 

5.8 

6.4 

13.0 

5.8 

5.9 

15.0 

8.6 

5.0 

1.0 

0.0 

5 

2.2 

4.4 

•8.8 

6.5 

9.5 

8.9 

7.0 

2.2 

0.4 

* 

20 
P.31 

occur when due to sky and wind conditions and interference from another plume, the observer felt that at 

times he was unable to make a determination of the opacity, and in these instances, a direct comparison 

would not be valid. ' 

1. Accuracy 

It is apparent that these determinations are generally considerably lower than the meter average. 

The deviations from the meter average are shown in Table 18. 

TABLE 18. DEVIATIONS FROM METERED OPACITY, STEAM STATION TEST 1 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

1 

-9.6 

-10.1 

-14.4 

-6.2 

-7.3 

-11.3 

-6.8 

-4.8 

-11.8 

* 

"incomplete Da 

Control Group 

2 

-11.6 

-15.3 

-15.0 

-7.6 

-9. 3 

-18.5 

-14.8 

-11.0 

-12.8 

* 

3 

-9.8 

-12.3 

-15.4 

-5.6 

-7.9 

-13.7 

-12.0 

-10.2 

-10.6 

* 

4 

-10.8 

-13.9 

-12.2 

-4.8 

-9.1 

-U. 5 

-10.2 

-4.6 

-7.4 

* 

ta Sheet. 

5 

-10.2 

-10.7 

-13.4 

-6.8 

-4.3 

-17.1 

-13.0 

-12.4 

-12.4 

* 

Meter 

16.0 

23.5 

26.0 

11.6 

15.7 

26.1 

24.4 

14.2 

13.0 

13.4 

1 

-10.6 

-16.9 

-15.2 

-6.4 

-8.1 

-13.9 

-16.9 

-9.8 

-11.4 

-11.4 

Experimental Group 

2 

-10.6 

-7.3 

-16.6 

-6.1 

-9.9 

-17.6 

-15.0 

-8.2 

-10.0 

-10.4 

3 

-14.2 

-19.7 

-18.2 

-7.5 

-9.8 

-18.6 

-19.8 

-13.2 

-12.8 

-13.4 

4 

-10.2 

-17.1 

-13.0 

-5.8 

-9.8 

-11.1 

-15.8 

-9.2 

-12.0 

-13.4 

5 

-13.8 

-19.1 

-17.2 

-5.1 

-6.2 

-17.2 

-17.4 

-12.0 

-12.6 

* 

To assess the accuracy of the method under these conditions the control group data is used. 

These observers had taken the optimum viewing position consistent with the method, and thus are considered to best represent the accuracy that could be expected of the method. 

The deviations are fit to a regression model as with the data from the previous tests. The leastsquares fit to these points is given by 

deviation = —3.01 — 0.40 (meter average). 

The t statistic for this fit is tc = 5.89 with 43 df. This far exceeds the critical value of / Q5 (43) 

« 2.02, and this equation may be said to be valid in the range up to about 25 percent opacity. 

TABLE 19. PREDICTED DEVIATION 

FROM METERED OPACITY, STEAM 

STATION TEST 1 

Substituting into this equation, it is possible to predict 

what the deviation would be at selected opacities in the applicable 

range. This is done for the 5 percent increments and the results 

shown in Table 19. As can be seen, a plume opacity up to 10 percent 

is barely distinguishable from zero under these conditions. I 

2. Precision 

The precision estimates are obtained using both groups' 

determinations from runs where the experimental group was reading in 5-percent increments. The 1-percent increment data were 

intended only to evaluate that variation as a possible improvement to the published method when working 

on low opacity plumes, and due to the viewing conditions, no evaluation using these data is performed. The 

precision estimation is shown in Appendix B.4, using runs 1,2,3,7,8 and 9, omitting run 10 where there 

were 6 incomplete determinations. ] 

Percent Opacity 

5 

10 

15 

20 

25 

Predicted Deviation 

-5.01 

-7.01 

-9.01 

-11.01 

-13.01 

21 
P.32_ 

The estimated within-observer variance is 

a

2

 =3.31 

with 45 df. This gives an estimated standard deviation of 

d= 1.82 percent opacity 

The observers are determined to be a significant source of difference between observed values. The F-ratio 

is 4.50 which exceeds the critical value of 4.08 with 8 and 54 df. Thus, a\ is estimated as 

8-3 = 1.93 

with 8 df. The estimated observer bias standard deviation is 

bL=JTm 

= 1.39 percent opacity. 

Combining the above estimates, the between-observer component can be estimated. The between-observer 

variance, a\, is estimated by 

bl = b2 + b2

L 

= 3.31 + 1.93 

= 5.24. 

Thus, the estimated between-observer standard deviation is 

ab=j5l4 

= 2.29 percent opacity 

3. Predicted Results 

Using the results of the previous two sections, it is possible to estimate the range of opacities 

that could be expected from a qualified observer determining average opacity under these conditions. 

The expected range at any level, k, of true opacity would be given by 

expected range: k + [a + b*] ± (1.96) 0 

at the 95-percent confidence level. Substituting gives 

expected range: k + [-3.01 + OAOk] ± 1.96 (1.82) 

: [0.60*-3.01] ±3.57. 

The range is calculated for selected opacities and shown in Table 20. As expected, there are no 

instances where an accurate determination can be expected under these conditions. 

The maximum difference that could be expected between two observers is estimated using the 

between-observer standard deviation. The difference would not be expected to exceed 

22 
P.33 

•T'l " 

TABLE 20. PREDICTED DETERMINATIONS, STEAM STATION 

TEST 1 

Percent Opacity 

5 

10 

15 

20 

25 

Expected Range 

0*-3.56 

0*-6.56 

2.42-9.56 

5.42-12.56 

8.42-15.56 

*Truncated to zero. 

TABLE 21. OBSERVER MEANS 

FOR STEAM STATION 

TEST 1 

Group 

Control 

Experimental 

Observer 

1 

2 

3 

4 

5 

1 

2 

3 

4 

5 

Mean 

Determination 

9.93 

6.10 

7.80 

9.67 

7.50 

6.05 

6.57 

3.20 

6.63 

4.17 

maximum difference = -rj.05 (8)\Z2bb 

= (2.306)(1.414X2.29) 

= 7.49 percent opacity 

at the 95-percent confidence level. 

4. Experience Effect 

The means of the observers are shown in Table 21 and these are used to determine if there is any 

significant difference between the average opacity as determined by an experienced as opposed to an inexperienced observer. The test statistic is a r-statistic based upon a contrast among the means. The details are 

shown in Appendix B.4. 

The calculated f-statistic is 

r c= 1.39 

with 45 df. There can be said to be a difference between the two groups at the 5-percent level only if tc 

exceeds the tabled value. Since frj.05 (45) **• 2.016, the difference is not significant at the 5-percent level. 

Thus, for these conditions, the relative experience of the observer had no noticeable effect. 

B. Test 2 

There were 18 runs made at the second test period with 10 collaborators participating. The personnel 

breakdown was identical to the first test, with 4 experienced and 6 relatively inexperienced observers. One 

run, run 10, could not be completed. During the course of the run, the opacity meter began its automatic 

calibration check. During this time, the meter displays only the calibration opacities, 0 and 95 percent, and 

no true value is available for comparison. Only ten readings were made before the run was halted, and thus 

no determinations could be calculated. 

The determinations made by the observers are shown in Table 22. As in the previous test, missing j 

determinations occur when an observer is unable to make a determination of the plume opacity due to wind 

and sky conditions. 

23 
P.34 

TABLE 22. AVERAGE OPACITY DETERMINATIONS, STEAM STATION 

TEST 2 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

t 1 0 

11 

12 

13 

14 

15 

16 

17 

18 

*Inco 

fRun 

1 

11.2 

13.8 

10.0 

5.8 

20.0 

5.0 

13.8 

5.0 

14.4 

5.2 

5.6 

5.2 

9.4 

17.0 

7.8 

12.4 

7.6 

nplete c 

10 coul 

Control Group 

2 

5.8 

14.4 

9.2 

5.4 

15.0 

0.4 

11.4 

5.4 

10.6 

4.0 

2.2 

0.6 

7.0 

12.8 

7.0 

8.0 

6.0 

lata shet 

d not be 

3 

U.6 

13.2 

9.2 

5.6 

12.6 

4.4 

9.4 

6.6 

10.8 

5.0 

7.8 

5.0 

7.6 

16.8 

10.8 

10.0 

6.4 

:t. 

comple 

4 

10.6 

.14.8 

12.0 

6.2 

16.2 

1.0 

14.2 

5.2 

15.2 

7.6 

6.4 

0.0 

11.8 

21.8 

9.8 

12.4 

7.6 

ted. 

5 

4.2 

5.6 

5.2 

3.4 

13.6 

0.0 

10.4 

0.8 

10.6 

4.4 

2.6 

0.0 

7.4 

15.2 

3.2 

8.2 

5.0 

Meter 

14.4 

13.2 

11.2 

5.6 

16.4 

6.2 

11.6 

9.5 

15.0 

7.5 

10.8 

4.7 

10.1 

23.6 

13.5 

13.4 

13.6 

1 

8.0 

13.7 

13.0 

4.6 

20.0 

0.4 

# 

1.8 

8.6 

4.4 

2.7 

0.0 

6.6 

13.6 

7.0 

8.4 

5.0 

Experimental Group 

2 

6.1 

7.2 

5.2 

1.4 

13.8 

1.6 

8.0 

5.6 

6.0 

5.0 

3.4 

0.0 

4.8 

13.0 

6.0 

7.6 

6.0 

3 

4.3 

9.4 

3.4 

0.2 

11.4 

0.0 

6.6 

0.6 

5.4 

0.1. 

0.0 

0.0 

0.6 

9.8 

2.3 

1.8 

2.2 

4 

11.7 

11.3 

4.2 

3.4 

17.8 

0.0 

* 

4.2 

9.4 

2.6 

2.5 

0.0 

6.4 

15.6 

5.4 

10.0 

7.8 

5 

8.3 

8.6 

9.0 

4.0 

19.0 

3.0 

10.6 

3.8 

8.8 

3.6 

1.8 

0.0 

2.0 

12.3 

4.0 

7.0 

6.6 

1. Accuracy 

The deviations of the determinations from the meter average are shown in Table 23. As before, 

the determinations are generally below the meter due in large part to the viewing conditions. A linear regression of the deviations is used to assess the accuracy, and as in the first test, only the control group data is 

used. 

The best fit to these points is given by 

deviation = —1.02 — 0.19 (meter average) 

for the range from 5 to 25 percent average opacity. The t statistic for this model is tc = 2.56 with 83 df, 

which is significant at the 5-percent level. 

Using the above equation, it is possible to predict what deviation would be expected at various 

opacity levels. This is done in Table 24 for selected values in the appUcable range. These are somewhat better 

than those from the first test, but still have a strong negative bias at the low range of opacities. 

2. Precision 

The precision components for this test will be estimated using runs 3-9, 13, 14, 17 and 18. The 

remaining runs were those where the experimental group was reading in 1-percent increments, and a direct 

comparison between the two sets of readings is not proper. 

The precision components are estimated by an ANOVA procedure comparable to that for the 

first test. The details and ANOVA table are shown in Appendix B.5. The within-observer component is 

estimated from the error term of the ANOVA. 

24 
P.35 

ff-i'-'i! 

TABLE 23. DEVIATIONS FROM METERED OPACITY, STEAM STATION TEST 2 

(Percent Opacity) 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

11 

12 

13 

14 

15 

16 

17 

18 

*Inco 

1 

-3.2 

0.6 

-1.2 

0.2 

3.6 

-1. 2 

2.2 

-4.5 

-0.6 

-2.3 

-5.2 

0.5 

-0.7 

-6.6 

-5.7 

-1.0 

-6.0 

Con 

2 

-8.6 

1.2 

-2.0 

-0.2 

-1.4 

-5.8 

-0.2 

-4.1 

-4.4 

-3.5 

-8.6 

-4.1 

-3.1 

-10.8 

-6.5 

-5.4 

-7.6 

mplete Data Sheet. 

trol Group 

3 

-2.8 

0.0 

-2.0 

0.0 

-3.8 

-1.8 

-2.2 

-2.9 

-4.2 

-2.5 

-3.0 

0.3 

-2.5 

-6.8 

-2.7 

-3.4 

-7.2 

4 

-3. 8 

1.6 

0.8 

0.6 

-0.2 

-5.2 

2.6 

-4.3 

0.2 

0.1 

-4.4 

-4.7 

1.7 

-1.8 

-3.7 

-1.0 

-6. 0 

5 

-10.2 

-7.6 

-6.0 

-2.2 

-2.8 

-6.2 

-1.2 

-8.7 

1

 -4.4 

-3.1 

-8.2 

-4.7 

-2.7 

-8.4 

-10.3 

-5.2 

-8.6 

Meter 

14.4 

13.2 

11.2 

5.6 

16.4 

6.2 

11.6. 

9.5 

15.0 

7.5 

10.8 

4.7 

10.1 

23.6 

13.5 

13.4 

13.6 

1 

-6.4 

0.5 

1.8 

-1.0 

3.6 

-5.8 

* 

-7.7 

-6.4 

-3.1 

-8.1 

-4.7 

-3.5 

-10.0 

-6.5 

-5.0 

-8.6 

Experimental Group 

2 

-8.3 

-6.0 

-6.0 

-4.2 

-2.6 

-4.6 

-3.6 

-3.9 

-9.0 

-2.5 

-7.4 

-4.7 

-5.3 

-10.6 

-7.5 

-5.8 

-7.6 

3 

-10.1 

-3.8 

-7.8 

-5.4 

-5. 0 

-6.2 

-5.0 

-8.9 

-9.6 

-7.4 

-10.8 

-4.7 

-9.5 

-13.8 

-11.2 

-11.6 

-11.4 

4 

-2.7 

-1.9 

-7.0 

-2.2 

1.4 

-6.2 

* 

-5.3 

-5.6 

-4.9 

-8. 3 

-4.7 

-3.7 

-8.0 

-8.1 

-3.4 

-5.8 

5 

-6.1 

-4.6 

-2.2 

-1.6 

2.6 

-3.2 

-1.0 

-5.7 

-6.2 

-3.9 

-9.0 

-4.7 

-8.1 

-11.3 

-9.5 

-6.4 

-7.0 

TABLE 24. PREDICTED DEVIATION 

FROM METERED OPACITY, STEAM 

STATION TEST 2 

The within-observer variance, a

2

 , is estimated by 

a

2

 = 3.37 

with 88 df. This gives an estimated standard deviation of 

d = V33 7 

= 1.84 percent opacity 

The observer-within-group term is used to determine 

if there is a significant observer bias component. The F-ratio is 

Fc = 8.37, wliich is significant at the 5-percent level. This is 

equivalent to saying that the observer bias component, a\, is greater than zero. The observer bias variance 

is estimated from the observer mean square as 

a\ = 2.26 

with 8 df. The observer bias standard deviation is estimated by 

Percent Opacity 

5 

10 

15 

20 

25 

Predicted Deviation 

-1.97 

-2.92 

-3.87 

-4.82 

-5.77 

aL =VT2 6 

= 1.50 percent opacity 

The between-observer component is estimated from the above. The between-observer variance, 

Oh, is estimated as 

= 2.26 + 3.37 

= 5.63. 

This gives an estimated standard deviation of 

Ob=j5l3 

= 2.37 percent opacity 

25 
P.36 

3. Predicted Results 

The accuracy and precision statements above can be combined to predict the performance that 

could be expected when using Method 9 under these conditions. 

The range of opacities that could be expected from a qualified observer at *-percent opacity, at 

the 95-percent confidence level, is given by 

expected range: * + [a + b*] ± 1.96 & 

: *+ [-1.02-0.19*] ± 1.96(1.84) 

: [0.81* - 1.02] ±3.61 

TABLE 25. PREDICTED DETERMINATIONS, STEAM STATION 

TEST 2 

Percent Opacity 

5 

10 

15 

20 

25 

Expected Range 

0*-6.64 

3.47-10.69 

7.52-14.74 

11.57-18.79 

15.62-22.84 

*Truncated to zero. 

Values for this expected range are shown in Table 25 for 

the range of opacities studied. As can be seen, the observer would be 

expected to be biased on the low side above 10 percent opacity. 

The between-observer standard deviation can be used to 

estimate the difference that could be expected between two observers. 

The maximum expected difference is calculated as 

maximum difference = fo.05(8)\/2 ab 

at the 95-percent confidence level. The 8 df comes from the observer 

bias term. Substituting gives 

expected difference = (2.306X1.414X2.37) 

= 7.73 percent opacity 

4. Experience Effect 

The relative experience of an observer is investigated using the data from the ANOVA in Appendix 

B.5. The means of the observers over the 11 runs are calculated, and these are shown in Table 26. 

TABLE 26. OBSERVER MEANS FOR STEAM 

STATION TEST 2 

The 1*5. variation runs are excluded to avoid the 

possibility of this variation influencing the results. Run 7 is 

also excluded, due to the two missing observations. 

The details of the test for significance are presented 

in Appendix B.S. The value of the test statistic is tc = 3.19. 

From a Student's t distribution with 88 df, the critical value 

is approximately 1.99, and the hypothesis of equality between 

experienced and non-experienced observers is rejected since 

tc exceeds 1.99. 

C. Test 3 

There were 8 coUaborators for the third test. Of these, 

4 were from state and county agencies, 2 were from EPA 

offices and 2 were from a private contractor. The observers were divided into two equal groups as in the two 

previous tests. There were 10 observation runs on the first day and 14 on the second for a total of 192 individual determinations. These are shown in Table 27, along with the meter average concurrently obtained. 

Group 

Control 

Experimental 

Observer 

1 

2 

3 

4 

5 

1 

2 

3 

4 

5 

Mean 

Determination 

9.48 

6.76 

7.82 

8.76 

5.42 

6.84 

5.20 

2.56 

6.32 

6.32 

26 
P.37 

TABLE 27. AVERAGE OPACITY DETERMINATIONS, STEAM STATION 

TEST 3 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

1 

5.0 

13.6 

5.0 

9.0 

10.4 

6.6 

11.0 

5.8 

7.6 

6.8 

25.0 

40.8 

11.2 

17.0 

12.8 

26.0 

13.4 

29.2 

23.8 

23.0 

33.8 

i7.4 

23.8 

12.6 

Control 

2 

5.2 

13.6 

5.0 

8.4 

6.8 

6.6 

10.2 

6.0 

• 5.0 

6.0 

23.0 

39.0 

9.8 

15.2 

10.8 

25.6 

12.4 

25.2 

23.0 

19.4 

34.6 

12.6 

19.8 

15.0 

Group 

3 

3.0 

15.4 

4.0 

8.6 

8.8 

5.4 

8.4 

5.8 

5.4 

5.4 

36.2 

33.0 

5.6 

6.4 

7.8 

19.0 

11.2 

24.0 

18.4 

16.6 

30.0 

10.0 

18.0 

9.4 

4 

5.0 

5.4 

5.0 

5.2 

5.2 

5.0 

5.6 

5.2 

5.0 

5.0 

16.8 

39.6 

6.2 

10.2 

10.8 

25.2 

7.6 

25.0 

21.2 

12.4 

33.2 

8.0 

19.2 

6.8 

Meter 

3.1 

7.5 

4.2 

7.2 

6.7 

5.0 

5.4 

3.4 

4.2 

4.8 

21.2 

36.0 

10.3 

14.2 

12.2 

29.6 

14.6 

28.3 

34.6 

27.2 

36.9 

15.2 

27.8 

14.4 

Experimental Group 

1 

4.2 

12.2 

4.2 

7.8 

9.2 

5.6 

5.4 

3.2 

3.0 

3.8 

15.3 

25.2 

10.2 

18.0 

14.4 

29.8 

16.6 

30.0 

21.8 

22.8 

34.6 

14.0 

21.2 

15.0 

2 

4.6 

8.6 

3.0 

7.0 

6.4 

6.0 

5.6 

2.0 

1.6 

2.0 

13.5 

28.7 

9.0 

14.2 

16.6 

26.6 

16.4 

30.6 

25.6 

21.6 

40.2 

13.4 

25.2 

9.2 

3 

2.1 

6.1 

2.4 

1.8 

3.8 

4.0 

4.0 

2.0 

3.3 

2.3 

16.5 

25.7 

8.6 

12.2 

9.6 

24.2 

10.0 

22.0 

15.8 

13.5 

31.6 

11.8 

22.2 

8.8 

4 

3.1 

10.8 

5.0 

6.8 

7.8 

4.8 

6.0 

1.6 

4.5 

5.3 

10.2 

18.1 

7.4 

8.8 

12.8 

21.6 

12.8 

27.2 

21.6 

18.8 

31.8 

12.2 

24.8 

12.8 

To evaluate the observer performance at this test, the accuracy and precision will be estimated as for 

the first two sites. In addition, the relative performance of the tested variations to the method will be evaluated. 

i 

1. Accuracy 

The evaluation of the accuracy ofthe method is performed using the deviations from the meter 

obtained from the control group data as shown in Table 28. These deviations were all from determinations 

made within the constraints of the method, and thus offer the most applicable information. 

TABLE 28. DEVIATIONS FROM METERED OPACITY, STEAM STATION TEST 3 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

1 

1.9 

6.1 

0.8 

1.8 

3.7 

1.6 

5.6 

2.4 

3.4 

2.0 

3.8 

4.8 

0.9 

2.8 

0.6 

-3.6 

-1.2 

0.9 

-10.8 

-4.2 

-3.1 

2.2 

-4.0 

-1.8 

Control 

2 

2.1 

6.1 

0.8 

1.2 

0.1 

1.6 

4.8 

2.6 

0.8 

1.2 

1.8 

3.0 

-0.5 

1.0 

-1.4 

-4.0 

-2.2 

-3.1 

-11.6 

-7.8 

-2.3 

-2.6 

-8.0 

0.6 

Group 

3 

-0.1 

7.9 

-0.2 

1.4 

2.1 

0.4 

3.0 

2.4 

1.2 

0.6 

15.0 

-3.0 

-4.7 

-7.8 

-4.4 

-10.6 

-3.4 

-4. 3 

-16.2 

-10.6 

-6.9 

-5.2 

-9.8 

-5.0 

4 

1.9 

-2.1 

0.8 

-2.0 

-1.5 

0.0 

0.2 

1.8 

0.8 

0.2 

-4.4 

3.6 

-4.1 

-4.0 

-1.4 

-4.4 

-7.0 

-3. 3 

-13.4 

-14.8 

-3.7 

-7.2 

-8.6 

-7.6 

Meter 

3.1 

7.5 

4.2 

7.2 

6.7 

5.0 

5.4 

3.4 

4.2 

4.8 

21.2 

36.0 

10.3 

14.2 

12.2 

29.6 

14.6 

28.3 

34.6 

27.2 

36.9 

15.2 

27.8 

14.4 

Experimental Grou 

1 

1.1 

4.7 

0.0 

0.6 

2.5 

0.6 

0.0 

-0.2 

-1.2 

-1.0 

-5.9 

-10.8 

-0.1 

3.8 

2.2 

0.2 

2.0 

1.7 

-12.8 

-4.4 

-2.3 

-1.2 

-6.6 

0.6 

2 

1.5 

1.1 

-1.2 

-0.2 

-0.3 

1.0 

0.2 

-1.4 

-2.6 

-2.8 

-7.7 

-7.3 

-1.3 

0.0 

4.4 

-3.0 

1.8 

2.3 

-9.0 

-5.6 

3.3 

-1.8 

-2.6 

-5.2 

3 

-1.0 

-1.4 

-1.8 

-5.4 

-2.9 

-1.0 

-1.4 

-1.4 

-0.9 

-2.5 

-4.7 

-10.3 

-1.7 

-2.0 

-2.6 

-5.4 

-4.6 

-6.3 

-18.8 

-13.7 

-5.3 

-3.4 

-5.6 

-5.6 

P 

4 

0.0 

3.3 

0.8 

-0.4 

1.1 

-0.2 

0.6 

-1.8 

0.3 

0.5 

-11.0 

-17.9 

-2.9 

-5.4 

0.6 

-8.0 

-1.8 

-1.1 

-13.0 

-8.4 

-5.1 

-3.0 

3.0 

-1.6 

27 
P.38 

As was the case with the smoke generator test, there appears to be a relationship between the 

magnitude and direction of the deviation and the meter average. To test this, a linear regression model is fit 

in the manner of Appendix B.l. The least-squares line obtained is 

deviation = 2.27 - (0.24)(meter average). 

The t statistic for this test is tc = 6.10 with 94 df, which is significant at the 5-percent level. This equation 

is valid in the range from 5 to 35 percent average opacity. 

By substituting into the equation, it is possible to predict what the deviation would be at 

different levels of true average opacity. This is done in Table 29. These predicted deviations are 

comparable to those obtained in the smoke generator test. The observers are fairly accurate in the low 

opacity ranges, but acquire a low bias as the opacity increases. 

For comparison, the deviations from the meter are calculated for the experimental group as 

well. The three cases, 45°, 90°, and 1 percent are treated separately and regression lines calculated for 

each case. These are: 

Percent Opacity Oft 

10 Oft 

20 

25 

30 

35 

Predicted Deviation 

1.07 

-0.13 

1.33 

-2.53 

-3.73 

-^.93 

-6.13 

TABLE 29. PREDICTED DEVIATION 

FROM METERED OPACITY, deviation = -0.68 - 0.03 (opacity) 

STEAM STATION TEST 3 v ' 

deviation =1.34-0.19 (opacity) 

deviation = 1.76 - 0.39 (opacity) 

respectively, for the three cases. The first line does not 

have a significant slope, while the second two do. However, 

it is easy to see that the three slopes are different, and 

thus that the observers' determinations differed when the manner and position of observation differed. 

It is interesting to note that the most accurate readings were made when the group was at an 

approximate 45° angle to the sun. The mean deviation was -1.18 over the range from 5—32 percent average 

opacity. 

2. Precision 

The model used for estimating the precision of the method is similar to that used in the two previous 

tests. The variance components are estimated from an ANOVA of all determinations made by both groups 

on the 45° and 90° runs. The ANOVA is presented in detail in Appendix B.6. Precision estimation using the 

1 percent variation runs is contained in a separate evaluation. 

The estimated within-observer variance is 

a

2

 = 3.57 

with 90 df. The estimated within-observer standard deviation, then, is 

a=jni 

= 1.89 percent opacity 

The F-ratio for observers/groups isFc = 14.99. From a table of the F distribution, the critical 

value at the 5-percent significance level is F0 0 5 (6,90) *= 2.30. Thus, the observer/group term is significant, 

28 
P.39 

T'l""!!''' 

which is equivalent to saying that an observer bias variance term, a^ , does exist. The observer bias variance is 

estimated by 

&| = 3.12 

with 6 df. The estimated observer standard deviation, then, is 

. bL =V3Tl2" 

= 1.77 percent opacity. 

The between-observer variance is estimated from the above two terms as 

b

2

b = a

2

L+b2 

= 3.12 + 3.57 

= 6.69. 

This gives a between-observer standard deviation of 

bb=j6.69 

= 2.59 percent opacity. 

3. Predicted Results 

The above results can be combined to give estimates of the type of average opacities tliat would 

be expected from field use of the method. The expected range of opacities that would be reported by ah 

independent observer are obtained by using the predicted deviation and the within-observer standard deviation. 

The range of opacities, at * percent opacity, is defined as 

expected range: [* +predicted deviation] ± (1.96)6 

at the 95-percent confidence level. The normal variate 1.96 is used since there are 69 df for the within-observer 

component. Substituting gives 

expected range: *% +2.27 - (0.24)* ± (1.96X1-89) 

(0.76)* + 2.27 + (3.70) percent opacity 

TABLE 30. PREDICTED DETERMINATIONS, 

STEAM STATION TEST 3 

Percent Opacity 

5 

10 

15 

20 

25 

30 

35 

Expected Range 

2.37-9.77 

6.17-13.57 

9.97-17.37 

13.77-21.17 

17.57-24.97 

21.37-28.77 

25.17-32.57 

Values for the expected range are given in Table 30 fbr 5-percent increments in the applicable range. Similar to the previous results, these ranges contain the true opacities at the 

low end, but acquire a negative bias beginning at the 25-percent level. 

The between-observer component is used to 

estimate the difference that would be expected between 

two observers making independent observations of the plume 

opacity. The maximum difference diat would beexpected 

is '• 

29 
P.40 

maximum difference = fo.05 (6) V^SJT 

= (2.447X1.414)(2.59) 

= 8.96 percent opacity 

at the 95-percent confidence level. 

The t value has 6 df from the observer bias variance term. This maximum difference is slightly 

larger than the numbers previously obtained. 

4. Experience Effect 

The observer means shown in Table 31, are used to test the hypothesis that the experienced 

observers read the same average opacity as the inexperienced. The test is a contrast among the means, and 

the details are given in Appendix B. 6. 

TABLE 31. OBSERVER MEANS FOR The test statistic is based on Student's t distribution, 

STEAM STATION TEST 3 and compares the difference between the four experienced observers, 1, 2, 5, and 6, and the four inexperienced, 3,4, 7, and 

8. The value of the statistic is tc = 8.89 with 69 df. The tabled 

value is rn.os(69)

 !*s

 2.00, and thus the hypothesis is clearly rejected. The conclusion, then, is that the experience observers 

read different, and in this case higher, average opacities than the 

inexperienced. By inspection ofthe deviations, it appears that 

this difference occurs mainly in the high opacity range ( > 25%) 

where the inexperienced observers read much lower than the 

experienced. As it was previously, though, the experienced 

observers compare more favorably to the meter average. 

5. 1-Percent Increments 

On runs 1,2,9, 10, 11, 12, 19 and 20, the experimental group read from the same viewing position as the control, but recorded their observations to the nearest 1 percent opacity rather than the nearest 5 percent. These 

runs are considered separately from the others in terms of their accuracy and precision. 

a. Accuracy 

As the regression line in Section VI.C.l above indicates, there was a negative bias in tlie determinations. Using that line, predicted deviations are calculated for the applicable range, and these are calculated 

and presented in Table 32. 

Group 

Control 

Experimental 

Observer 

1 

2 

3 

4 

1 

2 

3 

4 

Mean 

Determination 

15.31 

14.00 

11.40 

11.46 

14.95 

14.46 

11.19 

12.76 

TABLE 32. PREDICTED DEVIATIONS, 

1-PERCENT INCREMENT DATA 

Opacity 

Ln 

10 

15 

20 

25 

30 

35 

Expected Deviation 

-0.19 

-2.14 

-4.09 

-6.04 

-7.99 

-9.94 

-11.84 

In addition, the runs are broken down into 

single readings, and the opacity from the meter is used to group 

the observations. All observations made at the same opacity 

level are treated as a single sample, and the accuracy of each is 

calculated. The results are summarized in Table 33. 

The meter values ranged from 3 to 62 percent 

opacity. For each, a mean is calculated and a standard deviation. 

A 95-pefcent confidence interval is calculated using the expression 

CI0.95 x ±CQ.05 V^T 

30 
P.41 

TABLE 33. 1-PERCENT DATA SUMMARY where co.05 is the tabled value, 

taken either from the standard 

normal or from Student's t distribur 

tion, and s is the calculated standard 

deviation. The observations are j 

accurate when the "true value" lies! 

i 

within the interval. As can be seen | 

from the table, the 1-percent data 

are generally accurate up to 20 percent opacity, but beyond 20 percent 

the accuracy standard is met only 

once. Also included in the tables ' 

are the maximum and minimum obr 

servations at each opacity level. | 

b. ' Precision 

The precision of the 

1-percent variation is investigated 

using an ANOVA, as before. The 

details are contained in Appendix 

B.7. The estimated within-observer 

variance is 

a

2

 = 8.29 

with 21 df. This gives an estimated 

within-observer standard deviation , 

of 

b = J%29 

= 2.88 percent opacity. 

This value is somewhat 

larger than that obtained from the 

5-percent variation. To test whether 

or not these two variance terms are' 

equivalent, an F-ratio is calculated comparing this estimate to the variance estimate from the 5-percent in- , 

crement data. The statistic is Fc = 2.32 with 21 and 90 df. From the tables, the critical value for this test ' 

is F0.o5 (21,90) a- 1.75. Since the calculated F exceeds the tabled F, the two variances may be said to be 

different. 

The F-ratio for observers is Fc = 1.84 with 3 df. This is not significant at the 5-percent level, 

which indicates that there was no observer effect in these runs. Thus, a\ is taken to be zero, and 

Opacity 

3 

4 

5 

6 

7 

8 

9 

10 

11 

13 

17 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

44 

45 

46 

50 

58 

62 

X 

3.3 

3.2 

4.6 

9.4 

6.0 

9.5 

9.8 

10.4 

11.0 

14.3 

13.3 

13.5 

13.9 

13.3 

15.1 

14.9 

20.0 

18.3 

19.1 

17.3 

18.6 

20.0 

20.3 

20.3 

21.4 

22.2 

20.7 

20.4 

22.8 

23.5 

27.0 

21.3 

22.8 

32.3 

31.0 

30.5 

32.0 

36.3 

36.5 

s 

2.0 

2.0 

3.1 

3.7 

3.3 

2.9 

5.0 

2.7 

2.3 

4.0 

2.2 

5.0 

3.8 

3.4 

4.5 

2.7 

1.6 

4.0 

6.2 

4.2 

4.6 

4.2 

4.0 

6.6 

3.9 

6.7 

6.8 

6.1 

3.6 

4.4 

8.8 

6.1 

1.7 

5.4 

4.7 

4.9 

5.4 

4.8 

6.6 

n 

108 

100 

112 

20 

28 

4 

8 

8 

8 

4 

4 

4 

24 

44 

16 

12 

4 

16 

32 

20 

32 

12 

16 

8 

16 

20 

32 

36 

8 

4 

4 

8 

4 

4 

4 

4 

4 

4 

4 

r 

1.96 

1.96 

1.96 

2.093 

2.052 

3.182 

2.365 

2.365 

2.365 

3.182 

3.182 

3.182 

2.069 

2.021 

2.131 

2.201 

3.182 

2.131 

2.042 

2.093 

2.042 

2.201 

2.131 

2.365 

2.131 

2.093 

2.042 

2.031 

2.365 

3.182 

3.182 

2.365 

3.182 

3.182 

3.182 

3.182 

3.182 

3.182 

3.182 

CI0.9S 

UL 

3.677 

3.592 

5.174 

11.132 

7.280 

14.114 

13.981 

12.658 

12.923 

20.664 

16.800 

21.455 

15.505 

14.336 

17.497 

16.616 

22.546 

20.431 

21.338 

19.266 

20.260 

22.669 

22.431 

25.819 

23.478 

25.336 

23.155 

22.465 

25.810 

30.500 

41.001 

26.401 

25.505 

40.891 

38.478 

38.296 

40.591 

43.937 

47.001 

LL 

2.923 

2.808 

4.026 

7.668 

4.720 

4.886 

5.619 

8.142 

9.077 

7.936 

9.800 

5.545 

12.295 

12.264 

12.703 

13.184 

17.454 

16.169 

16.862 

15.334 

16.940 

17.331 

18.169 

14.781 

19.322 

19.064 

18.245 

18.335 

19.790 

16.500 

12.999 

16.199 

20.095 

23.709 

23.522 

22.704 

23.409 

28.663 

25.999 

Max 

10 

9 

16 

17 

14 

13 

18 

15 

15 

19 

15 

19 

23 

26 

24 

20 

22 

28 

28 

25 

25 

25 

26 

28 

25 

30 

34 

36 

28 

28 

39 

28 

25 

38 

36 

37 

38 

40 

44 

Min 

0 

0 

0 

4 

1 

6 

5 

8 

8 

10 

10 

7 

8 

8 

8 

12 

18 

12 

5 

11 

9 

12 

12 

8 

16 

7 

5 

5 

19 

18 

21 

12 

21 

25 

25 

25 

25 

30 

30 

8.29, 

with 21 df as above. 

c. Predicted Results 

Using the results obtained above, the range of opacities that would be expected from the use 

of this variation can be predicted. As before, the range is calculated as 

31 
P.42 

/\li"/c*- S<£ e^ax^Jie^/ 

expected range: * + predicted deviation ± tQ0S (21) a 

: * + [ 1.76 - 0.39*] t (2.080)(2.88) 

: [0.71*+ 1.76] ±(5.99) 

Values of/.his range are listed in Table 34 for selected opacity levels. The data indicate that there is fairly 

good ag**eement at the lower opacities, but that a negative bias appears above 25 percent. This is a comparable result to the 5-percent increment data. 

The maximum difference that would be expected between observations by two independent 

observers is estimated using the between-observer standard deviation. As before, the equation is 

maximum difference = r0.05 (21) \F^[ 

JJ-cJc-

= (2.080) VHT58 

= (2.080X4.07) 

= 8.47 percent opacity 

As expected, this value is greater than that for the 5-percent increment data. The apparent 

conclusion is that there was more variability in the 1-percent data than the 5 percent. A contributing factor 

to this was undoubtedly that the observers had not been trained to read to the nearest percent, but it is 

impossible to determine how much effect this actually had. From a second ANOVA shown in Appendix 

g7j)i p tum groups nf observers cannot be shown to be reading different average opacities on these runs. 

TABLE 34. PREDICTED DETER- TABLE 35. OPACITY DETERMINATIONS 

MINATIONS, 1-PERCENT DATA USING PAIRED OBSERVERS 

Opacity 

5 

10 

15 

20 

25 

30 

35 

40 

Expected Range 

0*-ll-3 0 

2.87-14.85 

6.42-18.40 

9.97-21.95 

13.52-25.50 

17.07-29.05 

20.62-32.60 

21.17-36.15 

"Truncated to zero. 

6. Two Observers 

A second variation to be 

studied involved talcing the average 

of two observers results as opposed to 

a single observer's average. The 6 

possible pairings among the control 

group are made, and the determinations 

are shown in Table 35 with the deviations shown in Table 36. 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

(1,2) 

5.1 

13.6 

5.0 

8.7 

8.6 

6.6 

10.6 

5.9 

6.3 

6.4 

24.0 

39.9 

10.5 

16.1 

11.8 

25.8 

12.9 

27.2 

23.4 

21.2 

34.2 

15.0 

21.8 

13.8 

0,3) 

4.0 

14.5 

4.5 

8.8 

9.6 

6.0 

9.7 

5.8 

6.5 

6.1 

30.6 

36.9 

8.4 

11.7 

10.3 

22.5 

12.3 

26.6 

21.1 

19.8 

31.9 

13.7 

20.9 

11.0 

Observer Pair 

(1,4) 

5.0 

9.5 

5.0 

7.1 

7.8 

5.8 

8.3 

5.5 

6.3 

5.9 

20.9 

40.2 

8.7 

13.6 

11.8 

25.6 

10.5 

27.1 

22.5 

17.7 

33.5 

12.7 

21.5 

9.7 

(2,3) 

4.1 

14.5 

4.5 

8.5 

7.8 

6.0 

9.3 

5.9 

5.2 

5.7 

29.6 

36.0 

7.7 

10.8 

9.3 

22.3 

11.8 

24.6 

20.7 

18.0 

32.3 

11.3 

18.9 

12.2 

(2,4) 

5.1 

9.5 

5.0 

6.8 

6.0 

5.8 

7.9 

5.6 

5.0 

5.5 

19.9 

39.3 

8.0 

12.7 

10.8 

25.4 

10.0 

25.1 

22.1 

15.9 

33.9 

10.3 

19.5 

10.9 

(3,4) 

4.0 

10.4 

4.5 

6.9 

7.0 

5.2 

7.0 

5.5 

5.2 

5.2 

26.5 

36.3 

5.9 

8.3 

9.3 

22.1 

9.4 

24.5 

19.8 

14.5 

31.6 

9.0 

18.6 

8.1 

Meter 

3.1 

7.5 

4.2 

7.2 

6.7 

5.0 

5.4 

3.4 

4.2 

4.8 

21.2 

36.0 

10.3 

14.2 

12.2 

29.6 

14.6 

28.3 

34.6. 

27.2 

36.9 

15.2 

27.8 

14.4 

32 
P.43 

T 

There are 15 deviations of 

absolute magnitude greater than 7.5 percent out of the 144 pairings, and also 

15 out of the original 96 determinations. 

Thus, there was a decrease in the frequency of the large deviation. The percentages are 0.10 as opposed to 0.16. 

In Appendix B.8, it is shown tliat this 

is a significant decrease in frequency. 

The precision that would be 

expected from this variation is estimated by taking one-half of the betweenobserver variance term from the previous 

analysis. The variance between two 

observations, then, would be 

o£ = 1/2 (6.69) 

= 3.35 

and a standard deviation of 

5ft = 1.83 percent opacity. 

TABLE 36. DEVIATIONS FROM OPACITY, PAIRED OBSERVERS 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

(1,2) 

2.0 

6.1 

0,8 

1.5 

1.9 

1.6 

5.2 

2.5 

2.1 

1.6 

2.8 

3.9 

0.2 

1.9 

-0.4 

-3.8 

-1.7 

-1.1 

-11.2 

-6.0 

-2.7 

-0.2 

-6.0 

-0.6 

(1,3) 

0.9 

7.0 

0.3 

1.6 

2.9 

1.0 

4.3 

2.4 

2.3 

1.3 

9.4 

0.9 

-1.9 

-2.5 

-1.9 

-7.1 

-2.3 

-1.7 

-13.5 

-7.4 

-5.0 

-1.5 

-6.9 

-3.4 

Observer Pair 

(1,4) 

1.9 

2.0 

0.8 

-0.1 

1.1 

0.8 

2.9 

2.1 

2.1 

1.1 

-0. 3 

4.2 

-1.6 

-0.6 

-0.4 

-4. 0 

-4.1 

-1. 2 

-12.1 

-9.5 

-3.4 

-2.5 

-6. 3 

-4.7 

(2,3) 

1.0 

7.0 

0.3 

1.3 

1.1 

1.0 

3.9 

2.5 

1.0 

0.9 

8.4 

0.0 

-2.6 

-3.4 

-2.9 

-7.3 

-2.8 

-3. 7 

-13.9 

-9. 2 

-4.6 

-3.9 

-8.9 

-2. 2 

(2,4) 

2.0 

2.0 

0.8 

-0.4 

-0.7 

0.8 

2.5 

2.2 

0.8 

0.7 

-1.3 

3.3 

-2.3 

-1.5 

-1.4 

-4.2 

-4.6 

-3.2 

-12.5 

-11.3 

-3.0 

-4.9 

-8.3 

-3.5 

(3,4) 

0.9 

2.9 

0.3 

-0.3 

0.3 

0.2 

1.6 

2.1 

1.0 

0.4 

5.3 

0.3 

-4.4 

-5.9 

-2.9 

-7.5 

-5.2 

-3.8 

-14.8 

-12.7 

-5.3 

-6.2 

-9.2 

-6.3 

1 

Meter 

7.5 

il 

7.2 

6.7 

5.0 

5.4 

3-4 

4.2 

4.8 

21.2 

36.0 

10.3 

14.2 

12.2 

2SJ.6 

14.6 

28.3 

34.6 

27.2 

36.9 

15.2 

27.8 

14.4 

. i 

The 95-percent confidence limit on the difference between two determinations made this way 

would be 

maximum difference: frj.05(6) V2("j 

: (2.447X1-414X1.83) 

: 6.33 percent opacity. 

This is a 29-percent reduction from the single observer determination result. 

33 
P.44 

VII. COMPOSITE ESTIMATION 

As a final evaluation, it is investigated whether the precision and accuracy from all the tests may be 

combined to produce statements that are applicable to any site. The accuracy statements are derived from 

the training generator and Steam Station Test 3 data, where good background was available. The sulfuric 

acid test data is not used since it applies to a much narrower range of opacities. 

A. Accuracy 

The slopes of the regression lines for the training generator and steam station test are tested for equality. A test statistic is calculated for comparing the three estimated slopes using their standard deviations and 

an uncertainty factor. The details are given in Appendix B.9. 

The slopes can be said to be estimating the same true value if they differ from each other by no more 

than 0.12. As can be seen, the difference between the largest and the smallest slope estimate is 0.10, and 

thus the three values are insignificantly different from one another. 

Because of this, a composite line is calculated using all the points from the three sets of data. The 

equation thus calculated is 

deviation = 3.13 —(0.31) (percent opacity) 

for the range from 5 to 35 percent average opacity. The expected deviation calculated using this equation is 

shown in Table 37 for values in that range. 

TABLE 37. PREDICTED DEVIATION B. Precision 

FROM METERED OPACITY, 

COMPOSITE ESTIMATE 

Opacity 

5 

10 

15 

20 

25 

30 

35 

Expected Deviation 

1.58 

0.03 

-1.52 

-3.07 

-4.62 

-6.17 

-7.72 

The six estimates of the within-observer variance, a

2

, are compared using Bartlett's test*-3

'. The test statistic is a chi-square, and is 

calculated to be 13.77 with 5 df, and the significance level for this 

value is approximately 0.02. This is sufficient to accept the hypothesis that all are estimating the same true variance. 

The combined estimate is obtained by "pooling" the variances, 

as described in Appendix B.9. The pooled variance is 

a = 4.22 

with 693 df. This gives an estimated within-observer standard deviation of 

a = y^2 2 

= 2.05 percent opacity. 

Similarly, the 6 values of o^ are tested for equality using Bartlett's test. The test statistic is 4.72 with 

5 df, which is not significant. Thus, for these components as well, the hypothesis of equality is accepted. 

The pooled estimate ofthe observer bias variance is 

bl = 1.66 

with 44 df. This gives an estimated observer bias standard deviation of 

bL = 1.29 percent opacity. 

34 
P.45 

Combining the above estimates, the between-observer variance is estimated as ' 

b

2

b = a

2

L+b2

 : 

= 4.22 + 1.66 

i 

= 5.88. 

This gives a between-observer standard deviation of 

db = JSM 

= 2.42 percent opacity. 

C. Predicted Results 

Using the results of the previous two sections, the expected range and maximum expected difference 

can be calculated for the composite values. The expected range would be ! 

expected range: * + [3.13 —0.31*] ± 1.96 5 

: (0.69*+ 3.13) ±1.96 (2.05) 

: (0.69*+ 3.13) ±4.02 [ 

for any true opacity *, at the 95-percent confidence level. The expected range is presented for selefcted I 

values of * in Table 38. As before, the results show accuracy up to about 25 percent opacity, then acquire 

a low-side bias. I 

TABLE 38. PREDICTED DETERMINATIONS OF AVERAGE OPACITY, 

COMPOSITE ESTIMATE 

Percent Opacity Oft 

10 

15 

20 

25 

30 

35 

Expected Range 

2.56-10.60 

6.01-14.05 

9.46-17.50 

12.91-20.95 

16.36-24.40 

19.81-27.85 

23.26-31.30 

The maximum difference that could be expected between two 

independent observers is calculated using the between-observer standard 

deviation. At the 95 percent confidence level, the difference could not 

be expected to exceed > 

maximum difference: r0.os (44) \J2 b\ 

: (2.021) (1.414) (2.42) 

: 6.92 percent opacity. 

The 44 df are due to the observer bias term. 

35 
APPENDIX A. EPA METHOD 9 FOR VISUAL DETERMINATION 

OF OPACITY 

37 
,:,.. ...,„. 

P.47 

A.1. Federal Register, Vol 36, No. 247-Thursday, December 23, 1971 

RULES AND REGULATIONS 24895 

Rom, Jerome J., Maintenance. Calibration, 

and Operation of Isokinetic Source Sampling Equipment, Environmental Protection 

Agency, Air Pollution Control Office Publication No. APTD-0376. 

Shell Development Co. Analytical Department, Determination of Sulfur Dioxide and 

Sulfur Trioxide in Stack Gases, Emeryville 

Method Series, 4616/5»ft. 

1IETHOD 9 VISUAL DETERMINATION Or THE 

OPACITY OP EMISSIONS FROM STATTONARr 

SOCBCES 

1. Principle and applicability. 

1.1 Principle. The relative opacity of an 

emission from a stationary source is determined visually by a qualified observer. 

1.2 Applicability. This method is applicable for the determination of the relative 

opacity of visible emissions from stationary 

sources only when specified by test procedures for determining compliance with the 

New Source Performance Standards. 

2. Procedure. 

2.1 The qualified observer stands at approximately two stack heights, but not more 

than a quarter.of a mile from the base of 

the stack with the sun to his back. Prom a 

vantage point perpendicular to the plume, 

the observer studies the point of greatest 

opacity in the plume. The data required in. 

Figure 9-1 i_ recorded every 15 to 30 seconds 

to the nearest 5'>: opacity. A minimum of 25 

readings is taken. 

3. Qualifications. 

3.1 To certify as an observer, a candidate 

must complete a smokereading course conducted by EPA, or equivalent; ln order to 

certify the candidate must assign opacity 

readings in 5% lncrementa to 25 different 

black plumes and 25 different white plumes, 

with an error not to exceed lo percent on 

any one reading and an average error not to 

exceed 7.5 percent ln each category. The 

smoke generator used to qualify the observers must be equipped with a calibrated 

smoke indicator or light transmission meter 

located ln the source stack, if the smoke 

generator is to determine the actual opacity 

of the emissions. All qualified observers must 

pass this test every 6 months in order to 

remain certified. 

4. Calculations. 

4.1 Determine the average opacity. 

5. References. 

Air Pollution Control District Rules and 

Regulations, Los Angeles County Air Pollution Control District, Chapter 2, Schedule 6, 

Regulation 4, Prohibition, Rule 50,17 p. 

Kudluk. Rudolf, Ringelmann Smoke Chart, 

VJS. Department of Interior, Bureau of Mines, 

Information Circular No. 8333, May 1987. 

i 

• 

SSig o i a i *> 

0 

1 

«_ 

1

 i 

1 1 

• r 

; 

1 

1 

. 

K.?45 • i .•» I >• ! « 

1 JO | ! i 

»• 1 1 ! i 

» 1 

»l 

** 1 

35 

36 

37 

33 

39 

4 0 

41 

*>I 

43 

44 

4 1 

4 « 

47 

4 » 

4 9 

SO 

51 

5 1 

53 

54 

SS 

5 6 

5 7 

58 

59 

-

j 

I 

i 

! 

! 

. j 

j | 

t 

1 

f 

I 

I 

i 

I 

I i 1

 *l 

! 

1 i 

1 ! 

t-M.-f 

-tl-u-h ln.ll« a . 

0*>**r*_>f 

[**•«• 

T I M 

DiatMc * l-> sl-tcW 

W.M-f fflr-Bflui.* 

Sw« e f no*. r*c-*tf*4t 

Tou t no. r*4d'n«& 

-

Figure 9-1. Field data. 

{FRDoc.7_-13624 Filed 12-22-71; 8:45 am) 

FED-SAL RcGISTES, VOL. 36, NO. 247—THURSDAY, D-C-M3ER ?3, 1971 

39 
A.2. Federal Register, Vol 39, No. 177-Wednesday, September 11, 1974 

PROPOSED RULES 328.ri7 

(e) For the purpose of reports pursu- <1> A continuous monitoring system (1) For facilities which operate at 

ant to 8 60.7(c), periods of excess emls- for the measurement of the opacity of levels greater than 5% oxygen In the flue 

sions that shall be reported are defined emissions discharged into the atmos- gases, the oxygen content of the flue 

as any two consecutive hourly periods phere from the fluid catalytic cracking gases shall be determined at least 

during which the average nitrogen ox- unit catalyst regenerator. monthly by sampling at the same point 

ides emissions exceed the limits of (2) A continuous monitoring system in the duct specified by 5 60.106(d) and 

8 60 72(a) tor the measurement of carbon monox- by analyzing the sample for oxygen by 

- Ide ln gases discharged Into the atmos- orsat analysis or by use of the oxygen 

Subpart H—Standards of Performance ror pher e frQ m flu]d catalytl c cracking unit continuous monitoring Instrument under 

Sulfuric Acid Plants catalyst regenerators, except where the § 60.105(a) (3). The results shall be used 

§ 60.83 [Amended] requirements of paragraph (a) (3) of to adjust the daily conversion factors 

11 Pnram-anh (a)(2) of 160 83 la this section are met. monthly (Orsat analysis) or daily (conamended ^deleting the second sentence. (3) Continuous monitoring systems tinuous monitor) as follows: 

12 Section 60.84 is amended by revls- for toe mewurement of firebox tem- /CF W ao.w \ 

tag paragraphs (a), (b), (c), (d) and perature and oxygen ln exhaust gases (CF) ^u .,. d = ( ^ f \ 

Te) tVrVad as foUows:

 fr ^a n y

 tactaerator-waste heat boiler whe_e ; V •" / V *w-%° , / 

which combusts the exhaust gases from ___,. , 

§ 60.84 Emission monitoring. a fluid catalytic cracking unit catalyst ° ^-^Tw d

 (m g HS/dsc m 

(a) A continuous monitoring system regenerator, except where the require- ^o.=perccnt oxygen by volume (expressed 

for the measurement of sulfur dioxide ments of paragraph (a)(2) of this sec- as percent), dry basis. 

shall be Installed, calibrated, maintained, tion are met. .... . 

and operated ln any affected facility by (4) A continuous monitoring system 

the owner or operator. for the measurement of hydrogen sulfide Subpart L—Standards of Performance for 

(b) The owner or operator shall estab- in fuel gases burned to any fuel gas com- secondary Lead smelters 

llsh a conversion factor for the purpose bustion device, except where the require- § 60.122 [Amended] 

of converting monitoring data into units ments of paragraph (a) (5) of this 1 8 0--H.,-. 6 n m is amended hv rie 

of the applicable standard (kg/metric section are met. Fuel gas combustion de- w w na_WaDh(c) 

ton). The conversion factor shall be vices having a common source of fuel

 e w 

established by measuring emissions with gas may be monitored at one location if Subpart M—Standards of Performance for 

the continuous monitoring system ln ac- sampling at this location produces re- Secondary Brass and Bronze Ingot Procordance with 8 60.13(d) at the same suits representative of the hydrogen sul- duction Plants 

time as emissions are determined for the fide concentration In the fuel gas burned. § 60.152 [Amended] 

applicable reference method tests (860.- (5) A continuous monitoring system ,_ „„,,„„ „. ,-„ ,„ . . . . 

85). Using emission data from the per- for the measurement of sulfur dioxide . . 7

 Section 6 ° " 2

. * amended by deformance test and only that portion of ln the gases discharged Into the atmos-

 letm g

 Paraen-P"1 (c>. 

the continuous monitoring emission data phere from the combustion of fuel gases Subpart O—Standards of Performance for 

that represents emission measurements except where the requirements of para- Sewage Treatment Plants 

concurrent with the reference method graph (a)(4) of this section are met. s 60 152 [Amended! 

test periods, the conversion factor shall (b) The owner or operator of an afbe determined by dividing the perform- fected facility required to Install a 18. Paragraph (a)(2) of 8 60.152 Is 

ance test data Integrated averages by the continuous monitoring system under amended by deleting the second sentence. 

continuous emission monitoring test paragraph (a) (5) of this section shall

 19

- Appendix A Is amended by revising 

data averages to obtain a ratio expressed establish daily a conversion factor (mg Method 9 as follows: 

ln units of the applicable standard to H»S/dsc_n of fuel gas per ppm SO, In flue METHOD 9 VISUAL DK"*"en Ml NATION OP THE 

units of the monitoring data, le., kg/ gas) for the purpose of converting mon- OPACITY or IUIBSIDNS FOB STATIONARY SOTTKCES 

metric ton per ppm (lb/short ton per ltoring data Into units of the applicable , Principle and owaecWH.y 

ppm). standard. The conversion factor shall be 1.1 principle. The ouactty of emissions 

(c) The owner or operator shaU record established by measuring ppm SO: with from stationary sources is determined visthe daily production rates and hours of the continuous monitoring system ln ac- uaiiy by a qualified observer. 

operation. cordance with paragraph (a) (5) of this 12 Applicability. This method is applicable 

(d) Paragraph (m) of 8 60.13 does not _„ H _ .„-,J,,.H_JT_-,T__ - ,._n„ „, „-,„ ' o r th e determination or the opacity of apply to this subpart. section, conducting analyses dally of any emisslona fro m stationary sources pursuant 

.... . fuel gas combusted using A.S.T_M. meth- to S 60.11(b) and for qualifying observers for 

(e) For the purpose 0/ reports pursu- od. D1071-55 (sampling) and D1946-67 «""&£»£**£ Xrter^uaXT n sc 

ant to 8 60.7(c). periods of excess emls- (analysis), and computing the factor as ccaa, ^ wlt n paragraph 3 or this method 

sions that shall be reported are defined follows: shall use tbe following procedures for visuaiir 

as any two consecutive hourly periods , a \ determining -J\e opacity of emissions: 

during which the average sulfur dioxide CF= (0 0162)1 ^~*X,Y h *"'*

 Posltlon

- Tb' qualified observer simii 

emissions exceed the limits of 8 60.82. " \f_"i '/

 stan d a t

 » distance sufficient to provide a 

clear view of the emissions with the sun 

Subpart I—Standards of Performance for "cr-dally eonr«n__n t_cfc>r Cn* Hi-/ds.m per ppm) °r*«nted tn the quadrant to his back. ConAsphaK Concrete Plants Xi--u*__lor__tn_ ooostant, «nd si-tent with maintaining the above reqmro-

,,.„ . r . • , , _"i«Tol__netric pwoent of foal t« eompontiit, dry ment. the observer shall, as much as possihic 

g 60.92 lAmendedJ „

 bafe-„,«,„m-„_, make his observations from a position snch 

13. Paragraph (b) of 8 60.92 la ---ttmB-roieompoc-au. that his line of vision te approximately peramended by deleting the second sentence. TABU or VALUIS Tt» X, pendlcular to the plume direction, and when 

• _ Cnmnonsnt- X observing opacity of emissions from rectnnSubpart J—-Standards of Performance for "-^J*""1

"- 1 ^ gular outlets (e.g. roof monitors, open bagPetroleum Refineries jj*g Q 64 bouses, nonclrcular staclcs), approximately 

860 102 [Amended] CO "'/AA'.AAAAAAA.AAAAA.AAAAAAA. UM porpeiidlcular to the longer axis of the outlet. 8

 CH, . . 8.62 3.2 Field records. The observer shall record 

14. Paragraph (a)(2) of 8 60.102 la c,H, IS. IS the name of the plant, emission location, tvpe 

amended by deleting the second sentence. C.B, 21.8 facility, observer's name and affiliation, and 

15. Section 60.105 la amended by revls- C,H,0 28.4 tbe date on a field data sheet (Figure 8-1). 

ing paragraphs (a) and (b) to read as

 C.HU 36 •' 7° ' time ' ""mated distance to the emission 

ft*jv>TM. C^i,, 41.7 location, approximate wind direction, estl-

' C,H 13.3 mated wind speed, description of the sky 

§60.105 Emission monitoring. crH4 '.. 19. B condition (presence and color of clouds), and 

fo> rvmtlmmin monltorirur svstem.

 crH

.

 ia 0 plum e l*»e*-f"*'°"*>d are recorded on a field 

v. ,. I_5I . i?_^.-S^_^f«i^_Jf__ ?

 C A *i«•« <I

»

ta ehee t a t th e Ume opacity readings are 

shaU be Installed, calibrated, maintained, C S" _ M 2 mitia ed and completed. 

and operated ln any affected facility by CH_H„ _ se.s 2.3 observations, opacity observations 

the owner or operator as follows: Insrts 1.0 shall be made at the point of greatest opacity 

FEDEKAl lEGIJTU, VOL 39, NO. 177—WfON.SOAY, SlfTEM-El 11, 1974 

40 
I p- ,., , 

32858 PROPOSED RULES 

In that portion of the plume where condensed 

water vapor is not present. The observer shall 

not look continuously at the plume, but Instead shall observe the plume momentarily at 

15-second intervals. 

2.3.1 Attached steam plumes. When condensed water vapor Is present with in the 

plume as lt emerges from the emission outlet, 

opacity observations shall be made beyond 

the point in the plume at which condensed 

water vapor Is no longer visible. The observer 

shall record the approximate distanoe from 

the emission outlet to the point at which 

the observations are made. 

2.3.2 Detached steam plume. When water 

vapor in the plume condenses at a distinct 

distance from the emission outlet, the opacity 

of emissions may be evaluated at the emission 

outlet prior to the condensation of water 

vapor and the formation of the steam plume. 

2.4 Recording observations. Opacity observations shall be recorded to the nearest 6 

percent at 15-second Intervals on an observational record sheet (Figure 9—2). Each 

momentary observation recorded shall represent the opacity of emissions for that 15-

second time period. 

2.5 Data reduction. Determine the opacity 

standard appUcable to the affected facility 

being observed and compute minutes of noncompliance using the appropriate procedure 

as follows: 

2.5.1 For all opacity standards eapept average opacity, mark on the observation record 

sheet (Figure 9-2) all observations which 

exceed the opacity level specified by the 

standard. Compute the aggregate number of 

minutes during which the opacity of emissions was observed to exceed the appUcable 

standard. Exclude from this computation the 

number of minutes of operation exempted 

by the applicable opacity standard or by 

5 60.11(c) (If any). Record the minutes of 

noncompliance on Figure 9-1. 

2.5.2 For average opacity standards, sum 

on the observation record sheet (Figure 9—3) 

all observations for any specific time period 

(use time periods specified by the standard 

when applicable), and compute tbe arithmetic mean average bv dividing by the total 

number of observations lor- jihe time period 

evaluated. Exclude from tiiis computation 

any minutes of opeFntion exempted by the 

applicable opacity standard or § 80.11(c) (if 

any). Record tbe minutes of each time period 

of noncompl ianoe on Figure 9—1. 

3. Qualifications and testing. 

3.1 Certification requirements. To receive 

certification as a qualified observer, a candidate must be tested and demonstrate the 

ability to assign opacity readings ln 5-percent 

increments to 25 different black plumes and 

25 different white plumes, wtth an error not 

to exceed 15-peroent opacity on any one reading and an average error not to exceed 7.5-

percent opacity tn each category. Candidates 

shaU be tested according to 1__e procedures 

described ln paragraph 3.2. Smoke generators 

used pursuant to paragraph 3-1 shall be 

equipped wtth a smoke meter which xneeta 

the requirements of paragraph 3 J. 

The certification shall be valid for a period 

of 8 months, at which time the qualification 

procedure must be repeated by any observer 

ln order to retain certification. 

S3 Certification procedure. The smoke test 

consists of showing the candidate a complete 

run of 50 plumes—25 black plumes and 35 

white plumes—generated by a smoke generator. Plumes within each Beit of 26 black 

and 25 white runs shall be presented ln random order. The candidate assigns an opacity 

value to each plume and records his observation on a suitable form. At the completion of 

each run of 50 readings, the score of tbe 

trainee is determined. If a trainee falls to 

qualify, the complete run of 60 readings must 

be repeated ln any retest. T"he smoke test may 

be administered as part of a smoke school 

or training program, and may be preceded by 

training or familiarization runs of the smoke 

generator during which candidates are shown 

black and white plumes of known opacity. 

3.3 Smoke generator specifications. Any 

smoke generator used for the purposes of 

paragraph 3.2 shall be equipped with a smoke 

meter Installed to measure opacity across the 

diameter of the smoke generator stack. The 

smoke meter output shall display ln-stack 

opacity based upon a pathlength equal to 

the stack exit diameter, on a full 0 to 100 

percent chart recorder scale. The smoke meter 

optical design and performance shall meet 

the specifications shown ln Table 9-1. The 

smoke meter shall be calibrated as prescribed 

ln paragraph 3.3.1 prior to the conduct of 

each smoke reading test. At the completion of 

each test, the zero and span drift shall be 

ch-.cked and if the drift exceeds ±1 percent 

opacity, the condition shall be corrected prior 

to conducting any subsequent test runs. The 

smoke meter shall be demonstrated, at the 

time of Installation, to meet the specifications listed in Table B-l. This demonstration 

shall be repeated following any subsequent 

repair or replacement of the photocell or associated electronic circuitry including the 

chart recorder or output meter, or every 6 

months, whichever occurs first. 

TA_U-E 9- 1 SMOKE METER DESIGN AND 

PEBrOBMANCS SPECOTC-nONS 

Parameter: 

a. Light source. 

b. Bpectral response 

of photocell. 

c. Angle of view 

d. Angle of projection. 

e. Calibration error. 

f. Zero and span 

drift. 

g. Response time— 

Specification 

Incandescent lamp 

operated at nominal rated voltage. 

Photopic (Daylight 

spectral response 

of the human eye: 

reference 4-3). 

15* m«-r1mT7wn total 

15* iruTlmiim tota l 

±3% opacity mul -

xouao. 

±1 % opacity, 80 

minutes. 

-=5 aeeorula. 

3.3.1 Callbratlo-- The smoke meter Is calibrated after allowing a minimum of SO m__tutea warmup by alternately producing a_R_alated opacity o_ 0 percent and 100 percent. 

When stable response at 0 percent or 100 

percent is noted, the smoke meter Is adjusted to produce an output of 0 percent or 

100 percent, as appropriate. This callbrattan 

shall be repeated until stable 0 percent and 

100 percent readings are produced without 

adjustment, simulated 0 percent and 100 

percent opacity values may be produced by 

alternately switching tbe power to the light 

source on and off while the smoke generator 

is not producing smoke. 

8.8.3 Smoke meter evaluation. Tbe smoke 

metier design and performance are to be 

evaluated as follows: 

3.32.1 Light source. Verify from manufacturer's date, and from voltage jmeasurements made at the lamp, as Installed, that 

the lamp is operated within ± 6 'percent of 

tbe nominal rated voltage, i {I 

8.8.2.3 Spectral response of photocell. Verify 

from manufacturer's data that the Iphotooell 

has a photopic response; i.e, the spectral 

sensitivity of the cell shall closely] approximate the standard spectral-iurnlhoslty curve 

for photopic vision which Is referenced In 

(b) of Table 9-1. I 

3.3.2.3 Angle of view. Check construction 

geometry to ensure that the total' angle of 

view of the smoke plume, as' seen by the 

photoceU, does not exceed 15*. Tlie' total angle 

of view may be calculated from:1 f— 2 tan-1 

d/2L, where 0 = total angle1 of view. d = the 

sum of the photocell diameter + the diameter 

of the limiting aperture; and L__tne distance 

from the photocell to the limiting! aperture. 

The limiting aperture Is the: point ln the 

path between the photocell and, the smoke 

plume where tbe angle of view Is most 

restricted. In smoke generator smoke meters 

this Is normally an orifice plate; ' I 

3.3.2.4 Angle of projection. Check construction geometry to ensure that the! total angle 

of projection of the lamp on the smoke 

plume does not exceed 16*. The ] total angle 

of projection may be calculated; from: »=2 

tan-" d/2L, where «=total raiige of projection; 

'd-_tho sum of the length ot the, [lamp filament + the diameter ot the limiting aperture; and L=the distance from the Lamp to 

the limiting aperture. I | 

3.8.2.5 Calibration error. Using neutraldensity filters of known opacity. Icheok the 

error between the actual response and the 

theoretical linear response of 'the smoke 

meter. This check Is aocompUshed try first 

calibrating the smoke meter' according to 

3.8.1 and then inserting a series of three 

neutral-density filters of nominal I opacity of 

20, 60, and 75 percent in the smoke meter 

pathlength. FUters calibrated I within ± 2 

percent shall be used. Cere should be taken 

when inserting the filters to prevent stray 

light trom affecting the meter. Make a total 

of five noneooseevr-tve readings for (each filter. 

The maximum error on any one reading 

shall be 3 percent opacity. ' j | 

3.3J2.6 Zero and span drift. Determine the 

zero and span drift by calibrating' and operating the smoke generator ln a normal manner over a 1-hour period. The drift Is 

measured by chef-ring the EeroJ and span 

at the end of this period | 

3.3.2.7 Response time. Determine the response time by producing a series of five 

simulated 0 percent and 100 percent opacity 

values and obouvlng tbe; tltae required to 

reach stable response. Opacity. values of 0 

percent and 100 percent may he simulated by 

alternately switching the power! to the light 

source off and on while the smoke generator 

Is not operating. ' I 

4. References. j 

4.1 Air Pollution Control District Rules and 

Regulations, Los Angeles !count7J Air Pollution Control District, Regulations IV, Prohibitions. Bule 60. I 

•__» Weisburd, Melvin I, Field \ Operations 

and Enforcement Manual for Air, VS. Envlronment-J Protection Agency! Research 

Triangle Park, N.C. AFTD-llOO.(August 1972, 

pp. 4.1-4.36. | !| 

4.8 Condon, S. TJ, and Odtshaw, H.. Handbook of Physics, McGraw-Hill Co4 New York, 

N.Y, 1958, Table S.l. p. 6-62. ' 

FEOCtAl REGISTft, VOL. 39, NO. 177—WE0N-SOAY, SSTT-MflH- 11 , 1974 
.P.50 , 

PROPOSED RUIES 32839 

Figure 9-1 

uca s or vuuu. PSTHIMIHATIO- or OPACITY 

Psge_ 

VIST roust 

rm 7AciurT__ 

coram, DEVICI 

soots or OBsmvATioH 

_-SB-V-g rotsavs- cnnncATios DATE 

css-ura ApnuATico ~ 

torn or DOSS-OS 

ffllCBT Or OlSO-UtOE tOIKI 

lecord the follnrlay l-foraetlaB prior to end opon coopletloa of obeervatioas at each source. 

If obaervet-ooa ore aad* over aa extended period of tlae, additional recordings should ba made 

pa applicable. 

: a.'eu 

CBsaVBt Loanos 

Distance to Discherge 

Direction frac, Discharge 

Baigbt of Observation Point 

JAO-JIOOSD nsaima i 

SUIHB OOOTTIOHS 

Vlod Direction 

Vlnd (peed 

-M-laot Teapererure 

t n coKDinare (ci««r, 

overcast, Sclouds, etc.) 

naa p_scs.imai 

Color 

Dlstsnce Visible 

•amis or JOOCOHPLIASCCOMPANY 

LOCATION 

TEST HWBW 

DATE ' 

FIGURE 9-2 OBSERVATION RECORD PAGE OF 

OBSERVER 

TYPE FACILITY ' ~ 

POINT OF EMISSTTjnT 

Hr. 

. • 

Hfn. 

0 

i 

2 

3 

li 

S 

6 

7.. 

e 

9 

' 10 

11 

.u 1 3 

IU 

I S 

. . « 

17 

I-,,-. 

19 

VI. 

21 

22 

2 3 

2U 

25 

27 

28 

29 

Seconds 

6 15 

T -

30 .4.5 

' " * " 

STOW pum 

(.check If aw-llcable) Attached 

.... . 

- - • 

Detached C0**WENTS 

No. 177—Pt. II 2 •tGlSTEB, VOL 39, NO. 177—WEDNESDAY SEPTEMBE* 11, 1974 
!' Is 

P.51 

.12860 PROPOSED RULES 

FIGURE 9-2 OBSERVATION RECORD 

(Cont.) 

PAGb OF 

COMPANY 

LOCATION 

TEST.NUMBliT 

DATE 

OBSERVER ' 

TYPE FACIIITY" " ~ 

POINT OF EMISSTORT 

Hr. Min.. 

30 

3 1 • 

32 

33 

3>t 

35 

36 

37 

36 

39 

UO 

ui 

U2 

U3 

1)1* 

U5 

1*6 

"»7 

i»8 

1(9 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

Seconds 

0 15 30 45 

STEAM PLUMf. 

(check 1f aocllcable) 

Attached 

< 

-

-

Detached COMMENTS 

, 

, 

. 

20. Appendix B is added as follows: 

APPKNDU B—-PKBPOBMANCE SPECIFICATIONS -

PESJrOaA_L___NCE SPECIFICATION 1—PE-BPOBMANCE 

SPECIFICATIONS AND SPECIFICATION TKST PROCroTJtUES FOB T&ANS___-ISSOU___TE_l SYSTEMS FO B 

co-rrmruous UZASUBJEBEENT OP THE OPACITY 

OP STACK. rFTLOTNTS 

1. Principle and Applicability. 

i.l Principle. Transmlssometry Is a direct 

measurement of attenuation of visible radiation (opacity) by particulate matter in a 

stack effluent. Light from a lamp Is projected 

across the stack of a pollution source to a 

light sensor. The light la attenuated due to 

absorption and scatter by the. particulate 

matter In the effluent. The percentage of light 

attenuated is defined as the opacity of the 

emission. Transparent stack emissions that 

do not attenuate light will have a transmittance of 100 or an opacity of 0. Opaque stack 

emissions that attenuate all of the light will 

have a transmittance of 0 or an opacity of 

100 percent. 

: 2 Applicability. This method Is applicable 

to the Instrument systems specified In the 

subparts for continuously monitoring the 

opacity of emissions. Specifications for contlMuous measurement of visible emissions are 

given tn terms of design, "performance, and 

"nstallation parameters. Performance spec lflcallous and test procedures are given for 

traiismtssometer systems to test their capability before approving the systems Installed 

by an affected facility. 

2. Apparatus. 

2.1 Neutral Density Filters. Filters with 

neutral spectral characteristics and known 

optical densities to visible light. One each 

low, mid, and high range filters. 5- or 6-Inch 

square or 6-inch diameter, with nominal optical densities of 0.1, 0.2, and 0.3 (20, 37, and 

50 percent opacity) are required. Calibrated 

filters with accuracies certified by the manufacturer to within 3 percent shall be used. It 

is recommended that filter calibrations be 

checked with a well-coll lmated photopic 

transmissometer of known linearity prior to 

use. 

2.2 Chart Recorder. Analog chart recorder 

with input voltage range and performance 

characteristics compatible with the measurement system output. 

2.3 Opacity Measurement System. An instack transmissometer (folded or single path) 

with the optical design specifications designated below, associated-control units and apparatus to keep optical surfaces clean. 

3. Definitions. 

3.1 Measurement System. The total equipment required for the continuous determination of a pollutant concentration ln a 

source effluent. The system consists of three 

major subsystems: 

3.1.1 Sampling Interface—That portion of 

the measurement system that performs one 

or more of the following operations: delineation, acquisition, transportation, and conditioning of a sample of the source effluent, or 

protection of the analyzer from tlie effluent. 

3.1.2 Analyzer—That portion of the system which senses the pollutant and generates 

a signal output that is a' function of tho 

pollutant concentration. I 

3.1.3 Data Recorder—That portion of the 

measurement system that processes the analyzer output and provides: a permanent record of the output signal in terms of pollutant 

concentration. 

3.2 Span. The value of opacity at which 

the measurement system Is set to produce 

the maximum data display output. For the 

purpose of this method, the span*shall be set 

at an opacity of 50 percent for a pathlength 

equal to the stack exit diameter of the source. 

3.3 Calibration Error. The difference between the opacity reading indicated by the 

measurement system and the known values 

of a series of test standards. For this method 

the test standards are a series of calibrated 

neutral density filters. ' 

3.4 Zero Drift. The change in measurement 

system output over a stated period of time 

of normal continuous operation | when the 

pollutant concentration at the time of the 

measurements is zero. I 

3.5 Calibration Drift. The change in measurement system output over a stated period 

of time of normal continuous | operation 

when the pollutant concentration at the time 

of the measurements Is the same known upscale value. | 

3.6 System Response. The time Interval 

from a step change ln opacity in the stack 

at the input to the measurement1 system to 

the time at which 95 percent of the corresponding final value is reached as displayed 

on the measurement system data presentation device. I i 

3.7 Operational Test Period. AJ minimum 

period of time over which a measurement 

system is expected to operate within certain performance specifications without unscheduled maintenance, repair, Jor adjustment. | 

3.8 Transmittance. The fraction of incident light that Is transmitted' through an 

optical medium of Interest. | 

3.9 Opacity. The fraction of Incident light 

that is attenuated by ah optical medium 

of Interest. Opacity (O) and transmittance 

(T) are related as follows:, ! 

0=1- T | 

3.10 Optical Density. A logarithmic measure oi the amount of light that| is attenuated by an optical medium of interest. Optical density (D) is related to Ithe transmittance and opacity as follows :| 

D= -log, 0T i 

D = -log,, (i-O) I 

3.11 Mean Spectral Response- |Tl_e wavelength which bisects the total area under 

the curve obtained pursuant to, paragraph 

9.2.1. | 

3.12 Angle of View. The maximum (total) 

angle of radiation that Is seen byj the photodetector assembly of an optical transmissometer. 

3.13 Angle of Projection. The, maximum 

(total) angle of radiation that is projected 

by the lamp assembly of an optical transmissometer. | 

3.14 Pathlength. The depth ofj effluent ln 

the light beam between the receiver and the 

transmitter of the single-pass' transmissometer. or the depth of effluent; between the 

transceiver and reflector of a liouble-pass 

transmissometer. i t 

4. installation Specification. | 

4.1 Location. The transmissometer must 

be located across a section of duct or stack 

that will provide a particulate matter flow 

through the optical volume of I the transFEDEftAL REGISTER, VOL. 39, NO. 177—WEDNESDAY, SEPTEMBER 11, 1974 

43 
P.52 

,...,. ,,,.„,, 

APPENDIX B. STATISTICAL METHODS 

45 
P.53 

APPENDIX B. STATISTICAL METHODS 

B.1 Linear Regression and Test for Significance 

In order to obtain the best estimate of the average deviation from the metered opacity, the relationship 

between the deviation and the meter average is investigated. To investigate this, the method of least-squares 

is used to give the equation of the best straight line that fits the data obtained. The line is defined by its 

slope and intercept, estimated by: 

•LXiYiln-xy 

b

 =

: Zxj/n-x2 

and 

a = y - bx 

where 

Xi — the i'th value of the independent variable 

Yt - the ;'th value of the dependent variable 

x ,y - the sample means of A" and Y, respectively 

n — the number of paired observations. 

To determine if the line is a good estimate of the relationship between the two variables, the slope of 

the line is tested. A linear relationship exists if the slope is non-zero. To test this, a statistic is used that is 

based on Student's t distribution. The statistic is 

b 

tc = — 

where 

tc — the calculated value 

and 

sb — the standard deviation of the slope, b. This statistic has n — 2 df associated with it for 

n pairs of observations. 

The standard deviation of the slope, sb, is calculated by first calculating the standard deviation around 

the regression \ine,syx. The equation fbr the variance, _>2_y x is: 

n-2 

1 

n-2 

1 

n-2 

46 

52[Yi-(a + bXi)]2 

[2r,2 -a -LYi-blXiYi) 
" -• r*" T •*)!•• • 

The variance of the slope, b, is then given by 

sl = 

y-x 

[ZXt2 -nx2] 

Taking the ratio of the slope to its standard deviation, gives the desired statistic. To determine if this 

is significant, the value is compared to a Student's t distribution with n - 2 df. 

B.2 Precision Estimation for Training Generator Test 

1. White Smoke 

An analysis of variance was performed on the average opacities determined by the 8 collaborators 

who completed all 20 runs. The model is a random effects model represented by i 

Yij = ii + pi + jf + e,7 

where 

Pi 

tl 

the determination by observer / in run i 

overall mean 

the effect of run ; 

the effect of collaborator/ 

and 

the random error associated with Y>. 

» / • 

This is an additive or no-interaction model. This means that the collaborator and run effects are assumed to 

be independent of each other, or that an observer reads consistently low or high with respect to the other 

observers regardless ofthe opacity level. 

TABLE Bl. ANALYSIS OF VARIANCE FROM TRAINING 

GENERATOR TEST, WHITE SMOKE 

Source 

Runs 

Observers 

Error 

Total 

df 

19 

7 

133 

159 

SS 

5545.06 

165.04 

754 J 1 

6464.61 

MS 

__* 

23.58 

5.67 

*Not of interest. 

tSignificant. Fc > FQQ5(1,1 33) <* 2.09 

F 

_* 

4.16| 

. 

EMS 

_* 

a

2

 + 20 o\ 

The ANOVA results are shown int 

Table Bl. The expected mean squares indicate 

the proper F-ratios and the means of obtaining 

estimates of the desired precision components. 

The EMS of the error term is a

2

, the within- ' 

observer variance. Thus, the error mean square 

is the estimated within-observer variance, and 

this gives j 

a

2

 = 5.67 

with 133 df. This gives an estimated withinobserver standard deviation of 

b = j5ZT 

= 2.38 percent opacity. 

47 
P.55 

The significance ofthe observer term is determined by comparing the observer mean square to the 

error mean square. The F-ratio isFc = 4.16 which exceeds the critical value,F0.os (7, 133) **» 2.09. Thus 

there are differences among the observers, and an observer bias variance can be estimated . 

The EMS of the observer term is a

2

 + 20 a\, so that the observer bias variance estimate is 

MSL-62 

•>_ — 

2 0 

23.58 - 5.67 

20 

_ 17.91 

20 

= 0.90 

with 7 df. The estimated observer bias standard deviation is 

o

2

L =J03Q 

= 0.95 percent opacity. 

2. Black Smoke 

The ANOVA table for the black smoke determinations is in Table B2. The model is identical to 

that for the white smoke. 

TABLE B2. ANALYSIS OF VARIANCE FROM TRAINING 

GENERATOR TEST, BLACK SMOKE 

The expected value of the error 

mean square is a2, the within-observer variance. 

Thus, the estimated value is 

b

2

 =3.38, 

the error mean square. There are 105 df associated with this estimate. The within-observer 

standard deviation is 

& = v/-T38 

= 1.84 percent opacity. 

The ratio of the observer mean square to the error mean square tests for differences among the 

observers. The calculated F-statistic is Fc = 5.73, which exceeds the critical value of 2.13, approximately, 

with 7 and 105 df. Thus, there can be said to be differences among the observers. 

The observer bias variance is estimated as 

MSL - a

2 

Source 

Runs 

Observers 

Error 

Total 

df 

15 

7 

105 

127 

SS 

3963.43 

135.58 

354.81 

4453.82 

MS 

_* 

19.37 

3.38 

*Not of interest. 

tSignificant. F Q 05 (7,105) « 2.12. 

F 

_* 

5.73t 

EMS 

_* 

a

2

 + 16 ol 

o

1 

<£ 16 

48 
P.56 

as indicated by the EMS for observers. This gives 

«i19.37-3.38 

16 

_ 15.99 

16 

= 1.00 

with 7 df. Thus the observer bias standard deviation is 

bL = 1.00 percent opacity. 

B.3 Precision Estimation for Sulfuric Acid Plant and Tests of Hypotheses 

The precision estimates for use ofthe method at a sulfuric acid plant are obtained from an analysis of 

variance. The model for the data is a random effects model, 

Yij = M + 7,- + P/ + €ij 

where 

Y

a 

M 

li 

Pi 

the observation by observer i in run / 

the overall mean 

the effect due to collaborator i 

the effect due to run / 

and 

— the random enor associated with Y, V 

The model assumes that there is no interaction between the run and the collaborator. This is equivalent 

to saying that an observer's tendency to read higher or lower than other observers is independent of the true 

opacity level. The error term, then, is taken from the interaction between the observers and the runs. I 

The ANOVA is summarized in Table B3. There are 29 df from the 30 runs and 8 df for the observer 

term. This leaves a remainder of 232 for error. The expected mean square (EMS) column gives the basis for 

forming F-ratios to test for significance and for estimating the individual variance components. 

The EMS of the error term is a

2

 , the within-observer variance term. Thus, the estimated withinjobserver 

variance is 

•-,* -4.51, 

the error mean square. This gives an estimated standard deviation of 

&=V4lT 

= 2.12 percent opacity 

49 
P.57 

•"ITTABLE B3. ANALYSIS OF VARIANCE FROM 

SULFURIC ACID PLANT TEST 

Source 

Runs 

Observers 

Error 

Total 

df 

29 

8 

232 

269 

SS 

2636.68 

259.06 

1046.56 

3942.30 

*Not of interest. 

tSignificant. F0.05 (8,232) * 

MS 

90.92 

32.38 

4.51 

2.00. 

F 

_* 

7.18| 

EMS 

_* 

CT" + 30a*; 

a'

 L 

The EMS of the observer term is a

2

 + 30a£. 

The factor 30 results from the fact that each 

observer mean is the average over the 30 runs. 

The ratio of the observer mean square to the error 

mean square provides the proper ratio for determining if there is a significant observer term 

The value of Fc is 7.18, which exceeds the tabled 

value for the F distribution at the 95-percent 

confidence level. The tabled value isFn.05 (8,232) 

« 2.00 and, thus, there is a significant observer 

effect. 

Solving the EMS for a\ gives 

4-

so that an estimate is given as 

4 

EMSpbserver-P2 

30 

MSobserver — a

2 

30 

32.38-4.51 

30 

27.87 

30 

= 0.93 

with 8 df. The estimated observer bias standard deviation, then, is 

bL =V093 

= 0.96 percent opacity. 

Combining these two estimates gives 

H-ol+b2 

= 0.93+4.51 

= 5.44 

ab =JSA4 

= 2.33 percent opacity. 

and 

The test for significance of a\ is a test for the equality among the observers of the mean opacity 

determined. A significant value of a\ is equivalent to saying that not all the means are equal. The next 

problem is to investigate where the differences lie. 

50 
P.58 

For this test, the only comparison of interest concerns the difference between the observers from the 

enforcement agency and those from the private sector. The enforcement personnel were observers 4, 5, 6 and 8. 

The means for the 9 collaborators who participated in all 30 runs are shown in Table 16. 

i | , 

To determine if there is a significant difference between the two groups, a contrast among the rneans is 

tested. A contrast is of the form 

Ew=° 

where 

M, 

the ith true mean 

the coefficient of the itn mean 

and 

5>=o. 

The null hypothesis to be tested is that there is no difference between the two groups of observers. The 

contrast that tests this hypothesis is written as 

H0- 5(>4 +/is +M6 +Hs)-40ii

 +Mi +M3 +M7 +H<>) = 0 

where 5 and 4 are chosen so that the sum of the coefficients is 0. 

The test statistic follows Student's t distribution and is defined by 

tc = ' 

2CjXi 

& 

where 

and 

5 — the standard deviation for error 

x i — the i'tn sample mean 

n — the number of determinations used to obtain x, 

The degrees of freedom for this statistic are the df associated with the estimated variance. 

For this test, 

SCJX ,-= 5(6.47 + . . . + 5.40) - 4(5.00 + .. . + 5.73) 

= 29.54. 

6= 2.12, from Table B3 

51 
P.59 

so that 

2c?=4(5 2) + 5(42)=l80 

n = 30 

29.54 

tr = ~ /180 

2.12 / 

V 30 

29.54 

29.54 

5.19 

5.69. 

A t value at the 0.05 level with 232 df is essentially a standard normal value or 1.96. Since tc exceeds 

1.96, we reject the null hypothesis, and conclude that the observers from the enforcement agency read 

a higher opacity than did the observers from the private sector. 

B.4 Analysis of Variance and Tests of Hypotheses from Riverbend Steam Station Test 1 

The determinations from the first test are used to obtain precision estimates for within- and betweenobserver and observer bias components. The determinations used are taken from runs 1, 2, 3, 7, 8 and 9. 

Runs 4, 5, and 6 are eliminated since the experimental group was reading in 1-percent increments. Run 10 

was eliminated since there were no determinations from 6 of the 10 observers, including the entire control 

group. This was due to the fact that sky conditions and interference from another plume at times prevented 

the observer from making a reading. 

The model for the ANOVA is represented by 

' Yijk = P + ^ + 7//l + Pk + ei)k 

a completely random model, where 

Yjjk — the kth observation by collaborator/ in group / 

/j — the overall mean 

/.,• — the effect due to group i 

fj/i - the effect due to observer/, nested within group i 

pk - the effect due to run k 

and 

€jjk — the random error associated with Yj/k 

The observers are treated as a nested factor since the observers differ from one group to another. 

52 
P.60 

TABLE B4. ANALYSIS OF VARIANCE FROM 

STEAM STATION TEST 1 

The ANOVA table is shown in Table |B4 

Source 

Groups 

Runs 

Observers/Group 

Error 

Total 

df 

1 

5 

8 

45 

59 

SS 

124.42 

662.03 

119.05 

149.10 

1054.60 

•Significant. FQ.05 d-8) = 5.32. 

|Not of interest. 

{Significant. F0.05 (8,45) « 4.08. 

MS 

124.42 

-t 

14.88 

3.31 

F 

8.36* 

-t 

4.507 

EMS 

-t 

-t 

o* + 6o7

L 

The expected mean squares (EMS) determin LL. e 

were generally biased low, however, this indicates that the 

more accurately than the experimental. 

the proper F-ratio for each factor. The group 

mean square is divided by the observer mean 

square to test for a difference between groups. 

The F-ratio is Fc = 8.36 with 1 and 8 degrees 

of freedom. The critical value from the ! , , 

F-distribution isFrj.os (1,8) =5.32, so that 

the group term is significant. The means 

for the two groups are 8.20 and 5.32 ' ! 

for the control and experimental, j 

respectively, so that the control group ! 

was reading significantly higher opacities 

during the test. Since the determinations 

' 1 ! ]' 'I 

control group was able to judge the opacity 

The EMS of the error term is a

2

, the within-observer component. This gives an estimated withinobserver variance of 

a

2

 = 3.31 

with 45 df. The estimated within-laboratory standard deviation, then is 

< 

a = vTJi 

= 1.82 percent opacity 

To determine if there is a significant observer effect, the observer mean square is compared to i 

the error mean square. The ratio is Fc = 4.50. The critical value for this test is FQ.05 (8,45) *«'4.08, 

and the observer bias term, a\ ,is determined to be greater than zero. 

t 

The observer bias is estimated from the observer group mean square. The EMS is a

2

 + a\, so the J 

estimated variance is ' 

*LMSobserver ~ °2 

14.88-3.31 

= 1.93 

with 8 df. The df are calculated as (5-1) df for each group.

 : 

Since there are differences among the observers, the experience levels of the observers are important 

considerations.. The test is based on the means of the collaborators, and a contrast among the means is 

tested. The hypothesis is : 

Ho--'Eciiii = 0vsHA:jrciHi*0 

where c,- is the coefficient of the 'th mean, chosen so that 

'5>=o. 

53 
P.61 

Since there are 4 experienced observers and 6 inexperienced observers, the c/ are chosen as 

Ho- 6(/ii +M_ +Me +P7)-4(/_3 +/_4 + /_5 + p& + /_„ +Mio) 

is the hypothesis tested. The test statistic is based on Student's t distribution, and given by 

ZCjXj 

'\fF 

where n is the number of determinations comprising each mean, in this case 6. Substituting gives 

6(*i + 

l 9.1 1 

1.82/ 

tc ' 

_ 

-...+x,)-4(* 3 + 

+ ... + 62 + 42 + . . . 

6 

6(28.65) - 4 (38.97) 

144+96 

1.82 

6 

171.90- 155.88 

1.82 v/40 

16.02 

= 1.39 

..+x 

+ 42 

i o ) 

11.50 

This statistic has 45 df associated with it. These df come from the estimated variance, a, used in the calculation. 

A f-value with 45 df must exceed 2.016, approximately, to be considered significant at the 0.05 level. Thus, 

no difference is determined between the experienced and the inexperienced observer for these data. 

B.5 Precision Estimation and Tests of Hypotheses for Riverbend Steam Station Test 2 

The deviations shown in Table 23 are submitted to an ANOVA procedure to estimate the precision of 

the method. The model selected is a completely random model represented by 

Yijk = M + 0/ + Ijji + Pk + etfk 

where 

Yjjk — the observed value in run k by observer/ in group / 

j_ — the overall mean 

0,- — the effect due to group i 

jj/i — the effect due to collaborator/ in group / 

Pk — the effect due to run k 

and 

e,y£ — the random error associated with Yj/k 

54 
The observer term is nested within groups, since a different set of observers comprised each group. The 

run term is crossed with both the group and the observer terms. The error term is estimated from the inter-'| 

action of the run and group, and of the run and observer, with the interactions assumed to be zero. The 

resulting ANOVA table is in Table B5. 

I 

The EMS column tells which mean squares provide the proper denominator for the F-ratio, and how 

the resulting variance components may be estimated. j 

The within-observer variance is estimated from the error term. Since the EMS is a

2

, the estimated variance 

is 

a

2

 = 3.37, 

the mean square for error. There are 88 df for this estimate. The standard deviation is estimated as 

& = V337 

= 1.84 percent opacity. 

TABLE B5. ANALYSIS OF VARIANCE FROM STEAM 

STATION TEST 2 

Source 

Groups 

Runs 

Observers/Groups 

Error 

Total 

df 

1 

10 

8 

88 

107 

SS 

156.77 

1866.06 

225.71 

296.21 

. 2544.75 

•Significant. F0 .05 (9,8) = 5.32. 

t Not of interest. 

{Significant. FQ.0 5 (8,88) « 2.10. 

MS 

156.77 

186.61 

28.21 

3.37 

F 

5.56* 

-t 

8.37t 

, 

EMS 

-t 

• - t 

a* + llor£ 

The observer bias term is estimated from 

I i 

the observer term in the ANOVA. The 

| t : 

denominator for the observer F-ratio|is 

i j 

the error term, and the test statistic is 

Fc = 8.37 with 8 and 88 df. The tabled 

l l ' 

F value at the 5-percent level is approximately 2.10 and the observer term is 

determined to be significant. Thelexpec-ted 

value of the mean square is a

2

 + 1; 1 o\. 

Thus, we estimate the variance byj 

. 2 MS L - a 2 : 

_ n 

where MS/, is the observer/group mean square. Substituting gives 

28.21 -3.3 7 

ol = 

11 

24.84 

11 

= 2.26 

with 8 df. The degrees of freedom are calculated as n — 1 

observer bias standard deviation is 

5 — 1=4 from each group. The estimated 

bL=j226 

= 1.50 percent opacity. 

The F-ratio for groups is the ratio of the group mean square to the observer/group mean square. The 

statistic is Fc = 5.56. To determine if this value is significant, Fc is compared to a tabled F value aUhe1 5-perj 

cent significance level. The tabled value is Fo,os(l-8) = 5.32, so that a significant difference can be saijd 

to exist between the two groups in the determination of average opacity. This is an indication that thei angle 

of view is an important consideration in the visual estimation of opacity. ' 

55 
P.63 

Since it has been determined that there are differences among the observers, the hypothesis that the 

experienced observers differ from the inexperienced can be tested. This is done by use of a contrast among 

the means. A contrast is represented by 2 c,"-,-, where the c,- are coefficients applied to the means, constructed 

so that ZCJ = 0. For this test, the null hypothesis is stated as 

H0: 6(/_i +/_._ +M6 +M7) -40..3 +/_4 + Vs +A*8 +M. +Mio) = 0 

where 

Hi — the mean for observer i. 

Observers 1, 2, 6 and 7 are experienced, and 3,4, 5, 8, 9 and 10 are relatively inexperienced. The test 

statistic is given by 

ICjXi 

2c,-2 

where 

and 

x { — the sample mean for observer / 

a — the estimate of the within-observer standard deviation 

n — the number of determinations that comprise Xj. 

For these data, the statistic is: 

(6) (29.60)+(-4) (37.20) 

1.84 

177.60-148.80 

1.84 \/24 

28.80 

9.02 

3.19 

There are 88 df for the statistic taken from the estimated variance. By comparing this statistic to a tabled t 

with 88 df, tc = 3.19 exceeds fo.05(88) ** 1.99 and thus a significant difference does exist. The conclusion 

is that tlie experienced observers did determine a higher average opacity than the inexperienced. 

B.6 Precision Estimation and Tests of Hypotheses for Riverbend Steam Station Test 3 

The determinations of average opacity made by the collaborators as shown in Table 27 are submitted 

to an ANOVA procedure to estimate the precision components. The model far these data is a completely 

random model, 

56 
I'|'IT.-Ij l ••>' 

P.64 

where 

and 

Y

ijk ~ 

M 

ft -

-Ti/i ~ 

Pk -

Pft* ~ 

e

ijk ~ 

Yijk = M + ft + 7//i*

 + Pk+ Pft* + Ci/Jt 

the observation on run k by observer / in group / 

the overall mean 

the effect of the it h group 

the effect of the /th collaborator in group 

the effect due to run k 

the interaction between run k and group i 

the random error associated with 

The two groups are considered together with respect to precision under the assumption that a more 

direct sun angle would not affect the precision ofthe individual observer. To test this further, separate estimates of the error variance are made using the run by observer interaction within each group. The estimated 

values of a

2

 are 

0

2

 = 3.49 

8 | = 4.09 

for the control and experimental groups, respectively. To test whether the experimental estimate is significantly larger, an F-ratio is used. The calcualted statistic is 

F„ = 

4.09 

3.49 

1.17 

with 45 and 45 df. The critical value is F0.os (45,45) « 1.69, and the two values may be said to be estimating the same true value. 

The ANOVA is summarized in Table B6 for the third test. The evaluation is made using the 16 runs 

where the experimental group read in 5-percent increments. The EMS column provides the basis for testing! 

for significant effects and estimating the variance components. 

TABLE B6. ANALYSIS OF VARIANCE FROM STEAM STATION TEST 3 

Source 

Groups 

Runs 

Group X Run 

Observer/Group 

Error 

Total 

*Not significant. 

fNot of interest 

± Significant, FQ 

df 

1 

15 

IS 

6 

90 

127 

SS 

2.88 

9440.54 

138.39 

321.05 

313.73 

10216.59 

0 5 (6,90) - 2.30. 

MS 

2.88 

629.37 

9.23 

53.51 

3.57 

698.56 

F 

0.31* 

-+ 

-t 

14.99$ 

EMS 

a

2

 + 16a£ + 32o)j c + 64CT£; 

-t 

a' + l6o'L + 32oJjG 

a

2

 + 16o£ 

o

2 

57 
P.65 

The error term comes from the observer-run interaction. The assumption made is that this effect 

is equal to zero, which is equivalent to saying that if a particular observer reads higher opacities than the 

others on one run, he would not read lower on other runs. The EMS of the error term is a

2

, which gives 

an estimated within-observer variance of 

a

2

 =3.57 

with 90 df. This results in a within-observer standard deviation estimate of 

o = \/3757 

= 1.89. 

The EMS for observers/group is a

2

 + 16ajj,, since each observer mean is the average over the 16 runs. 

The F-ratio is the ratio ofthe observer mean square to the error mean square. This gives Fc = 14.99 with 

6 and 90 degrees of freedom. The criMcal value is Fo.rj5(6,90) «* 2.30. Thus, there is a significant observer 

effect at the 5-percent level. 

To estimate the observer variance component, the EMS is again used. 

. , MS^-a 2 

of = L

 16 

where MS/, is the observer mean square, and a

2

 is the error mean square. Substituting gives 

. 53.51-3.57 

16 

_ 49.94 

16 

= 3.12. 

There are 6 df for laboratories calculated as (4-1) for each group. The estimated observer bias standard 

deviation is 

= 1.77 percent opacity 

To test whether there is a significant group effect, an F-ratio is constructed for the group term. The 

denominator is the group by run interaction, and the statistic is Fc = 0.31 with 1 and 15 df. The critical 

value is F0.os (1, 15) = 4.54, and no group effect is found. This indicates that the angle of observation had 

essentially no effect in this test. 

The means of the observers over the 16 runs are used to determine if there was a significant difference 

in this test between the experineced and the inexperienced observers. A contrast among the means is used 

for the test. The hypothesis is of the form 

H0: ZciPi = 0 versus HA : ZC,VJ ¥= 0 

where 

Xc, = Q 

58 
and 

IU is the mean of collaborator i. 

For this test, the c,- are chosen to be 1 for the experienced and - 1 for the inexperienced observer means. [ 

The test statistic is given by 

2c^ 

fXa2 

a 

n 

where 

and 

xt is the sample mean for collaborator i 

a is the estimated within-observer standard deviation 

n is the number of determinations used to obtain Xt. 

Substituting from Table 31 gives 

(15.31 + .. . + 14.46) -(11.40 + .. . + 12.76) 

1.89 

V l6 

_ (58.72)-(46.81) 

(1.89) (0.71) 

11.91 

~ 1.34 

= 8.89. 

There are 90 df associated with this statistic, and this gives a critical value of r0 0 5 (90) « 2.00. Thus, 

there was a significant difference between the experienced and inexperienced observers. 

B.7 Precision Estimation for Riverbend Steam Station Test 3, 1-Percent Increment Runs 

The determinations made in increments of 1 percent are submitted to an ANOVA procedure according 

to the completely random model 

YiS = p+pi + yf + ei} 

where 

Yjj — the observation in run i by observer; 

H — the overall mean 

Pi — the effect due to run . 

y; — the effect due to observer/ 

59 
P.67 

'WiWW1 "*f*f"P» 

and 

tlie random error associated with Y. U 

The model assumes that there is no interaction between run and observer. This assumption is equivalent 

to saying thai the observers will be consistently high or low with respect to each other, regardless of the density 

of the plume. By making this assumption^ blocking the runs in order to make an estimate of the within-observer 

variance is nol necessary. 

TABLE B7. ANALYSIS OF VARIANCE FROM 

STEAM STATION TEST 3, 1% VARIATION 

Source 

Runs 

Observers 

Error 

Total 

df 

7 

3 

: i 

31 

SS 

2105.62 

45.75 

174.07 

2325.44 

MS 

_* 

15.25 

8.29 

*Not of interest. 

i-Not significant. FQ.OS (3-21) = 3.07. 

F 

_* 

1.84f 

EMS 

— * 

There were 8 runs by 4 the observers in the control 

group for a total of 32 determinations. The ANOVA 

is summarized for these data in Table B7. The EMS of 

the error term is a

2

, the within-observer variance. Thus, 

the estimated value of a

2

 is 

a

2

 = 8.29 

with 21 df. This gives a within-observer standard 

deviation of 

a=VcU9 

= 2.88. 

The EMS of the observer term is a2 + 8o£. Thus, the ratio of lhe observer term to the error term tests 

for significance. The resultant F-ratio isFc = 1.84. The critical value for this test is F0 05 (3,21) = 3.07. 

and thus, the observer term is not significant. This implies that the between-observer term. a\. is identical 

to o:. and gives 

bb = b= 2.88 percent opacity 

as before. 

The within-observer term for these runs is higher than that for the previous runs. An F-test is conducted to determine if a significant difference exists between the true variances of the two sets. The F-ratio 

is 

8.29 

3.57 

2.32 

with 2! and 90 df. The critical value for this test isF0.os (21. 90) ~ 1.75. Thus, the hypothesis of equality 

is rejected, and we can say that there is more variability reading in 1 percent increments. 

To determine if there was any difference between the performance of the two groups, a second ANOVA 

is done in which the control group data is included. The model is 

where 

Yijk = M + ft + 7,7/ + Pk'+ Pft* + euh 

Yijk ~ the determination by observer/ of group i in run k 

p — the overall mean 

60 
P.68 

' T I"' ||"| 

(3/ — the effect due to group i 

yj/i — tire effect due to observer; in group i 

Pk — the effect due to run k 

p$ik — the run by group interaction 

and 

eijk — the random error associated with Yjjk 

As before, the run by observer interaction is assumed to be zero and used to estimate the error term. 

TABLE B8. ANALYSIS OF VARIANCE FROM STEAM STATION 

TEST 3, 1%RUNS 

Source 

Groups 

Runs 

Group X Run 

Observer/Group 

Error 

Total 

df 

1 

7 

,7 

6 

42 

63 

SS 

268.96 

5549.59 

408.16 

127.69 

476.61 

6831.01 

MS 

268.96 

792.80 

58.31 

21.28 

11.35 

F 

4.61* 

- 1 

-t 

-t 

EMS 

a" + 8o£ + 16ofcG + 32a2 G 

-t 

o" + 8a"| + 16oJjg 

a

7

 +Sol 

<75 

•Not significant. FQ.0 5 (1,7) = 5.59. 

tNot of interest. 

The ANOVA is summarized in Table B8. The only term of interest is the group term. The F-ratio is 

formed by dividing the group mean square by the group by run mean square. The calculated value isF c = J4.61 

with.-l and 7 df. The critical value is Fn.osCl ,7) = 5.59, and so no group effect can be determined. 

B.8. Significance of Reduction of Frequency of Large Deviations 

To determine if a significant decrease is noted in the frequency of large deviations, a confidence interval 

is set up around the observed proportion. The confidence interval is constructed using ' 

P±1.96 

P(a -P) 

where 

and 

1.96 

the sample proportion 

the number of items in the sample 

the standard normal deviate at the 95-percent confidence level. 

The proportion of large deviations (absolute value greater than 7.5) in the sample is obtained by taking 

the number of large deviations, and dividing by the size of the sample. This gives j 

15 

144 

= 0.10. 

61 
P.69 . 

Substituting tiiis into the above formula gives 

/(o.ioxi-o.io) 

CI0 95 : 0.10 ± 1.96 V : : 

: 0.10±1.96(0.03) 

or from 0.05 to 0.15 

The frequency of large deviations in the original data set is 15/96 or 0.16. Thus, since this falls outside 

the above confidence interval, the two may be said to represent different true proportions of occurrence. Thus, 

the frequency of large deviations was reduced by averaging two observers' result. 

B.9. Multiple Comparison Tests and Composite Estimation 

The slopes of the three regression lines obtained as representative of observer deviation from plume 

opacity are compared for equality using the least significant difference (LSD) test. The test statistic provides 

a number which must be exceeded in order for two sample values to be said to represent different true values. 

The standard deviations of the slopes is calculated as in Appendix B.l for each regression line. For the 

white training generator smoke, black training generator smoke and steam station data, these values are 0.04, 

0.05, and 0.04, respectively. Since these are close to each other, it is reasonable to assume that there is a 

common variance, sl, for all three slopes, and to estimate it by pooling the three estimates. A pooled variance 

is of the form 

; = 1 

*P» 

k 

Ed* 

i= 1 

where 

dfi - the number of degrees of freedom in the /th sample 

s

2

 — the variance of the /'th sample 

k — the number of samples. 

Pooling the variance gives an estimated value of s2, = 0.0019 with 393 df. The df are obtained by summing the df for the individual variance estimates. 

The LSD at the 5-percent significance level is given by 

LSD0.05 = 1-96VSF 

= 1.96V0.0038 

= 0.12. 

All three slopes can be said to be equivalent if they differ from each other by no more than 0.12. The difference between tlie greatest and least values is 0.34 - 0.24 = 0.10, so that all three slopes can be said to be 

estimating the same true value. 

62 
P.70 

LIST OF REFERENCES 

1. Environmental Protection Agency, "Standards of Performance for New Stationary Sources," Federal Register, 

Vol. 36, No. 247, December 23, 1971, pp. 24876-24893. 

2. Environmental Protection Agency, "Stationary Sources, Proposed Emission Monitoring and Performance 

Testing Requirements," Federal Register, Vol. 39, No. 177, September 11, 1974, pp. 32852-32874. 

3. Dixon, W.J. and Massey, F.J., Jr., Introduction to Statistical Analysis, 3rd Edition, McGraw-Hill, New York, 

1969. 

63 
P.71 

TECHNICAL REPORT DATA 

(Please read Instructions on the reverse before completing) 

1 REPORT NO. 

EPA-650/4-75-009 

4. TITLE ANOSUBTITLE 

"Evaluation and Collaborative Study of Method for Visual Determination 

of Opacity of Emissions from Stationary Sources." 

7. AUTHOR(S) 

Henry F. Hamil, Richard E. Thomas and Nollie F.Swynnerton 

8. PERFORMING ORGANIZATION REPORT M 

SwRl #01-3462-006 

9. PERFORMING ORGANIZATION NAME AND ADDRESS 

Southwest Research Institute 

8500 Culebra Road 

San Antonio. Texas 78284 

12. SPONSORING AGENCY NAME AND ADDRESS 

U.S. Environmental Protection Agency 

Office of Research and Development 

Washington, D.C. 20460 

3. RECIPIENT'S ACCESSION-NO. 

5. REPORT DATE 

January 1975 (date of approval) 

6. PERFORMING ORGANIZATION CODE 

10. PROGRAM ELEMENT NO. 

1HA327 

11. CONTRACT/GRANT NO. 

68-02-0626 

13. TYPE OF REPORT AND PERIOD COV_.fi 

Task Order 

14. SPONSORING AGENCY CODE 

15. SUPPLEMENTARY NOTES 

16. ABSTRACT 

This study presents the results of statistical analyses of determinations ofthe average opacity of emissions. The 

determinations are based on 25 readings made by qualified observers at three types of sources. The tests were conducted 1) using training smoke generators, 2) at a sulfuric acid plant and 3) at a coal-fired power plant. Observers 

used in the tests came from both enforcement agencies and private companies, and varied in the amount of field 

experience in the use of the method. 

For each test, the accuracy and precision of the determinations is investigated. Accuracy is measured by the 

deviation of the determination from a concurrent meter average, used as true opacity for these tests. The precision 

of the method is measured as standard deviations for within-observer, observer bias and between-observer terms. 

For each test, the expected range of determinations by a single observer and the maximum difference expected between two observers are calculated. 

The results of all the tests are used to estimate the accuracy and precision ofthe method independent ofthe 

nature of the site or color of the plume. These estimates show a reasonable degree of accuracy and precision for 

the method when used in the probable range of opacities that would occur in field use, 0 to 35 percent opacity. 

17. KEY WORDS ANO DOCUMENT ANALYSIS 

DESCRIPTORS b.lDENTIFIERS/OPEN ENDED TERMS c. COSATl Field/Group A 

Emission 

Field tests 

Statistical analysis 

Plume 

Opacity 

EPA Method 9 

Stationary Sources 

Visual method 

Smoke generator 

Collaborative testing 

13B 

14B 

13. DISTRIBUTION STATEMENT 

Unlimited 

19. SECURITY CLASS (This Report) 

Unclassified 

21 NO. OF PAGES 

70 

20. SECURITY CLASS {Thispage) 

Unclassified 

22. PRICE 

EPA Form 2220-1 (9-73) 
P.72 

'.'_• 

/ 

ERRATA 

EPA-650/4-75-009 

EVALUATION AND COLLABORATIVE STUDY OF METHOD FOR 

VISUAL DETERMINATION OF OPACITY OF EMISSIONS 

by 

Henry F. Hamil 

Richard E. Thomas 

Nollie F. Swynnerton 

The following correction is applicable to the above cited report which was issued under Project No. 

01-3462-006, dated January, 1975. 

Page 32 

Paragraph 2 is deleted in its entirety and the following paragraph is substituted: 

This value is comparable to that for the 5-percent increment data. From a second ANOVA shown 

in Appendix B.7, the two groups of observers cannot be shown to be reading different average opacities on 

these runs. 
00 

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T#ct»ica l Publications Branch 

Off i cm of Administration 

ftasaarch Triangla Park. N. C 27711 

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ENVIRONMENTAL PHOTfcCTiON AGENCt 

EPA . 335 

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A N EQUAL OPPORTUNITY tMPLOYER 

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PUBLICATION NO. EPA-650/4-75-009