United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-82-016a
August 1982
Air
Proposed Revisions
to Reduce Number
of Traverse Points
in Method !  -
Background
Information
Document

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                                    EPA-450/3-82-016a
       Proposed  Revision to Reduce
Number of Traverse Points in Method I
    Background Information Document
                  Emission Measurement Branch

              Emission Standards and Engineering Division
              U.S. ENVIRONMENTAL PROTECTION AGENCY
                 Office of Air, Noise, and Radiation
               Office of Air Quality Planning and Standards
              Research Triangle Park, North Carolina 27711

                      August 1982

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This report has been reviewed by the Emission Standards and Engineering Division of the Office of Air Quality Planning
and Standards, EPA, and approved for publication. Mention of trade names or commercial products is not intended to
constitute endorsement or recommendation for use. Copies of this report are available through the Library Services
Office (MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; or, for a fee, from
the National Technical Information Services, 5285 Port Royal Road, Springfield, Virginia 22161.
                                    Publication No. EPA-450/3-82-027

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                                 CONTENTS

Introduction	   1
Fluidyne Report	   1
TRW Report	   3
Entropy Reports  	   4
Emission Measurement Branch Report 	   6
British Coal Utilisation Research Association  	   7
References	   8

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              BACKGROUND INFORMATION FOR PROPOSED REVISIONS




             TO REDUCE NUMBER OF TRAVERSE POINTS IN METHOD 1









INTRODUCTION




     On December 23, 1971, the Environmental Protection Agency (EPA)




published in the Federal Register (36 FR 2kQl6) Method 1, which




specifies the minimum number of traverse points required for velocity




and particulate matter sampling from stationary sources.  This method




was later revised and published on August 18, 1977 (^2 FR klJ5k).




     During 1976, 1977, and 1980, several published reportsl- indicated




that the number of traverse points could be reduced from those specified




by Method 1.  The results of these studies served as the basis for




revising Method 1 to utilize a lesser number of traverse points.   These




studies and a 1961 study7 are summarized below.




FLUIDYNE REPORTl




     Fluidyne Engineering Corporation conducted its study under EPA




Contract No. 68-02-12UU.  In this study, 27 velocity and U particulate




profiles were obtained from a literature survey, laboratory-scale




modeling, and field testing.  The data were fitted by polynomial equations,




and various traverse schemes were then compared against the value determined




by integrating the polynomials over the cross-sectional area of the duct.




The results of the study are summarized in Tables 1, 2, and 3.  Table 1




summarizes the velocity relative errors based on 21 rectangular ducts, and




Table 2 lists data from 6 circular stacks.  Table 3 summarizes the




particulate mass rate relative errors for four rectangular ducts.

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                TABLE 1.  VELOCITY RELATIVE ERRORS FROM 21




                           RECTANGULAR DUCTS1*2
Matrix
1x1
2x2
3x3
k x 3
U x U
5 x U
5x5
6 x 5
6x6
8x6
No. of
traverse points
1
k
9
12
16
20
25
30
36
1+8
Average
relative error, a
percent
lU.90
It. 01
0.92
O.TO
O.U7
O.UO
0.33
0.29
0.25
0.21
95% tolerance region
for average relative error, ^
percent
50.59
+12. UO
+ 2.39
+ 1-95
+_ 1.51*
+. 1.29
+_ 1.11
+_ 1.07
+_ 0.85
+_ 0.82
  Average of absolute relative errors.




  Considered signs in calculations.




               TABLE 2.  VELOCITY RELATIVE ERRORS FROM SIX




                             CIRCULAR STACKS1
No. of traverse points
No. of stacks having maximum error less than:
One diameter
U
8
12
16
Total3-
8
16
2U
32
6.0%
6
6
6
6
k.0%
5
6
6
6
2.0%
I
5
5
5
1.0%
1
3
U
k
a
  Two perpendicular diameters.

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              TABLE 3.  PARTICULATE MASS RATE ERRORS FROM FOUR

                             RECTANGULAR DUCTS1
Matrix
1x1
2x2
3x3
1+ x 3
1+ x U
5 x U
5 x 5
6 x 5
6x6
8x6
No. of
traverse points
1
U
9
12
16
20
25
30
36
U8
Average
relative error, a
percent
12.51
8.37
2.1U
1.58
1.02
0.82
0.58
O.U8
0.38
0.20
95% tolerance region
for average relative error, ^
percent
+39-35
27.33
_+ 6.81
+_ k.96
jf 2.85
+_ 2.21
_+ 1.60
_+ 1.27
+_ 1.07
+ 0.58
  Average of absolute relative errors.
b
  Considered signs in calculations.

TRW REPORTS

     This study was conducted by TRW Systems Group under EPA Contract

No. 68-02-1U12.  As part of this project, 18 velocity traverses were

examined.  A curve fitting technique was used to generate the data, which

were then compared to those obtained from a 25- by 21-point matrix.  The

report concluded that there was no notable increase in accuracy for matrices

in excess of 16 traverse points and that the average velocity error for the

l6-point traverse was l.U percent with an expected standard deviation of

less than 2 percent.

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ENTROPY  REPORTS1*^

      Two studies were  conducted by  Entropy  Environmentalists,  Inc.,  under

EPA Contract  No. 68-01-3172.   One study  dealt with  velocity, and  the other

'dealt with particulate traverses.   For the  velocity study,  data from some

150 circular  ducts  and more than 120  rectangular  stacks  were evaluated.

In  the analysis, however,  each traverse  line was  considered to be a  separate

test.  Each traverse line  was  fitted  to  a curve,  and the various  number

of  traverse points  were compared to 2k points.  The results of this  study

are summarized  in Table k.

      The particulate study was similar to that  of the Fluidyne study except

the basis for comparison was the 7- by 7-point  matrix.   The results  are

summarized in Table 5

              TABLE  k.   VELOCITY ERRORS FROM 150 CIRCULAR STACKS

                         AND 120 RECTANGULAR DUCTS1*
No. of traverse
points on a line
2
U
6
8
12
16
20
2k
Average relative error, percent8-
Circular
7.19
2.76
1.27
1.28
0.08
0.09
0.02
_
Rectangular
1.90
0.50
-
0.53
0.16
0.09
-
_
   Average  of absolute  errors.

 Note:   Tolerance  regions  not calculated because  of  insufficient  information
        in  report.

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              TABLE 5.  PARTICULATE MASS RATE ERRORS FROM




                         10 RECTANGULAR DUCTS5
Matrix
3x3
k x 3
U x h
5 x U
5x5
6x5
6x6
7x6
12 x U
7x7
traverse points
9
12
16
20
25
30
36
U2
U8
U9
Average
relative error, a
percent
3.00
3.11
2.60
3.05
1.89
1.30
1.51
1.1*5
1.30
_
95% tolerance region
for average relative error,13
percent
+8.68
7.60
^7.68
+9.61
5-12
+U.13
+k.29
+_5.00
_+3.8l
_
Average of absolute relative errors.
Considered signs in calculations.

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EMISSION MEASUREMENT BRANCH REPORT6




     The Emission Measurement Branch (EMB) of EPA conducted a study to determine-




the least number of sampling points for particulate mass flow rate in circular




stacks.  Three different particulate profiles were studied, and various numbers




of traverse points on a line were compared to a 2l*-point traverse.  The results




are summarized in Table 6.




          TABLE 6.  PARTICULATE MASS RATE ERRORS FROM THREE TYPES




                     DISTRIBUTIONS IN CIRCULAR STACKS6
No. of traverse
points on a line
2
1*
6
8
10
12
Ik
16
18
20
22
21*
Percentage error
U-shaped
+0.1*
+0.1*
-0.1*
+0.1*
0
+0.1*
+3.1
+0.1*
0
+0.1*
+0.1*
_
Skewed
+18.0
+37.8
+ 3.6
0
+ 0.9
+ U.5
+ 0.9
0
0
+ 1.8
0
_
Parabolic
-0.8
+0.4
+0.1+
+O.U
0
0
0
0
0
0
-0.1*
_

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BRITISH COAL UTILISATION RESEARCH ASSOCIATION!




     A report on a study performed by the British Coal Utilisation Resesarch




Association (BCURA) is included here because it covers a wide range of




conditions in rectangular ducts, including steep gradients of solids flow.




The bias due to sampling a limited number of points was calculated from




different mass flow profiles found in a number of plants.  The results are




summarized in Table J.




                TABLE 7.  MAGNITUDE OF BIAS DUE TO SAMPLING




                   AT A FINITE NUMBER OF SAMPLING POINTS
No. of
sampling points
1
u
8
9
95% confidence limits
of bias expressed as
percentage of
true value
+U2
+13
+_ 5.0
+ 3.9




DISCUSSION AND CONCLUSIONS




     The summaries of the data from the various reports clearly show that




the number of traverse points can be reduced from the 48 points specified in




Method 1 with no significant loss in measurement accuracy on an average.  The




average accuracy improves dramatically up to about eight or nine points, then




improves very slowly beyond a total of nine traverse points.  For example,




Table 1 shows that the average absolute relative error for velocity measurements




decreases rapidly from lU.90 to 0.92 when the number of traverse points goes

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from 1 to 9, while the error changes from 0.92 to 0.21 percent when the number




of traverse points is increased from 9 to kB,   This effect is graphically




illustrated in Figure 1 for the data presented in Tables 1 and 3.




     The 95 percent tolerance region for nine particulate or velocity traverse




points are conservatively estimated to be +10 percent.  To reduce  the tolerance




region to +5 percent, the number of traverse points must be increased to 16




for velocity and 2k for particulate mass flow rate measurements.   The effect of




the 95 percent tolerance region against the number of traverse points is




graphically illustrated in Figure 2.




     Since none of the studies considered the effect of the number of traverse




points on accuracy in relation to the number of equivalent diameters from points




of disturbances, an arbitrary decision was made to leave unchanged the present




8-diameter-downstream and 2-diameter-upstream criteria and to limit the decrease




of the number of sampling points to the 2 to k diameters downstream and 0.5 to




1 diameter upstream.




     The proposed revisions to Method 1 are given in Figures 3 and U.




REFERENCES



     1.  Hanson, H.A., R.J. Davini, J.K. Morgan, and A.A. Iversen.   Particulate




Sampling Strategies for Large Power Plants Including Nonuniform Flow.  U.S.




Environmental Protection Agency.  Research Triangle Park, N.C.  Publication




No. EPA-600/2-76-170.  June 1976.  350 p.




     2.  Knapp, K.T.  The Number of Sampling Points Needed for Representative




Source Sampling.  In:  Proceedings of the Fourth National Conference on Energy

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and the Environment, Theodore, L., et al. (ed.).  Dayton, Dayton Section of the




American Institute of Chemical Engineers.  October 3-7, 1976.  p. 563-568.




     3.  Brooks, E.F., and R.L. Williams.  Flow and Gas Sampling Manual.  U.S.




Environmental Protection Agency.  Research Triangle Park, N.C.  Publication No.




EPA-600/2-76-203.  July 1976.  93 p.




     U.  Entropy Environmentalists, Inc.  Determination of the Optimum Number




of Traverse Points:  An Analysis of Method 1 Criteria.  EPA Contract No.




68-01-3172.  April 1977.  23 p.




     5.  Entropy Environmentalists, Inc.  Traverse Point Study.  EPA Contract




No. 68-01-3172.  June 1977.  19 p-




     6.  Brown, J., and K. Yu.  Test Report:  Particulate Sampling Strategy in




Circular Ducts.  Emission Measurement Branch, Emission Standards and Engineering




Division, U.S. Environmental Protection Agency.   Research Triangle Park, N.C.




277H.  July 31, 1980.  12 p.




     7.  Hawksley, P.G.W., S. Badzioch, and J.H. Blackett.  Measurement of




Solids in Flue Gases.  Leatherhead, England, The British Coal Utilisation Research




Association, 1961.  p.  129-133.

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0
50
            10          20          30          40
                    NUMBER  OF  TRAVERSE POINTS
Figure 1.  Average relative error vs.  number of traverse points.
                                 10

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    +60
    +50
    +40
o
ii
CD
o:   .1-
    +30
Q-   _
in
    +20
    +10
      0
        0
9 VELOCITY  (FROM TABLE  1)
S PARTICULATE  (FROM TABLE  3)
A PARTICULATE  (FROM TABLE  5)
                          40
50
                 10          20          30
                       NUMBER OF TRAVERSE POINTS
Figure 2.  95 percent tolerance region vs. number of  traverse  points.
                                     11

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     0:5
   50
 to
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n.
to
cc
LU
O

CC
LU
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?  10
   DUCT DIAMETERS UPSTREAM FROM FLOW DISTURBANCE^(DISTANCE A)



               1.0                  1.5                  2.0
                                                                                     2.5
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'DISTURBANCE

MEASUREMENT
r~ " SITE;
DISTURBANCE
x 1
                                                     STACK DIAMETER > 0.61 m (24 in.)
         * FROM POINT OF ANY TYPE OF

           DISTURBANCE (BEND, EXPANSION. CONTRACTION. ETC.)
                                            STACK DIAMETER = 0.30 TO 0.61 m (12-24 in!
                                                                 i
    J         4          5         6         7          89

                                                    . *
DUCT DIAMETERS DOWNSTREAM FROM FLOW DISTURBANCE (DISTANCE B)



 Figure  3.   Minimum number of traverse points for paniculate traverses.
                                                                                     10

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      DUCT DIAMETERS UPSTREAM FROM FLOW DISTURBANCE (DISTANCE A)
0.5                  1.0                1.5                 2.0
                                                                              2.5
5U

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1




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STACK DIAMETER "= 0.30 TO 0.61 m (12-24 in.)

I I I
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2345         6        7          8         9
    DUCT DIAMETERS DOWNSTREAM FROM FLOW DISTURBANCE"(DISTANCE B)
                                                                               10
 Figure 4.  Minimum number of traverse points for velocity (nonparticulate) traverses..

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                                    TECHNICAL REPORT DATA
                             (Please read Instructions on the reverse before completing)
 . REPORT NO.
EPA-450/3-82-016a
                              2.
                                                             3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Proposed Revisions  to Reduce Number of Traverse Points
in Method 1 - Background Information Document
              5. REPORT DATE
               	August  1982
              6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Roger T.  Shigehara
                                                             8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Emission Measurement Branch  (MD-19)
Emission Standards  and Engineering Division
U.S.  Environmental  Protection Agency
Research Triangle Park, N.C. 27711
                                                              10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Air Quality Planning  and Standards  (MD-10)
Office of Air, Noise, and Radiation
U.S.  Environmental  Protection Agency
Research Triangle  Park, N.C. 27711
                                                              13. TYPE OF REPORT AND PERIOD COVERED
              14. SPONSORING AGENCY CODE
                EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
      This document  summarizes  the  data from  several  studies  on the number  of

traverse points specified by EPA Method 1.   This  summary  is  used as the basis

for  revising Method 1  to utilize a lesser number  of traverse points.
17.
                                 KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
Sampling Tests
 Stationary  Sources
13B
18. DISTRIBUTION STATEMENT

Unlimited
19. SECURITY CLASS (This Report)
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 16
                                                20. SECURITY CLASS (This page)

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                                                                            22. PRICE
EPA Form 2220-1 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE

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