CEM Report Series
Report Status: Revision No. 1
Date: July 1982
No.: 5-411-7/82
AN UPDATE AND DISCUSSION OF THE CRITICAL ASPECTS
OF PROPOSED EPA REFERENCE METHOD 6B
JULY 1982
Office of Air, Noise and Radiation
Division of Stationary Source Enforcement
Washington, D C. 20460

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UPDATE AND DISCUSSION OF THE
OF PROPOSED EPA REFERENCE
CRITICAL ASPECTS
METHOD 6B
JULY 1982
Prepared By:
Guy B. Oldaker III, Ph.D
Entropy Environmentalists, Inc.
Research Triangle Park
North Carolina
Prepared For:
U. S. Environmental Protection Agency
Division of Stationary Source Enforcement
Task Manager
Contract No.
Task No.
Report No.
Anthony P. Wayne
68-01-6317
28
5-411-7/82

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DISCLAIMER
This document was prepared by Entropy Environmen-
talists, Inc. under Contract No. 68-01-6317, Task No. 28,
and therefore, was wholly or partially funded by the U. S.
EPA. This document has not been subjected to the Agency's
required Peer and Policy Review. Therefore, this document
does not necessarily reflect the views of the Agency, and
official endorsement should not be inferred.

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Executive Summary
The U.S. EPA has undertaken the development of Reference
Method 6B, a wet-chemical method which can be used in lieu of,
or as a back-up for sulfur dioxide continuous emission
monitoring systems required at stationary sources of air
pollution. The measurement technique for Method 6B is based
upon the simultaneous determination of sulfur dioxide and carbon
6
dioxide with emission rates, in units of lb SOj>/10 Btu,
computed according to the F-Factor method. Method 6B has
evolved significantly since its proposal in early 1981. In this
report, Method 6B, as it is currently envisioned for
promulgation, is described, and in addition, the reasons for the
changes to the method that have occurred since proposal are
briefly discussed.

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TABLE OF CONTENTS
Introduc t ion	1
General Description of Proposed Reference Method 6B	4
Descriptions and Discussions of Critical Aspects of the
Proposed Method	8
Heated Borosilicate Glass or Stainless Steel Probe
Equipped With Filters	8
Absence of Impinger Containing Isopropanol Solution.... 10
Two Impingers Containing Hydrogen Peroxide Solution... .11
Bubbler (or Tube) Containing Drierite 	13
Erlenmeyer Bubbler (or Tube) Containing Ascarite II ...13
Dry Gas Meter	16
Pump	16
Flow Meter	17
Notes	18
Appendix - Proposed Reference Methods 6A and 6B	20

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Introduction
1
Since 1971 , fossil fuel fired steam generators subject
to New Source Performance Standards (NSPS) have been required to
install monitors to measure emission rates of sulfur dioxide in
g
units of lb SOj?/10 Btu heat input. Two monitors are required
for determining SOg emission rates: (a) an SOg, monitor and (b) a
diluent monitor which measures either oxygen or carbon dioxide.
From the pollutant and diluent data provided by the monitors,
emission rates can be computed according to the F-Factor
2
Method.	The emission rate data supplied by these monitors,
commonly termed continuous emission monitors (CEMs), may be
interpreted by the Agency as being indicative of the operation
and maintenance of the source's air pollution control system.
The scope of continuous emission monitoring requirements
was significantly broadened when New Source Performance
3
Standards were promulgated in 1979 for "Subpart Da - Electric
Utility Steam Generating Units for Which Construction is
Commenced After September 18, 1978." According to the
continuous monitoring requirements of Subpart Da, the SO-j
emission rate data may be used as indicators of compliance with
standards for emission rates and sulfur removal. Emission rates
are computed on a 30-day rolling average basis, which itself is
calculated from the daily average emission rates determined
using continuous emission monitoring systems.
1

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Within Subpart Da it is stated that if minimum daily SO
emission rate data cannot be obtained using continuous
monitoring systems, then the necessary emission rate data are to
be acquired using Reference Methods 3 and 6. However, from the
4
time of the proposal of Subpart Da , it was recognized within
the Agency that this method of data acquisition would be
potentially burdensome, and consequently, work was started on
the development of a sulfur dioxide emission rate measurement
method which would be inexpensive, reliable, and accurate, and
more importantly, which would be capable of making
determinations over time periods as long as 24 hours.
The methodology considered for development was
essentially based upon a simple modification of the Reference
5
Method 6 sampling train: a carbon dioxide absorber was placed
within the sampling train following the impingers containing the
hydrogen peroxide solution. This modification enabled the
concurrent determination of sulfur dioxide and carbon dioxide
concentrations, which could be used according to the F-Factor
6
method to compute the SO emissions rate in units of lb SO^/IB
6
Btu. In 1978, Whittle and Westlin reported the results from a
field evaluation of "an intermittant integrated SOg/CO^ emission
sampling procedure," which demonstrated the feasibility of the
methodology with regard to unattended operation and acceptable
precision. This methodology was formally proposed as Reference
7
Method 6B in January 1981. (Proposed Reference Methods 6A and
6B are contained in the Appendix.)
2

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At this writing, the method has been sent for "red border
review" and has not yet been promulgated. Collaborative testing
0
is scheduled to begin in the Fall of 1982.
This paper has a three-fold purpose:
(a)	to provide those individuals involved in the field
of stationary source emission measurement with an
understanding of Reference Method 6B as it is
currently envisioned for promulgation,
(b)	to update those individuals already familiar with
the method regarding developments and changes which
have occurred as a consequence of the results of
past and ongoing investigations, and
(c)	to provide guidance in the form of recommendations
for those who are currently using the method and its
variants.
In the sections which follow, a general description of
the proposed method is presented first; detailed discussions are
then presented which address the critical aspects of the method.
3

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General Description of Proposed Reference Method 6B
Using the method as proposed, the following can be determined
over periods up to 24 hours:
(a)	lb SO2/106 Btu,
(b)	ppra SOg (dry and wet bases),
(c)	%C02 (dry and wet bases), and
(d)	%H£0.
The sampling train consists of the following major components:
(a)	a heated, glass, or stainless steel probe equipped
with a filter (either in-stack, out-of-stack, or
both) ;
(b)	two midget impingers each containing 15 mL 3% (v/v)
hydrogen peroxide to absorb the sulfur dioxide;
(c)	one midget bubbler containing about 25 g Drierite®
(anhydrous calcium sulfate) to remove water vapor
from the effluent sample stream;
(d)	an Erlenmeyer bubbler containing a weighed amount of
(around 100 g) Ascarite II® (sodium hydroxide on a
vermiculite solid support) to absorb carbon dioxide;
and
(e)	a pump and dry gas meter equipped with an industrial
t imer-swi tch.
These components are illustrated in Figure 1.
Samples are obtained at a flow rate of 1.0 L/min (+ 10%).
The timer controls the sampling duration and frequency; sampling
is conducted from 2 to 4 minutes on a 2-hour repeating cycle for
24 hours. The final sample volumes should be between 20 and 40
L.
Sulfur dioxide (as sulfate ion) is determined
9
titrlmetrically according to the barium-thorin method contained
in Reference Method 6.
4

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THERMOMETER
PROBE (END PACKED'
WITH QUARTZ OH
PVREX WOOL)
*T\
k
MACK WAIL
MIDGET BUBBLERS
MIDGET IMPINGERS

y
ICE BAIH
"IHERMQMETER —
c-f25
nnv
GAS MCTEll
jj HA1E METER NEEW.E VALVE
/
PUMP
TIMER
SURGE TANK
Tu
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ijur-e
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Moisture may be determined gravimetrically using the procedure
10	®
o£ Stanley and Westlin. The mass gained by the Ascarite II is
used to compute the concentration of carbon dioxide. Finally,
the SOg emission rate is calculated according to the F-Factor
£
method, using the gravimetric data from the SO^ and COg
determinations. (It should be noted that gravimetric data may
be used in lieu of concentration data, because the sample
volumes associated with the S0£ and CO£ concentrations are
essentially equal.)
In the proposed method it is noted that continuous
sampling, as distinguished from intermittant sampling, is
technically feasible; brief specifications for the application
of the continuous sampling mode are provided:
Note.—Sampling	may be conducted
continuously if a low flow-rate sample
pump (> 24 ml/min) is used. Then the
timer-switch is not necessary. In
addition, if the sample pump is designed
for constant rate sampling, the rate meter
may be deleted. The total gas volume
collected should be between 20 and 40
liters for the amounts of sampling
reagents prescribed in this method.
Since proposal of Reference Method 6B, considerable
attention has been directed toward placing the methodology of
such continuous mode sampling on a firm technical basis, so that
the ultimately promulgated Reference Method 6B will detail both
sampling modes thoroughly, and therefore, consistently. In this
regard emphasis has been placed on (1) evaluating the
6

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performance of pumps and associated flow controls when applied
to low sampling rates (< 100 mL/min), (2) determining the
quantities and concentrations of reagents necessary for large
sample volumes (e.g., up to 80 L); and (3) investigating systems
to separate sulfur trioxide and sulfuric acid from sulfur
d ioxide.
7

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Descriptions and Discussions of
Critical Aspects of the Proposed Method
In the following paragraphs the proposed Reference Method
6B (both sampling modes) is addressed in detail. Attention is
focused on those items that distinguish the proposed Reference
Method 6B from Reference Method 6. In addition, recommendations
which reflect the results from investigations conducted since
the date of proposal are provided.
Heated Borosilicate Glass or Stainless Steel Probe
Equipped with Filter(s)	
For sample acquisition, heated borosilicate glass or
stainless steel probes are required. Relative to stainless
steel probes, glass probes are clearly more susceptible to
breakage. Glass probes, on the other hand, are insensitive to
corrosive compounds in the effluent stream and are much easier
to clean. These two attributes are important because of the
potential for spurious reactions between probe contaminants and
sulfur dioxide; such reactions could lead to low results for SO2
determinations. The choice of probe material is best made on a
case-by-case basis, taking into account source specific
variables such as vibrations at the sampling location and
particulate matter and sulfuric acid concentrations in the
effluent.
8

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Filtration is necessary in order to remove particulate
matter from the effluent sample prior to impingement in the
hydrogen peroxide solution. The barium-thorin titration, which
is performed on the hydrogen peroxide solution, is sensitive to
interference by alkali metal ions, which may occur at
significant concentrations within particulate matter. In
addition, particulate matter may contain water soluble sulfates
which would be ultimately determined as SO2 if allowed to enter
the impingers containing the hydrogen peroxide solution. An
in-stack filter, e.g., a plug of borosilicate glass wool, is
capable of removing this particulate matter. Nevertheless, a
second filter, located out-of-stack, is currently recommended in
order (1) to ensure quantitative removal of interfering
particulate matter, and (2) to minimize passage of sulfuric acid
aerosol (mist) which either may exist in the effluent or may
form in the effluent sample after passage through the first
filter.
The SOg emission rate determination using the
barium-thorin method will be biased high if sulfur oxides such
as SO3 and H^SO^j are collected in the hydrogen peroxide
solutions. This potential bias may be minimized through proper
selection and control of the temperature of the effluent sample
8
within the probe. The results from recent investigations
indicate that the method's precision is optimized when the
sampling temperature is approximately 20°F above the effluent
moisture (i.e., water) dewpoint — as distinguished from the
sulfuric acid dewpoint. This empirically selected temperature
9

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reflects the necessary control of two physical processes which
can affect the results of the determination. First, the
temperature must be above the moisture dewpoint, because sulfur
dioxide dissolves and oxidizes in liquid water; using
barium-thorin titrimetry, this oxidation product cannot be
distinguished from sulfuric acid. Second, the temperature
should be in the range where equilibrium favors the presence of
filterable sulfuric acid aerosol, rather than the other higher
sulfur oxide compound, sulfur trioxide, which exists as a gas.
Thus, by selecting a sampling temperature that favors the
presence of an aerosol, the contribution of SO^ and H^SO^j can be
minimized through removal by the second, out-of-stack filter.
Nevertheless, data pertaining to the magnitude of SO^ and
H2SO4 biases on SO^ determinations using the proposed Reference
Method 6B are currently unavailable; thus, the significance of
the potential bias is unknown.
Absence of Impinger Containing Isopropanol Solution
11
As reported by Butler and Westlin , isopropanol
interferes with the collection of CO2 by Ascarite II.
Laboratory investigations have shown that during sampling,
isopropanol can penetrate the impingers containing the hydrogen
peroxide solution and the Driente . In addition,
investigations have shown that masses of isopropanol less than
one gram are sufficient to reduce CO£ absorption by 50 percent.
Consequently, the use of isopropanol has not been included
within the procedure for either sampling mode of the method.
10

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In Reference Method 6 the primary function of the
isopropanol is to separate SO3 and HgSO^ from the SO2 sample.
The critical importance of the probe temperature setting and the
presence of probe filters is better understood when viewed in
light of the fact that the proposed Reference Method 6B sampling
train has no provisions for the removal of these potentially
biasing species. This potential bias has not gone unrecognized;
considerable efforts have been made to identify means of
separating higher sulfur oxides from the sulfur dioxide sample.
For example, drawing from the equilibrium expressions for the
SC^/water system, investigators proposed the use of acidic
solutions for scrubbing SOj and H2SO4 from the effluent sample.
Of the common acids available, hydrochloric acid was judged
unsuitable because of its volatility, and consequently, its
potential to interfere with the barium-thorin titration method.
Nitric acid was not considered because of its oxidizing
properties. Sulfuric acid was investigated, but its use was
found to offer no noticeable improvement over the proposed
method. Investigations are in progress to identify other
practical means of accomplishing the SO£ separation.
Two Impingers Containing Hydrogen Peroxide Solution
The proposed method calls for midget impingers, each
containing 15 mL 3% hydrogen peroxide; this method of absorbing
S02 is identical to that specified within Reference Method 6.
11

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To accomodate flow rates greater than 24 mL/min and
consequently, greater sample volumes, larger impingers (e.g.,
Mae West) containing 75 mL of more concentrated peroxide (6% to
10% (v/v)) , have been used with continuous mode sampling.
For Reference Method 6 sampling, the alternative use of
10% (v/v) hydrogen peroxide, has been approved	in lieu of the
12
specified 3% (v/v) hydrogen peroxide. While it	would appear
that even greater concentrations could be applied	to continuous
mode sampling to ensure that sufficient hydrogen peroxide is
always available, concentrations greater than the	approved 10%
(v/v) are not recommended for use at this time.	Investigators
15
in the past have noted a negative bias when S0£ was absorbed in
concentrated hydrogen peroxide; however, since quantitative data
were not provided due to the limitations of analytical methods
at that time, the significance of the bias is unknown. The EPA,
QAD is currently investigating this potential bias through the
use of ion chromatography, a methodology that only recently has
14
been available.
The impingers containing the hydrogen peroxide solution
should be protected from direct sunlight because of the
potential for photodecomposition. If a significant quantity of
the hydrogen peroxide were to decompose, sulfur dioxide would
not be absorbed quantitatively, and a negative bias could result
Q
for determinations of ppm S02 and lb SO2/10 Btu. Relative to
Reference Method 6, photodecomposition is a greater potential
problem because of the extended sampling period. It should be
noted that photodecomposition does not necessarily demand
12

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sunlight. For example,	mercury vapor lights may affect
photodecomposition also.	For the reasons touched upon above, it
is recommended that the	impingers containing hydrogen peroxide
be covered throughout the	sampling period.
Bubbler (or Tube) Containing Drierite
An accurate determination of carbon dioxide can be
accomplished only if moisture has been quantitatively removed
from the effluent sample prior to reaching the Ascarite II .
Drying is accomplished using indicating Drierite , which signals
loss of drying activity by changing its color from blue to pink.
For the intermittant sampling mode, approximately 25 g
Drierite is specified; for the continuous mode the specified
mass is approximately 150 g. The design of the Drierite
container is not critical; however, it is imperative that the
container be oriented in a manner to minimize channeling that
could be aggravated as a consequence of settling. For example,
®
if tubes are used for containing the Drierite , these tubes must
be secured in a vertical position; otherwise, channeling along
the top of the tube would be likely.
Erlenmeyer Bubbler (or Tube) Containing Ascarite II
Both sampling modes envisioned employ sodium hydroxide
for absorbing the carbon dioxide in the effluent sample. (it
should be noted that as proposed, the method specifies the use
13

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of Ascarite ; since that time the supplier has changed the
product's formulation so that vermiculite is used rather than
asbestos. Ascarite II , the approximate formulation being 96%
(w/w) sodium hydroxide and 4% (w/w) vermiculite solid support,
is functionally equivalent to Ascarite .)
For intermittant mode sampling, 100 g Ascarite II in a
250 mL Erlenmeyer bubbler is specified. Most versions of
continuous mode sampling systems employ 150 g Ascarite II®
contained in a glass tube.
Of all the method's operations, the Ascarite II®
absorption presents the greatest potential for causing serious
error. And in this regard, the specie of notable concern is
water. Water's role in causing bias is best understood in light
of the reaction that occurs during CO2 absorption.
In the Ascarite II container, carbon dioxide reacts with
sodium hydroxide to afford anhydrous sodium carbonate and water
vapor. Water vapor rather than liquid water is formed because
of the (appreciable) heat of reaction. During sampling the
extent of reaction is indicated by the advance of a white zone,
which is the anhydrous sodium carbonate (and which is capable of
reacting with water). The water vapor, on the other hand, is
swept ahead into the effluent sample stream, (which then
contains no carbon dioxide) and condenses on the fresh sodium
hydroxide beyond the reaction zone. The greater proportion of
this condensed water is visible as a wet zone, which, as
previously indicated, moves ahead of the reaction. Nevertheless,
not all the condensed moisture is visible.
14

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The reaction described above must be isolated and
contained within the preweighed COg absorption container. As
indicated earlier, water vapor can interfere with the method.
Two interfering mechanisms are possible. First, if water vapor
breaks through the Drierite , it will react with the anhydrous
sodium carbonate. This added mass can bias COg concentration
g
determinations high, and lb SO;?/10 Btu determinations low. In
addition, because the reaction products (sodium carbonate
hydrates) have greater molar volumes, sample flow through the
absorber may be reduced and potentially stopped altogether.
The water vapor produced by the COg reaction is the other
problem. Accordingly, the location of the wet zone is a poor
breakthrough indicator, because a significant quantity of water
is generally present some distance ahead of this zone. If water
vapor exits the absorber, CO2 determinations may be biased low,
£
and lb SO£/10 Btu determinations, high.
Many investigators have approached the problem through
use of two C0£ absorbers in series. The use of a back-up
ensures that a valid sample will be obtained in the event that
C0£ breaks through the first absorber. The unreacted sodium
hydroxide in the back-up appears to possess adequate dessicating
ability to handle the resultant moisture. Moisture
breakthrough, however, is best prevented by including a back-up
®	5
absorber that contains either Drierite , or silica gel.
15

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Dry Gas Meter
The proposed Reference Method 6B requires the use of a
dry gas meter when pollutant and diluent concentrations are
determined in conjunction with S0£ emission rates. However, an
15
abbreviated procedure is permitted if only emission rate data
are desired. This abbreviated procedure essentially entails
omitting the dry gas meter from the sampling train. It should
be recognized, however, that anomalous emission rate data may be
impossible to rationalize when the associated concentration data
are unavailable. The use of a dry gas meter for all
applications of Reference Method 6B is currently advised because
of its value for assessing quality control.
Pump
The proposed Reference Method 6B specifies the use of a
diaphragm pump for sample acquisition. Problems with pumping
have been encountered during the development of the Method as
applied using the continuous sampling mode. Peristaltic pumps,
although capable of operating at low flow rates, were found to
be unreliable, especially when applied to "negative" pressure
effluent streams. Diaphragm pumps, on the other hand, exhibit
reliability problems when operated at low (< 100 mL/min) flow
rates. Thus, the small volumes of gas handled create what is
called a dead-head condition, leading in turn to overheating,
and, at the extreme, failure. This problem can be minimized by
16

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providing the	pump with sample recirculation capability. (Pump
recirculation	is illustrated in Figure 5-1 within Reference
Method 5.)
Sample	acquisition has also been accomplished using
16
compressed air aspiration.
Flow Meter
For the intermittant sampling mode, the proposed
Reference Method 6B specifies the use of a flow meter and a
sampling rate of 1.0 L/min (+ 10%). Within the proposed method
it is noted that if a constant flow sampling pump is employed
for the continuous sampling mode, the flow meter may be deleted
from the sampling train.
The results from field evaluations of the continuous
sampling mode have shown that when sampling trains are operated
unattended, constant sampling rates (i.e., + 10%) cannot be
guaranteed. The reason for this is due to the fact that the
(S)
reaction product at the Ascarite Il^absorber chokes the gas
passages therein, causing the pressure drop across the CO^
absorber to increase with sampling time. Conditions of varying
sample flow rates may result in biases which would reflect the
acquisition of non-representative samples. The use of critical
orifices in conjunction with diaphragm pumps is being
investigated as a potential means of maintaining constant
sampling rates.
It is currently recognized that the proposed Method 6B
train should be equipped with a flow meter.
17

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FOOTNOTES
December 23, 1971.
£
Federal Register, Vol. 36,
No
247 - Thursday,
Subpart
1979
D
3
F-Factor
and within
methods are described within 40 CFR 60,
40 CFR 60, Appendix A, Reference Method 19.
Federal Register, Vol. 44, No. 113 - Monday, June 11,
September 19, 1979
Federal Register, Vol. 43,
No,
182 - Tuesday,
for
In:
Carbon
Book of
and
ASTM
Philadelphia, Pa
Hydrogen
Standards,
, 1980.
in the
Part 26,
Standard Method
Analysis of Coal and Coke.
ASTM Designation D 3178-73,
g
R. N. Whittle and P. R. Westlin, "Air Pollution Test
Development and Evaluation of an Intermittant Integrated
Emission Sampling Procedure." Environmental Protection
Emission Standard and Engineering Division, Emission
Measurement Branch, Research Triangle Park, North Carolina,
December 1979.
7
Federal Register, Vol. 46, No
Report:
so2/co2
Agency,
16 - Monday, January
26, 1981
8
9
F. E. Butler, U. S. EPA Telecon, May 19, 1982.
Fr i tz
Chem.,
and S. Yamamura,
27, 1461 (1955)
"Rapid Microtitrations of
J. S.
Sulfate," Anal. 	 	
10
J. Stanley and P. R. Westlin, "An Alternative Method
for Stack Gas Moisture Determination." Environmental Protection
Agency, Emission Standard and Engineering Division, Emission
Measurement Branch, Research Triangle Park, North Carolina.
August 1978.
11
F. E. Butler, J. E. Knoll, T. J. Logan, and M. R.
Midget, "Method Development for 24-Hour Analysis of Sulfur
Dioxide and Carbon Dioxide at Fossil Fuel Combustion Sources
(Method 6B)," presented at National Symposium on Recent Advances
in Pollutant Monitoring of Ambient Air and Stationary Sources,
Raleigh, North Carolina, May 4, 1982.
18

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12
R. T. Shigehara, Environmental Protection Agency,
Emission Measurement Branch, Emission Standard and Engineering
Division, Memorandum, July 6, 1978.
1?
H. Wagner, Microchim. Acta, 19 (1957).
LA
John Margeson, U.S. EPA, QAD, (personal communi-
cation) , June 1982.
15
The abbreviated procedure is described within proposed
Reference Method 6A which is cited as a procedural source with
Method 6B. Proposed Reference Method 6A is contained in the
Appendix.
16
Joe Leslie, Virginia Electric and Power Company
(Vepco), (personal communication), March 1982.
19

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APPENDIX
20

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Monday
January 26, 1981
Part IX
Environmental
Protection Agency
Standards for Performance for New
Stationary Sources; Revisions to General
Provisions and Additions to Appendix A,
and Reproposal of Revisions to
Appendix B

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3354
Federal Register / Vol. -18. Nfo. is / Monday. January 28. 1981 / Pronosed Rules
3. In Performance Specification 2. the
definition of "Relative Accuracy" is
incorrect Instead of a degree of
correctness, it is actually a measure or
"relative error." One commenter feels
chat "relative accuracy" should be
changed to "relative error."
7. In Section 7.3 of Performance
Specification 2. the tester is allowed to
reject up to three samples provided that
the total number of test results used to
determine the relative accuracy is
greater than or equal to nine. EPA had
considered using statistical techniques
to reject outliers, but found that these
techniques were too restrictive. One
commenter feels that statistical
techniques should be used. At a
minimum, the commenter feels that the
control agencies should be consulted
before any data is rejected.
Miscellaneous
Authority: This proposed rule malrmg u
issued under the authority of sections 111.
114. and 301(a) of the Gean Air Act as
amended (42 U-S.C. 7411.7414. and 7sn(a]).
Dated: laanary 13.1981.
Douglas M. Coetla,
Administrator.
It is proposed that 93 60.13, 60.46. and
60.47a. Appendix A. and Appendix B of
40 CFR Part 60 be amended as follows:
1. By revising } 60.13(b), 60.13(c)(2)(ii),
and 60.13(d), by removing
subparagraphs (1). (2). and (3) of
5 50.13(b), and by removing
subparagraphs (1). (2). and (3) of
§ 60.13(d) as follows:
} SQL13 Monitoring requirement*.
• • # • •
(b) All continuous monitoring systems
and monitoring devices «hall be
installed and operational prior to
conducting performance tests under
$ 303. Verification of operational status
shall, as a minimimi include completion
of the manufacturer's written
requirements or recommendations for
installation, operation. *nri calibration
of the device.
(e),* —
(ii)'Continuous monitoring systems for
measurement of nitrogen oxides or
sulfur dioxide shall be capable of
measuring emission levels within ±20
percent with a confidence level of 95
percent The performance tests and
calculation procedures set forth in
Performance Specification 2 of
Appendix B shall be used for
demonstrating compliance with
specS canon.
» • • • •
(d) Owners and operators of all
cacnnuous emission monitoring systems
installed in accordance with the
provisions of this part shall check the
zero and span drift at least once daily in
accordance with the method presaibed
by the manufacturer of such systems
unless the manufacturer recommends
adjustments at shorter intervals m
which case such recommendations shall
be followed. The zero and span shall. as
a minimum, be adjusted whenever the
24-hour zero drift of 24-hour span drift
limits of the applicable performance
specifications in Appendix B are
exceeded. The amount of excess zero
and span drift measured at the 24-hour
interval checks shall be quantified and
recorded. For continuous monitoring
systems measuring opacity of emissions,
the optical surfaces exposed to the
eiEuent gases shall be cleaned prior to
performing the zero and span drift
adjustments except that for systems
using automatic zero adjustments, the
optical surfaces shall be cleaned when
the cumulative automatic zero
compensation exceeds 4 percent
opacity. Unless otherwise approved by
the Administrator, the following
procedures shall be followed for
continuous monitoring systems
measuring opadty of emissions.
Minimum procedures shall Include a
method for producing a simulated zero
opacity condition and an upscale(span)
opacify condition using a certified
neutral density filter or other related
technique to produce a known
obscuration of the light beam. Such
procedures shall provide a system check
of the analyzer internal optical surfaces
and all electronic circuitry Including the
lamp and photodetector assembly.
•	••It
1 By revising S 60.46(a)(4) as follows:
3 60.46 Test mettioda and procedures,
(a)*"
(4) Method 8 for concentration of SO*
Method SA may be used whenever
Methods 8 and 3 data are used to
determine the SC. emission rate in ng/J,
and
•	• • • •
3.	By revising § 60.47a(h)(l) as follows:
§ 60.47a Emission monitoring.
• • • • •
W*
(1) Reference Methods 3, 8. and 7 as
applicable, are used. Method SB may be
used whenever Methods 8 and 3 data
are used to determine the SO* emission
race in ng/J. The sampling location(s)
are the same as those used for the
continuous monitoring system.
• • • • »
4.	By adding to Appendix A of 40 CFR
Part 30 two new methods. Methods 8A
and Method SB. to read as follows:
Appendix A—Reference Test Methods
Method OA—Oeiamw.aaon of Sulfur
Dioxide. Moisture, and Cirban Dioxide
Emissions from Fossil F-jel Coabusr.on
Sources
1.	Applicability and Principle
1.1 Applicability. Thy method inplies to
the determination of sulfur dioxaa (SOi)
emissions from fossil fuel combustion sources
In terms of concentration (aig/m*) and m
terms of emission rate (ag/f) and to the
determination of carbon aionde (CJ,)
concentration (percent). Moisture, if desired,
may aiso be determined by this method.
The """""mi detectable limit, the upper
limit and the interferences of the method for
the measurement of SOi are the same as for
Method 1 For i 20-liter sample, the method
has a precision of 0 S percent COt for
concentrations between 2J and 25 percent
COi and 1.0 percent moisture for moisture
concentrations greater than 3 percent
1-2	Principle. The principle of sample
collection is tbe same as for Method 9 except
that moisture and COt are collected in
addition to SOi is the same sampling train.
Moisture and CO« fractions are determined
gravunetncally.
2.	Apparatus
2.1 Sampling. The sampling train is
shown in Figure 8A-L. the equipment
required is the same as for Method & except
as specified below:
2.1.1 Midget tepirgers. Two 30-ml midget
Impmgern with a 1-ma restricted tip.
2-1-2	Midget Subtler. One 30-ml midget
bubbler with an unrestrxted tip.
2J J COt Absorber. One 250-ml
Erienmeyer babbler with as unrestricted tip.
or equivalent
12 Sample Rxovey and Analysis. The
equipment needed for sample recovery and
analysis is the lame as required for Method
9. in addition, a balance to oeasure within
0.09 % is needed for analysis.
3.	Reagents
Unless otherwise indicated, ail reagents
must conform to the specifications
established by the Committee on Analytical
Reagents of the American Chemical Society.
Where such specficadons are not available,
use the best availaole grade.
3.1 Sampling. The reagents required for
sampling are the same u specified in Method
3. except that 80 percent Isopropanol and 10
percent potassium iodide solutions are not
required. In addition, the following reagents,
are required:
nujMQ coos iiw » m

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Federal Register / Vol. 46. No. 16 / Monday. January 23. 1931 / ProDOsed Rules
6355
THERMO METE 3
MIDGET BUBBLERS J
STACK WALL
PRC3E |ENO PACKED
WITH QUARTZ OR
PYRSX WOOL)
MIDGET IMPINGEHS
>V/C:
o g*.
«Q
t.l
ICE BATH
NEEDLE VALVE
RATE METER
OSY
GAS METER
SURGE TANK
Figure 6A-1. Sampling train.
BIUJNQ COW U60-H-C

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3356
Federal Register / Vol. 46, No. 16 / Monday, January 2S. 1981 / Proposed Ruies
3 1.1 Orar.'s.' Anhydrous calcium mifate
.CaSO,) aesiccant. 3 mesa.
j.l — Ascar.te. Sodium hydroxide coated
isoestos fcr absorption of COi. 3 to 13 mesa.
3	2 Saaiole Hies vary end Ar.clysx. The
•si?ecu needed torsacoie recover/ and
aai:vsis axe the sane as for Method d.
;ecaoa3 3-2 ana 3.3. rsspeccvely
4. Procedure
4.1
4.1.1	Prsparzuan of Callecv.cm Trcin.
Measure *.J ml of 3 percent hydrogen
peroxide ji'.o eacn of the first t*.vo midget
impingers. Into the midget bubbler, piaca
about 25 g of.dner.te. Cean the outsides of
the lxo Lagers and the dnente buboler and
weigh (at room temperature. — 20* CI :o the
nearest 0.1 g. Weign lie three vessels
simultaneously and record this initial mass.
PUca a small amount of glass wool in the
EHenmeyer bubbler. The glass wool should
cover the entire bottom of the flask and be
about i-an thick. Place about ICO g of
ascante on top of the glass wool and
carerily uuert the buobler top. Plug the
buobier exhaust leg and invert the bubbler to
remove any ascanta fom the bubbler tube. A
wire may be useful in assuring that no
ascante remains in die tube. With the phig
removed and tha'ouiside of the bubbler
cleaned weigh (at room temperature (at room
temp«ratura. — 20* CI to the nearest 0.1 g.
Record this Initial masa.
Assemble the train as shown In Figure 3A-
1. Adjust the probe heater to a 'emperature
suficient to prevent water condensation.
Place ensiled Ice and water around the
tmpingsrs and bubblers.
Not#.—For stack gas streams with high
particulate loadings, an in-stack ar heated
out-of-stack glass nber mat filter may be used
in place of the glass wool plug m the probe
4.1.2	Leak-Check Procedure end Sample
Collection. The leak-check procedure and
sample collection procedure are the same as
soen£ed In Method 6. Sections 4.1.2 and
4.L3. respectively.
4	2 Sample Recovery.
4-2.1 Moisture Steosuremer.L Disconnect
the oeroxide impmgen and the dnente
buboler !na the sample train. Allow time
(aoout 10 minutes) for them to reach rocm
temperature. dean the outsides and then
weigh them simultaneously in the same
manner as in Sedan 4.1.1. Record mis final
mass.
4^2 Peroxide Solution. Pour the contents *
of the midget uspuigen into a leak-tree
polyethylene bottle for shipping. Rinse the
two midget impingers and connecting tubes
with deicmzed distilled water, and add the
wasnings to the same storage container.
'Mantloo ai Ssds uih ar tptofic orcducu
does sol satuttata radmesunt by ;re U S
£r.wonseotal Pretacsoa Agescy
4.2-3 COi Absorber. Allow the Erienmever
buobier to warm to room timaeranre f aoout
10 mmutes). clean the outside, and weign to
'ne nearest 0.1 g in the same manner is in
Seccon 4.L1. Record this final mass a.-.d
aboard ±e used iscanta.
4J Sarpte Analysts. The samnle analysis
aroceavre for SOi is the same as soecinea ,n
Method 3. Sedan 13.
5. CaiioKVon
Tie calibrations and checks are the sarr.e
as required in Method 3. 5ec*_c.i 5.
9. CaitrjJauons
Carry out calculations, retaining at least l
extra decimal figure beyond that cf the
acquired data. Round off figures after final
calculation. The calculaaon aomeaclanire
and sraceaure are the same as specfied in
Method o with the addition ot tie fallowing-
7 Emission Rate Pncec'ire
If the only emission measurement desired
is in terms of emission rats of SOi (ng/H- an
aboreviated procedure may be used. The
differences between Method 6A and the
abbreviated procedure are aesenbed beiow
71 Sample Train. The samole train .s the
same as mown m Figure 3A-1 ar.d as
31 Nomenclature.
CH>*o = Concentraaon of moisture, percent.
;oH="Concentration of CC\ in basts
percent
f3„ = initial mass o: peroxide tmrtr.gers and
iner.te buooler. %.
ra,, = rinal mass ot paroxice imomgers ana
ar.ente bucoier g.
mu»ln.aal mass of ascar.te buobier g
citf—rinal mass of ascar.te buocier j.
Standard ecuivaient volume of
COt collected, dr/ sasis.
3.2	COi volume collected, corrected *o
standard condmons.
Veo, w™5.4a"XO"'(m^-m. ] fEq SA-1)
9.3	Moisture volume csilected. correctea
to standard conditions.
SA-2)
. 5A-3)
. 6A-4)
SA-5)
aesenbed in Secyon 4. except *hat he ziy
gas Jie'er >s not neecel
7 2 Prtparsron or '.•* zotiez: rr::n.
Follow the same procedure *.* .n Section
4.1.1. except that the pero\iae imcingers and
dnente oubbler need not be "e^ned before
or after the test run.
7 3 Sairphng Ooe-a ta the tain as
aesenbed in Section 4.! 3. jxcept that ar/ jas
».(,„) • 1.336 x !0-3 (V - )
6.4 SOj concentration.
(Vt - /tb)
*S0 ™ 32.03 i» i * v	(
^	m(std' 'C02(std)
5.5 CO2 concantraffon.
VC0-(std)
^CO " V	* 7 (s'd) X 1 CO	(£c
2 n(std) 'cO-(Svd)
5.6 Mo1 star? ccncsntratioj.
'H9fl(std)
M2Q '-n(std) ^ VH,0(std) * vC0-(std)

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Federal Register / Vol. 46, No. 16 / Monday, January 26. 1981 / ProDosed Rules
8337
meter readings, barometric pressure. and dry
gas meter temperatures need not be recordsd.
7 4 Scaipla Recovery Follow the
procedure in Section 4 2. except that the
peroxide impir.gers and dnen'.e bubbler need
not be weighed.
Where:
Eufi«Emission rate of SO* ng/J.
F,—Carbon F factor for the fuel burned,
m'/J, from Method 19.
9. Bibliography
3.1 Same as for Method 8. ataaoos 1
through 8, with the addition of the following;
&2 Stanley, [on and P R. Westlin. An
Alternate Method for Stack Gas Moisture
Determination. Source Evaluation Society
Newsletter. Volume X Number 4. November
1978. '
8J Whittle, Richard N. and Pit. Westlin.
Air Pollution Test Report Development and
Evaluation of an Intermittent Integrated
SOj/COt Emission Sampling Procedure.
Environmental Protection Agency,
Emission Standard and Engineering
Division. Emission Measurement
Branch. Research Triangle Park. North
Carolina. December 19*9.14 page3.
7 5 Sample \nalysis. Analysis of the
peroxide solution is the same as described in
Section 4 3.
7 8 Calculations.
7.8.1 SQ» mass collected.
(Eq. 6A-7)
(Eq. 6A-8)
Method SB—Determination of Sulfur Dioxide
and Carbon Dioxide Daily Avenge
Emissions From Fosui Fuel Combustion
Sources
1. Applicability and Frinciple
1.1 Applicability. This method applies to
the determination of sulfur dioxide (SOt)
emissions form combustion sources in terms
of concentration (rag/M1) and emission rate
(ag/n. for the determination of carbon
dioxide (COt) concentration (percent) oa a
daily [24 hours) basis.
The minimum detectable limit, upper limit
and the Interferences for SO, measurements
are the same as for Method S. For a 20-luer
sample, the method has a precision of OJ
percent COi for concentrations between 2.5
and 25 percent COt.
1-2 Principle A gas sample is extracted
Erom the sampling point in the stack
Intermittently over a 24-hour or other
specified time penod. Sampling may also be
conducted continuously if the apparatus and
procedure are modeled [see the note in
Section 4.1.1). The SOi and COi are s-yarated
and collected in the sampling train The SOi
fraction is measured by the banum-thor:n
titration method and CO» is determined
gravunetrcally
Z. Apparatus
The equipment required for this method is
the same as snecifled for Method 6A. Section
2. with the addition of an industrial timer-
switch designed to operaie in the "on"
position from 3 to S continuous minutes and
"off" the remaining penod over a repeaUng,
2-hour cycle.
3. Reagents
Ail reagents for sampling and analysis are
the same as described in Method 3A. Section
3.
4.	Procedure
4.1 Sampling
4.1.1 Preparation of Collection Train.
Preparation of the sample train is the same a9
described in Method 8A. Section 4.1.4 with
the addition of the following;
Assemble the train as shown in Figure 6B-
"1. The probe must be heated to a temperature
sufficient to prevent water condensation and
must include a filter (either m-stack. out-cf-
(tack, or both) to prevent particulate
entrainment in the penoxide impingers. The
electnc supply for the probe heat should be
continuous and separate from the timed
operation of the sample pump.
Adjust the timer-switch to operate in the
"on" position form 2 to 4 minutes on a 2-hour
repeating cycle. Other tuner sequences may
be used provided there are at least 12 equal,
evenly spaced penods of operation over 24
hours and the total sample volume is
between 20 and 40 liters for the amounts of
sampling reagents prescribed in this method.
Add cold water to the tank anul the
impmgers and bubblers are covered at least
two-thirds of their length. The impingers and
bubbler 'auk must be covered and protected
Erom intense neat and direct sunlight. If
freezing conditions exist, the impinger
soluUon and the water bath must be
protected.
SU.UN4 cooc iiw » n
fltso - 32.03 (Yt - vto) N(ifSlXL)
* &
Where:
= Mass of S02 collected, irg.
7.6.2 Sulfur dioxide emission rate.
ntso
E«n " K 0.829 x TO9) 7=	L_
2 c

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PROBE (END PACKED'
wiiii QUAnrz oil
PVAEX WOOL)

k
/
IIIEIIMOMtlCJl
STACK WALL
MIDGL1 UUUULEIIS
MIDGET IMI'INGEHS

y
ICE 8 ATI I
THERMOMETER
a
GAS MEUIt
RATE MET Lit NEtDLE VALVE
Fiuuru 6B-1. Sampling train.	SUiiGC TANK
TIMtll
OIU1MO COOi

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Federal Register / Vol. 46, No. 15 / Monday. January 28. 1981 / Proposed Rules
8359
Note.—Sampling may be conducted
continuously if a low How-rats sample pump
(>24ml/min) is used. Then tha timer-switch
i not necessary. In addition, if the sample
pump is designed for constant rale sampling,
the rate meter may be deleted. The total gas
volume collected should be between 20 acd
40 Liters for the amounts of sampling reagents
prescribed m this method.
*.1.2 Leak-Check Procedure. The leak-
check procedure is the same as descnbedf in
Method & Section 4.12.
4.1J Sample Collection. Record the initial
dry gas meter reading. To begin sampling,
position the Up of the probe at the sampling
point, connect the probe to the first lmpinger
(or filter), and start the tuner and the sample
pump. Adjust the sample flow to a constant
rate of approximately 1.3 liter/min as
mdicated by the rotameter. Assure that tha
timer is operating as intended, LB- in the "on"
position 3 to 5 minutes at 2-hour intervals, or
other time interval specified.
During the 24-hour sampling period, record
the dry gas meter temperature between MO
a_m. and 11.00 , and the barometric
pressure.
At the conclusion of the run. turn o3 the
timer and the sample pump, remove the probe
from the stack, and record the final gas meter
volume reading. Conduct a leak check'as
described  Initial bare me trie pressure for the test
penod. mm Kg.
To, o Absolute meter temp era rare for the
test period. "K.
7	Emission Rate Procedure
The emission rate procedure is the same as
described tn Method SA. Section 7. exceot
that the timer is needed and is operated as
described in this method.
a. Bibliography
Tha bibliography is the same as desenbed.
in Method SA. Section 8.
*	•	•	*	I
& By revising Performance 2 and
Performance 3 of Appendix B of 40 C7R
Part 60 to read as Follows:
Appendix 3—Performance Specifications
•	• • • •
Performance Specificatior 2—Specifications
and Test Procedures for SO, and A'£?,
Continuous Emission Monitoring Systems in
Stationary Sources
1.	Applicability and Principle
1.1 Applicability. This specification is to
be used for evaluating the acceptability of
SOi and NO, continuous emission monitoring
systems (CEMS) after the initial installanon
and whenever specified in an applicable
subpart of the regulaaons. The CEMS may
include, for certain stationary sources,
diluent (Ot or C0>) monitors.
L2 Pnnaple. Installation and
measurement location specifications,
performance and equipment specifications,
test procedures, and data reduction
procedures are included in this specification.
Reference method {RM) tests and calibration
dnft tests are conducted to determine
conformance of the CEMS with the
specification.
2.	Definition*
2.1 Continuous Emission Monitoring
System (CEMS). The total equipment
required for the determination of a gas
concentration or emission rate. T>e system
consists of the fallowing maiar subsystems:
2.1.1	Sample Interface. That portion of the
CEMS that is used for one or more of the
following* Sample acquisition, sample
transportation, and sample conditioning, or
protection of the monitor from the effects of
uie stack efiluent
2.1.2	Pollutant Analyzer. That portion of
the CStIS that senses the pollutant gas and
generates an output that is proportional to the
gas concentration.
2.1.3	Diluent Analyzer (if applicable}.
That portion of the CEMS that senses the
diluent gas (e g_ CO, orC>] and generates an
output that is proooraonal to the gas
concentration.
:.l 4 Data Recorder. That portion of the
CEviS that provides a permanent record of
the analyzer output The data recorder may
include automatic data reduction caoaoilities.
12 Pci-t CEMS. A CEMS that measures
the gas concentration either at a single point
or along a path that Is equal to or less than 10
percent c f the equivalent diameter of the
stack or duct cross section.
2.3	Path CEMS. A CEMS that mesures the
gas concentration along a path that is greater
than 10 percent of the equivalent diameter of
the stack or duct cross section.
2.4	Span Value. Tha upper limit of a gas
concentration measurement range that is
specified for atfected .source categories in the
applicable suboart of the regulations
2-5 Relative Accuracy. (RA). The absolute
mean difference-between the ;as
concentration or emission rate determined by
the CEMS and the value determined by the
reference tr.ethon(s) plus the 15 percent error
confidence coefficient of a ser.es of tests
divided by the mean of the reference method
(RM] tests or the applicable emission limit.
2.8	Cahbrction Drift (CD). The difference
in the CEMS output readings from the
established reference v'ai-e after a stated
period of operation during which no
unscheduled maintenance, repair, or
adjustment took place.
2.7 Cenav.-dal Area. A concentric area
that is geometrically jimiftr to the stack or
duct cross section and is no greater than 1
percent of 'he stack or duct rrass-seclianal
area.
2.9	Representor:-™ Results. As defined by
the RM test procedure ouuned tn this
specification.
3. Installation crd Mearurenert Location
Specifications
3.1 CEMS 'r.siai'.:t.on and Measurement
Location. Install the CEMS at an accessible
location where the pollutant concentration or
emission rat? measaements are directly
representative or can be corrected so as to be
representative of the total emissions from the
affected facility Then select representative
measurement points or paths for monitoring
such that the CEMS will pass the rsiatne
accuracy (RA) 'est (see Section 7]. If the
cause of failure to meet the 7>-\ test is
determined to be the measurement locaach,
the CEMS may be required to be relocated
Suggested measurement locations and
points or paths are listed below; other
locations and points or paths may be less
Likely to provide data that v. 11 meet the RA
requirements.
3.1.1	CEMS Location It is suggested that
the measurement location be at least two
equivalent diameters downstream from the
nearest control device or other point at which
a change in the pollutant concentration or
emission rate may occur and at least a haif
eouivalent diameter upstream from the
effluent exhaust
3.1.2	Point CEMS. It is suggested that the
measurement point, be (1) no less than 1.0
mater from the stack or dun walL or (2)
within or centrally located over the
centrotdai area of tie stack or duct cross
secion.

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