EPA-600/4-76-038
July 1976
Environmental Monitoring Series
THE APPLICATION OF EPA METHOD 6 TO
HIGH SULFUR DIOXIDE CONCENTRATIONS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five 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 a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
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 through the National Technical Informa-
tion Service. Springfield. Virginia 22161.
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THE APPLICATION OF EPA METHOD 6 TO HIGH SULFUR DIOXIDE CONCENTRATIONS
by
Joseph E. Knoll and M. Rodney Midgett
Quality Assurance Branch
Environmental Monitoring and Support Laboratory
Research Triangle Park, North Carolina 27711
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
-------
DISCLAIMER
This report has been reviewed by the Environmental Monitoring and
Support Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
ii
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CONTENTS
Page
List of Tables iv
Acknowledgments v
I Introduction 1
II Experimental 3
III Results and Discussion 5
IV Conclusions 12
V References 13
VI Appendix - Method 6 — Determination of Sulfur Dioxide 14
Emissions from Stationary Sources
m
-------
LIST OF TABLES
Number Page
1 Comparison of Prepared Gas Mixtures with
Values Obtained Using Method 6 6
2 Sulfur Dioxide Collection Efficiencies at
Various Concentrations 7
3 Effect of Readdition of H202 to Method 6
Impingers After Sample Collection 9
4 Test for the Presence of Peroxysulfates in 3%
H0 Solutions After Sulfur Dioxide Collection 11
iv
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ACKNOWLEDGMENTS
The authors wish to thank the following members of this Branch:
Mr. Berne I. Bennett for preparing sulfur dioxide/air mixtures and
Mr. Robert G. Fuerst for the iodimetric standardization of the sodium
metabisulfite solution used in this study.
-------
SECTION I
INTRODUCTION
The Quality Assurance Branch (QAB), Environmental Monitoring and
Support Laboratory, Environmental Research Center,^of the Environmental
Protection Agency, Research Triangle Park, North Carolina is engaged in
a program to evaluate methods, recommended and promulgated, for the
measurement of pollutant emissions from stationary sources. The present
investigation deals with an evaluation of EPA Method 6 -- a procedure for
the determination of sulfur dioxide emissions from stationary sources.
The study also attempts to answer certain questions regarding the
collection efficiency of the method and its usefulness at S02 concen-
trations higher than those previously employed.
Method 6 is applicable to the measurement of S02 emissions from
2
fossil fuel fired steam generating units. The standard of performance
is expressed in terms of an allowable SOo emission per thermal unit
(1.4 g/10 cal when liquid fuel is burned and 2.2 g/10 cal when fossil
fuel is burned). This standard, depending upon the proportion of excess
3
air, is equivalent to an SOp concentration in the 1000-1800 mg/m range.
4
Method 6 has been subjected to ruggedness testing and to precision and
5 3
accuracy studies over the 200-2000 mg/m concentration range. Results
of these investigations establish that the method is accurate below
500 mg/m3 but indicate that it acquires a S^lJLpercent negative bias
" 3
belowjthe true concentration, when S02 concentrations exceed 800 mg/m .
The present investigation is concerned with the validity of the latter
contention and with examination of features of the method that may
contribute to inaccuracy. Further, it is desirable to have a method
-------
that is accurate at higher SQy concentrations, as for example, in the
analysis of Claus Sulfur Recovery plant effluents in which S02 concen-
3
trations exceed 3000 mg/m . This report therefore presents information
obtained on the response of Method 6 at S02 concentrations up to 80,000
mg/m .
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SECTION II
EXPERIMENTAL
Method 6 analytical and sampling procedures (described in
Appendix I) were used with only minor modifications. The essential
features of Method 6 rely upon the following sequence: a measured
volume of gas is collected and passed through a filter to remove
particulate; through a midget bubbler containing 80% isopropyl alcohol
solution and glass wool to remove acid mist; and, finally, through two
midget impingers containing 3% ttp®?' wn^c'1 aDsor':)s S02 gas and oxidizes
it to FUSO,. The latter solutions are combined and analyzed for sulfate
by the barium-thorin method. Two modifications to the sampling trains
were made: inclusion of additional sulfur dioxide-absorbing impingers
and separate analysis of the impingers. In some instances, when quantities
of S02 were sampled that were sufficiently large to exhaust the ^02 in an
absorbing solution, additional H202 was added to determine the presence
of unreacted sulfite. An FLOo solution containing copious quantities
of absorbed SOo was tested for the presence of peroxysulfates. This
test was accomplished by boiling for 2 hours and comparing the solutions
with an unboiled aliquot that had been measured immediately after sample
collection. A similar test was carried out using reagent grade potassium
peroxydisulfate (K2S2Og) in dilute perchloric acid solution. A solution
of iodimetrically measured sodium metabisulfite (Na2S205) was subjected
to barium-thorin analysis after addition of \\J^2'
3
A 5270 mg/m sulfur dioxide/nitrogen standard gas mixture was
obtained from a commercial gas supplier; S02/air mixtures of 13,000,
3
63,900 and 79,900 mg/m were prepared by QAB. The tanks were connected
to a laboratory gas manifold by means of stainless steel tubing. A
3
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T-joint afforded symmetrical sampling ports to which the sampling
trains could be connected and duplicate samples withdrawn. The
gases were used undiluted and the system was operated slightly above
atmospheric pressure.
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SECTION III
RESULTS AND DISCUSSION
The S0? concentrations of several bottled gas mixtures were analyzed
and the results are compared with the values stated by the manufacturers.
This comparison is illustrated in Table I. Both positive and negative
deviations occurred. When a calibration gas was used (5,270 mg S02/m ),
the observed deviation was positive. Negative deviations were found when
mixed gases prepared by QAB were employed. However, the latter tanks were
not preconditioned nor analyzed by an independent means. The expected
increase in negative bias with increasing S02 concentration based on a
5 3
previous study , which described the method as accurate below 500 mg/m ,
3
but acquiring a negative bias above 800 mg/m , did not occur. See Table I.
Table II contains results of measurements which show the percent of
the total S02 sampled which was collected in each impinger. The Table also
includes values of the quantity of gas sampled as well as the SOp concen-
tration. There is no evidence for a dependency of the measured S0? value
on the quantity of gas sampled. Increasing the sampling flow rate from one
to three 1/min did not produce an increase in the fraction of the SO^ sample
collected in the second h^Op impinger. The 80% isopropyl alcohol bubbler
retained only traces of S02- Nearly all of the sample was collected in
the first HLOp impinger. An exception occurred when large volumes of
highly concentrated gas were sampled. In those instances, the use of
additional impingers assured adequate sample collection efficiency.
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Table 1. Comparison of Prepared Gas Mixtures with
Values Obtained Using Method 6.
Prepared Cone.
3
mg SC^/m
5,270*
13,300
63,900
79,900
Measured Cone.
mg SOp/ro
5,860
12,300
60,600
75,900
Relative
Deviation
+11.2
-7.5
-5.2
-5.0
Calibration gas mixture.
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Table 2. Sulfur Dioxide Collection Efficiencies at Various Concentrations
Sample
1
2
3
4
5
6
7
8
9
10
11
12
Metered
Volume
liters
8.2
11.1
20.3
61.4
20.7
21.2
20.8
5.6
8.3
11.1
20.5
35.4
S0?
Cone.
mg/m^
5,740
6,050
5,800
5,810
12,300
60,050
61,150
76,500
77,400
74,700
76,000
74,800
Measured Impinger Collection as Percent of
Total Sample
IPA Bubbler
NIL
NIL
NIL
NIL
0.05
0.02
0.06
0.06
NIL
0.05
0.001
0.001
1st H202
100
100
99.4
97.3
99.4
67.9
72.3
99.3
98.9
99.1
57.5
33.1
2nd H202
NIL
NIL
0.6
2.6
0.5
31.9
27.5
0.6
1.1
0.9
42.3
33.0
3rd H202
NIL
NIL
NIL
0.04
NIL
0.17
0.18
NIL
0.01
NIL
0.2
32.2
a6as samples were collected at a flow rate of one liter/min, except as noted.
Gas sample collected at three liter/min.
CA fourth and fifth
"•mPin9er analyzed 1.6 and 0.1 percent, respectively.
-------
A test was carried out to determine if unreacted S02 was present,
after sample collection, in the absorbing solutions used in the Method 6
train. Particular attention was given to the 80% isopropyl alcohol bubbler
that contained no added oxidant and in SCL absorbing solutions in which
the H202 had been depleted. For this purpose, a quantity of H202 sufficient
to raise the concentration by an additional 3% was added to aliquots of
the absorbing solutions. The solutions were then analyzed for sulfate.
Results were compared with measurements of identical aliquots that had
received no additional quantity of H202. Table III shows the results of
this comparison. Method 6 impingers contain approximately 14 millimoles
of H202 which reacts with SCL on a mole-for-mole basis. Table III shows
that the first impinger had its peroxide depleted, the second was partially
depleted; relatively little of the peroxide in the third impinger was con-
sumed. After readdition of peroxide, the quantity of sulfate detected in
the first H202 impinger increased, but by less than 1%. Values corresponding
to the other absorbing solutions actually decreased. However, those changes
were also small and probably represent measurement variations. Thus, the
results in Table III indicate that no unreacted S02 was detected by the
experiment under consideration.
8
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Table 3. Effect of Readdition of hLOg to Method 6 Impingers after
Sample Collection
S02 Collected Per Impinger3
mi Hi moles
Impinger
I PA Bubbler
1st H202
2nd H^
3rd H202
With Addition
0.0123
14.42
5.37
0.0282
Without Addition
0.0124
14.37
5.46
0.0288
aAfter collecting 20.82 std. liters of gas containing 60,600 mg S0?/m .
-------
A test was also made to determine if peroxysulfates were produced
during sample collection. Previous stoichiometric measurements have
shown that the primary oxidation product in the SCL/^Op reaction is
o
sulfate and that infinitesimal amounts of other substances were formed.
However, peroxy-compounds have been postulated to be intermediates in
the reaction between bisulfite ion and H^CL. Since these compounds are
insensitive to barium-thorin analysis, the conversion of S02 to these
species would result in erroneously low measurements. Above 90°C,
aqueous solutions of peroxysulfates are rapidly decomposed to sulfates.
Therefore, the following test was made to determine if peroxysulfates
were formed under the conditions of the present study. Sulfur dioxide
was collected in a 3% FLOp solution. An aliquot of the freshly prepared
solution was analyzed by the barium-thorin method; another aliquot was
measured after boiling for three hours. A comparison was made with a
quantity of KgSpOg in dilute HC10. solution that had received similar
treatment. The result, listed in Table IV, was only a negligible change
in the sulfate concentration after boiling. It must therefore be con-
cluded that no significant quantity of peroxysulfates had been present.
A further test for the efficiency of conversion of sulfur(IV) to
sulfur(VI) by 3% H202 solution was carried out as follows: A solution of
Na2S205 was made 3% in H202 and 0.015N in HCIO^ and analyzed by the
barium-thorin method. The results were compared with an iodimetric
analysis. The iodimetric and barium-thorin analyses yielded 441 and
454 micrograms of S02/ml, respectively.
10
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Table 4. Test for the Presence of Peroxysulfates in 3% HLCU Solution
after Sulfur Dioxide Collection
SO^ Detected
Solution Millimoles
S02 in 3% H202, freshly prepared 3.964
S02 in 3% H202, after boiling 3.993
K2S2°8 in 3% H2°2' freshly Prepared
K2S2Og in 3% H202, after boiling 0.214
o
aAfter collecting 20.82 std. liters of gas containing 12,300 mg S02/m
in air.
In 15 ml of solution.
C25 ml of 3% H202 solution, containing 0.004619 M K^Og and 0.012 M HC104.
11
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SECTION IV
CONCLUSIONS
A previous report indicating that Method 6 suffers from a negative
bias below the true value when measuring S02 concentrations greater than
3
2000 mg/m was not confirmed by the present study. Measurements made
using a calibration gas and other prepared gas mixtures in the 5000
to 80,000 mg S02/m concentration range did not produce consistently low
results. Analysis of individual impingers in multiple impinger trains
showed that more than 99% of the S02 under analysis was collected in the
first two impingers, except when sufficient sample was collected to
deplete the hLOp in the absorbing solutions, or when excessively high
flow rates were used. Tests also showed the absence of S02 retention in
the isopropyl alcohol bubbler, absence of unreacted S02 in the peroxide
absorbing solutions and absence of peroxysulfates. Further, analysis
of a standardized bisulfite solution yielded results consistent with an
5
iodimetric analysis. From the above considerations and earlier studies,
it must be concluded that Method 6 is efficient for the measurement of
3
gaseous S02 in the 200 to 80,000 mg/m concentration range, provided that
a sample flow rate of about 1 liter/min is maintained and a maximum volume
of about 20 liters of gas is sampled at the higher concentration.
12
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SECTION V
REFERENCES
1. "Standards of Performance for Mew Stationary Sources," Federal
Register. Vol. 36_, No. 247, December 23, 1971, pages 24890-24892.
2. "Standards of Performance for New Stationary Sources," Federal
Register, Vol. 36_, No. 247, December 23, 1971, page 24879.
3. de Lorenzo, 0. Combustion Engineering. Riverside Press, Cambridge,
Mass., 1948.
4. Hamil, Henry F., "Laboratory and Field Evaluations of EPh Methods II,
VI and VII," EPA-650/4-74-039, pages 31-40.
,- Hamil, Henry F. and David E. Camann. "Collaborative Study of Method ,-—
for the Determination of Sulfur Dioxide Emissions from Stationary
Sources." EPA-650/4-74-024, pages 10-26.
6. Berlie, E.M., R. K. Kerr, and R. P. Rankine. "The Role of the Claus
Sulfur Recovery Process in Minimizing Air Pollution," presented at the
67th Annual Meeting of the Air Pollution Control Association, Denver,
Colorado, June 6-13, 1974.
7. Fritz, James S. and Stanley S. Yamamura, "Rapid Microtitration of
Sulfate," Analytical Chemistry. 27: 1461, 1955.
8. Mader, P. M., "Kinetics of the Hydrogen Peroxide Sulfite Reaction in
Alkaline Solution," Journal of the American Chemical Society, 80: 2634,
1958.
9. Hoffman, M. R. and J. 0. Edwards, "Kinetics of Oxidation of Sulfite
by Hydrogen Peroxide in Acidic Solution," Journal of Physical Chemistry,
79: 2096, 1975.
10. Kolthoff, I. M. and I. K. Miller, "The Chemistry of Persulfate. I. The
Kinetics and Mechanism of the Decomposition of the Persulfate Ion in
Aqueous Medium," Journal of the American Chemical Society, 73: 3055,
1951.
13
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APPENDIX
METHOD 6 — DETERMINATION OF SULFUR DIOXIDE
EMISSIONS FROM STATIONARY SOURCES
14
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21S90
RULES AND REGULATIONS
PLANT.
DATE_
RUN NO.
CONTAINER
NUMBER
1
2
TOTAL
WEIGHT OF PARTICULATE COLLECTED.
mg
FINAL WEIGHT
:XL
TARE WEIGHT
IX
WEIGHT GAIN
•
FINAL
INITIAL
LIQUID COLLECTED
TOTAL VOLUME COLLECTED
VOLUME OF LIQUID
WATER COLLECTED
IMPINGER
VOLUME.
ml
SILICA GEL
WEIGHT.
9
fl*| ml
CONVERT WEIGHT OF WATER TO VOLUME BY DIVIDING TOTAL WEIGHT
INCREASE BY DENSITY OF WATER. {1 g. ml):
= VOLUME WATER, ml
Figure5-3. Analytical data.
6.6.2 Concentration in Ib./cu. ft.
'--'— = 2.1>05X10-';?—
Vlioro:
pis. Ib./f ••.{., tin \-:-.*i*.
Mir II).
in-.iil.-r in .<: :
equation 5-5
Mn -Total aiiiouut of paniculate matter collected,
inf.
V™tl-|--Volume of p:is sample through dry pas rnclT
f--|:inn.=U> of water, 1 p. ml.
B = Id.-al pas eon.-U.jit, 21.>3 Inches Hg-cn. ft. 11).
m,.l.. JH.
MojO-Mul'VuJar wotrlit of water, IS Ib./lb.-mola,
V«e« Volume of c:is ••.!::[>> ttsroiicn the dry gas meler
(mrt'T Cottihf I.H15 . CU. ft.
T«a"Ab^)hito avi-r.u:i» dry gas metor temperature
Pb«. = B:irorm-tric prc.. Indies ITf.
Aa = CroN«-s.ictioiial area of nozzle. «q. ft.
6.8 Acceptable results. The following
range sets the limit on acceptable Isokinetic
sampling results:
If 90^< I < llOTe, the results are acceptable.
otherwise, reject the results and repeal,
the test.
7. Reference.
Addendum to Specifications for Incinerator
Testing at Federal Facilities, PHS, NCAPC.
Dec. 6.1967.
Martin, Robert M., Construction Details of
Isokinetic Source Sampling Equipment, En-
vironmental Protection Agency, AFTD-0531.
Rom, Jerome J., Maintenance, Calibration.
and Operation of Isokinetic Source Sam-
pling Equipment. Environmental Protection
Agency, APTD-0576.
Smith, W. S., R. T. Shigehara, and W. F.
Todd, A Method of Interpreting Stack Sam-
pling Data, Paper presented at the 63d An-
nual Meeting of the Air Pollution Control
Association, St. Louis, Mo., June 14-19, 1970.
Smith. W. S., et al.. Stack Gas Sampling
Improved and Simplified with New Equip-
ment. APCA paper No. 67-119, 1967.
Specifications for Incinerator Testing at
Federal Facilities, PHS, NCAPC, 1967.
METHOD 8 DETERMINATION OF STJLFTTB DIOXIDE
EMISSIONS FROM STATIONARY SOURCES
1. Principle and applicability.
1.1 Principle. A gas sample is extracted
from the sampling point In the stack. The
acid mist, including sulfur trioxide. is sepa-
rated from the sulfur dioxide. The sulfur
dioxide fraction is measured by the bnnum-
thorin tltratlon method.
1.2 Applicability. This method is appli-
cable for the determination of sulfur dioxiae
emissions from stationary sources only when
specified by tho test procedures for determin-
ing compliance with New Source Performance
Standards.
2. Apparatus.
2.1 Sampling. See Figure 6-1.
2.1.1 Probe—Pyres1 gloss, approximately
6 to 6 mm. ID, with a heating system to
prevent condensation and a filtering medium
to remove particulate matter including sul-
f uric acid mist.
2.1.2 Midget bubbler—One, with glass
wool packed In top to prevent sulfuric acid
mist carryover.
2.1.3 Glass wool.
2.1.4 Midget impingers—Three.
2.1.5 Drying tube—Packed with 6 to 16
mesh Indicating-type silica gel, or equivalent.
to dry the sample.
2.1.6 Valve—Needle valve, or equivalent,
to adjust flow rate.
2.1.7 Pump—Leak-free, vacuum type.
2.1.8 Rate meter—Rotamptt-r or equiva-
lent, to me.-usure a 0-10 sc.f.h. flow range.
2.1.9 Dry pus meter—SuiiU-iemly accurate
to measure the s.ur.ple volume Within !•'.
2.1.10 Pilot tube—Type S. or equivalent.
5-0 'Trade names.
FEDrRAL SCCISTER, VOL 36. NO. 547—THURSDAY, DECEMBER 23. 1971
15
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necesRary only If a sample traverse la re-
quired, or 11 stuck gas velocity varies with
time.
2.2 Sample recovery.
9,3.1 Glass wash bottles—Two.
2.2.2 Polyethylene storage bottles—To
store Imptnger samples.
2.3 Analysis.
PROBE (END PACKED
WITH QUARTZ OR
PVREXWOOL
WE S PITOT TUBE
SILICA GEL DRVING TUBE
MIDGET BUBBLER MIDGET IMPINGERS
GLASS WOOL
\ 0/0
THERMOMETER
fUMP
DRY GAS METER HOTAMETER
Figure 6-1. S02 sampling train.
velocity. Take readings at least every five
minutes and when significant changes In
stack conditions necessitate additional ad-
justments In flow rate. To begin sampling,
position the tip of the probo at the first
sampling point and start the pump. Sam-
ple proportionally throughout the run. At
the concUmion of each run, turn oil the
pump and record the final readings. Remove
the probe from the stack and disconnect It
from the train. Drain the lea bath and purge
the remaining part of the train by drawing
clean ambient air through the system for 15
minutes.
4.2 Smiiplc recovery. Disconnect the 1m-
plngerti alter purging. Discard the contents
of the midget bubbler. Four the contents of
the midget implngcrs into a polyethylene
shipment lioUle. Rinse the three midget Im-
plngcrs and the connecting tubes with dis-
tilled water and add these washings to the
same storage container.
4.U Sample analysis. Transfer the contents
of the storage container to a 50 ml. volu-
metric flask. Dilute to the mark with de-
Ionised, distilled water. Pipette a 10 ml.
aliquot of this solution Into a 125 ml. Erlcn-
meyer flask. Add 40 ml. of Isupropanul and
two to four drops of Uiorln Indicator. Titrate
to a pink endpolnt using 0.01 N barium
pcrchlorate. Bun a blank with each series
of samples.
5. Calibration.
5.1 Use standard methods and equipment
9.3.1 Pipettes—Transfer type, B ml, and
10 ml, atees (0.1 mi, divisions) and 25 ml.
elzo (0.2 ml. divisions).
3.3.2 Volumetric flasks—SO ml., 100 ml.,
and 1,000 ml.
2 3.3 Burettes—5 ml. and 50 ml.
2.3.4 Erlcnmeyer flask—125 ml.
3. Reagents.
3.1 Sampling.
3.1.1 Water—Deionlzed, distilled.
3.1.2 Isopropanol, 80 %—Mix 80 ml, of Iso-
prnpanol with 20 ml. of distilled water.
3.1.3 Hydrogen peroxide, 3%—dilute 100
ml. of 30'.'. hydrogen peroxide to 1 liter with
distilled water. Prepare fresh dally.
3.2 Sample recovery.
3.2 i Water—Dclonlzed, distilled.
3.22 Isoprupunol, BO'.i.
33 Annhbls.
33.1 WatiT—Delonlzed, distilled.
33.2 I.Miprcpanol.
3.3.3 Thorln Indicator— l-(o-arsonophen-
yla<:rj|-2-nuphthol-3.6-dlsulfonlc acid, dlso-
dlum s-iit (or equivalent;. Dissolve 0.20 g. In
100 ml. dl.sined water.
3 3.4 Burl mil pcrchlorate (0.01 N)—Dls-
1'iK-e 1.95 *. of burlum perchlorate
IBfuC.'O.j, • 311 O| in 200 ml. distilled water
No.2i7-ri.il 3
which have been approved by the Admlnli-
trator to calibrate tlio rotamcter. pilot tube,
dry gas meter, and probe healer,
5.2 Standardize the barium perchlorftt*
ngalnst 25 ml. of standard sulfurlc acid con-
taining 100 ml. of Isopropanol.
0. Calculations.
0.1 Dry gas volume. Correct the sample
volume measured by the dry gas meter to
standard conditions (70* P. and 20.02 Inches
Hg) by using equation 6-1.
i n .* 1 1 K
/V»PI,.A
V. '!',„ / t
tiuut ion 0 - 1
where:
Vm.,4 — Volume of gus sample through the
dry gus meter (standard condi-
tions). cu. ft.
Vlu— Volume of gas sample through the
dry gas meter (meter condi-
tions), cu. ft.
T.,4— Absolute temperature at standard
conditions, 530* R.
T — Average dry gas meter temperature.
°R.
PMt— Barometric pressure at the orlnce
meter, Inches Hg.
P,,4= Absolute pressure at standard con-
ditions. 20.02 Inches Hg.
0.2 Sulfur dioxide concentration.
and dilute to 1 liter with Isopropanol. Stand-
ardize with sulfurlc acid. Barium chloride
may be used.
3.3.5 Sulfurlc acid standard (0.01 »)~
Purchase or standardize to ±0.0002 N
against 0.01N NnOH which baa previously
been standardized against potassium acid
phthalale (primary standard grade).
4, Procedure.
4.1 Sampling.
4.1.1 Preparation of collection train. Pour
15 ml. of 80% Isopropanol Into the midget
bubbler and 15 ml. of 3% hydrogen peroxide
into each of the first two midget impingers.
Leave the final -midget Implngcr dry. Assem-
ble the train ns shown In Figure 6-1. Leak
check the sampling truin at the sampling
site by plugging the probe Inlet and pulling
a 10 Inches Kg vacuum. A leakage rate not
In excess of 1% of the sampling rate Is ac-
ceptable. Carefully release the probe inlet
plug and turn oit the pump. Place crushed
ice around the Implngcrs. Add more ice dur-
ing the run to keep tlic temperature of the
gases leaving the loot Implngcr at 70° P. or
less.
4.1.2 Sample collection. Adjust the E.im-
ple How rate proportional to the stack gus
where:
Can.,—Concentration of sulfur dioxide
at standard conditions, dry
basis, Ib./cu. ft.
7.05X10-'—Conversion factor, Including the
number of grams per gram
equivalent of sulfur dioxide
(32 g./g.-eq.). 453.6 g./lb., and
1,000 ml./l.. lb.-l./g.-ml.
V, —Volume of barium perchlorate
tltrant used for the sample,
ml.
Vlk» Volume of barium perchlorate
tltrant used for the blank, ml.
.!¥•= Normality of barium perchlorate
tltrant, g.-eq./l.
V.ou—Total solution volume of sulfur
dioxide, GO ml.
V,—Volume of sample aliquot ti-
trated, ml.
Vm.,j=-Volume of gas sample through
the dry gas meter (standard
conditions), cu. ft., see Equa-
tion 6-1.
equation 6-2
7. References.
Atmospheric Emissions from Sulfurlc Acid
Manufacturing Processes, U.S. DIfEW, PHS,
Division of Air Pollution, Public Health Serv-
ice Publication No. 999-AP-13, Cincinnati,
Ohio, 1005.
Corbett, P. P., The Determination of BO,
and SO, In Flue Oases, Journal of the lustl-
tuto of Fuel, 24:237-243, 1801.
Matty. R. E. and E. K. Dlehl, Measuring
Flue-Gas SO3 and SO3, Power 101:94-87, No-
vember, 1357.
Patton, W. F. and J. A. Brink, Jr., New
Equipment and Technique for Sampling
Chemical Process Gases, J. Air Pollution Con-
trol Association, 13, 1C2 (19G3).
METHOD 7—DETERMINATION OF NITROGEN OXIDE
EMISSIONS' FROM STATIONARY SOURCES
1. Principle and applicability.
1.1 Principle. A grab sample Is collected
in an evacuated llask containing a dilute
sulfurlo acid-hydrogen peroxide absorbing
solution, and the nitrogen oxides, except
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5
FEDCrtAL REGISTER, VOL. 36, NO. 247—THURSDAY, DECEMBER 23, 1971
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. RtPORT NO.
2.
4. TITLE AND SUBTITLE
THE APPLICATION OF EPA METHOD 6 TO HIGH SULFUR DIOXIDE
CONCENTRATIONS
7. AUTHOR(S)
Joseph E. Knoll and M. Rodney Midqett
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Research and Development
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Research Trianqle Park, North Carolina 27711
12/SPONSORING AGENCY NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Trianqle Park, North Carolina 27711
15. SUPPLEMENTARY NOTES
3. RECIPIENT'S ACCESSION-NO.
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
1HD621
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT AND PERIOD COVERED
Fi nsl
14. SPONSORING AGENCY CODE
EPA-ORD
16. ABSTRACT
The application of EPA test method (M-6) to the analysis of higher
sulfur dioxide concentrations than had previously been employed has been
studied. The use of prepared gas mixtures showed that the method is
efficient for the measurement of gaseous sulfur dioxide in concentrations
of up to 80,000 mg/m . The investigation also showed no evidence of
retention of significant quantities of sulfur dioxide in the isopropyl
alcohol bubbler or of the production of sulfur compounds that are in-
sensitive to barium-thorin analysis. When multiple impinger trains were
employed, analysis of individual impinger contents showed that more than
99% of the sampled sulfur dioxide was collected in the first two impingers,
even at the higher concentration, except when sufficient sample was
collected to deplete the hydrogen peroxide in the absorbing solutions or
when excessively high flow rates were used. These results contradict
earlier reports that Method 6 suffers from a negative bias at high sulfur
dioxide concentrations.
17.
a. DESCRIPTORS
Sampling
Sulfur dioxide
Air pollution
Stack gases
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED TERMS C. COS ATI Field/Group
13B
19. SECURITY CLASS (This Report) 21. NO. OF PAGES
Unclassified 22
20. SECURITY CLASS (This page) 22. PRICE
llnrlassif ipH
EPA Form 2220-1 (9-73)
17
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