&EPA
United States
Environmental Protection
Agency
Environmental Monitoring and Support EPA-600/4-79-006
Laboratory February 1979
Research Triangle Park NC 27711
Research and Development
Stability
Evaluation of
Ambient
Concentrations of
Sulfur Dioxide,
Nitric Oxide and
Nitrogen Dioxide
Contained in
Compressed Gas
Cylinders
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
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.
-------
STABILITY EVALUATION OF AMBIENT CONCENTRATIONS OF
SULFUR DIOXIDE, NITRIC OXIDE, AND NITROGEN DIOXIDE
CONTAINED IN COMPRESSED GAS CYLINDERS
by
Berne I. Bennett
Quality Assurance Branch
Environmental Monitoring and Support Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
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 publica-
tion. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
11
-------
FOREWORD
The assessment of air quality must rely on instrumental measurements of
specific air contaminants. Air monitors require a calibration source that is
often contained in a compressed gas cylinder. The Environmental Monitoring
and Support Laboratory continues to investigate the commercial availability
of stable reactive gas standards.
This report presents the results of tests that were conducted over a 2-yr
period to evaluate the trustworthiness of available sub-ppm standards of sul-
fur dioxide, nitric oxide, and nitrogen dioxide contained in aluminum compressed
gas cylinders.
Thomas R. Hauser, Director
Environmental Monitoring and Support
Laboratory
Office of Research and Development
111
-------
ABSTRACT
Compressed gas samples of sub-ppm concentrations of sulfur dioxide, nitric
oxide, and nitrogen dioxide were evaluated for long- and short-term stability.
Except for several stainless steel tanks, the samples were contained in aluminum
cylinders. A degree of stability was achieved over the short term; however, all
of the samples were considered unstable over the term of the evaluations.
Utilization of ambient level compressed gas samples may be considered where
relative stability is required for no more than 2 or 3 months.
IV
-------
CONTENTS
Foreword . . . . iii
Abstract iv
Figures vi
Tables vii
Abbreviations and Symbols viii
Acknowledgment ix
1. Introduction 1
2. Conclusions and Recommendations 3
3. Experimental 5
Sulfur Dioxide . 5
Principle of Measurement 5
Calibration 5
Analysis 6
Oxides of Nitrogen 10
Principle of Measurement 10
Calibration 10
Analysis 11
4. Results and Discussion 13
Sulfur Dioxide 13
Oxides of Nitrogen 18
Nitric Oxide 18
Nitrogen Dioxide 18
References 23
v
-------
FIGURES
Number Page
la Gas blending system. . . 7
Ib Schematic of gas blending system 8
2 Permeation tube oven assembly 9
3 Delivery of sample gas to analyzer 9
4 Stability of Group 1 S0_ compressed gas samples 16
5 Stability of Group 2 SO_ compressed gas samples 16
6 Stability of Group 3 SO compressed gas samples 17
7 Stability of Group 4 SO compressed gas samples 17
8 Stability of NO compressed gas samples 21
9 Stability of N0? compressed gas samples 21
VI
-------
TABLES
Number Page
1 SO Evaluation Cylinders: Group 1 14
2 SO Evaluation Cylinders: Group 2 14
3 SO Evaluation Cylinders: Group 3 15
4 SO Evaluation Cylinders: Group 4 15
5 NO Evaluation Cylinders 19
6 NO Evaluation Cylinders 20
7 NO2 Evaluation Cylinders 22
VII
-------
LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
approx. — approximately
°C — degree Celsius
cm — centimeter
EMSL — Environmental Monitoring and Support Laboratory
EPA — U.S. Environmental Protection Agency
m — cubic meter
min — minute
mV — millivolt
NBS — National Bureau of Standards
nm — nanometer
o.d. — outside diameter
ppm — part per million
QAB — Quality Assurance Branch
RTF — Research Triangle Park, North ..Carolina
yr — year
SYMBOLS
CO
NO
N02
°
carbon monoxide
nitric oxide
nitrogen dioxide
ozone
sulfur dioxide
R
— coefficient of regression squared
Vlll
-------
ACKNOWLEDGMENT
Recognition is due staff members of the Ambient Air Section, Quality
Assurance Branch, and of Northrop Services, Inc., for diligent performance
of the many analyses contributing to development of this report.
IX
-------
SECTION 1
INTRODUCTION
The Quality Assurance Branch (QAB), Environmental Monitoring and Support
Laboratory (EMSL), U.S. Environmental Protection Agency at Research Triangle
Park, North Carolina (EPA-RTP) has been engaged in evaluating the stability of
several reactive gases contained in compressed gas cylinders. The stable
containment of sub-ppm concentrations of sulfur dioxide (SO_), nitric oxide
(NO), and nitrogen dioxide (NO ) was not considered possible until 1973, when
experiments suggested that stability might be achieved by use of high pressure
aluminum cylinders (1). The achievement and preservation, of stability of low
concentration levels of reactive mixtures require the application of a series
of cylinder pretreatments and subsequent scrupulous avoidance of atmospheric
contamination.
Several sizes of aluminum cylinders were available at the onset of this
study. Since the size 30 aluminum cylinders (0.84 m of gas) were being used
successfully in the EPA carbon monoxide (CO) performance surveys, little con-
sideration was initially given to any other size. Experiments demonstrated,
however, that size 30 cylinders contained insufficient gas for long-term use
and were frequently depleted before completion of the study. Cylinders sub-
sequently obtained for the study were of the larger size 80 (2.24 m of gas),
which proved to contain ample volume. Also utilized were several cylinders of
sizes 150 (4.2 m of gas) and 100 (2.8 m of gas).
Twenty-three samples of SO^ in a concentration range of from 0.1 to 0.9
ppm were evaluated over a 26-month period. The material appraised was pre-
pared in five different lots, including two stainless steel samples.
-------
Twenty-five aluminum cylinders and one of stainless steel comprised the
sample material for the NO evaluation. The concentration range examined was
from 0.2 to 1.1 ppm.
Twenty-six samples of NO in a concentration range of from 0.05 to 0.25
ppm were evaluated over a 10-month period; this evaluation involved aluminum
cylinders only.
-------
SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
SO samples acquired early in the evaluation program were both inaccurate
and unstable. Both of these qualities improved in the succeeding groups of
test samples, but none of the SO cylinders achieved absolute stability. Sev-
eral exhibited minimal decreases over a period of 1 to 3 months; over the term
of the evaluation, progressively greater reductions occurred. Careful avoid-
ance of atmospheric contamination was necessary to prevent any residual mois-
ture from entering the cylinders by back diffusion. The possibility of operator
contamination of the samples could not be excluded with absolute assurance;
however, all analysts handling the cylinders were cognizant of the importance
of preventing vitiation of the samples.
Eight of the 11 cylinders listed in Table 6 exhibited a constant or nearly
unchanged NO concentration for 9 months, demonstrating that it is possible to
contain sub-ppm concentrations of NO in aluminum cylinders. Between the test
periods of May and December 1976 (Table 5), 11 of the 14 cylinders remained
unchanged. The test period between November 1977 and February 1978 was one
of relative stabilization. Despite such periods of stability, however, the
overall performance during the assessment was one of unreliable stability.
The degree of short-term stability may be considered sufficient where relative
consistency over a 2- or 3-month period is adequate.
Although concentrations of several of the N0_ cylinders remained unchanged
for 3 months, the magnitude of the decreases of many others over the survey
period was so great that their utilization would be of questionable value.
-------
Even though absolute stability was not attained in our tests, the achieve-
ment of brief periods of relative stability suggests that advances in cylinder
treatment and gas handling will, in time, enable the production of stable and
reliable ultralow concentrations of reactive gas mixtures.
The evaluation of low level reactive compressed gas samples is a continu-
ing effort. Because of the need for reliable sub-ppm standards, samples from
as many different gas suppliers as practicable will be examined in a future
stability study.
-------
SECTION 3
EXPERIMENTAL
SULFUR DIOXIDE
Principle of Measurement
®
All measurements were obtained with Bendix Model 8300 Total Sulfur Ana-
lyzers (2) employing the principle of photometric detection of luminescence re-
sulting from the burning of sulfur compounds in a hydrogen-rich flame. The
primary components in this analytical process are the detector cell, burner
chamber, photomultiplier assembly, and gas and sample conduction tubing. Tub-
ing to the burner chamber that comes into contact with the sample is con-
®
structed of Teflon . The burning sulfur produces luminescence in the 394-nm
wavelength region and is coupled through an optical filter to the photomulti-
plier tube. The photomultiplier converts the luminescence into an electrical
signal that is proportional to the amount of sulfur burned. The output from
the detector cell is linearized by an exponential amplifier and presented as
a continuous readout on the panel meter and a continuous signal to a 10-mV re-
corder. A temperature controller maintains the burner block temperature at
110°C to stabilize the measurement process.
Calibration
Dynamic Dilution-
One method of calibration was dynamic dilution of a high concentration
of National Bureau of Standards (NBS) certified reference standard with SO9
free carrier air to produce working standards in the range of from 0.05 to 1.0
®
ppm. An Airco Model MB 532 Gas Blender incorporating three calibrated flow
-------
controllers was used to blend the SO with the diluent gas purified by use of
a Bendix Model 8833 Air Purification System. The blended mixture was delivered
through a glass mixing chamber to a Teflon sampling manifold. Since the
analyzer is sensitive to small pressure changes, the sample pressure was
monitored by use of a water manometer and adjusted to 0.1 inches water by
controlling the amount of sample gas vented. Teflon tubing (0.25 inches
o.d.) conducted the sample gas to the analyzer at a flow rate of approximately
175 c /min. Diagrams of the blending and delivery system are shown in Figures
la and Ib. Five SO concentrations and a zero were obtained in this manner.
The method of least squares was used to achieve a linear calibration equation
for recorder response v. SO concentration.
Permeation Tube-
Calibrations were also performed using a Bendix Model 8850 Permeation
System with a 5-cm calibrated permeation tube. A diagram of this permeation
oven is shown in Figure 2. An additional dilution step was added to obtain
lower concentration standards, enabling a calibration range of from 0.08 to
0.70 ppm. A five point plus zero linear calibration equation was determined
for recorder response v. concentration by the method of least squares. A
comparison between the two calibration methods showed that agreement over the
range tested was between 0.3% and 3%.
Analysis
Sample gas was conducted from the cylinder to the analyzer as shown in
Figure 3. A low-volume Veriflo Type 660 Pressure Regulator (without gauges)
was utilized to reduce the chances of back contamination of the cylinders and
to assure rapid and complete sample exchange. A pressure of 0.1 inches water
was maintained in the sample line. The sample was permitted to flow until a
fixed straight line trace was obtained on a strip chart recorder. The initial
sample cylinder commonly required about 60 min for a stabilized trace. Sub-
sequent samples needed approx. 15 min each to achieve a fixed response. The
SO concentrations proportional to the response were derived from the calibra-
tion equation. Duplicate analyses on different days were obtained in most
-------
Figure la. Gas blending system.
-------
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Figure Ib. Schematic of gas blending system.
-------
PERMEATION
DEVICE
SAMPLE OUTPUT
CARRIER FLOW
INPUT
ELECTRICAL INPUT
THERMO
ELECTRIC
COOLER
^TEMPERATURE
PROBE
COOLING
FINS
HOUSING
ASSEMBLY
Figure 2. Permeation tube oven assembly.
pressure gauge
(inches-water)
pressure
regulator
sample cylinder
pressure
relief valve
to analyzer sample
inlet
Figure 3. Delivery of sample gas to analyzer.
-------
cases. The results of the analyses of four groups of cylinders are summarized
in Tables 1 through 4.
OXIDES OF NITROGEN
Principle of Measurement
NO and NO measurements were obtained by use of Bendix Model 8101B
Oxides of Nitrogen Analyzers (3) employing the principle of photometric de-
tection of chemiluminescence resulting from the gas phase reaction of NO and
ozone (0 ). Since this gas phase reaction only occurs between NO and 0 , it
-J -J
is necessary to convert NO into NO so that its concentration can be measured.
Two temperature controllers are utilized: one to maintain the block tempera-
ture of the catalytic converter and the other to maintain the reaction chamber
block at 45°C to prevent formation of moisture condensation. The reaction
chamber of the detector cell provides the proper environment to assure the gas
phase reaction of NO and O~~. This reaction produces light particles or photons
that pass through the optical filter to the photomultiplier tube where they
are converted into electrical energy and amplified. The degree of gas phase
reaction is directly proportional to the amount of NO present in the air
sample, thus producing a proportional number of photons.
The principal components in this analytical process are the O generator,
catalytic converter, detector cell, reaction chamber, photomultiplier assembly,
and sample conductor tubing. To maintain the integrity of the reactive com-
ponent, the sample tubing is constructed either of Teflon or glass.
Calibration
Dynamic Dilution-
Calibration for NO was accomplished by use of a 100 ppm NBS certified
standard reference gas with a gas blending system to produce standard NO con-
centrations ranging from 0.15 to 1.20 ppm. A five point calibration was ob-
tained by this method. Figures la and Ib illustrate the blender. A baffled
10
-------
glass mixing bulb was installed at the mixture outlet to promote complete mix-
es)
ing. The mixture was conducted to the analyzer through Teflon tubing (0.25
inches o.d.). Sample pressure was monitored and controlled in the manner
described above (SO Analysis section). The method of least squares was used
to determine a linear calibration equation for analyzer response v. NO concen-
2
tration. Coefficients of linearity (R ) of 0.9999 were commonly obtained.
Permeation Tube—
®
For NO , calibration was achieved by use of Bendix Model 8850 Permeation
Systems and standard permeation tubes (NBS Standard Reference Material No. 1629)
Five point calibrations ranging from 0.17 to 1.4 ppm were obtained. The
diluent gas was high purity nitrogen which had passed through charcoal and
®
Ascarite adsorbents (4) to remove residual NO_. The blended standards were
®
delivered to the analyzer through Teflon tubing (0.25 inches o.d.). Sample
pressure was maintained at 0.1 inches water. A linear calibration equation
for instrument response v. NO concentration was determined by the method of
2
least squares. Response over the working range was linear, with an R of
0.9999.
Analysis
®
Inert Teflon and stainless steel were required to convey sample gas from
®
the cylinder to the analyzer. A low volume Veriflo Type 660 pressure regu-
lator (without gauges) was employed to reduce the risk of back .diffusion and
concomitant contamination of the cylinder. Use of this pressure regulator
lessened the equilibration time required to achieve a fixed recorder trace
from >1 hr to <10 min. Figure 3 illustrates delivery of sample gas to the
analyzer. Positive pressure of 0.1 inches water was maintained. A strip
chart recorder documented the analyzer response of individual evaluation
cylinders. NO and NO concentrations corresponding to recorder response were
calculated from the calibration equations. To determine the precision of the
measurements, duplicate analyses were performed on different days. The cumu-
lative results for each cylinder are shown in Tables 5 through 7.
11
-------
SECTION 4
RESULTS AND DISCUSSION
SULFUR DIOXIDE
In the early phase of the evaluations, some large discrepancies between
the supplier's certifications and our determinations were encountered. In all
such instances, the affected cylinders were tested by an independent laboratory
whose corroborative tests (together with our own) indicated substantial errors
in the supplier's certifications. The cylinders involved were those in Group 1
(Table 1). A progressive decline in SO. was characteristic of the entire group.
In several samples cited in Table 1, the decrease was on the order of 0.02 to
0.03 ppm between successive monthly analyses. In others, it was much greater
than 0.03 ppm/month.
The accuracy of the supplier's analyses improved in the Group 2 cylinders
evaluated over a 12-month period. As seen in Table 2, these samples were un-
stable. The average loss of SO in this group was 76%, or 0.03 ppm/month for
the life of the survey.
With the exception of one sample, the vendor accuracy of the cylinders in
Group 3 (Table 3) was on the same order as those of Group 2. This stability
assessment began in May 1977 and continued through March 1978. The average
rate of SO loss was 0.006 ppm/month. Although not completely stable, this
rate of decline was the lowest obtained up to that point, and represented a
substantial improvement over the cylinders examined earlier.
With the acquisition of two additional cylinders in July 1977, another
series of tests was begun. Four more aluminum and two stainless steel cylinders
13
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TABLE 1. SO EVALUATION CYLINDERS: GROUP 1
Cylinder
Number
FF 2249
FF 2124
FF 2136
FF 2244
FF 2246
FF 2245
Supplier
Certification
(ppm S02)
1.40
1.30
1.00
1.00
1.40
0.50
Analysis
1/76 2/76 3/76
0.89 0.87
0.70 0.72
0.57
0.50
0.76 0.77
0.29 0.32
0.85
0.67
-
0.44
0.70
0.29
Date
4/76
0.79
0.64
0.52
0.41
0.68
0.26
5/76
0.69
0.61
0.45
0.45
0.37
0.23
TABLE 2. SO
EVALUATION CYLINDERS:
GROUP
2
Cylinder
Number
CC 127
CC 141
CC 130
CC 140
CC 286
CC 146
Supplier
Certification
(ppm S02)
0.33
0.38
0.33
0.54
0.51
0.58
Analysis
1/76 3/76 4/76 5/76
0.32 0.29 0.24
0.31 0.25 0.23
0.31 0.25 0.23
0.47 0.38 0.36
0.47 0.40 0.35
0.66 0.59 0.53
0.20
0.19
0.18
0.24
0.29
0.46
Date
7/76 10/76 12/76
0.15
0.14
0.16
0.22
0.24
0.39
0.11 0.08
0.10 0.08
0.06 0.04
0.16 0.12
0.14 0.11
_ _
14
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TABLE 3. SO EVALUATION CYLINDERS: GROUP 3
Cylinder Supplier
Number Certification
(ppm S0_)
CC 5100 0.45
MM 13672 0.16
CC 4750 0.13
CC 5092 0.31
Analysis Date
5/77 7/77 12/77 1/78 3/78
0.44 0.46 0.34 0.38
0.07 0.05 0.05 0.04 0.04
0.11 0.10 0.07 0.08
0.30 0.30 - 0.25 0.24
TABLE 4. SO EVALUATION CYLINDERS: GROUP 4
Cylinder
Number
SS C118*
SS C105*
LL 4406
LL 4404
LL 4412
LL 4408
LL 4512
Supplier
Certification
(ppm SO2)
0.544
0.265
0.10
0.10
0.10
0.10
0.14
Analysis Date
12/77 1/78
0.54
0.13
0.12
0.13
0.12
0.11
0.11
0.45
0.00
0.11
0.12
0.11
0.11
0.09
3/78
0.45
-
0.10
0.11
0.11
0.11
0.08
*Stainless steel cylinder.
15
-------
E
a
a.
QC
LU
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a
a
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2
O
O
LU
Q
X
O
Q
CC
D
D
CO
TIME, months
TIME, months
Figure 4. Stability of Group 1 SO,
compressed gas samples-'
Figure 5. Stability of Group 2 SO,
compressed gas samples/
-------
0.5
E
a
a
Z
Z
LJJ
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LL4404
LL4512
0
TIME, months
TIME, months
Figure 6. Stability of Group 3 SO,
compressed gas samples.
Figure 7. Stability of Group 4 SO,
compressed gas samples."
-------
were subsequently added to this group, designated as Group 4 (Table 4). (Data
from one cylinder that was exhausted due to operator error are not included in
the table.) Examination of these specimens continued for 3 months. The degree
of stability of the aluminum cylinders over this abbreviated test period was
somewhat improved over that of Group 3, with an average decline in S0_ of
0.004 ppm/month. Of the two stainless steel cylinders, one deteriorated from
0.13 ppm to nil in 1 month, and the other achieved apparent stability at 0.45
ppm for a 2-month period after declining from 0.54 ppm. Figures 4 through 7
illustrate the loss of SO over time in the four groups.
OXIDES OF NITROGEN
Nitric Oxide
Several cylinders exhibited a relatively constant level of NO over an ex-
tended period of testing; many more evidenced reductions. Substantial errors
in the supplier's certifications were suspected, as illustrated in Tables 5
and 6. The single stainless steel cylinder admitted to the evaluation in
November 1977 exhibited a consequential reduction in NO. Figure 8 shows the
changes in NO concentration of four selected cylinders.
Nitrogen Dioxide
Ten of 26 cylinders demonstrated a degree of stability during the first
3 months after receipt. All of the samples declined materially over the 10-
month test period, with 10 being reduced to negligible NO_ content. The cumula-
tive test results are presented in Table 7. Figure 9 illustrates decline in
concentration of four representative cylinders.
18
-------
TABLE 5. NO EVALUATION CYLINDERS
Cylinder
Number
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
SSC
1573
1587
1634
1612
1595
1584
1583
1607
1585
1054
1456
1588
2501
2474
122*
Supplier
Certification
(ppm NO)
1.
1.
1.
1.
1.
1.
1.
1.
0.
0.
0.
0.
0.
0.
0.
03
02
03
02
02
03
02
03
51
51
52
51
30
30
44
3/76
1
1
1
1
1
1
1
1
0
0
0
0
0
0
.12
.14
.13
.12
.11
.12
.11
.14
.56
.57
.57
.56
.24
.25
-
Analysis Date
5/76 12/76 11/77
1
1
1
1
1
1
1
1
0
0
0
0
0
0
.09
.11
.10
.09
.08
.07
.07
.09
.53
.53
.55
.53
.23
.21
-
1
1
1
1
1
1
1
1
0
0
0
0
0
0
.09
.12
.11
.12
.03
.06
.06
.07
.53
.52
.55
.51
.20
.17
-
0.96
1.01
0.99
0.98
0.93
0.97
0.98
0.98
0.46
0.46
0.48
0.47
0.24
0.18
0.38
2/78
0.95
1.04
0.97
0.99
0.96
1.00
1.00
0.97
0.47
0.46
0.49
-
0.23
-
0.35
*Stainless steel cylinder.
19
-------
TABLE 6. NO EVALUATION CYLINDERS
Cylinder
Number
FF 1592
FF 2504
FF 2505
FF 2486
FF 2806
FF 1635
FF 1060
FF 1598
FF 2810
FF 2490
FF 2506
Supplier
Certification
(ppm NO)
1.02
0.31
0.30
0.29
0.30
0.52
0.51
0.51
0.30
0.31
0.30
3/76
1.13
0.26
0.24
0.24
0.25
0.56
0.55
0.56
0.25
0.25
0.25
Analysis
5/76
1.09
0.24
0.21
0.20
0.23
0.54
0.53
0.52
0.22
-
_
12/76
1.11
0.25
0.21
0.21
0.23
0.52
0.50
0.53
0.21
0.25
0.21
20
-------
1.5
a.
a
<
cc
o
z
o
o
LU
Q
X
O
o
en
FF1054
FF250T
FF1607:=
25
a
a
O
cc
t-
z
LU
CJ
2
O
CJ
LU
Q
X
O
Q
a
o
cc
I I I I I
TIME, months
4 6
TIME, months
10
Figure 8. Stability of NO compressed
gas samples.
Figure 9. Stability of NO compressed
gas samples.
-------
TABLE 7. N02 EVALUATION CYLINDERS
Cylinder
Number
LL 4315
LL 4331
LL 4310
LL 4354
LL 4338
LL 4321
LL 4324
LL 4327
LL 4314
LL 4333
LL 4313
LL 4329
LL 4358
LL 4320
LL 4359
LL 4353
LL 4339
LL 4349
LL 4346
LL 4335
LL 4326
LL 4325
LL 4318
LL 4348
LL 4328
LL 4312
Supplier
Certification
(ppm N02)
0.11
0.13
0.13
0.13
0.12
0.11
0.12
0.14
0.13
0.12
0.23
0.20
0.23
0.23
0.22
0.24
0.22
0.22
0.27
0.26
0.27
0.28
0.28
0.32
0.32
0.32
3/77
0.05
0.08
0.08
0.08
0.07
0.06
0.07
0.08
0.09
0.07
0.16
0.16
0.17
0.19
0.16
0.17
Q.14
0.17
0.19
0.17
0.18
0.20
0.17
- 0.22
0.23
0.25
Analysis Date
6/77
0.03
0.06
0.08
0.07
0.06
0.05
0.05
0.08
0.07
0.06
0.14
0.13
0.15
-
0.14
0.16
0.11
0.16
0.17
0.14
0.14
0.17
0.15
0.21
0.24
0.21
1/78
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
0.05
0.04
0.06
0.11
0.06
0.08
0.02
0.08
0.06
0.05
0.02
0.02
0.08
0.12
0.16
0.12
22
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REFERENCES
1. Wechter, S. G. Preparation of Stable Pollution Standards Using Treated
Aluminum Cylinders. Presentation before the Calibration Symposium,
American Society for Testing and Materials, Boulder, Colorado, 1975.
2. Bendix Model 8300 Total Sulfur Analyzer. Operation manual.
3. Bendix Model 8101B Oxides of Nitrogen Analyzer. Operation manual.
4. Mueller, P. K., Y. Tokiwa, E. R. deVera, W. J. Wehrmeister, T. Belsky,
S. Twiss, and M. Imada. A Guide for the Evaluation of Atmospheric
Analyzers. EPA 650/4-74-014, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, 1974.
23
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing!
1. REPORT NO.
EPA 600/4-79-006
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Stability Evaluation of Ambient Concentrations of
Sulfur Dioxide, Nitric Oxide and Nitrogen Dioxide
Contained in Compressed Gas Cylinders
5. REPORT DATE
February 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Berne I. Bennett
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Quality Assurance Branch, MD-77
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
10 PROGRAM ELEMENT NO.
1HD621
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research & Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT • . .
Compressed gas samples of sub-part per million concentrations of
sulfur dioxide, nitric oxide, and nitrogen dioxide were evaluated for long and
short term stability. Except for several stainless steel tanks, the samples
were contained in aluminum cylinders. A degree of stability was achieved
over the short term, however, all of the samples were considered unstable
over the term of the evaluations. Utilization of ambient level compressed
gas samples may be considered where relative stability is required for no
more than two or three months.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Gas Analysis
S0
Stability
Cylinders
13B
14B
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
23
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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