TRACEABILITY PROTOCOL FOR ESTABLISHING TRUE CONCENTRATIONS OF
GASES USED FOR CALIBRATION AND AUDITS OF
CONTINUOUS SOURCE EMISSION MONITORS
(Protocol No. 1)
June 15, 1978
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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Table of Contents
Page
1.0 TRACEABILITY PROTOCOL FOR ESTABLISHING TRUE 1
CONCENTRATION OF GASES USED FOR CALIBRATION AND AUDITS
OF CONTINUOUS SOURCE EMISSION MONITORS
1.1 OVERVIEW OF TRACEABILITY PROCEDURES ..... 1
1.2 ESTABLISHING TRACEABILITY OF COMMERCIAL CYLINDER 1
GASES TO NBS, SRfl CYLINDER GASES
1.2.1 Procedure for Instrument Calibration 2
1.2.1.1 Instrument Multipoint Calibration 2
1.2.1.2 Instrument Span Check for Linear Response .... 6
Instrument
1.2.1.3 Instrument Span Check for Non-Linear 6
Response Instrument
1.2.2 Procedure for Analysis of Cylinder Gas 7
for True Concentration
1.2.3 Use of Gas Manufacturer's Primary Standards ... 8
1.2.4 Verification of Cylinder Gas Stability 8
1.2.5 Reanalysis of Cylinder Gases 9
1.2.6 Minimum Cylinder Pressure 9
1.2.7 Cylinder Label and Analysis Report 9
1.3 PERFORMANCE AUDIT PROGRAM 10
1.4 REFERENCES 10
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Protocol No. 1
Revision No. 0
Date: June 15, 1978
Page 1 of 10
1.0 TRACEABILITY PROTOCOL FOR ESTABLISHING TRUE CONCENTRATION OF GASES
USED FOR CALIBRATION AND AUDITS OF CONTINUOUS SOURCE EMISSION
MONITORS
1.1 OVERVIEW OF TRACEABILITY PROCEDURES
Performance standards promulgated^ 's'5' by the U.S. Environmental
Protection Agency for stationary sources require the installation and operation
of continuous monitoring systems for specified pollutants. Extractive con-
tinuous monitoring systems for gaseous pollutants must be calibrated and
audited using gas standards that are accurate and stable.
The traceability procedure described here is intended to minimize
systematic and random errors during the analysis of calibration and audit
gas standards and to establish the true concentrations by means of National
Bureau of Standards, Standard Reference Materials (NBS, SRM). The procedure
provides for a direct comparison between the calibration and audit gas standards
and an NBS, SRM or a gas manufacturer's primary standard (GMPS) which is refer-
enced to NBS, SRM. All comparisons are made using instruments calibrated with
applicable NBS, SRM. Traceability must be performed by the gas standard manu-
facturer at the time of purchase. Reanalysis as described in 1.2.5 may be
performed by the gas standard manufacturer or by the user.
This procedure is applicable to any continuous, semi-continuous or
periodic analysis instrument which meets the performance requirements in the
following sections.
1.2 ESTABLISHING TRACEABILITY OF COMMERCIAL CYLINDER GASES TO NBS, SRM
CYLINDER GASES
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1.2.1 Procedure for Instrument Calibration
The following procedures for periodic multipoint calibration and
daily instrument span checks are prescribed to minimize systematic error.
Separate procedures for instrument span checks are described for linear and
non-linear instruments. For this purpose, a linear instrument is defined as
one which yields a calibration curve which deviates by 2% of full scale or
less from a straight line drawn from the point determined by zero gas to the
highest calibration point. To be considered linear, the difference between
the concentrations indicated by the calibration curve and the straight line
must not exceed 2% of full scale at any point on the curve.
1.2.1.1 Instrument Multipoint Calibration
A multipoint calibration curve is prepared monthly using two SRM
cylinder gases and zero gas. The zero gas must not contain more than 0.2%
of the full scale concentration of the component being analyzed. In addition,
zero gas must be free of any impurity that will give a response on the
analytical instrument. A list of SRM cylinder gases recommended for trace-
ability of commercial cylinder gases is shown in Table 1.1. A list of new
stationary sources which are required to install continuous source emission
monitors for gaseous pollutants and diluent gases (CL and CCL) is shown in
Table 1.2. This table also lists existing stationary sources that may be
required to install continuous source emission monitors for gaseous pollutants
and diluent gases.
The multipoint calibration is accomplished by diluting the highest
SRM with zero gas using a calibration flow system. Obtain the instrument
response for 6 points representing 0, 10, 30, 50, 75 and 100% of the instru-
ment full scale. Plot the data and construct the calibration curve. Obtain
the instrument response for the other lower SRM without dilution. Compare
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TABLE 1.1 NBS, SRM AVAILABLE FOR TRACEABILITY OF
CALIBRATION AND AUDIT GAS STANDARDS
Cylinder Gases
SRM
(1)
(1)
1661
1662
1663
1664
(2)
1684
1685
1686
1687
(3)
(3)
(3)
(3)
(4)
(4)
1609
Type
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Sulfur Dioxide in N2
Nitric Oxide in N2
Nitric Oxide in N2
Nitric Oxide in N2
Nitric Oxide in N2
Nitrogen Dioxide in Air
Nitrogen Dioxide in Air
Nitrogen Dioxide in Air
Nitrogen Dioxide in Air
Oxygen in N2
Oxygen in N2
Oxygen in N2
Size
liters at STP
870
870
870
870
870
870
870
870
870
870
870
870
870
870
870
870
870
870
Nominal
Concentrations
50 ppm
90 ppm
500 ppm
1000 ppm
1500 opm
2500 ppm
3500 ppm
100 ppm
250 ppm
500 ppm
1000 ppm
250 ppm
500 ppm
1000 ppm
2500 ppm
2%
10%
21%
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TABLE 1.1 (Continued)
Protocol No. 1
Revision No. 0
Date: June 15, 1978
Page 4 of 10
SRM
2622
2626
1674
(4)
1675
Type
Carbon Dioxide in N2
Carbon Dioxide in N2
Carbon Dioxide in N2
Carbon Dioxide in N2
Carbon Dioxide in N2
Size
liters at STP
870
870
870
870
870
Nominal
Concentrations
2%
4%
7%
10%
14%
(1) SRM currently under development, planned issue date September, 1979.
(2) SRM currently under development, planned issue date April, 1979.
(3) SRM currently under development, planned issue date July, 1979.
(4) SRM currently under development, planned issue date April, 1979.
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Protocol No. I
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Date: June 15, 1978
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TABLE 1.2 CONTINUOUS SOURCE EMISSION MONITORS FOR
NEW AND EXISTING STATIONARY SOURCES
Pollu-
tant
Source
EPA
Regulation
Monitors Mid-Range and Span
Gas Concentrations, ppm (3)
SO,
Steam Generation SPNSS (1)
Steam Generation SIP (2)
Petro. Refinery SPNSS
Sulfuric Acid Plant SPNSS
Sulfuric Acid Plant SIP
Primary Smelters: SPNSS
Copper, Lead & Zinc
Oil-500, 900; Coal-750, 1350
Coal-500 to 2000 (4)
50, 90
500, 900
2000 to 3500 (4)
1600 to 1800
NO
Steam Generation
Steam Generation
SPNSS
SIP
Gas & Oil - 250, 450
Coal - 500, 900
Coal - 400 to 1500 (4)
Nitric Acid Plant SPNSS
Nitric Acid Plant SIP
250, 450
200 to 1000 (4)
co
Steam Generation
Steam Generation
SPNSS
SPNSS
EPA Regulation 40 CFR 60
(SPNSS) does not require
a specific setting for
monitor full scale
(1) Standards of Performance for New Stationary Sources.
(2) State Implementation Plan? (for existing stationary sources).
(3) Required setting for monitor full scale (called span value) is
specified in SNPSS (40 CFR 60). Span is 90% and mid-range is 50%
of the monitor full scale.
(4) This is the range of typical operation. Mid-range and span gas
concentrations needed will depend on state regulations. However,
the concentrations should be within the range shown.
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the apparent concentrations from the calibration curve to the true concen-
tration of the lower SRM. If the difference between the apparent concentra-
tion and the true concentration of the lower SRM exceeds 3% of the true
concentration, repeat the multipoint calibration procedure. Test the cali-
bration curve for linearity as defined in 1.2.1 and proceed to either 1.2.1.2
or 1.2.1.3.
1.2.1.2 Instrument Span Check for Linear Response Instrument
At the start of each day that cylinder gases are to be analyzed,
check instrument response to the highest SRM (or GMPS) in the range to be
used and to zero gas. Adjust response to the value obtained in the most
recent multipoint calibration and proceed to 1.2.2. Cylinder gases analyzed
with a linear instrument must not have a concentration greater than 15% above
the highest available SRM concentration.
1.2.1.3 Instrument Span Check for Non-Linear Response Instrument
At the start of each day that cylinder gases are to be analyzed,
check instrument response to two SRM (or GMPS) in the range of calibration
gases to be analyzed and to zero gas as follows. First, set the instrument
zero with zero gas and then adjust the instrument response to the highest SRM
(or GMPS) to the value obtained in the most recent multipoint calibration.
Next, obtain the response to the lower SRM (or GMPS). If the response to the
lower SRM (or GMPS) varies by greater than 3% from the response obtained in
the most recent multipoint calibration, a full multipoint calibration must be
performed as in 1.2.1.1, otherwise, proceed to 1.2.2. Calibration gases
analyzed with a non-linear instrument must not have a concentration greater
than the highest available SRM concentration.
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1.2.2 Procedure for Analysis of Cylinder Gas for True Concentration
The following procedure is designed to establish the true concentra-
tion of a cylinder gas. The analyses involve the direct comparison of the
cylinder gas to the SRM (or GMPS) in order to compensate for variations in
instrument response between the time of daily span check and the time of
analysis. Significant variations in response often result from changes in
room temperature, line voltage, etc. Analyses are performed in triplicate
to expose erroneous data points and excessive random variations in instru-
ments response. After the gas cylinder has been filled, a minimum of 4 day
holding time must be observed before the following protocol analysis is
initiated. (Note: when steel cylinders are used for SOp, a minimum 15 day
holding time must be observed before the following protocol analysis is
initiated.)
(a) Analyze each cylinder gas directly against the nearest SRM
(or GMPS) by alternate analyses of the SRM and calibration gas in triplicate
(3 pairs). Adjust the instrument span if necessary prior to the analysis,
but do not adjust the instrument during the triplicate analyses. The
response to zero gas shall be obtained with sufficient frequency that the
change in successive zero responses does not exceed 1% of full scale.
(b) For each of the six analyses, determine the apparent concen-
tration of the SRM (or GMPS) or cylinder gas from the calibration curve.
(c) For each pair of analyses, one SRM (or GMPS) and one cylinder
gas, calculate the true concentration of the cylinder gas by:
-r o ,- ^ i n « i. ^ c ,* i o True Cone, of SRM (or GMPS)
True Cone, of Cyl. Gas = Apparent Cone, of Cyl. Gas x Apparent Cone, of SRM (or GMPS)
(d) Determine the mean of the three values for true concentration
of the cylinder gas.
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(e) If any one value differs from the mean by greater than 1.5%,
discard the data, reset the instrument span if necessary, and repeat steps (a)
through (d).
1.2.3 Use of Gas Manufacturer's Primary Standards
Gas manufacturer's primary standards (GMPS) are gas mixtures pre-
pared in pressurized containers and analyzed against SRM cylinder gases.
Their purpose is to conserve SRM where large quantities of gas cylinders are
analyzed. GMPS may be substituted for SRM for instrument span check in 1.2.1.2
and 1.2.1.3, and cylinder gas analysis in 1.2.2 if the following conditions
are met. In no case may GMPS be substituted for SRM for the required instrument
multipoint calibrations in 1.2.1.1.
(a) GMPS must have been analyzed against SRM cylinder gases as
described in 1.2.1 and 1.2.2 within 30 days of their use for cylinder gas
analysis. It is preferred that GMPS be analyzed on the days that instrument
multipoint calibrations are performed.
(b) GMPS must not have changed in concentration by more than 1% per
month (average) for the three-month period prior to their use for cylinder
gas analysis.
1.2.4 Verification of Cylinder Gas Stability
The stability of reactive gases (including cylinder gas of sulfur
dioxide, nitric oxide, and nitrogen dioxide) must be verified before use.
The stability of each cylinder gas is verified by performing a second set of
triplicate analyses (using procedure in 1.2.2) a minimum of 7 days after the
first set of triplicate analyses. The mean of the second triplicate analyses
must not differ from the mean of the first triplicate analysis by more than 1.5%.
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1.2.5 Reanalysis of Cylinder Gases
Reanalysis of reactive gases by the gas manufacturer or user must be
performed every 6 months from the last analysis date by the procedure in 1.2.2.
Cylinder gases used for audits may need to be analyzed more frequently than
every 6 months. Reanalysis of diluent gases (Op and CC^) by the gas manu-
facturer or user must be performed every 12 months from the last analysis date
by the procedure in 1.2.2
1.2.6 Minimum Cylinder Pressure
No cylinder gas should be used below a cylinder pressure of 200 pounds
per square inch as shown by the cylinder gas regulator.
1.2.7 Cylinder Label and Analysis Report
Each gas cylinder shipped by a gas manufacturer to a user must contain
the following minimum traceability information on a gummed label affixed to
the cylinder wall and/or a tag attached to the cylinder valve:
(a) Cylinder number
(b) Mean concentration of cylinder gas, ppm or mol %
(on last analysis date)
(c) Balance gas used
(d) Last analysis date
(e) Expiration date (six months after the last analysis date for
reactive gases and 12 months for diluent gases)
In addition, a written analysis report should be prepared which
certifies the cylinder gas has been analyzed according to this protocol. The
analysis report should contain the following information:
(a) Cylinder number
(b) Mean concentration of cylinder gas, ppm or mol % (on last
analysis date)
(c) Replicate analysis data
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(d) Balance gas used
(e) NBS, SRM numbers used as primary standards
(f) Analytical principle used
(g) Last analysis date
The user should maintain a file of all analysis reports for
three years.
1.3 PERFORMANCE AUDIT PROGRAM
With the initiation and use of this traceability protocol, the U.S.
Environmental Protection Agency will initiate a national performance audit
program of cylinder gas prepared by this protocol. Cylinder gas prepared
following the protocol will be obtained directly or indirectly by the U.S.
Environmental Protection Agency and analyzed in their laboratory for accuracy
compared to the gas manufacturer's reported concentration.
1.4 REFERENCES
1. Requirements for Submittal of Implementation Plans and Standards
for New Stationary Sources - Emission Monitoring. Federal
Register 40, Number 194, October 6, 1975, pages 46240-46270.
2. Part 60 - Standards of Performance for New Stationary Sources -
Emission Monitoring Requirements and Revisions to Performance
Testing Methods, Federal Register 40, Number 246, December 22, 1975,
pages 59204 and 59205.
3. Part 60 - Standards of Performance for New Stationary Sources -
Primary Copper, Zinc and Lead Smelters, Federal Register 40,
Number 10, January 15, 1976, pages 2332-2341.
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