ASTM D7165-10(2015)

Standard Practice for Gas Chromatograph Based On-line/At-line Analysis for Sulfur Content of Gaseous Fuels

SIGNIFICANCE AND USE
5.1 On-line, at-line, in-line, CFMS, and other near-real time monitoring systems that measure fuel gas characteristics, such as the sulfur content, are prevalent in the natural gas and fuel gas industries. The installation and operation of particular systems vary on the specific objectives, contractual obligations, process type, regulatory requirements, and internal performance requirements needed by the user. This standard is intended to provide guidelines for standardized start-up procedures, operating procedures, and quality assurance practices for on-line, at-line, in-line, CFMS, and other near-real time gas chromatographic based sulfur monitoring systems used to determine fuel gas sulfur content. For measurement of gaseous fuel properties using laboratory based methods the user is referred to Test Methods D1072, D1945, D4084, D4468, D4810 and Practices D4626, E594.
SCOPE
1.1 This practice is for the determination of volatile sulfur-containing compounds in high methane content gaseous fuels such as natural gas using on-line/at-line instrumentation, and continuous fuel monitors (CFMS). It has been successfully applied to other types of gaseous samples including air, digester, landfill, and refinery fuel gas. The detection range for sulfur compounds, reported as picograms sulfur, based upon the analysis of a 1 cc sample, is one hundred (100) to one million (1,000,000). This is equivalent to 0.1 to 1,000 mg/m3.  
1.2 This practice does not purport to measure all sulfur species in a sample. Only volatile compounds that are transported to an instrument under the measurement conditions selected are measured.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this practice to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-May-2015
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.12 - On-Line/At-Line Analysis of Gaseous Fuels

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7165 − 10 (Reapproved 2015)
Standard Practice for
Gas Chromatograph Based On-line/At-line Analysis for
Sulfur Content of Gaseous Fuels
This standard is issued under the fixed designation D7165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3764PracticeforValidationofthePerformanceofProcess
Stream Analyzer Systems
1.1 This practice is for the determination of volatile
D4084Test Method for Analysis of Hydrogen Sulfide in
sulfur-containing compounds in high methane content gaseous
Gaseous Fuels (Lead Acetate Reaction Rate Method)
fuels such as natural gas using on-line/at-line instrumentation,
D4468Test Method for Total Sulfur in Gaseous Fuels by
andcontinuousfuelmonitors(CFMS).Ithasbeensuccessfully
Hydrogenolysis and Rateometric Colorimetry
applied to other types of gaseous samples including air,
D4626Practice for Calculation of Gas Chromatographic
digester, landfill, and refinery fuel gas.The detection range for
Response Factors
sulfur compounds, reported as picograms sulfur, based upon
D4810Test Method for Hydrogen Sulfide in Natural Gas
the analysis ofa1cc sample, is one hundred (100) to one
Using Length-of-Stain Detector Tubes
million (1,000,000). This is equivalent to 0.1 to 1,000 mg/m3.
D5504TestMethodforDeterminationofSulfurCompounds
1.2 This practice does not purport to measure all sulfur
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
species in a sample. Only volatile compounds that are trans-
phy and Chemiluminescence
ported to an instrument under the measurement conditions
D6621Practice for Performance Testing of ProcessAnalyz-
selected are measured.
ers for Aromatic Hydrocarbon Materials
D6122Practice for Validation of the Performance of Multi-
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this variate Online,At-Line, and Laboratory Infrared Spectro-
photometer Based Analyzer Systems
standard.
D6228TestMethodforDeterminationofSulfurCompounds
1.4 This practice does not purport to address all of the
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
safety concerns, if any, associated with its use. It is the
phy and Flame Photometric Detection
responsibility of the user of this practice to establish appro-
E594Practice for Testing Flame Ionization Detectors Used
priate safety and health practices and determine the applica-
in Gas or Supercritical Fluid Chromatography
bility of regulatory limitations prior to use.
2.2 ISO Standards
2. Referenced Documents
ISO 7504Gas Analysis-Vocabulary
2.1 ASTM Standards:
3. Terminology
D1072Test Method for Total Sulfur in Fuel Gases by
Combustion and Barium Chloride Titration 3.1 Definitions:
3.1.1 calibration gas mixture, n—a certified gas mixture
D1945Test Method for Analysis of Natural Gas by Gas
with known composition used for the calibration of a measur-
Chromatography
ing instrument or for the validation of a measurement or gas
D3606Test Method for Determination of Benzene and
analytical method.
Toluene in Finished Motor andAviation Gasoline by Gas
3.1.1.1 Discussion—Calibration Gas Mixtures are the ana-
Chromatography
logues of measurement standards in physical metrology (ref-
erence ISO 7504 paragraph 4.1).
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
3.1.2 direct sampling—Sampling where there is no direct
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
Analysis of Gaseous Fuels.
connection between the medium to be sampled and the
CurrenteditionapprovedJune1,2015.PublishedJuly2015Originallyapproved
analytical unit.
in 2006. Last previous edition approved in 2010 as D7165–10. DOI: 10.1520/
D7165-10R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from International Organization for Standardization (ISO), 1, ch. de
Standards volume information, refer to the standard’s Document Summary page on la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
the ASTM website. www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7165 − 10 (2015)
3.1.3 in-line instrument—Instrument whose active element used to determine fuel gas sulfur content. For measurement of
is installed in the pipeline and measures at pipeline conditions. gaseous fuel properties using laboratory based methods the
user is referred to Test Methods D1072, D1945, D4084,
3.1.4 on-line instrument—Automated instrument that
D4468, D4810 and Practices D4626, E594.
samples gas directly from the pipeline, but is installed exter-
nally.
6. Apparatus
3.1.5 at-line instrument—instrument requiring operator in-
teraction to sample gas directly from the pipeline. 6.1 Instrument—Anygaschromatographicbasedinstrument
ofstandardmanufacture,withhardwarenecessaryforinterfac-
3.1.6 continuous fuel monitor (CFM)—Instrument that
ingtoanaturalgasorotherfuelgaspipelineandcontainingall
samples gas directly from the pipeline on a continuous or
features necessary for the intended application(s) can be used.
semi-continuous basis.
6.1.1 The chromatographic parameters must be capable of
3.1.7 total reduced sulfur (TRS)—Summation of sulfur spe-
obtaining retention time repeatability of 0.05 min. (3 sec.).
cies where the sulfur oxidation number is –2, excluding sulfur
Instrumentation must meet the performance characteristics for
dioxide, sulfones, and other inorganic sulfur compounds. This
repeatability and precision without encountering unacceptable
includes but is not limited to mercaptans, sulfides, and disul-
interference or bias. The components coming in contact with
fides.
sample, such as tubing and valving, must be passivated or
3.1.8 near-real time monitoring systems—Monitoring sys-
constructed of inert materials to ensure an accurate sulfur gas
temwheremeasurementoccurssoonaftersampleflowthrough
measurement.
the system or soon after sample extraction. The definition of a
6.2 Sample Inlet System—Asample inlet system capable of
near real time monitoring system can be application specific.
operating continuously above the maximum column tempera-
3.2 reference gas mixture, n—a certified gas mixture with
ture is necessary. A variety of sample inlet configurations can
known composition used as a reference standard from which
be used including but not limited to on-column systems and
other compositional data are derived.
split/splitless injection system capable of splitless operation
3.2.1 Discussion—Reference Gas Mixtures are the ana-
and split control from 10:1 up to 50:1. An automated gas
logues of measurement standards of reference standards (ref-
sampling valve is required for many applications. The inlet
erence ISO 7504 paragraph 4.1.1).
system must be constructed of inert material and evaluated
frequently for compatibility with reactive sulfur compounds.
4. Summary of Practice
The sampling inlet system is heated as necessary so as to
4.1 Arepresentative sample of the gaseous fuel is extracted
preventcondensation.Allwettedsamplingsystemcomponents
from a process pipe or pipeline and is transferred in a timely
must be constructed of inert or passivated materials. Sample
manner to an analyzer inlet system.The sample is conditioned
delivered to the inlet system should be in the gas phase free of
with minimum impact on sulfur content.Aprecisely measured
particulate or fluidic matter.
volume of sample is injected into the analyzer. Excess process
6.2.1 Carrier and Detector Gas Control—Constant flow
orpipelinesampleisventedorisreturnedtotheprocessstream
controlofcarrieranddetectorgasesiscriticalforoptimumand
dependant upon application and regulatory requirements.
consistent analytical performance. Control is achieved by use
4.2 Sample containing carrier gas is fed to a gas chromato- of pressure regulators and fixed flow restrictors. The gas flow
graph where the components are separated using either a
ismeasuredbyappropriatemeansandadjusted,asrequired,to
packedorcapillarycolumn.Measurementisperformedusinga the desired value. Mass flow controllers, capable of maintain-
suitable sulfur detection system.
ing a gas flow constant to within 6 1% at the flow rates
necessary for optimal instrument performance can be used.
4.3 Calibration, precision, calibration error, performance
6.2.2 Detector—Sulfurcompoundscanbemeasuredusinga
audit tests, maintenance methodology and miscellaneous qual-
variety of detectors including but not limited to: sulfur
ity assurance procedures are conducted to determine analyzer
chemiluminescence, flame photometric, electrochemical cell,
performancecharacteristicsandvalidateboththeoperationand
oxidative cell and reductive cells. In selecting a detector, the
the quality of generated results.
usershouldconsiderthelinearity,sensitivity,andselectivityof
particular detection systems prior to installation. The user
5. Significance and Use
should also consider interference from substances in the gas
5.1 On-line,at-line,in-line,CFMS,andothernear-realtime
stream that could result in inaccurate sulfur gas measurement
monitoring systems that measure fuel gas characteristics, such
due to effects such as quenching.
as the sulfur content, are prevalent in the natural gas and fuel
gas industries. The installation and operation of particular 6.3 Columns—Avariety of columns can be used to separate
systemsvaryonthespecificobjectives,contractualobligations, the sulfur compounds in the sample. Typically, a 60 m × 0.53
process type, regulatory requirements, and internal perfor- mmIDfusedsilicaopentubularcolumncontaininga5µmfilm
mance requirements needed by the user. This standard is thickness of bonded methyl silicone liquid phase is used. The
intended to provide guidelines for standardized start-up selected column must provide retention and resolution charac-
procedures, operating procedures, and quality assurance prac- teristics that satisfy the intended application.The column must
tices for on-line, at-line, in-line, CFMS, and other near-real be inert towards sulfur compounds. The column must also
time gas chromatographic based sulfur monitoring systems demonstrate a sufficiently low liquid phase bleed at high
D7165 − 10 (2015)
temperature such that a loss of the instrument response is not rate calculated from differential weight measurements of these
encountered while operating the column at elevated tempera- devices. It is suggested that certified permeation devices be
tures. used whenever available.
7.1.1.1 Permeation System Temperature Control—
6.4 Data Acquisition—Data acquisition and storage can be
Permeation devices are maintained at the calibration tempera-
accomplishedusinganumberofdevicesandmedia.Following
ture within 0.1 °C.
are some examples.
7.1.1.2 Permeation System Flow Control—The permeation
6.4.1 Recorder—As an example, a 0 to 1 mV range record-
flow system measures diluent gas flow over the permeation
ingpotentiometerorequivalent,withafull-scaleresponsetime
tubes within 62 percent.
of2sor less can be used.A4-20 mArange recorder can also
7.1.1.3 Permeation tube emission rates are expressed in
be used.
units of mass of the emitted sulfur compound contained inside
6.4.2 Integrator—An electronic integrating device or com-
per unit time, i.e. nanograms of methyl mercaptan per minute.
puter can be used. For GC based systems, it is suggested that
The sulfur emission rate is calculated knowing the molecular
the device and software have the following capabilities:
formula of the sulfur compound used in the permeation tube.
6.4.2.1 Graphic presentation of chromatograms.
7.1.1.4 Permeation tubes are inspected and weighed to the
6.4.2.2 Digital display of chromatographic peak areas.
nearest 0.01 mg on at least a monthly basis using a balance
6.4.2.3 Identification of peaks by retention time or relative
calibrated against NIST traceable “S” class weights or the
retention time, or both.
equivalent. Analyte concentration is calculated by weight loss
6.4.2.4 Calculation and use of response factors.
anddilutiongasflowrateasperPracticeD3606.Thesedevices
6.4.2.5 External standard calculation and data presentation.
are discarded when the liquid contents are reduced to less than
6.4.3 Distributed Control Systems (DCS)—Depending on
ten (10) percent of the initial volume or when the permeation
the site requirements, the analytical results are sometimes fed
surface is unusually discolored or otherwise compromised.
toadistributedcontrolsystem.Theinformationisthenusedto
7.1.1.5 Permeation tubes must be stored in accordance with
make the appropriate adjustments to the process. Signal isola-
the manufacturer’s recommendation. Improper storage can
tion between the analyzer and the distributed control network
result in damage and/or a change in the characteristics of the
is most often required. Communications protocols with the
permeation membrane. Such damage and/or characteristic
DCS will dictate the required signal output requirements for
changeresultsinanactualpermeationratethatdiffersfromthe
the analyzer.
certified permeation rate.
6.4.4 Data Management Systems—Data management sys-
tems or other data and data processing repositories are some- 7.2 Compressed Gas Standards—Alternatively, blended
times used to collect and process the results from a wide
gaseous sulfur standards in nitrogen, helium or methane base
variety of instrumentation at a single facility. The information gas may be used. Care must be exercised in the use of
is then available for rapid dissemination within the organiza-
compressed gas standards since they can introduce errors in
tion of the operating facility. Communications protocols with measurement due to lack of uniformity in their manufacture or
the data management system will dictate the required signal
instability in their storage and use. Standards should be
output requirements for the analyzer.
blended such that components will not condense under storage
orwhilethestandardisinuse.Theprotocolforcompressedgas
7. Reagents and Materials
standards contained in the appendix can be used to ensure
NOTE 1—Warning: Sulfur compounds contained in permeation tubes
uniformity in compressed gas standard manufacture and pro-
or compressed gas cylinders may be flammable and harmful or fatal if
vide for traceability to a NIST or NMi (Nederlands Meetinsti-
ingested or inhaled. Permeation tubes, which emit their contents
tuut) reference material.
continuously, and compres
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7165 − 10 D7165 − 10 (Reapproved 2015)
Standard Practice for
Gas Chromatograph Based On-line/At-line Analysis for
Sulfur Content of Gaseous Fuels
This standard is issued under the fixed designation D7165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice is for the determination of volatile sulfur-containing compounds in high methane content gaseous fuels such
as natural gas using on-line/at-line instrumentation, and continuous fuel monitors (CFMS). It has been successfully applied to other
types of gaseous samples including air, digester, landfill, and refinery fuel gas. The detection range for sulfur compounds, reported
as picograms sulfur, based upon the analysis of a 1 cc sample, is one hundred (100) to one million (1,000,000). This is equivalent
to 0.1 to 1,000 mg/m3.
1.2 This practice does not purport to measure all sulfur species in a sample. Only volatile compounds that are transported to
an instrument under the measurement conditions selected are measured.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.standard.
1.4 This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this practice to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D1072 Test Method for Total Sulfur in Fuel Gases by Combustion and Barium Chloride Titration
D1945 Test Method for Analysis of Natural Gas by Gas Chromatography
D3606 Test Method for Determination of Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatog-
raphy
D3764 Practice for Validation of the Performance of Process Stream Analyzer Systems
D4084 Test Method for Analysis of Hydrogen Sulfide in Gaseous Fuels (Lead Acetate Reaction Rate Method)
D4468 Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
D4626 Practice for Calculation of Gas Chromatographic Response Factors
D4810 Test Method for Hydrogen Sulfide in Natural Gas Using Length-of-Stain Detector Tubes
D5504 Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and
Chemiluminescence
D6621 Practice for Performance Testing of Process Analyzers for Aromatic Hydrocarbon Materials
D6122 Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer
Based Analyzer Systems
D6228 Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and
Flame Photometric Detection
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
2.2 ISO Standards
ISO 7504 Gas Analysis-Vocabulary
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line Analysis
of Gaseous Fuels.
Current edition approved Jan. 1, 2010June 1, 2015. Published February 2010 July 2015 Originally approved in 2006. Last previous edition approved in 20062010 as
D7165D7165–06.–10. DOI: 10.1520/D7165-10.10.1520/D7165-10R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7165 − 10 (2015)
3. Terminology
3.1 Definitions:
3.1.1 calibration gas mixture, n—a certified gas mixture with known composition used for the calibration of a measuring
instrument or for the validation of a measurement or gas analytical method.
3.1.1.1 Discussion—
Calibration Gas Mixtures are the analogues of measurement standards in physical metrology (reference ISO 7504 paragraph 4.1).
3.1.2 direct sampling—Sampling where there is no direct connection between the medium to be sampled and the analytical unit.
3.1.3 in-line instrument—Instrument whose active element is installed in the pipeline and measures at pipeline conditions.
3.1.4 on-line instrument—Automated instrument that samples gas directly from the pipeline, but is installed externally.
3.1.5 at-line instrument—instrument requiring operator interaction to sample gas directly from the pipeline.
3.1.6 continuous fuel monitor (CFM)—Instrument that samples gas directly from the pipeline on a continuous or semi-
continuous basis.
3.1.7 total reduced sulfur (TRS)—Summation of sulfur species where the sulfur oxidation number is –2, excluding sulfur
dioxide, sulfones, and other inorganic sulfur compounds. This includes but is not limited to mercaptans, sulfides, and disulfides.
3.1.8 near-real time monitoring systems—Monitoring system where measurement occurs soon after sample flow through the
system or soon after sample extraction. The definition of a near real time monitoring system can be application specific.
3.2 reference gas mixture, n—a certified gas mixture with known composition used as a reference standard from which other
compositional data are derived.
3.2.1 Discussion—
Reference Gas Mixtures are the analogues of measurement standards of reference standards (reference ISO 7504 paragraph 4.1.1).
4. Summary of Practice
4.1 A representative sample of the gaseous fuel is extracted from a process pipe or pipeline and is transferred in a timely manner
to an analyzer inlet system. The sample is conditioned with minimum impact on sulfur content. A precisely measured volume of
sample is injected into the analyzer. Excess process or pipeline sample is vented or is returned to the process stream dependant
upon application and regulatory requirements.
4.2 Sample containing carrier gas is fed to a gas chromatograph where the components are separated using either a packed or
capillary column. Measurement is performed using a suitable sulfur detection system.
4.3 Calibration, precision, calibration error, performance audit tests, maintenance methodology and miscellaneous quality
assurance procedures are conducted to determine analyzer performance characteristics and validate both the operation and the
quality of generated results.
5. Significance and Use
5.1 On-line, at-line, in-line, CFMS, and other near-real time monitoring systems that measure fuel gas characteristics, such as
the sulfur content, are prevalent in the natural gas and fuel gas industries. The installation and operation of particular systems vary
on the specific objectives, contractual obligations, process type, regulatory requirements, and internal performance requirements
needed by the user. This standard is intended to provide guidelines for standardized start-up procedures, operating procedures, and
quality assurance practices for on-line, at-line, in-line, CFMS, and other near-real time gas chromatographic based sulfur
monitoring systems used to determine fuel gas sulfur content. For measurement of gaseous fuel properties using laboratory based
methods the user is referred to Test Methods D1072, D1945, D4084, D4468, D4810 and Practices D4626, E594.
6. Apparatus
6.1 Instrument—Any gas chromatographic based instrument of standard manufacture, with hardware necessary for interfacing
to a natural gas or other fuel gas pipeline and containing all features necessary for the intended application(s) can be used.
6.1.1 The chromatographic parameters must be capable of obtaining retention time repeatability of 0.05 min. (3 sec.).
Instrumentation must meet the performance characteristics for repeatability and precision without encountering unacceptable
interference or bias. The components coming in contact with sample, such as tubing and valving, must be passivated or constructed
of inert materials to ensure an accurate sulfur gas measurement.
6.2 Sample Inlet System—A sample inlet system capable of operating continuously above the maximum column temperature is
necessary. A variety of sample inlet configurations can be used including but not limited to on-column systems and split/splitless
D7165 − 10 (2015)
injection system capable of splitless operation and split control from 10:1 up to 50:1. An automated gas sampling valve is required
for many applications. The inlet system must be constructed of inert material and evaluated frequently for compatibility with
reactive sulfur compounds. The sampling inlet system is heated as necessary so as to prevent condensation. All wetted sampling
system components must be constructed of inert or passivated materials. Sample delivered to the inlet system should be in the gas
phase free of particulate or fluidic matter.
6.2.1 Carrier and Detector Gas Control—Constant flow control of carrier and detector gases is critical for optimum and
consistent analytical performance. Control is achieved by use of pressure regulators and fixed flow restrictors. The gas flow is
measured by appropriate means and adjusted, as required, to the desired value. Mass flow controllers, capable of maintaining a gas
flow constant to within 6 1 % at the flow rates necessary for optimal instrument performance can be used.
6.2.2 Detector—Sulfur compounds can be measured using a variety of detectors including but not limited to: sulfur
chemiluminescence, flame photometric, electrochemical cell, oxidative cell and reductive cells. In selecting a detector, the user
should consider the linearity, sensitivity, and selectivity of particular detection systems prior to installation. The user should also
consider interference from substances in the gas stream that could result in inaccurate sulfur gas measurement due to effects such
as quenching.
6.3 Columns—A variety of columns can be used to separate the sulfur compounds in the sample. Typically, a 60 m × 0.53 mm
ID fused silica open tubular column containing a 5 μm film thickness of bonded methyl silicone liquid phase is used. The selected
column must provide retention and resolution characteristics that satisfy the intended application. The column must be inert
towards sulfur compounds. The column must also demonstrate a sufficiently low liquid phase bleed at high temperature such that
a loss of the instrument response is not encountered while operating the column at elevated temperatures.
6.4 Data Acquisition—Data acquisition and storage can be accomplished using a number of devices and media. Following are
some examples.
6.4.1 Recorder—As an example, a 0 to 1 mV range recording potentiometer or equivalent, with a full-scale response time of
2 s or less can be used. A 4-20 mA range recorder can also be used.
6.4.2 Integrator—An electronic integrating device or computer can be used. For GC based systems, it is suggested that the
device and software have the following capabilities:
6.4.2.1 Graphic presentation of chromatograms.
6.4.2.2 Digital display of chromatographic peak areas.
6.4.2.3 Identification of peaks by retention time or relative retention time, or both.
6.4.2.4 Calculation and use of response factors.
6.4.2.5 External standard calculation and data presentation.
6.4.3 Distributed Control Systems (DCS)—Depending on the site requirements, the analytical results are sometimes fed to a
distributed control system. The information is then used to make the appropriate adjustments to the process. Signal isolation
between the analyzer and the distributed control network is most often required. Communications protocols with the DCS will
dictate the required signal output requirements for the analyzer.
6.4.4 Data Management Systems—Data management systems or other data and data processing repositories are sometimes used
to collect and process the results from a wide variety of instrumentation at a single facility. The information is then available for
rapid dissemination within the organization of the operating facility. Communications protocols with the data management system
will dictate the required signal output requirements for the analyzer.
7. Reagents and Materials
NOTE 1—Warning: Sulfur compounds contained in permeation tubes or compressed gas cylinders may be flammable and harmful or fatal if ingested
or inhaled. Permeation tubes, which emit their contents continuously, and compressed gas standards should only be handled in well ventilated locations
away from sparks and flames. Improper handling of compressed gas cylinders containing air, hydrogen, argon, nitrogen or helium can result in an
explosion or in creating oxygen deficient atmospheres. Rapid release of argon, nitrogen or helium can result in asphyxiation. Compressed air supports
combustion.
7.1 Sulfur Standards—Accurate sulfur standards are required for the quantitation of the sulfur content of natural gas. Permeation
and compressed gas standards should be stable, and of the highest available accuracy and purity.
7.1.1 Permeation Devices—Sulfur standards can be produced on demand using permeation tubes, one for each selected sulfur
species, gravimetrically calibrated and certified at a convenient operating temperature. With constant temperature, calibration gases
covering a wide range of concentration can be generated by varying and accurately measuring the flow rate of diluent gas passing
over the tubes. Permeation devices delivering calibrant at a known high purity must be used since contaminants will adversely
impact the calculation of analyte concentration due to error in permeation rate calculated from differential weight measurements
of these devices. It is suggested that certified permeation devices be used whenever available.
7.1.1.1 Permeation System Temperature Control—Permeation devices are maintained at the calibration temperature within 0.1
°C.
7.1.1.2 Permeation System Flow Control—The permeation flow system measures diluent gas flow over the permeation tubes
within 62 percent.
D716
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