ASTM D6968-03(2009)
(Test Method)Standard Test Method for Simultaneous Measurement of Sulfur Compounds and Minor Hydrocarbons in Natural Gas and Gaseous Fuels by Gas Chromatography and Atomic Emission Detection
Standard Test Method for Simultaneous Measurement of Sulfur Compounds and Minor Hydrocarbons in Natural Gas and Gaseous Fuels by Gas Chromatography and Atomic Emission Detection
SIGNIFICANCE AND USE
Gaseous fuels, such as natural gas, petroleum gases and bio-gases, contain varying amounts and types of sulfur compounds. They are generally odorous, corrosive to equipment, and can inhibit or destroy catalysts employed in gas processing. Their accurate measurement is essential to gas processing, operation and utilization, and may be of regulatory interest.
Small amounts (typically, 1 to 4 ppmv) of sulfur odorants are added to natural gas and other fuel gases for safety purposes. Some sulfur odorants can be reactive, and may be oxidized, forming more stable sulfur compounds having lower odor thresholds. These gaseous fuels are analyzed for sulfur odorants to help in monitoring and to ensure appropriate odorant levels for public safety.
This method offers a technique to determine individual sulfur species in gaseous fuel and the total sulfur content by calculation.
Gas chromatography is commonly and extensively used to determine all components in gaseous fuels including fixed gas and organic components (Test Methods D 1945 and D 1946). Major components measured are often used for the determination of gas property, such as heating value and relative density. Higher molar mass hydrocarbons are of interest even when present in small amounts because their larger impact on heating value, hydrocarbon dew point and gas quality relating to gas operation, gas utilization and environmental impacts.
SCOPE
1.1 This test method is for the determination of volatile sulfur-containing compounds and minor hydrocarbons in gaseous fuels including components with higher molar mass than that of propane in a high methane gas, by gas chromatography (GC) and atomic emission detection (AED). Hydrocarbons include individual aliphatic components from C4 to C6, aromatic components and groups of hydrocarbons classified according to carbon numbers up to C12 at least, such as C6-C7, C7-C8, C8-C9 and C9-C10, etc. The detection range for sulfur and carbon containing compounds is approximately 20 to 100 000 picograms (pg). This is roughly equivalent to 0.04 to 200 mg/m3 sulfur or carbon based upon the analysis of a 0.25 mL sample.
1.2 This test method describes a GC-AED method employing a specific capillary GC column as an illustration for natural gas and other gaseous fuel containing low percentages of ethane and propane. Alternative GC columns and instrument parameters may be used in this analysis optimized for different types of gaseous fuel, provided that appropriate separation of the compounds of interest can be achieved.
1.3 This test method does not intend to identify all individual sulfur species. Unknown sulfur compounds are measured as mono-sulfur containing compounds. Total sulfur content of a sample can be found by summing up sulfur content present in all sulfur species.
1.4 This method is not a Detailed Hydrocarbon Analysis (DHA) method and does not intend to identify all individual hydrocarbon species. Aliphatic hydrocarbon components lighter than n-hexane, benzene, toluene, ethyl benzene, m,p-xylenes and o-xylene (BTEX) are generally separated and identified individually. Higher molar mass hydrocarbons are determined as groups based on carbon number, excluding BTEX. The total carbon content of propane and higher molar mass components in a sample can be found by summing up carbon content present in all species containing carbon.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard 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 standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
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: D6968 − 03(Reapproved 2009)
Standard Test Method for
Simultaneous Measurement of Sulfur Compounds and
Minor Hydrocarbons in Natural Gas and Gaseous Fuels by
1
Gas Chromatography and Atomic Emission Detection
This standard is issued under the fixed designation D6968; 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 BTEX. The total carbon content of propane and higher molar
mass components in a sample can be found by summing up
1.1 This test method is for the determination of volatile
carbon content present in all species containing carbon.
sulfur-containing compounds and minor hydrocarbons in gas-
eous fuels including components with higher molar mass than 1.5 The values stated in SI units are to be regarded as
that of propane in a high methane gas, by gas chromatography standard. No other units of measurement are included in this
(GC) and atomic emission detection (AED). Hydrocarbons standard.
include individual aliphatic components from C to C , aro-
4 6
1.6 This standard does not purport to address all of the
matic components and groups of hydrocarbons classified
safety concerns, if any, associated with its use. It is the
according to carbon numbers up to C at least, such as C -C ,
12 6 7
responsibility of the user of this standard to establish appro-
C -C,C -C and C -C , etc. The detection range for sulfur
7 8 8 9 9 10
priate safety and health practices and determine the applica-
and carbon containing compounds is approximately 20 to
bility of regulatory limitations prior to use.
100000 picograms (pg). This is roughly equivalent to 0.04 to
3
200 mg/m sulfur or carbon based upon the analysis of a 0.25 2. Referenced Documents
mL sample. 2
2.1 ASTM Standards:
1.2 This test method describes a GC-AED method employ- D1265Practice for Sampling Liquefied Petroleum (LP)
ingaspecificcapillaryGCcolumnasanillustrationfornatural Gases, Manual Method
gas and other gaseous fuel containing low percentages of D1945Test Method for Analysis of Natural Gas by Gas
ethane and propane. Alternative GC columns and instrument Chromatography
parametersmaybeusedinthisanalysisoptimizedfordifferent D1946Practice for Analysis of Reformed Gas by Gas
types of gaseous fuel, provided that appropriate separation of Chromatography
the compounds of interest can be achieved. D3609Practice for Calibration Techniques Using Perme-
ation Tubes
1.3 This test method does not intend to identify all indi-
D4626Practice for Calculation of Gas Chromatographic
vidual sulfur species. Unknown sulfur compounds are mea-
Response Factors
sured as mono-sulfur containing compounds. Total sulfur
D5287Practice for Automatic Sampling of Gaseous Fuels
contentofasamplecanbefoundbysummingupsulfurcontent
D5504TestMethodforDeterminationofSulfurCompounds
present in all sulfur species.
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
1.4 This method is not a Detailed Hydrocarbon Analysis
phy and Chemiluminescence
(DHA) method and does not intend to identify all individual
D5623Test Method for Sulfur Compounds in Light Petro-
hydrocarbon species. Aliphatic hydrocarbon components
leum Liquids by Gas Chromatography and Sulfur Selec-
lighter than n-hexane, benzene, toluene, ethyl benzene, m,p-
tive Detection
xylenes and o-xylene (BTEX) are generally separated and
D6228TestMethodforDeterminationofSulfurCompounds
identified individually. Higher molar mass hydrocarbons are
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
determined as groups based on carbon number, excluding
phy and Flame Photometric Detection
E840PracticeforUsingFlamePhotometricDetectorsinGas
Chromatography
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
2
Special Constituents of Gaseous Fuels. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2009. Published September 2009. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2003. Last previous edition approved in 2003 as D6968–03. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6968-03R09. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6968 − 03 (2009)
2.2 Other References: ing sulfur and carbon. The AED uses a microwave induced
ISO 19739Natural Gas—Determination of Sulfur Com- helium plasma to disassociate molecules and atomize/excite
3
po
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.