ASTM D7551-10(2015)
(Test Method)Standard Test Method for Determination of Total Volatile Sulfur in Gaseous Hydrocarbons and Liquefied Petroleum Gases and Natural Gas by Ultraviolet Fluorescence
Standard Test Method for Determination of Total Volatile Sulfur in Gaseous Hydrocarbons and Liquefied Petroleum Gases and Natural Gas by Ultraviolet Fluorescence
SIGNIFICANCE AND USE
5.1 The sulfur content of gaseous hydrocarbons, LPG, and LNG used for fuel purposes contributes to total SOx emissions and can lead to corrosion in engine and exhaust systems. Some process catalysts used in petroleum and chemical refining can be poisoned by trace amounts of sulfur-bearing materials in the feed stocks. This test method can be used to determine the total volatile sulfur content in process feeds, to control the total volatile sulfur content in finished products and, as applicable, to meet regulatory requirements. Practice D1072 has previously been used for the measurement of total sulfur in gaseous fuels.
SCOPE
1.1 This test method covers the determination of total volatile sulfur in gaseous hydrocarbons, Liquefied Petroleum Gases (LPG) and Liquefied Natural Gas (LNG). It is applicable to analysis of natural gaseous fuels, process intermediates, final product hydrocarbons and generic gaseous fuels containing sulfur in the range of 1 to 200 mg/kg. Samples can also be tested at other total sulfur levels using either pre-concentration methods or sample dilution using a diluent gas. The methodology for preconcentration and dilution techniques is not covered in this test method. The precision statement does not apply if these techniques are used in conjunction with this test method. The diluent gas, such as UHP nitrogen, zero nitrogen or zero air, shall not have a significant total sulfur concentration.
1.2 This test method may not detect sulfur compounds that do not volatilize under the conditions of the test.
1.3 This test method covers the laboratory determination and the at-line/on-line determination of total volatile sulfur in gaseous fuels, LPG, and LNG.
1.4 This test method is applicable for total volatile sulfur determination in gaseous hydrocarbons, LPG, and LNG containing less than 0.35 mole % halogen(s).
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. See Sections 4.1, 7.3, 7.4, 11.2, and Section 8.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7551 − 10 (Reapproved 2015)
Standard Test Method for
Determination of Total Volatile Sulfur in Gaseous
Hydrocarbons and Liquefied Petroleum Gases and Natural
Gas by Ultraviolet Fluorescence
This standard is issued under the fixed designation D7551; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of total
volatile sulfur in gaseous hydrocarbons, Liquefied Petroleum D1070 Test Methods for Relative Density of Gaseous Fuels
D1072 Test Method for Total Sulfur in Fuel Gases by
Gases (LPG) and Liquefied Natural Gas (LNG). It is applicable
to analysis of natural gaseous fuels, process intermediates, final Combustion and Barium Chloride Titration
D1265 Practice for Sampling Liquefied Petroleum (LP)
product hydrocarbons and generic gaseous fuels containing
sulfur in the range of 1 to 200 mg/kg. Samples can also be Gases, Manual Method
D3588 Practice for Calculating Heat Value, Compressibility
tested at other total sulfur levels using either pre-concentration
methods or sample dilution using a diluent gas. The method- Factor, and Relative Density of Gaseous Fuels
D3609 Practice for Calibration Techniques Using Perme-
ology for preconcentration and dilution techniques is not
covered in this test method. The precision statement does not ation Tubes
D4150 Terminology Relating to Gaseous Fuels
apply if these techniques are used in conjunction with this test
method. The diluent gas, such as UHP nitrogen, zero nitrogen D4177 Practice for Automatic Sampling of Petroleum and
Petroleum Products
or zero air, shall not have a significant total sulfur concentra-
tion. D4784 Specification for Liquefied Natural Gas Density Cal-
culation Models
1.2 This test method may not detect sulfur compounds that
D5287 Practice for Automatic Sampling of Gaseous Fuels
do not volatilize under the conditions of the test.
D5503 Practice for Natural Gas Sample-Handling and Con-
1.3 This test method covers the laboratory determination
ditioning Systems for Pipeline Instrumentation (With-
and the at-line/on-line determination of total volatile sulfur in
drawn 2017)
gaseous fuels, LPG, and LNG.
D5504 Test Method for Determination of Sulfur Compounds
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
1.4 This test method is applicable for total volatile sulfur
phy and Chemiluminescence
determination in gaseous hydrocarbons, LPG, and LNG con-
D6228 Test Method for Determination of Sulfur Compounds
taining less than 0.35 mole % halogen(s).
in Natural Gas and Gaseous Fuels by Gas Chromatogra-
1.5 The values stated in SI units are to be regarded as
phy and Flame Photometric Detection
standard. No other units of measurement are included in this
D6299 Practice for Applying Statistical Quality Assurance
standard.
and Control Charting Techniques to Evaluate Analytical
1.6 This standard does not purport to address all of the
Measurement System Performance
safety concerns, if any, associated with its use. It is the
D7166 Practice for Total Sulfur Analyzer Based On-line/At-
responsibility of the user of this standard to establish appro-
line for Sulfur Content of Gaseous Fuels
priate safety and health practices and determine the applica-
E617 Specification for Laboratory Weights and Precision
bility of regulatory limitations prior to use. See Sections 4.1,
Mass Standards
7.3, 7.4, 11.2, and Section 8.
E691 Practice for Conducting an Interlaboratory Study to
1 2
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fuels and is the direct responsibility of Subcommittee D03.06.02 on Analysis of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Minor Constituents by Gas Chromatography. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2015. Published December 2015. Originally the ASTM website.
approved in 2010. Last previous edition approved as D7551-10. DOI: 10.1520/ The last approved version of this historical standard is referenced on
D7551–10R15. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7551 − 10 (2015)
Determine the Precision of a Test Method 4. Summary of Test Method
F307 Practice for Sampling Pressurized Gas for Gas Analy-
4.1 A gaseous sample is injected into the analyzer, either by
sis
a sample valve, direct injection at a constant flow rate, or by
2.2 ASTM Manuals:
syringe. A LPG or LNG sample is vaporized in an appropriate
ASTM MNL 7
expansion chamber and injected into the analyzer by a sample
2.3 GPA Standards:
valve or a syringe or a sample valve connected to an expansion
GPA 2166 Obtaining Natural Gas Samples for Analysis by
chamber. The gaseous sample then enters into a high tempera-
Gas Chromatography
ture combustion tube where the sulfur-containing compounds
GPA 2174 Obtaining Liquid Hydrocarbon Samples for
in the sample are oxidized to SO . Water produced during the
Analysis by Gas Chromatography
sample combustion is removed, as required, and the sample
combustion gases are then exposed to a source of continuous or
3. Terminology
pulsed UV light. The SO absorbs the energy from the UV light
3.1 Defintions:
to form SO *. Fluorescence emitted from SO * as it returns to
2 2
For definitions of at-line instrument and on-line instrument see
SO , is detected by a photomultiplier tube. The resulting signal
Terminology D4150.
is a measure of the sulfur contained in the sample. Warning—
Exposure to excessive quantities of UV light is injurious to
3.2 Acronyms:
health. The operator shall avoid exposing any part of their
3.2.1 LNG—liquefied natural gas
person, especially their eyes, not only to direct UV light but
3.2.2 LPG—liquefied petroleum gas
also to secondary or scattered radiation that is present.
3.2.3 NIST—National Institute of Standards and Technology
4.2 The design and installation details for the on-line/at-line
3.2.4 NMi—Nederlands Meetinstituut
process analyzer needs to conform to application-specific
3.2.5 NTRM—NIST traceable reference material
requirements including, but not limited to, acceptable design
practices as described in Practice D7166, hazardous area
3.2.6 QA—quality assurance
classifications, safety practices, and regulatory requirements.
3.2.7 QC—quality control
Fig. 1 illustrates a general flow diagram applicable for an
3.2.8 SO —ground state sulfur dioxide
on-line/at-line process analyzer. Sample collection and
3.2.9 SO *—excited state sulfur dioxide
conditioning, sample introduction and detection system are
depicted. Modifications to meet site-specific and/or application
3.2.10 SOx—sulfur oxides
specific requirements may be required.
3.2.11 SRM—standard reference material
3.2.12 UHP—ultra high purity 5. Significance and Use
3.2.13 UV—ultraviolet
5.1 The sulfur content of gaseous hydrocarbons, LPG, and
LNG used for fuel purposes contributes to total SOx emissions
3.2.14 VSL—Van Swinden Laboratorium
and can lead to corrosion in engine and exhaust systems. Some
process catalysts used in petroleum and chemical refining can
MNL 7AManual on Presentation of Data and Control Chart Analysis, Seventh
be poisoned by trace amounts of sulfur-bearing materials in the
Edition, ASTM International, West Conshohocken. 2002.
feed stocks. This test method can be used to determine the total
Available from Gas Processors Association (GPA), 6526 E. 60th St., Tulsa, OK
volatile sulfur content in process feeds, to control the total
74145, http://www.gasprocessors.com.
FIG. 1 General Flow Diagram—On-Line Analyzer
D7551 − 10 (2015)
volatile sulfur content in finished products and, as applicable, 7. Reagents
to meet regulatory requirements. Practice D1072 has previ-
7.1 Purity of Reagents—Reagent grade chemicals shall be
ously been used for the measurement of total sulfur in gaseous
used in tests. Unless otherwise indicated, it is intended that all
fuels.
reagents shall conform to the specifications of the Committee
on Analytical Reagents of the American Chemical Society,
6. Apparatus
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
6.1 Furnace—An electric furnace held at a constant tem-
sufficiently high purity to permit its use without lessening the
perature in accordance with the analyzer manufacturer’s rec-
accuracy of the determination.
ommendations (nominally 1000 to 1125°C) sufficient to oxi-
dize the entire sample to carbon dioxide and water and oxidize
7.2 Inert Gas—Argon or helium only, high purity grade
the sulfur in the sample to SO .
(that is, chromatography or zero grade), 99.998 % minimum
purity, moisture 5 mg/kg maximum, as required.
6.2 Combustion Tube—A quartz tube constructed to allow
the direct injection of the sample into the heated oxidation zone 7.3 Oxygen—High purity, that is, chromatography or zero
of the furnace by syringe or sample valve using either oxygen grade, 99.75 % minimum purity, moisture 5 mg/kg maximum,
or air for the oxidation of the sample. Other tube materials dried over molecular sieves, as required. Warning—Oxygen
suitable for use at the furnace operating conditions can be used vigorously accelerates combustion.
so long as performance is not degraded. The oxidation section
7.4 Air—Use dry, sulfur free air, that is, chromatography
shall be large enough to ensure complete conversion of the
˚
grade or zero grade, –40 C dew point or lower, as required.
sample to carbon dioxide and water and oxidize the sulfur in
Nitrogen/oxygen or helium/oxygen bottled gas blends contain-
the sample to SO .
ing no more than 30 % oxygen can also be used, as required.
Warning—Never use pure oxygen as a substitute for air on
6.3 Flow Control—The apparatus shall be equipped with
analyzers designed to operate using air as a carrier gas.
flow controllers capable of maintaining a constant volumetric
flow rate of the carrier gases necessary for performing the total
7.5 Calibration Standards—Certified liquid or gas phase
sulfur analysis.
calibration standards from commercial sources or calibration
gases prepared using certified permeation tube devices are
6.4 Drier—The oxidation of the sample produces reaction
required (see Notes 2 and 3). Accurate volatile sulfur contain-
products that include water vapor which, if in excess, must be
ing standards are required for quantization of the volatile total
removed prior to measurement by the detector. This can be
sulfur content. Permeation tubes and compressed gas standards
accomplished with a membrane drying tube, or a permeation
should be stable, of high purity, and of the highest available
dryer that utilizes a selective capillary action for water re-
accuracy. Use of standards consisting of a sulfur compound
moval.
and matrix similar to samples to be analyzed is recommended.
6.5 UV Fluorescence Detector—A quantitative detector ca-
NOTE 2—Other sulfur sources and diluent materials can be used if
pable of measuring light emitted from the fluorescence of SO
precision and accuracy are not degraded. The use of solvent based
generated by continuous or pulsed UV light.
calibration standards that are liquid at ambient temperatures and pressures
is not recommended.
NOTE 1—For an on-line analyzer, detection of uncombusted hydrocar-
bons in the UV Fluorescence Detector can be used to ensure complete NOTE 3—Calibration standards are typically re-mixed and re-certified
conversion of the hydrocarbons to carbon dioxide and water and to on a regular basis depending upon frequency of use and age. LPG
minimize the potential for coke formation in the analytical system. calibration standards have a typical useful life of about 6–12 months.
NOTE 4—Enhanced oxygen containing combustion gasses, such as
6.6 Sample Inlet System—Either of the following two types
30 % Oxygen balance Helium, Nitrogen, and/or Argon, can be used if
of sample inlet systems can be used.
precision and accuracy are not degraded.
NOTE 5—Warning: Compressed gas cylinders as well as sulfur
6.6.1 Sample Valve System—The system provides a gas-
compounds contained in permeation tubes may be flammable and harmful
sampling valve, or an LPG or LNG gas or liquid sampling
or fatal if ingested or inhaled. Permeation tubes and compressed gas
valve with an expansion chamber, or both, with access to the
standards should only be handled in well ventilated locations away from
inlet of the oxidation area. The system is swept by the carrier
sparks and flames. Improper handling of compressed gas cylinders
containing air, nitrogen, helium, or other gasses can result in unsafe
gas at the manufacturer’s recommended flow rate.
conditions that can cause severe damage to equipment and significant
6.6.2 Sample Injection—The sample inlet system for gas-
harm, including death, to people. Rapid release of nitrogen or helium can
eous samples shall be capable of allowing the quantitative
result in asphyxiation. Compressed air supports combustion.
delivery of the material to be analyzed into an inlet carrier
7.5.1 Permeation Devices—Standards containing volatile
stream which directs the sample into the oxidation zone at a
sulfur compounds can be made from permeation tubes, one for
controlled and repeatable rate. For a laboratory analysis, a
each selected sulfur species, gravimetrically calibrated and
syringe drive mechanism that discharges the sample from the
certified at a convenient operating temperature. With constant
syringe at a rate of approximately 1 mL/s is required. For at
temperature, calibration gases covering a wide range of con-
line and on-line analysis a constant volumetric flow rate
centration can be generated by varying and accurately measur-
delivery device is used.
ing the flow rate of diluent gas passing over the permeation
6.7 Strip Chart Recorder, equivalent electronic data logger, tubes. These calibration gases can be used to calibrate the
integrator or, recorder (optional). analyzer system.
D7551 − 10 (2015)
7.5.1.1 Permeation System Temperature Control— lected in accordance with manufacturer’s recommendations for
Permeation devices are maintained at the calibration tempera- the
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