ASTM D7940-21

Standard Practice for Analysis of Liquefied Natural Gas (LNG) by Fiber-Coupled Raman Spectroscopy

SIGNIFICANCE AND USE
5.1 The composition of liquefied gaseous fuels (LNG, LPG) is important for custody transfer and production. Compositional determination is used to calculate the heating value, and it is important to ensure regulatory compliance. Compositional determination is also used to optimize the efficiency of liquefied hydrocarbon gas production and ensure the quality of the processed fluids.  
5.2 Alternatives to compositional measurement using Raman spectroscopy are described in Test Method D1945, Practice D1946, and Test Method D7833.  
5.3 The advantage of this practice over other standards stated in 5.2, is that Raman spectroscopy can determine composition by directly measuring the liquefied natural gas. Unlike chromatography, no vaporization step is necessary. Since incorrect operation of on-line vaporizers can lead to poor precision and accuracy, elimination of the vaporization step offers a significant improvement in the analysis of LNG.
SCOPE
1.1 This practice is for both on-line and laboratory instrument-based determination of composition for liquefied natural gas (LNG) using Raman spectroscopy. Although the procedures in this practice refer specifically to liquids, the basic methodology can also be applied to other light hydrocarbon mixtures in either liquid or gaseous states, provided the data quality objectives and measurement needs are met. From the composition, gas properties such as heating value and the Wobbe index may be calculated. The components commonly determined according to this test method are CH4, C2H6, C3H8, i-C4H10, n-C4H10, iC5H12, n-C5H12. Components heavier than C5 are not measured as part of this practice.
Note 1: Raman spectroscopy does not directly quantify the component percentages of noble gases; however, inert substances can be calculated indirectly by subtracting the sum of the other species from 100 %.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2021
• ICS: 75.060 - Natural gas
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.12 - On-Line/At-Line Analysis of Gaseous Fuels

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:D7940 −21
Standard Practice for
Analysis of Liquefied Natural Gas (LNG) by Fiber-Coupled
1
Raman Spectroscopy
This standard is issued under the fixed designation D7940; 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
1.1 This practice is for both on-line and laboratory 2.1 ASTM Standards:
instrument-based determination of composition for liquefied D1945 Test Method for Analysis of Natural Gas by Gas
natural gas (LNG) using Raman spectroscopy. Although the Chromatography
procedures in this practice refer specifically to liquids, the D1946 Practice for Analysis of Reformed Gas by Gas
basic methodology can also be applied to other light hydrocar- Chromatography
bon mixtures in either liquid or gaseous states, provided the D3588 Practice for Calculating Heat Value, Compressibility
data quality objectives and measurement needs are met. From Factor, and Relative Density of Gaseous Fuels
the composition, gas properties such as heating value and the D4150 Terminology Relating to Gaseous Fuels
Wobbe index may be calculated. The components commonly D7833 Test Method for Determination of Hydrocarbons and
determinedaccordingtothistestmethodareCH ,C H ,C H , Non-Hydrocarbon Gases in Gaseous Mixtures by Gas
4 2 6 3 8
i-C H , n-C H ,iC H , n-C H . Components heavier than Chromatography
4 10 4 10 5 12 5 12
C5 are not measured as part of this practice. E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
NOTE1—Ramanspectroscopydoesnotdirectlyquantifythecomponent
3
percentages of noble gases; however, inert substances can be calculated 2.2 BS EN Standards:
indirectly by subtracting the sum of the other species from 100 %.
BS EN 60079-28 Explosive Atmospheres. Protection of
Equipment and Transmission Systems using Optical Ra-
1.2 Units—The values stated in SI units are to be regarded
diation
as standard. No other units of measurement are included in this
BS EN 60825-1 Safety of Laser Products Part 1: Equipment
standard.
Classification, Requirements and User’s Guide
1.3 This standard does not purport to address all of the
4
2.3 ISO Standards:
safety concerns, if any, associated with its use. It is the
ISO 6974-5 Natural Gas—Determination of Composition
responsibility of the user of this standard to establish appro-
with Defined Uncertainty by Gas Chromatography, Part 5:
priate safety, health, and environmental practices and deter-
Determination of Nitrogen, Carbon Dioxide and C1 to C5
mine the applicability of regulatory limitations prior to use.
and C6+ Hydrocarbons for a Laboratory and On-line
1.4 This international standard was developed in accor-
Process Application Using Three Columns
dance with internationally recognized principles on standard-
ISO 6976:2016(E) Natural Gas—Calculation of Calorific
ization established in the Decision on Principles for the
Values,Density,RelativeDensityandWobbeIndicesfrom
Development of International Standards, Guides and Recom-
Composition
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
1
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous Standards volume information, refer to the standard’s Document Summary page on
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line the ASTM website.
3
Analysis of Gaseous Fuels. Available from British Standards Institution (BSI), 389 Chiswick High Rd.,
Current edition approved Nov. 1, 2021. Published November 2021. Originally London W4 4AL, U.K., http://www.bsigroup.com.
4
approved in 2014. Last previous edition approved in 2014 as D7940 – 14. DOI: Available from International Organization for Standardization (ISO), 1, ch. de
10.1520/D7940-21. la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
1

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D7940−21
3. Terminology 3.3.2 IS—industry standard
3.3.3 NIST—NationalInstituteofStandardsandTechnology
3.1 Definitions:FordefinitionsofgeneraltermsusedinD03
Gaseous Fuels standards, refer to Terminology D4150.
3.3.4 NMI—National Metrology Institute
3.2 Definitions of Terms Specific to
...

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: D7940 − 14 D7940 − 21
Standard Practice for
Analysis of Liquefied Natural Gas (LNG) by Fiber-Coupled
1
Raman Spectroscopy
This standard is issued under the fixed designation D7940; 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 standard practice is for both on-line and laboratory instrument-based determination of composition for liquefied natural
gas (LNG) using Raman spectroscopy. The Although the procedures in this practice refer specifically to liquids, the basic
methodology can also be applied to other light hydrocarbon mixtures in either liquid or gaseous states, if the needs of the
application are met, although the rest of this practice refers specifically to liquids. provided the data quality objectives and
measurement needs are met. From the composition, gas properties such as heating value and the Wobbe index may be calculated.
The components commonly determined according to this test method are CH , C H , C H , i-C H , n-C H , iC H , n-C H ,
4 2 6 3 8 4 10 4 10 5 12 5 12
neo-C H , N , O . The applicable range of this standard is 200 ppmv to 100 mol %. Components heavier than C5 are not measured
5 12 2 2
as part of this practice.
NOTE 1—Raman spectroscopy does not directly quantify the component percentages of noble gases,gases; however, inerts inert substances can be
calculated indirectly by subtracting the sum of the other species from 100 %.100 %.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D3588 Practice for Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels
D4150 Terminology Relating to Gaseous Fuels
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
D1945 Test Method for Analysis of Natural Gas by Gas Chromatography
D1946 Practice for Analysis of Reformed Gas by Gas Chromatography
D3588 Practice for Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels
1
This test method 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 June 1, 2014Nov. 1, 2021. Published July 2014November 2021. Originally approved in 2014. Last previous edition approved in 2014 as D7940
– 14. DOI: 10.1520/D7940-14.10.1520/D7940-21.
2
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D7940 − 21
D4150 Terminology Relating to Gaseous Fuels
D7833 Test Method for Determination of Hydrocarbons and Non-Hydrocarbon Gases in Gaseous Mixtures by Gas
Chromatography
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3
2.2 BS EN Standards:
BS EN 60079-28 Explosive Atmospheres. Protection of Equipment and Transmission Systems using Optical Radiation
BS EN 60825-1 Safety of Laser Products Part 1: Equipment Classification, Requirements and User’s Guide
4
2.3 ISO Standards:
ISO 6974-5 Natural Gas—Determination of Composition with Defined Uncertainty by Gas Chromatography, Part 5:
Determination of nitrogen, carbon dioxideNitrogen, Carbon Dioxide and C1 to C5 and C6+ hydrocarbonsHydrocarbons for
a laboratory
...