ASTM D8221-23

Standard Practice for Determining the Calculated Methane Number (MN<inf>C</inf>) of Gaseous Fuels Used in Internal Combustion Engines

SIGNIFICANCE AND USE
5.1 The methane number (MN) is a measure of the resistance of the gaseous fuel to autoignition (knock) when used in an internal combustion engine. The relative merits of gaseous fuels from different sources and having different compositions can be compared readily on the basis of their methane numbers. Therefore, the calculated methane number (MNC) is used as a parameter for determining the suitability of a gaseous fuel for internal combustion engines in both mobile and stationary applications.
SCOPE
1.1 This practice covers the method to determine the calculated methane number (MNC) of a gaseous fuel used in internal combustion engines. The basis for the method is a dynamic link library (DLL) suitable for running on computers with Microsoft Windows operating systems.  
1.2 This practice pertains to commercially available natural gas products that have been processed and are suitable for use in internal combustion engines. These fuels can be from traditional geological or renewable sources and include pipeline gas, compressed natural gas (CNG), liquefied natural gas, liquefied petroleum gas, and renewable natural gas as defined in Section 3.  
1.3 The calculation method within this practice is based on the MWM Method as defined in EN 16726, Annex A.2 The calculation method is an optimization algorithm that uses varying sequences of ternary and binary gas component tables generated from the composition of a gaseous fuel sample.3 Both the source code and a Microsoft Excel-based calculator are available for this method.  
1.4 This calculation method applies to gaseous fuels comprising of hydrocarbons from methane to hexane and greater (C6+); carbon monoxide; hydrogen; hydrogen sulfide; nitrogen; and carbon dioxide. The calculation method addresses pentanes (C5) and higher hydrocarbons and limits the individual volume fraction of C5 and C6+ to 3 % each and a combined total of 5 %. (See EN 16726, Annex A.) The calculation method is performed on a dry, oxygen-free basis.  
1.5 Units—The values stated in SI units are to be regarded as standard. Other units of measurement included in this standard are provided for information only and are not considered 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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: 30-Apr-2023
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.03 - Determination of Heating Value and Relative Density 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: D8221 − 23
Standard Practice for
Determining the Calculated Methane Number (MN ) of
C
1
Gaseous Fuels Used in Internal Combustion Engines
This standard is issued under the fixed designation D8221; 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 1.5 Units—The values stated in SI units are to be regarded
as standard. Other units of measurement included in this
1.1 This practice covers the method to determine the calcu-
standard are provided for information only and are not consid-
lated methane number (MN ) of a gaseous fuel used in internal
C
ered standard.
combustion engines. The basis for the method is a dynamic
1.6 This standard does not purport to address all of the
link library (DLL) suitable for running on computers with
safety concerns, if any, associated with its use. It is the
Microsoft Windows operating systems.
responsibility of the user of this standard to establish appro-
1.2 This practice pertains to commercially available natural
priate safety, health, and environmental practices and deter-
gas products that have been processed and are suitable for use
mine the applicability of regulatory limitations prior to use.
in internal combustion engines. These fuels can be from
1.7 This international standard was developed in accor-
traditional geological or renewable sources and include pipe-
dance with internationally recognized principles on standard-
line gas, compressed natural gas (CNG), liquefied natural gas,
ization established in the Decision on Principles for the
liquefied petroleum gas, and renewable natural gas as defined
Development of International Standards, Guides and Recom-
in Section 3.
mendations issued by the World Trade Organization Technical
1.3 The calculation method within this practice is based on
Barriers to Trade (TBT) Committee.
2
the MWM Method as defined in EN 16726, Annex A. The
calculation method is an optimization algorithm that uses 2. Referenced Documents
varying sequences of ternary and binary gas component tables 4
2.1 ASTM Standards:
3
generated from the composition of a gaseous fuel sample.
D4150 Terminology Relating to Gaseous Fuels
Both the source code and a Microsoft Excel-based calculator
E29 Practice for Using Significant Digits in Test Data to
are available for this method.
Determine Conformance with Specifications
5
1.4 This calculation method applies to gaseous fuels com-
2.2 CEN Standard:
prising of hydrocarbons from methane to hexane and greater
EN 16726 Gas infrastructure—Quality of gas—Group H,
(C6+); carbon monoxide; hydrogen; hydrogen sulfide; nitro-
Annex A—Calculation of methane number of gaseous
gen; and carbon dioxide. The calculation method addresses
fuels for engines
6
pentanes (C5) and higher hydrocarbons and limits the indi-
2.3 ISO Standard:
vidual volume fraction of C5 and C6+ to 3 % each and a
ISO 14912 Gas analysis—Conversion of gas mixture com-
combined total of 5 %. (See EN 16726, Annex A.) The
position data
calculation method is performed on a dry, oxygen-free basis. 7
2.4 ASTM Adjuncts:
ASTM_D8221_mzdll_ver2.32.0.dll
ASTM_D8221_MNc_Method_ver1.32.1.xlsb
1
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
NOTE 1—The adjuncts listed above are the Microsoft Office 32-bit
Fuels and is the direct responsibility of Subcommittee D03.03 on Determination of
Heating Value and Relative Density of Gaseous Fuels.
Current edition approved May 1, 2023. Published June 2023. Originally
ɛ1
4
approved in 2018. Last previous edition approved in 2018 as D8221 – 18a . DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D8221-23. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
2
European Standards (ENs) are documents that have been ratified by one of the Standards volume information, refer to the standard’s Document Summary page on
three European Standardization Organizations (ESOs), CEN, CENELEC or ETSI; the ASTM website.
5
recognized as competent in the area of voluntary technical standardization as for the Available from European Committee for Standardization (CEN), Avenue
EU Regulation 1025/2012. EN16726 was developed by the Technical Committee Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
6
CEN/TC 234. Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
3
Leiker, M., Christoph, K., Rankl, M., Cartellieri, W., and Pfeifer, U., “Evalu- 4th Floor, New York, NY 1
...

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.
´1
Designation: D8221 − 18a D8221 − 23
Standard Practice for
Determining the Calculated Methane Number (MN ) of
C
1
Gaseous Fuels Used in Internal Combustion Engines
This standard is issued under the fixed designation D8221; 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
ε NOTE—The Excel filenames in 2.4, A1.1.1, and A1.1.4.5 were updated editorially in August 2019.
1. Scope
1.1 This practice covers the method to determine the calculated methane number (MN ) of a gaseous fuel used in internal
C
combustion engines. The basis for the method is a dynamic link library (DLL) suitable for running on computers with Microsoft
Windows operating systems.
1.2 This practice pertains to commercially available natural gas products that have been processed and are suitable for use in
internal combustion engines. These fuels can be from traditional geological or renewable sources and include pipeline gas,
compressed natural gas (CNG), liquefied natural gas (LNG), gas, liquefied petroleum gas (LPG), gas, and renewable natural gas
(RNG) as defined in Section 3.
2
1.3 The calculation method within this practice is based on the MWM Method as defined in EN 16726, Annex A. The calculation
method is an optimization algorithm that uses varying sequences of ternary and binary gas component tables generated from the
3
composition of a gaseous fuel sample. Both the source code and a Microsoft Excel-based calculator are available for this method.
1.4 This calculation method applies to gaseous fuels comprising of hydrocarbons from methane to hexane and greater (C6+);
carbon monoxide; hydrogen; hydrogen sulfide; nitrogen; and carbon dioxide. The calculation method addresses pentanes (C5) and
higher hydrocarbons and limits the individual volume fraction of C5 and C6+ to 3 % each and a combined total of 5 %. (See EN
16726, Annex A.) The calculation method is performed on a dry, oxygen-free basis.
1.5 Units—The values stated in SI units are to be regarded as standard. Other units of measurement included in this standard are
provided for information only and are not considered 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.03 on Determination of Heating
Value and Relative Density of Gaseous Fuels.
Current edition approved Dec. 1, 2018May 1, 2023. Published April 2019June 2023. Originally approved in 2018. Last previous edition approved in 2018 as
ɛ1
D8221D8221 – 18a –18. DOI: 10.1520/D8221-18AE01. DOI: 10.1520/D8221-23.
2
European Standards (ENs) are documents that have been ratified by one of the three European Standardization Organizations (ESOs), CEN, CENELEC or ETSI;
recognized as competent in the area of voluntary technical standardization as for the EU Regulation 1025/2012. EN16726 was developed by the Technical Committee CEN/TC
234.
3
Leiker, M., Christoph, K., Rankl, M., Cartellieri, W., and Pfeifer, U., “Evaluation of Antiknocking Property of Gaseous Fuels by Means of Methane Number and its
Practical Application to Gas Engines,” ASME, 72-DGP-4, 1972.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D8221 − 23
1.7 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
4
2.1 ASTM Standards:
D4150 Terminology Relating to Gaseous Fuels
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
5
2.2 CEN Standard:
EN 16726 Gas infrastructure—Quality of gas—Group H, Annex A—Calculation of methane number of gaseous fuels for
engines
6
2.3 ISO Standard:
ISO 14912 Gas analysis—Conversion of gas mixture composition data
7
2.4
...