1.1 本规程涵盖了确定计算甲烷数（MN）的方法 C )指用于内燃机的气体燃料。该方法的基础是适用于在具有Microsoft Windows操作系统的计算机上运行的动态链接库（DLL）。 1.2 该实践涉及已加工并适用于内燃机的市售天然气产品。这些燃料可以来自传统的地质或可再生资源，包括第节中定义的管道天然气、压缩天然气（CNG）、液化天然气、液化石油气和可再生天然气 3. 。 1.3 本规程中的计算方法基于EN 16726附录A中定义的MWM方法。 2. 该计算方法是一种优化算法，使用由气体燃料样品的成分生成的三元和二元气体成分表的不同序列。 3. 源代码和基于Microsoft Excel的计算器都可用于此方法。 1.4 该计算方法适用于包括从甲烷到己烷及更大的碳氢化合物（C6+）的气体燃料；一氧化碳； 氢硫化氢；氮和二氧化碳。该计算方法涉及戊烷（C5）和高级烃，并将C5和C6+的单个体积分数限制为3 % 每个和总共5个 %. （见EN 16726，附录A.）计算方法在干燥、无氧的基础上进行。 1.5 单位- 以国际单位制表示的数值应视为标准。本标准中包含的其他计量单位仅供参考，不属于标准计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 甲烷数（MN）是在内燃机中使用时气体燃料对自燃（爆震）的抵抗力的量度。来自不同来源和具有不同组成的气体燃料的相对优点可以根据它们的甲烷数容易地进行比较。因此，计算出的甲烷数（MN C )用作确定气体燃料在移动和固定应用中用于内燃发动机的适用性的参数。

1.1 This practice covers the method to determine the calculated methane number (MN C ) 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. ====== 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 (MN C ) is used as a parameter for determining the suitability of a gaseous fuel for internal combustion engines in both mobile and stationary applications.