本标准介绍了在基本条件下，根据成分计算天然气混合物以下性质的程序:总热值、相对密度（真实和理想）、压缩系数和理论碳氢化合物液体含量，在美国，通常表示为GPM，即每千立方英尺气体中液体加仑数的缩写。严格计算水对这些计算的影响是复杂的。由于本文件主要与监护权转移有关，因此包含的水效应是可接受的合同计算。 本标准附录A包含对水的影响的详细调查，以及本标准中给出的方程式的详细推导。

This standard presents procedures for calculating, at base conditions from composition, the following properties of natural gas mixtures: gross heating value, relative density (real and ideal), compressibility factor and theoretical hydrocarbon liquid content which in the U.S. is typically expressed as GPM, the abbreviation for gallons of liquid per thousand cubic feet of gas. Rigorous calculation of the effect of water upon these calculations is complicated. Because this document relates primarily to custody transfer, the water effect included is an acceptable contractual calculation. Annex A of this standard contains a detailed investigation of the effect of water and detailed derivations of the equations presented in the standard.