ISO 18453:2004规定了一种为用户提供天然气中水分含量和水露点之间可靠数学关系的方法，其中一种已知。由GERG开发的计算方法；适用于含水量和水露点的计算。 ISO 18453:2004给出了相关性的不确定度，但未尝试量化测量不确定度。

ISO 18453:2004 specifies a method to provide users with a reliable mathematical relationship between water content and water dew point in natural gas when one of the two is known. The calculation method, developed by GERG; is applicable to both the calculation of the water content and the water dew point. ISO 18453:2004 gives the uncertainty for the correlation but makes no attempt to quantify the measurement uncertainties.