The calculation method for gas calorific value is based on the following standards
GB/T13610-2014 "Composition Analysis of Natural Gas - Gas Chromatography Method"
GB/T 12206-2006 "Determination of Heating Value and Relative Density of Urban Gas"
GB/T11062-1998 "Methods for calculating calorific value, density, average density, and Wopo index of natural gas" - Requirements for testing and analysis