This International Standard concerns the measurement of the calorific value of natural gas and natural gas substitutes by non-separative methods, that is methods which do not involve the determination of the composition of the gas or the calculation from it. It describes the operating principles of a variety of instruments used for this purpose, and it provides guidelines for their selection, evaluation, performance evaluation, installation and operation.
NF X20-515*NF EN ISO 15971:2014 Referenced Document
ISO 14532 Natural gas - Vocabulary*， 2014-06-01 Update
ISO 6976 Natural gas - Calculation of calorific values, density, relative density and Wobbe indices from composition*， 2016-08-01 Update