BS EN ISO 15971:2014

Specifies the measurement of calorific value of natural gas and natural gas substitutes by non-separative methods, i.e. methods that do not involve the determination of the gas composition, nor calculations from it.

This InternationalStandard concerns the measurement of calorific value ofnaturalgas and natural gas substitutes by non-separative methods, i.e. methods that do not involve the determination of the gas composition nor calculation from it. It describes the principles of operation of a varietyof instruments in use forthis purpose, and providesguidelines for the selection, evaluation, performance assessment, installation andoperation of these.

Calorific values can be expressed on a mass basis, a molar basis or, more commonly,a volume basis. The working range for superior calorificvalue of natural gas, on the volume basis, is usuallybetween 30MJ/m³and 45 MJ/m³ at standard reference conditions (see ISO13443). The corresponding range for the Wobbeindex is usuallybetween 40 MJ/m³ and 60 MJ/m³.

This International Standard neitherendorses nor disputes the claims of any commercial manufacturer for theperformance of an instrument. Its central thesis is that fitness-for-purpose in anyparticular application (defined in terms of a set ofspecific operational requirements) can be assessed onlybymeans of a well-designed programme of experimental tests. Guidelines are provided for the proper content of these tests.