General

This report applies specifically to energy-based custody transfer measurement of natural gas. It may or may not be suitable to other applications, as determined by the user.

Heating value measurement is used in tandem with volume flow or mass flow measurement, the use of which is guided by other reports and industry standards. This report is not intended to supersede, extend or duplicate the content of flow measurement documents.

For ease of use, this report supports two approaches to estimating heating value from composition: simplified ‘table look-up' or full calculation. The approaches are functionally equivalent because the look-up tables were produced with the calculation methods.

The tables A.1.1 and A.1.2 provide pre-calculated heating values of common gas constituents for a range of common reference conditions. The detailed methods and data elsewhere in this report are primarily for traceability.

Report No. 5 differs in scope from other documents concerning energy measurement. In addition to technical data and formulas, this report recommends performance criteria.

The physical property data reproduced in this report were drawn from widely-accepted industry sources, including NIST[1] and CODATA[12]. Results obtained using this report will agree closely with results from methods sharing its lineage.

In keeping with gas industry practice, this report supports both SI and Imperial units of measure.