ISO/NP 26989

Gas analysis — Guidelines for using atomic weights

Scope

This document sets requirements and provides guidance for the derivation and use of atomic weights, molecular weights, and their conversion to molar masses for applications in gas analysis.
This document also provides recommended reference values for the atomic weights in general, as well as reference values for specific applications (e.g., calibration gas mixture preparation from high-purity gases, air quality, natural gas). The generally recommended values for the atomic weights are given in Annex A and the recommended values for reference atomic weights are given in Annex B.