Revised Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (First Revision) which is identical with ISO 6142-1 : 2015 ‘Gas analysis - Preparation of calibration gas mixtures - Part 1 : Gravimetric method for class I mixtures’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation of the Industrial Gases Sectional Committee and approval of the Chemical Division Council.

This standard specifies a gravimetric method for the preparation of calibration gas mixtures in cylinders with traceable values for the amount-of-substance fraction (amount fraction) of one or more components. This standard describes a method for calculating the uncertainty associated with the amount fraction of each component. This standard is only applicable to mixtures of gaseous or totally vaporized components, which may be introduced into the cylinder in the gaseous or liquid state. Both binary and multi-component gas mixtures (including natural-gas type mixtures) are covered by this standard.

This standard, which was originally published in 2014, was identical with ISO 6142 : 2001. The ISO standard was revised and bifurcated in 2015, with part 1 addressing class I mixtures. The first revision of this standard has been undertaken to align it with ISO 6142-1 : 2015.

In this revision, the methods of preparation, estimation of uncertainty and validation of composition of gravimetrically prepared calibration gases have been updated. Also, the amendment to the previous version of ISO 6142 has been amalgamated.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminologies and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker, while in Indian Standards, the current practice is to use a point (.) as the decimal marker.