Reaffirmed 2024

NATIONAL FOREWORD

This Indian Standard (Part 6) (First Revision) which is identical with ISO 6145-6 : 2017 ‘Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 6: Critical flow orifices’ 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 the method for the dynamic preparation of calibration gas mixtures containing at least two gases (usually one of them is a complementary gas) from pure gases or gas pre-mixtures using critical flow orifice systems. The method applies principally to the preparation of mixtures of non-reactive gases that do not react with any of the materials in the gas circuit inside the critical flow orifice system or auxiliary equipment. It has the merit of allowing multi-component mixtures to be prepared as readily as a binary mixture, if an appropriate number of critical flow orifices are used. The range of flow rates covered by this standard extends from 1 ml/min to 10 l/min.

This standard, which was originally published in 2015, was identical with ISO 6145-6 : 2003. The first revision of this standard has been undertaken to align it with ISO 6145-6 : 2017.

This Indian Standard is published in several parts. The other parts in this series are:

Part 1 Methods of calibration

Part 2 Pistonpumps

Part 4 Continuous syringe injection method

Part 5 Capillary calibration devices

Part 7 Thermal mass-flow controllers

Part 8 Diffusion method

Part 9 Saturation method

Part 10 Permeation method

Part 11 Electrochemical generation

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’ appears 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.