New Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Part 4) (Second Revision) which is identical with ISO 4126-4 : 2013 ‘Safety devices for protection against excessive pressure - Part 4: Pilot operated safety valves’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Chemical Engineering Plants and Related Equipment Sectional Committee and approval of the Mechanical Engineering Division Council.

This standard was originally published in 1988. The second revision of this standard has been undertaken to keep pace with the latest technological developments and align it with the latest version of ISO 4126-4 : 2013. The standard is being bifurcated into six parts in this revision.