ICS 23.100.50                         PGD 36

Revised Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Second Revision) which is identical with ISO 5781 : 2016 'Hydraulic fluid power - Pressure-reducing valves, sequence valves, unloading valves, throttle valves and check valves - Mounting surfaces' issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation of the Fluid Power Systems Sectional Committee and approval of the Production and General Engineering Division Council.

In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure circulating within an enclosed circuit. The most typical components found in such systems are hydraulic valves. They control flow direction, pressure or the flow rate of liquids in the enclosed circuit.

This standard was first published in 1994 by adopting ISO 5781 : 1987 'Hydraulic fluid power - Pressure control valves (excluding pressure-relief valves), sequence valves, unloading valves, throttle valves and check valves - Mounting surfaces'. It was subsequently revised in 2005 to align with ISO 5781 : 2000. The second revision of this standard has been undertaken to align it with the latest version of ISO 5781 : 2016.