The Safety Requirements Specification is a requirement of the IEC61511 standard ‘Functional Safety – Safety Instrumented Systems for the Process Industry Sector’. The SRS is one of the more important activities to be carried out during the SIS safety lifecycle as it defines and collates all the information necessary to build Safety Instrumented Functions. The SRS is used throughout the Life of the facility from the initial design of the SIS and SIF’s through to validation where it is used as a reference to check that safety requirements are implemented in the SIS and into Operation where it is often referenced in Proof Testing Procedures. For an Operational Facility the lack of an SRS would imply poor management of SIFs.

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• SIS Scope

• Reference Documents

• General Design Assumptions and Parameters

• SIS Response Time

• SIS Availability and Failure Modes

• Application Software Requirements Specification

• SIS Operations Interfaces

• SIF Identification

• Process & Operations Requirements

• Overall Functional Performance Requirements

• Instrument Proof Testing

• SIF Data Revisions

 

Common design data should be collated together to avoid duplication.