Suppliers of equipment which is part of an instrumented safety system are responsible for providing evidence that the equipment is suitable for use in safety related applications.
This evidence is normally presented in a Safety Manual, and shall demonstrate compliance with the requirements defined in the project Safety Requirement Specifications (SRS).
The Safety Manual shall include necessary information to demonstrate compliance, such as:
- Equipment description
- Failure rates
- Diagnostic coverage
- Response time
- Frequency of testing
- Operational constraints
The IEC 61508 standard lists information that shall be available for each safety-related subsystem and documented in the Safety Manual.
The classification of equipment failures may be documented through the use of Failure Mode, Effect and Criticality Analysis (FMECA).
