This standard defines the functional safety requirements established by IEC 61508 in process industry sector terminology.
IEC 61511 provides good engineering practices for the application of safety instrumented systems in the process sector.
For example, in Great Britain, it is published by the national standards body, BSI, as BS EN 61511.
IEC 61511 covers the design and management requirements for SISs throughout the entire safety life cycle.
An SIS is composed of a separate and independent combination of sensors, logic solvers, final elements, and support systems that are designed and managed to achieve a specified safety integrity level (SIL).
Field data are collected through operational and mechanical integrity program activities to assess actual SIS performance.
When the required performance is not met, action should be taken to close the gap, ensuring safe and reliable operation.