Safety Instrumented Systems (SIS) is one of the most important layers of protection against accidents in the process industry. IEC 61511 series covers the application of electrical, electronic and programmable electronic equipment. IEC 61511 covers the design and management requirements for SIS throughout the entire safety life cycle.
BS EN 61511-3 provides information on the underlying concepts of risk and the relationship of risk to safety integrity, the determination of tolerable risk, a number of different methods that enable the SIL for the safety instrumented functions to be determined, and the impact of multiple safety systems on calculations determining the ability to achieve the desired risk reduction.
BS EN 61511-3 applies when functional safety is achieved using one or more safety instrumented functions for the protection of either personnel, the general public, or the environment and may be applied in non-safety applications such as asset protection.
Note: BS EN 61511-3 does not specify the safety integrity level required for specific applications and also does not give examples of determining the requirements for other methods of risk reduction.
BS EN 61511-3 on Safety Instrumented Systems is useful for:
The design and implementation of SIS systems meet good engineering practices and avoid failures in the process industry like chemicals, refineries, petrochemicals, power etc. The IEC 61511 series is intended to lead to a high level of consistency (for example, of underlying principles, terminology, information) within the process industries. IEC 61511 series sets out an approach for SIS safety life-cycle activities to achieve these minimum standards.
BS EN 61511-3 deals with guidance in the area of determining the required SIL in hazards and risk assessment. The information herein is intended to provide a broad overview of the wide range of global methods used to implement hazards and risk assessment.
BS EN 61511-3 illustrates typical hazard and risk assessment methods that may be carried out to define the safety functional requirements and SIL of each safety instrumented function. BS EN 61511-3 also illustrates techniques and measures available for determining the required safety integrity level and provides a framework for establishing SIL.
BS EN 61511-3:2017 supersedes BS EN 61511-3:2004, which is withdrawn. BS EN 61511-3:2017 includes a technical change with respect to BS EN 61511-3:2004. This includes Additional H&RA examples and quantitative analysis consideration annexes are provided.
EN 61511-3:2017
IEC 61511-3:2016