Functional safety focuses on the detection of a potentially dangerous condition and depends on automatic protection or correction to prevent an unwanted consequence or reduce its severity. The automatic protection system is designed to respond appropriately to errors, hardware failures, and operational stressors.
When every specified safety function is carried out and meets the set level of performance, functional safety is achieved. This requires a process that includes:
- Identifying the required safety functions, usually through HAZIDs, HAZOPs, reviews of accidents, and process reviews
- Assessing the risk reduction required; setting a safety integrity level (SIL), which applies to the safety instrumented function (SIF) intended to prevent the hazardous event
- Ensuring that the safety function performs under various conditions, including failure modes and operator error; personnel must be qualified and competent to test these functions against IEC/ISA 61511
- Verifying that the system and software meets the assigned SIL by determining the probability of failure, checking minimum levels of redundancy, and reviewing systematic capability; these three metrics are often called “the three barriers”
- Conducting regular safety audits to make sure that the appropriate safety lifecycle management techniques have been applied throughout the life of a product or system
The functional safety lifecycle provides an end-to-end approach, beginning at the concept design phase and ending at decommissioning. It’s a closed loop model that identifies and assesses risks, creates a design, and then implements, verifies, and maintains that design.
The International Society of Automation (ISA) can help your company advance its safety goals.
Contact one of our experts to talk about your safety training options with ISA: