A system approach to reliability and life-cycle cost of process safety-systems

An analytic method, PDS, allows the designer to assess the cost effectiveness of computer-based process safety-systems based on a quantification of reliability and life-cycle cost. Using PDS in early system design, configurations and operating philosophies can be identified in which the reliability of field devices and logic control units is balanced from a safety and an economic point of view. When quantifying reliability, the effects are included of fault-tolerant and fault-removal techniques, and of failures due to environmental stresses and failures initiated by humans during engineering and operation. A failure taxonomy allows the analyst to treat hardware failures, human failures, and software failures of automatic systems in an integrated manner. The main benefit of this taxonomy is the direct relationship between failure cause and the means used to improve safety-system performance