A Probabilistic Approach to Safety System Testing and Maintenance

Abstract

This paper presents a method to quantify in terms of probabilistic availability the effects of testing and maintenance schedule on the performance of a standby safety system and it describes the mathematical rationale which lies behind it. The purpose of periodic testing and maintenance is to detect any unannounced failures in the system, repair them, and thus ensure the readiness or availability of the equipment. A scheme is given to model generally any complex system in terms of easily visualized equivalent block diagrams such that the formulas developed in this paper or similarly developed formulas can be easily applied. Also presented is a method for incorporating the field failure data to refine á priori assumed failure rates which were used in the initial computations.