Risk Analysis For Product Safety : Advanced FTA and Case Study of Risk Analysis for Electric Vacuum-Cleaners

Abstract

Risk analyses are carried out by taking a vacuum-cleaner with a power-dusting brush as an example. Hazards of the vacuum-cleaner could pose a product-liability problem. Here, two countermeasures are supposed for product-liability prevention. These are an automated powerdusting-brash stopper and a sequential-switching-on mechanism. The hazards are analyzed using fault-trees. New techniques using both rigid and flexible priority-AND gates are introduced for the development of the fault-trees. Then, ideas of sequential minimal cut-sets are proposed. This is called advanced FTA (a…FTA). Finally, an estimation of the hazard-controllability of the systems with safety countermeasures is demonstrated with the proposed technique. It is made clear that the techniques of hazard-identification and sequential failure logic are essential for the risk analysis of man-machine systems.