Safety Instrumented Systems

Abstract

One of the most common engineered safeguards in the process industry is a safety instrumented system (SIS). It uses instrumentation to detect process excursions and takes action on the process to prevent further propagation. Over the years, many terms have been used to describe types of SISs. Often, terms are used which facilitate more rapid understanding of the system's specific purpose, such as safety critical systems, high integrity protective systems, emergency shutdown systems and safety interlocks. Because they have a wide variety of functions and applications, SISs are generally designed to address specific process hazards. Keywords: safety instrumented system; process safety; hazards analysis; safety integrity level