Key Words: Emergency Shutdown Systems (ESD); automation systems; automatic control systems; temperature; pressure; level; Safety Integrity Levels (SIL).
Abstract. Emergency Shutdown (ESD) systems are a fundamental part of the functional safety structure of modern industrial plants and are intended to protect personnel, equipment, the environment and production assets when hazardous deviations occur in technological processes. Their principal task is to detect conditions that may lead to loss of containment, fire, explosion, equipment damage or uncontrolled release of hazardous substances and to bring the process, or a defined part of it, to a predetermined safe state within the available process safety time. Unlike the basic process control system, which maintains production variables around their normal operating set points, the ESD system performs independent safety functions and remains capable of acting when the normal control layer is unavailable or has failed. For this reason, appropriate physical and functional separation from the BPCS/DCS, independent power supplies and communication paths, fail-safe design principles and controlled access to application software are essential requirements. A typical ESD architecture comprises field sensors and transmitters, a safety logic solver and final control elements. Pressure, temperature, flow, level, flame, smoke and gas concentration may be monitored depending on the hazards identified during the risk assessment.
