ohutusinstrumentatsioonisüsteem

An ohutusinstrumentatsioonisüsteem, often abbreviated as SIS, is a system designed to detect potentially hazardous situations and bring a process or machine to a safe state. Its primary goal is to prevent or mitigate dangerous events that could lead to harm to people, the environment, or equipment. SIS operates independently of the basic process control system (BPCS) to ensure that even if the main control system fails, the safety functions can still be executed.

The core components of a SIS include sensors that monitor critical process parameters, logic solvers (often programmable logic controllers) that process the sensor data and determine if a hazardous condition exists, and final elements (such as actuators or shutdown valves) that initiate the safe state action. The design and implementation of SIS are governed by international standards, such as IEC 61508 and IEC 61511, which specify requirements for reliability, performance, and safety integrity levels (SILs).

The safety integrity level (SIL) is a discrete level from 1 to 4 that indicates the degree of risk reduction provided by a safety instrumented function. A higher SIL means a higher level of confidence that the SIS will perform its intended safety function when needed. SIS are crucial in industries where processes involve high pressures, temperatures, or hazardous materials, including oil and gas, chemical processing, power generation, and manufacturing. Their effective design, operation, and maintenance are essential for ensuring overall industrial safety.