What is the primary function of a safety instrumented system (SIS)?

The primary function of a safety instrumented system (SIS) is to prevent hazardous events. An SIS is designed to mitigate risks associated with industrial processes by taking automatic actions to bring the process to a safe state when certain predetermined conditions are met. This is critical in maintaining safety in environments where there are potential dangers, such as chemical plants or oil refineries, where accidental releases or process upsets can lead to catastrophic outcomes.

The architecture of an SIS typically includes various sensors, logic solvers, and final control elements that work together to detect hazardous situations and initiate safety measures instantaneously. The focus is on life preservation, the protection of the environment, and the safeguarding of physical assets. By minimizing the probability of dangerous incidents occurring, an SIS plays a vital role in ensuring overall safety within industrial processes.