Acronyms & Terms Glossary

Safety Instrumented System (SIS)

Safety Instrumented System is a system of hardware and software controls engineered to perform "specific control functions" in order to prevent or mitigate hazardous events by taking a process to a safe state when predetermined conditions are violated. What and how the system should perform may be determined via HAZOPS (Hazard and operability studies) or LOPA (layers of protection analysis).