{"id":"safety-instrumented-system","model_id":"Safety instrumented system","name":"Safety instrumented system (SIS)","summary":"A safety instrumented system (SIS) is composed of sensors, logic solvers, and final control elements. Its purpose is to take the process to a safe state when predetermined conditions are violated. The document also lists emergency shutdown system, safety shutdown system, and safety interlock system as other terms for this type of system.","study_notes":["Composed of sensors, logic solvers, and final control elements.","Purpose is to take the process to a safe state when predetermined conditions are violated.","Other terms commonly used include emergency shutdown system (ESS), safety shutdown system (SSD), and safety interlock system (SIS)."],"safety_notes":["Safety function: takes the process to a safe state when predetermined conditions are violated."],"sources":[{"url":"https://csrc.nist.gov/glossary/term/safety_instrumented_system","title":"safety instrumented system - Glossary | CSRC","accessed":"2026-10-25"}],"verification":{"status":"source_checked","checked_at":"2026-10-25","values":2,"method":"llm_source_check"},"updated_at":"2026-10-25","type":"operational","spec":{"kind":"system","origin":"ANSI/ISA-84.00.01 via NIST SP 800-82r3","related":[]},"url":"https://machineschema.com/operational/safety-instrumented-system","license":"https://creativecommons.org/licenses/by/4.0/"}