# Safety instrumented system (SIS)

Operations · `Safety instrumented system` · verification: source checked

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.

## Specification

| Property | Value |
|---|---|
| Kind | system |
| Origin | ANSI/ISA-84.00.01 via NIST SP 800-82r3 |

## Safety

- Safety function: takes the process to a safe state when predetermined conditions are violated.

## 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).

## Sources

1. [safety instrumented system - Glossary | CSRC](https://csrc.nist.gov/glossary/term/safety_instrumented_system) (accessed 2026-10-25)

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