Siemens AG
SIL Safety Manual ULTRAMAT 6 Gas analyzers 6 of 19
A5E00729183-02
2
General Safety Instructions
2.1 Safety-instrumented system
Definition: Safety-instrumented system
A safety instrumented system executes the safety functions that are required
to achieve or maintain a safe status in a system. It consists of a sensor, logic
unit/ control system and final controlling element.
Example:
A safety instrumented system is made up of an analyzer (for example CO
concentration), a PLC and a control valve (Figure 2-1).
Definition: Safety function
Defined function executed by a safety instrumented system with the
objective of achieving or maintaining a safe system taking into account a
defined dangerous occurrence.
Example:
CO concentration
Definition: Dangerous failure
Failure with the potential to bring the safety instrumented system into a
dangerous or non-functional status.
Description
The analyzer logic unit/control system is a final controlling element combine
to form a safety-instrumented system, which executes a safety function.
Note
This document deals with the ULTRAMAT 6 exclusively as part of a safety function.
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