General Safety Instructions; Safety-Instrumented System - Siemens CALOMAT 6 Instructions Manual

Siemens AG
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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 H
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:
O -concentration
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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 CALOMAT 6 exclusively as part of a safety function.
SIL Safety Manual CALOMAT 6 Gas Analyzers
A5E00729184-02, 07/2010
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