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Functional Safety Manual
IP101/FSM, Rev AA
January 2012
Horizontal Float Switch
Magnetic Level Switch Functional Safety Manual
INTRODUCTION
Scope and Purpose of
the Safety Manual
This safety manual contains the information to design, install, verify and maintain a
Safety Instrumented Function (SIF) utilizing the Mobrey magnetic level switch.
The manual provides the necessary requirements to enable the integration of the
horizontal point-level float switch when showing compliance with the IEC 61508 or
IEC 61511 functional safety standards. It indicates all assumptions that have been
made on the usage of the level switch. If these assumptions cannot be met by the
application, the Safety Integrity Level (SIL) capability of the product may be adversely
affected.
NOTE:
For product support, use the contact details on the back page.
Skill Level Requirement System design, installation and commissioning, and repair and maintenance shall be
carried out by suitably qualified personnel.
Terms, Abbreviations,
And Acronyms
Basic Safety
Freedom from unacceptable risk of harm.
BPCS
Basic Process Control System – a system which responds to input signals from the
process, its associated equipment, other programmable systems and/or an operator
and generates output signals causing the process and its associated equipment to
operate in the desired manner but which does not perform any safety instrumented
functions with a claimed SIL greater than or equal to 1.
Fail-safe State
State where switch output is in the state corresponding to an alarm condition. In this
condition the switch contacts will normally be open.
Fail Dangerous
Failure that does not respond to an input from the process (i.e. not switching to the
fail-safe state).
Fail Dangerous Detected
Failure that is dangerous but is detected.
Fail Dangerous Undetected
Failure that is dangerous and that is not detected.
Fail No Effect
Failure of a component that is part of the safety function but that has no effect on the
safety function.
Fail Safe
Failure that causes the switch to go to the defined fail-safe state without an input from
the process.