Emerson Process Management M310-FSM User Manual
Functional Safety Manual
M310/FSM, Rev AA
January 2012
Horizontal Float Switch
Mobrey Magnetic Level Switches
Functional Safety Manual
www.mobrey.com
Functional Safety Manual
M310/FSM, Rev AA
Horizontal Float Switch
January 2012
Contents
Introduction Scope and Purpose of the Safety Manual ...........................................................page 3
Skill Level Requirement .......................................................................................page 3
Terms, Abbreviations, And Acronyms ..................................................................page 3
Documentation and Standards.............................................................................page 5
Product Description Level Switch Purpose ..........................................................................................page 6
Operation Principle ..............................................................................................page 6
Ordering Information ............................................................................................page 7
Designing A Safety
Function Using The
Level Switch
Installation And
Commissioning
Operation And
Maintenance
Safety Function ....................................................................................................page 8
Environmental Limits............................................................................................page 8
Application Limits .................................................................................................page 8
Design Verification ...............................................................................................page 8
SIL Capability.......................................................................................................page 9
Connection of the Level Switch to the SIS Logic Solver ....................................page 10
General Requirements .......................................................................................page 10
Installation..........................................................................................................page 10
Physical Location And Placement...................................................................... page 10
Electrical Connections .......................................................................................page 10
Proof-test Requirement...................................................................................... page 11
Repair and Replacement ................................................................................... page 11
Notification Of Failures....................................................................................... page 11
Useful Lifetime Useful Life ..........................................................................................................page 12
Proposed Proof-test
Procedure
Suggested Proof-test ......................................................................................... page 13
Proof Test Coverage .......................................................................................... page 13
Level Switches Certified
to IEC 61508
2
Level Switches for General Purpose Applications (Stainless Steel Wetside)..... page 14
Level Switches for General Purpose Applications (Stainless Steel Wetside)..... page 14
Level Switches for General Purpose Applications (Aluminum Bronze Wetside) page 15
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.
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Horizontal Float Switch
FIT
FIT is the abbreviation for Failure In Time. One FIT is 1x10-9 failure per hour
FMEDA
Failure Modes, Effects, and Diagnostics Analysis.
Functional Safety
Part of the overall safety relating to the process and the BPCS which depends on the
correct functioning of the Safety Instrumented System (SIS) and other protection
layers.
HFT
Hardware Fault Tolerance.
Low demand
Mode of operation, where the frequency of demands for operation made on a
safety-related system is no greater than twice the proof test frequency.
PFD
Average Probability of Failure on Demand.
Functional Safety Manual
M310/FSM, Rev AA
January 2012
AVG
SFF
Safe Failure Fraction – a fraction of the overall random failure rate of a device that
results in either a safe failure or a detected dangerous failure.
SIF
Safety Instrumented Function – a safety function with a specified SIL which is
necessary to achieve functional safety. Typically a set of equipment intended to reduce
the risk due to a specified hazard (a safety loop).
SIL
Safety Integrity Level – a discrete level (one out of four) for specifying the safety
integrity requirements of the safety instrumented functions to be allocated to the safety
instrumented systems.
SIL 4 has the highest level of safety integrity, and SIL 1 has the lowest level.
SIS
Safety Instrumented System – an instrumented system used to implement one or
more safety instrumented functions. An SIS is composed of any combination of
sensors, logic solvers, and final elements.
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Functional Safety Manual
IP101/FSM, Rev AA
January 2012
Horizontal Float Switch
Documentation
and Standards
Table 1.
Associated Documentation
Table 2.
Associated Standards
This section lists the documentation and standards referred to by this safety manual.
Documents Purpose of Documents
IEC 61508-2: ed2, 2010 Functional Safety of Electrical/Electronic/Programmable
Electronic Safety-Related Systems
Exida EM 10/08-36 R001 FMEDA Report Version V1, Revision R2 for the
IP101 Mobrey magnetic level switch Product Data Sheet
M310 Mobrey magnetic level switch Instruction leaflet
Standards Purpose of Standards
IEC 61508: ed2, 2010 Functional Safety of electrical/electronic/programmable
IEC 61511
(ANSI/ISA 84.00.01-2004)
Mobrey magnetic level switch with a F84 Float
electronic safety-related systems
Functional safety - Safety instrumented systems for the
process industry sector
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