10
Functional Safety Manual
M310/FSM, Rev AA
January 2012
Horizontal Float Switch
Connection of the Level
Switch to the SIS Logic
Solver
The Mobrey level switch should be connected to the safety-rated logic solver which is
actively performing the safety function as well as automatic diagnostics (if any)
designed to diagnose potentially dangerous failures within the level switch.
NOTE:
For all product information and documentation downloads, visit www.mobrey.com.
General Requirements • The system and function response time shall be less than the process safety time
The Mobrey level switch will move to its defined safe state in less than this time
with relation to the specific hazard scenario.
• All SIS components, including the Mobrey level switch, must be operational before
process start-up
• The user shall verify that the Mobrey level switch is suitable for use in safety
applications by confirming the float level switch nameplate and model number are
properly marked
• Personnel performing maintenance and testing on the Mobrey level switch shall
first be assessed as being competent to do so
• Results from periodic proof tests shall be recorded and periodically reviewed
• The Mobrey level switch shall not be operated beyond the useful lifetime as listed
on page 12 (and in the specification section of the product document M310)
without undergoing overhaul or replacement
INSTALLATION AND
COMMISSIONING
NOTE:
For all product information and documentation downloads, visit www.mobrey.com.
Installation The Mobrey level switch must be installed as described in the installation section of the
product instructions leaflet M310. Check that environmental conditions do not exceed
the ratings in the specification section.
The Mobrey level switch must be accessible for physical inspection.
Physical Location And
Placement
The Mobrey level switch shall be accessible with sufficient room for cover removal and
electrical connections, and allow for manual proof-testing to take place.
The switch point is determined by the location of the Mobrey level switch, and
consideration must be given to allow the safe proof-testing of the level switch by
forcing liquid to put the switch into its Fail-Safe state.
Electrical Connections Wiring should be adequately rated and not be susceptible to mechanical damage.
Electrical conduit is commonly used to protect wiring.