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© ABB
| Slide 12
Risk Reduction
Independent Protection Layers (IPL)
§
Each IPL must
independently protect
against the hazard they
are designed to
safeguard
§
Hazard occurs when a
layer fails to respond to
the process demand
§
Objective of SIS IPL
must be maintained
Operator
Intervention
Automatic SIS
Safety relief valve
Rupture disk, etc
Containment
Dike, Bunker, etc
Plant response
Community response
Process variable
BPCS
ALARMS
SIS