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LOPA Model
LOPA Model
Intiating Event
Independent
Protection Layer 1
Independent
Protection Layer 2
Independent
Protection Layer 3
Independent
Protection Layer 4
Outcome
Successfully Operated
Initiating Event
Successfully Operated
Frequency
ƒ
1
=
x
Failed to Operate
Successfully Operated
PFD
1
=
y
1
ƒ
1
=
x
x
y
1
Failed to Operate
Successfully Operated
PFD
2
=
y
2
ƒ
2
=
x
x
y
1
x
y
2
Failed to Operate
PFD
3
=
y
3
ƒ
3
=
x
x
y
1
x
y
2
x
y
3
Failed to Operate
PFD
4
=
y
4
Failure - Incident
ƒ
4
=
x
x
y
1
x
y
2
x
y
3
x
y
4
Safe
Safe
Safe
Safe