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1
2
3
4
>=10
-2
to <10
-1
>=10
-3
to <10
-2
>=10
-4
to <10
-3
>=10
-5
to <10
-4
Low demand mode
of operation
Average probability of
dangerous failure on demand
[PFDavg]
Safety
Integrity
Level
(SIL)
10,000 - 100,000
1000 - 10,000
100 - 1000
10 - 100
F2 / F1 = PFDavg
Frequency Reduction
Target Failure Measures: Low Demand Mode
F1 / F2 = Frequency Reduction
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Agenda
1. What is proof testing?
2. Overview of the requirements of IEC 61511
3. Proof test principles
4. Proof Test Procedures
5. Importance of Recording Proof Test Results
6. Concluding comments