SIL Verification (PFDavg) Calculator
Verify the Safety Integrity Level of a Safety Instrumented Function (SIF) by calculating PFDavg for sensor, logic solver, and final element subsystems. Supports 1oo1, 1oo2, 2oo3, and 1oo2D voting architectures with common cause failure analysis per IEC 61508, IEC 61511, and ISA 84.00.01.
SIF Configuration
years
Should not exceed useful life of equipment (typically 10-20 years)
Sensor Subsystem
/hr
/hr
/hr
%
months
hours
Logic Solver Subsystem
/hr
/hr
/hr
%
months
hours
Final Element Subsystem
/hr
/hr
/hr
%
months
hours
Understanding SIL Verification
What is SIL Verification?
SIL verification confirms that a Safety Instrumented Function (SIF) design achieves the required Safety Integrity Level by calculating PFDavg based on component failure rates, redundancy architecture, proof test intervals, and common cause failures.
SIL Levels (Low Demand):
SIL 1: PFDavg 0.01 - 0.1 (RRF 10-100)
SIL 2: PFDavg 0.001 - 0.01 (RRF 100-1,000)
SIL 3: PFDavg 0.0001 - 0.001 (RRF 1,000-10,000)
SIL 4: PFDavg 0.00001 - 0.0001 (RRF 10,000-100,000)
Key Standards:
IEC 61508 (generic functional safety), IEC 61511 (process industry SIS), ISA 84.00.01 (US adoption of IEC 61511), ISA TR84.00.02 (SIL verification technical report).
📚 Learn the Theory
Understand PFDavg calculation methods, architectural constraints, common cause failures, and IEC 61508/61511 requirements