Definition:
Risk Reduction Factor (RRF) is the inverse of PFDavg, representing how much a SIF reduces risk. This term really exists as it is easier for humans to process a number like this versus a very small exponential number like PFDavg.
Different levels of PFDavg relate to permitted safety integrity levels (SIL) and risk reduction factor (RRF).
Key Points:
- RRF = 1 / PFDavg.
- Higher RRF means better risk reduction.
- Using RRF vs PFDavg is more of a preference.
Example:
A PFDavg of 2.5E-2 corresponds to an RRF of 250.
See Also: PFDavg
Cited Source:
- IEC 61511-1:2016, Table 4
- IEC 61508-6:2010, Annex B.