What Does SIF Loop Verification Mean?
A Safety Instrumented Function (SIF) loop verification is the process used to calculate the performance of the SIF in order to determine whether it meets with the target Safety Integrity Level (SIL). The SIL for every SIF loop is typically specified during the SIL classification performed during the design stage.
Safeopedia Explains SIF Loop Verification
For each SIF, the average probability of failure on demand (PFDavg) will be calculated and the results compared with the PDFavg range for the target SIL.
The verification of a SIF involves reviewing the loop design and gathering the required information to calculate the probability of failure on demand (PFDavg) for the loop. The types of information required during SIF loop verification includes, but is not limited to, hardware failure rate, percentage of common mode failure, and proof test coverage.
For basic SIFs, the PFDavg is a simple function of instrument failure rates and test intervals.