When performing SIL verifications, there is more to the calculation of probability of failure than just a simple unreliability or simple unavailability. In the early years of SIL verification, the PFD was calculated only using unreliability due to dangerous undetected failures. While only using this term is appropriate in some circumstances, in many others it is not. The way that a plant operates, tests, and maintains its equipment will cause other factors to be considered. Such as…
- Unavailability due to detected failures (safe or dangerous) because the plant continues to operate with the component in a failed state.
- Unavailability due to bypass of SIS components for online testing.
- Unreliability related to never detected failures that result from imperfect manual proof tests.
- Any of course, for redundant configurations that possibility of common cause failures cannot be discounted.
Register for this webinar on Wednesday 29Nov2023 10:00am EST (UTC -5.00) at the bottom of the page.
This webinar will present all the terms used in SIL verification calculations. The means to calculate and the physical meaning of all the terms will be discussed along with their equations – as shown in the IEC EC50 training class on functional safety. The webinar will also show how these terms are treated and displayed in the best-in-class Kenexis Vertigo software for SIS safety lifecycle management.