Frequently Asked Question
We have a SIF with 5 streams (each stream with 1oo2 shutoff valves) that trips all of the valves on these 5 streams in case of an event. How do we configure this SIF voting?
Last Updated 5 years ago
A question - do you really need all 5 streams to close to avoid the one hazard scenario that the SIF is protecting against? Are some of these auxiliary actions that are not essential and therefore should not be included in the SIF?
To model the 5oo5, select the 5oo5 model in exSILentia SILver.
For the 1oo2 voting, you will then need to specify a user defined item that represents the 1oo2 voting. To determine the 1oo2 voting equivalent failure rates, model the valves in a separate SIF, set the demand mode to high and the mission time to the proof test interval.
The resulting PFH and MTTFS can be used to determine the equivalent lambdaDU and lambdaSU for the 1oo2 voting.
To model the 5oo5, select the 5oo5 model in exSILentia SILver.
For the 1oo2 voting, you will then need to specify a user defined item that represents the 1oo2 voting. To determine the 1oo2 voting equivalent failure rates, model the valves in a separate SIF, set the demand mode to high and the mission time to the proof test interval.
The resulting PFH and MTTFS can be used to determine the equivalent lambdaDU and lambdaSU for the 1oo2 voting.