Verifying SIF Response Time

For the SIF Analysis the Overall Functional Response Time is calculated as the longest response times of the Sensor Subsystems plus the longest of the Logic Solver Subsystems and the longest response time of the Final Element Subsystems. For each of those Subsystems, the Response Time is the longest of the Response Times of the individual Equipment. If this is smaller than the specified Process Safety Time (PST), Response time is verified, and a green checkmark is shown. The individual Response Times are specified on Equipment level (in the Repair section), while the Process Safety Time is specified in the SIF Analysis Details on the General Tab and can be entered when a new SIF Analysis is started. 

If the overall Response time is smaller than the specified Process Safety Time (PST), a green check will show. 

Note: The Process Safety Time is defined in IMS as: The time that elapses between the trip setting, for example HH level, to the Top Event, for example tank overfill. Typically, this value should be provided by a process engineer, or a technical safety engineer, to the SIF designer. The value entered in the  Process Safety Time field is checked against the total response time of the SIF. The limiting factor in this is typically the response time of a valve, as large valves can take a long time to close. In the Equipment details of a sensor or valve, the response time of a sensor, or closing time of a valve, can be set.