SIL level of the SIS loop

SIL classification: This is determined by the process safety experts, who assign a SIL level to each interlock circuit – SIL 1, 2, or 3 – and it has little to do with instruments. SIL verification: Based on the PFD parameters for ESD-PLCs, transmitters, on/off valves, and solenoid valves, calculations are performed for each interlock circuit to verify whether the SIF of that circuit meets the specified SIL level. If it does not meet the requirement, the settings of the instrument are adjusted until the requirement is satisfied. SIS is a unit for SIL verification, and it is responsible for providing safety parameters (which may be what you refer to as “grading”). The mapping table is a verification sheet; for this project, the PFD of the SIS is 1.18X10-4, a value provided by the SIS manufacturer based on the final configuration, and this parameter meets the user’s minimum requirements.