The emergency shutdown system for terminal consists of the following:
- SIL certified PLC system
- Interfacing with Terminal control system
- ESD Push buttons at critical locations in terminal
- ROSOVs
- Flame detectors
- Gas detectors (Point Type and Open path)
- Audio Visual alarms
- Manual call points in field
- Vibrating fork type level switch
As per OISD guidelines the SIL classification study shall be carried out to determine the required SIL level. SIL of the safety instrumented function for the tank including overfill protection shall be meeting the requirement of Part 1 of EN 61511. ESD system shall be only through push buttons with wired connection.
As per OISD guidelines Remote operated shut off valve (ROSOV) is not a regularly operated valve and is kept normally open; the second motor operated valve (MOV) is a regular operating valve. ROSOV shall be fail safe and fire safe (shall close in case of signal failure). The actuator shall be fail-safe. The cables leading to the control room shall be fire retardant. ROSOV shall have only close operation from control room or at a strategic remote location. The Open/Close push buttons of ROSOV shall be provided in field i.e. just outside the dyke. These push buttons shall have distinctive feature so that opening is different than action required for closing (e.g. pull type and push type).