On a Gas Carrier, which High Level alarms/shutdowns are installed and how are they tested?
There are 3 High level alarms:
- High Level Alarm at 95%
- High-High Level Alarm at 99%
- Extremely High Level Alarm at 99.5%
High and Extremely High Level Alarms are tested by simulation - adjusting the setpoint.
High-High level is connected to independent float switch and tested by physical commutation in the circuit.
High-High and Extremely High Alarms activate ESD when triggered. Therefore, it is important to revert all changes (setpoint or circuit modifications) back to normal after completion of testing. There were incident with inadvertent activation of ESD caused by incorrect (lower) setpoint settings.
