Fixed CO2 release goes unnoticed

Mars Report – Lessons learned

The Nautical Institute has issued Mars Report on an incident where fixed CO2 release  was not detected to highlight  how crew can easily identify the status of a fixed CO2 system.

The Incident

During the annual servicing of a KIDDE CO2 system on a passenger ferry, it was discovered that an undetected discharge of the CO2 system within the emergency generator room had taken place. Although the time of the inadvertent discharge could not be determined, the cause was a worn internal mechanism within the control head.

The crew was unaware of the discharge in the emergency generator room because the space did not require any indicators (eg alarm, smoke/heat detection) to alert them of the discharge and was unoccupied during discharge.

This circumstance presented three latent unsafe conditions:
1 The failure could have occurred while someone was within the space;
2 A person could have entered the space after the release, and;
3 The space remained unprotected for an unknown period of time.

Identifying the status of a fixed CO2 system can easily be done by eye. The control head of the valve has a slot that lines up with either the ‘set’ or the ‘released’ position and the indicators are the same whether the control head is electrically operated (left photograph) or pneumatically operated (right photograph).

The photo below is an example of a second visual indicator for checking system status. It indicates the pressure switch position for the CO2 system. If the indicator is in the down ‘set’ position, no CO2 has been released and the system is ready for operation. If the indicator is in the up position, it indicates that the system has been ‘operated’ (released) and that the proper servicing company should be contacted immediately to bring the system back to readiness.


Due to the risks associated with an inadvertent discharge of a fixed CO2 system, it is highly recommended that owners and operators ensure that appropriate vessel personnel:

  • Receive adequate training to perform routine inspections of their vessel’s fixed CO2 systems and fully understand their operation, particularly those protecting large spaces or multiple areas.
  • Frequently review and update operating manuals, checklists, and safety management systems associated with vessel extinguishing systems onboard.
  • Post clear instructions for fixed CO2 system emergency operation.

Source & Image Credit: Mars Reports/ The Nautical Institute

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