(a) Procedure for CO₂ Release in Engine Room Fire:

• On outbreak of fire, the fire alarm will sound, and the bridge officer will be alerted to the fire's location.
• All crew members must be gathered at the muster station for a head count.
• If the fire is small, an attempt should be made to extinguish it using a portable extinguisher.
• If unsuccessful, the bridge must be informed of the situation.
• The Chief Engineer, in consultation with the Master, should decide to flood the engine room with CO₂.
• The emergency generator must be started manually, as CO₂ flooding requires all engine room machinery (including auxiliary generators) to be stopped.
• Boundary cooling should be initiated and continued until the temperature drops to a safe level.
• The ship’s speed should be reduced, and the main engine stopped at a safe location. If within a coastal zone, the Captain must inform the nearest coastal authority.
• Open the cabinet of the CO₂ operating system in the fire station using the key provided in the nearby glass case. This action triggers an audible CO₂ alarm in the engine room.
• Certain machinery such as engine room blowers and fans will trip automatically upon opening the CO₂ cabinet. Cross-check all systems to ensure they have tripped as intended.
• Repeat the head count to ensure no one remains inside the engine room.
• Operate all remote closing switches for quick-closing valves, funnel flaps, fire flaps, engine room pumps and machinery, watertight doors, etc.
  • This will stop the main engine and generators, resulting in a blackout.
  • The emergency generator should then be brought on load.
• Confirm that all entrances, funnel flaps, blower flaps, skylights, and any other openings to the engine room are shut and that the room is completely airtight.
• Operate the control and master valve inside the CO₂ cabinet. This will sound a second alarm, and after a 60-second delay, CO₂ will be released into the engine room to extinguish the fire.
• If there is a need to re-enter the engine room for rescue (which must be avoided if possible), SCBA sets and lifelines must be used.
• Safety of personnel should always remain the highest priority.

Safeguards Against Inadvertent CO₂ Release in Engine Room:

To prevent accidental and hazardous discharge of CO₂ into the engine room, the following critical safeguards are incorporated in CO₂ fire suppression systems:

• Two-Stage Release System: Activation occurs in two stages. First, a pilot cylinder is triggered (manually or electrically), which then activates the main CO₂ bank. This design prevents full discharge from a single accidental action.
• Locked or Sealed Manual Controls: Manual release stations are protected with break-glass panels or sealed enclosures. Some systems require a key or a two-step activation process (e.g., pull and then press) to initiate release.
• Time Delay Devices: A time delay (typically 20–30 seconds) is incorporated after activation, providing personnel enough time to evacuate. This delay is accompanied by sirens and flashing lights.
• Alarm Systems: Audible alarms (sirens/hooters) and visual indicators (flashing lights) are activated when CO₂ release is initiated, warning crew to evacuate immediately.
• Mechanical Interlocks: These ensure CO₂ cannot be released unless certain preconditions are met, such as all engine room doors and ventilation dampers being closed, ensuring the space is sealed.
• Control from Outside the Protected Space: All CO₂ controls are located outside the engine room, minimizing the risk of personnel exposure during system operation.
• Electrical Interlock and Supervision: Electrical systems are supervised to prevent unintentional solenoid or valve activation due to faults, ensuring reliable operation and avoiding false discharges.
• Signage and Crew Training: Clear signage warns of CO₂ system presence and danger. Regular crew training ensures understanding of system operation, risks involved, and correct emergency procedures.