A typical fixed fire-fighting installation for a machinery space uses a bulk CO2 system. This system consists of large pressure vessels built to Class 1 construction standards, with low-temperature properties down to -50°C. These vessels are heavily insulated and kept cool by two refrigeration units, one in use and one on standby. The system can maintain its temperature for up to 24 hours without refrigeration before boil-off occurs.

System Components

• Pressure Vessels: The system uses pressure vessels designed for low temperatures.
• Refrigeration Units: Two refrigeration units are used, one active and one on standby, to maintain the low temperature.
• Relief Valves:
  • Set A: Vented to the atmosphere at 21.5 bar.
  • Set B: Vented to a CO2 compartment in case of fire at 27 bar.
  • Each set has a cock for isolating one valve for repairs.
• Level Indicators: The system has two means of indicating content level: a remote electrical display and a standby indicator.
• Alarms: Alarms are activated for the following conditions:
  • 5% loss of content.
  • Overfilling at 98% of tank capacity.
  • Leakage past the main discharge valve.
  • Opening of a section valve.
  • High CO2 pressure (25 bar), which protects against liquid locks.

  System Operation

  To operate the system, the appropriate section valve and the main discharge valve are opened. The main discharge valve is typically fitted with an actuator for remote control. CO2 is then discharged for a specific period, after which the main valve is closed.

  Testing Procedures

  Part (b)

  Testing Procedure for Bulk CO2 Equipment

  Weekly: Check the pressure and temperature of the CO2 in the tank and the cooling plant.

  Fortnightly: Check the contents of the bulk CO2 system and the master gauge reading.

  Monthly:

  1. Check for tightness around stuffing boxes, valves, joints, and removable covers using CO2 gas detectors or a soap solution.
  2. Verify that the alarm can be heard throughout the machinery space when the door switch on the control panel is opened.

  Annually:

  1. Test the flow through the CO2 gas system piping with excess compressed air. This should also trigger the gas-operated alarm.
  2. Conduct a mandatory annual survey.

  Every 10 years: Perform an internal inspection of the bulk CO2 tank.

  Part (c)

  Testing Procedures for Other Equipment

  (i) Remote Shutdown

  All fuel transfer pumps, oil-fired unit pumps, similar fuel pumps, and ventilation fans or blowers must have remote shutdown connections located outside the space where the machinery is situated. Any pipe connected to an oil fuel storage, settling, or daily service tank (not a double-bottom tank) that could create a fire hazard if damaged must be fitted with a valve or cock capable of being closed from a readily accessible location outside the tank's space.

  These systems should be tested during fire drills if possible. Otherwise, they must be operated during a port stay to ensure they function properly.

  (ii) Other Equipment for an Engine Room Fire

  The fixed fire system is a last resort, used only after a preliminary attack on the fire has failed. Before that, other equipment is used.

  • Portable Fire Extinguishers: The appropriate type of portable extinguisher should be used first, depending on the class of fire. During fire drills, a few extinguishers may be tested, then refilled and made ready for use.
  • Fire Pumps and Hoses: Fire pumps, hoses, and nozzles are provided as per regulations. These should be tested during fire drills. The emergency fire pump should also be tested.
  • Firefighter's Outfits: As per SOLAS 74, Chapter II-2, Regulation 10, firefighter's outfits are provided.
  • Breathing Apparatus & EEBDs: Breathing apparatus and Emergency Escape Breathing Devices (EEBDs) are available to facilitate firefighting and escape, respectively. During drills, personnel should wear this equipment to test its proper function.

  Local Application Fire-Fighting Systems

  In addition to the main fixed system, machinery spaces of Category A with a volume over 500m³ must be protected by an approved fixed water-based or equivalent local application fire-fighting system. This is required for:

  • Fire hazard portions of internal combustion engines used for propulsion and power generation.
  • Boiler fronts.
  • Fire hazard positions of incinerators.
  • Heated oil purifiers.

  This system can be checked zone by zone. To do so, shut the isolating valve, connect compressed air, and manually operate the zone's solenoid valve. Air should then come out through the nozzles of that zone, confirming they are clear. The pump can be tested by shutting the isolating valve and opening the drain valve before it, ensuring the pump is working correctly.