Question 63 RVR04 - Master or Mate of LT 200 GRT

The Correct Answer is D. ### Why Option D ("All of the above") is Correct Using a fixed CO2 (Carbon Dioxide) fire suppression system requires adherence to strict safety protocols because CO2 displaces oxygen, making the atmosphere immediately lethal to humans. Furthermore, the system is only effective if the fire can be starved of oxygen and fuel sources. Therefore, before activating the system: 1. **Evacuate all engine room personnel (Option B):** This is the paramount safety measure. An audible and visual alarm must sound, and confirmation must be received that the space is clear before release. 2. **Secure the engine room ventilation (Option A):** CO2 must be contained within the space to achieve the required concentration (typically 30% by volume) to extinguish the fire. All ventilation (supply and exhaust fans) and dampers must be sealed to prevent the gas from escaping and to prevent fresh air from feeding the fire. 3. **Secure the machinery in the engine room (Option C):** Machinery must be stopped (particularly main and auxiliary engines, purifiers, and pumps) to eliminate ignition sources (hot surfaces) and to stop the flow of combustible liquids (fuel or lube oil) that could feed the fire, ensuring a complete knockdown. Since all three actions are mandatory preconditions for the safe and effective use of a fixed CO2 system, "All of the above" is the correct choice. ### Why the Other Options are Incorrect (as standalone answers) While A, B, and C are individually correct steps, they are incomplete as the sole answer to the comprehensive requirement: * **A) secure the engine room ventilation:** This is vital for effectiveness, but activating the CO2 without evacuating personnel first (B) would be fatal. * **B) evacuate all engine room personnel:** This is vital for safety, but if the ventilation is left running (A) or machinery is still pumping fuel (C), the CO2 will be ineffective, and the fire may flash back when the space is opened. * **C) secure the machinery in the engine room:** This is vital for eliminating fuel sources, but ignoring personnel safety (B) or gas containment (A) makes the action incomplete or dangerous.