Exam Question

This answer evaluates the merits and demerits of Carbon Dioxide (CO2), Pressure Water Spray (Water Mist), and High Expansion Foam fixed fire fighting systems for a ship's engine room, as would be expected for a full-mark response in a Class 1 examination.
### (a) Carbon Dioxide (CO2) Total Flooding System
**Principle of Operation:** The primary fire-extinguishing mechanism of CO2 is **smothering**. By rapidly discharging a large volume of CO2 gas into a sealed space, it displaces the atmospheric oxygen, reducing the oxygen concentration from ~21% to below 15%, which is insufficient to sustain combustion for most materials. A secondary, minor effect is cooling, as the liquid CO2 expands into a gas (Joule-Thomson effect), but this is not its primary function.
#### Merits (Advantages):