For firebox appliances with a volume of 0.14 or less, what type of extinguisher must be installed?

• A. 2-A rated water type or wet chemical extinguisher
• B. 4-A rated water type
• C. 5-A rated water type
• D. 1-A rated water type

Answer: (A)

The key idea here is that extinguisher choice depends on the size of the space and the expected fire load. For a firebox appliance with a volume of 0.14 m^3 or less, the heat that must be absorbed to control an initial fire in that small volume is met by a modest cooling capacity. A water-type extinguisher rated at 2-A provides enough cooling to handle typical Class A fires in such a confined space. An alternative that fits the same scenario is a wet chemical extinguisher, which is effective in spaces where cooking oils or fats might be involved and also offers cooling and smothering action suitable for small, enclosed areas. Higher-rated water extinguishers would exceed what’s needed for this small volume, and a lower rating wouldn’t provide sufficient cooling capacity. Therefore, the correct choice is a 2-A rated water-type extinguisher or a wet chemical extinguisher.