Which item is best for extinguishing smouldering fires in tightly packed combustible materials?

The best choice for extinguishing smouldering fires in tightly packed combustible materials is Class A foam. Class A foam is specifically formulated to enhance the effectiveness of water on certain types of fires, particularly those involving ordinary combustibles such as wood, paper, and textiles. When applied, it creates a blanket of foam that smothers the fire and helps to cool the surrounding materials, penetrating into tight spaces where smouldering may be occurring. This penetration is crucial in tightly packed materials, where water alone may not effectively reach all smouldering areas.

Class A foam also has added wetting agents that reduce the surface tension of water, allowing it to spread more easily and soak into combustible materials, which can be essential for extinguishing hidden fires. In contrast, while water fog can be effective in certain situations, it may not provide the same degree of penetration and smothering effect. Dry chemical agents are more suited for flammable liquid fires or gas fires and might not be as effective on smouldering combustibles. A piercing nozzle is designed to reach fires that are in concealed spaces or through structural obstacles, but it does not provide the same extinguishing effectiveness on the cooling and smothering fronts as Class A foam does.

Thus, Class A