Fighting Metal Fires

Nearly all metals burn under certain conditions. Some oxidize rapidly in the presence of air or moisture, generating sufficient heat to reach their ignition temperatures. Others oxidize so slowly that heat generated during oxidation is dissipated before the metals become hot enough to ignite. Certain metals like calcium, lithium, magnesium, potassium, sodium, titanium, and zinc are referred to combustible metals because of the ease of ignition of thin particles, or molten metal. However, the same metals in massive solid form are comparatively difficult to ignite.

Some metals, such as aluminum, iron, and steel, that are not considered combustible, may ignite and burn when in finely divided form. Dust clouds of most metals in air are explosive. Alloys, consisting of different metals or metallic compounds combined in varying proportions, may differ widely in combustibility from their constituent elements.

Hot or burning metals may react violently upon contact with other materials, such as any of the extinguishants used on fires involving ordinary combustibles or flammable liquids. Temperatures produced by burning metals are generally much higher than temperatures generated by burning flammable liquids. Some hot metals can continue burning in carbon dioxide, nitrogen, or steam atmospheres in which ordinary combustibles or flammable liquids do not burn.