Storage, Processing, and Extinguishing Fires in Calcium and Zinc

PYROPHORIC METALS

DOE-HDBK-1081-94

Spontaneous Heating and Pyrophoricity

spontaneously in air. It should be noted that barium and strontium are very

similar to calcium in their fire properties.

Zinc

Zinc does not introduce a serious fire hazard in sheets, castings, or other

massive forms because of the difficulty of ignition. Once ignited, however,

large pieces burn vigorously. Moist zinc dust reacts slowly with the water to

form hydrogen, and, if sufficient heat is released, ignition of the dust can

occur. Zinc dust clouds in air ignite at 599 C (1,110 F). Burning zinc

generates appreciable smoke.

Storage, Processing, and Extinguishing Fires in Calcium and Zinc

The storage, handling, and processing recommendations for magnesium are generally

applicable to calcium and zinc.

Metals Not Normally Combustible

Aluminum

The usual forms of aluminum have a sufficiently high ignition temperature so that its

burning is not a factor in most fires. However, very fine chips and shavings are

occasionally subject to somewhat the same type of combustion as described for

magnesium. Powdered or flaked aluminum in its pure form can ignite spontaneously

in air and can be explosive in air.

Iron and Steel

Iron and steel are not usually considered combustible; in a massive form (as in

structural steel, cast iron parts, etc.), they do not burn in ordinary fires. Steel in the

form of fine steel wool or dust may be ignited in the presence of heat from, for

example, a torch, yielding a form of sparking rather than actual flaming in most

instances. Fires have been reported in piles of steel turnings and other fine scrap

which presumably contained some oil and were perhaps also contaminated by other

materials that facilitated combustion. Spontaneous ignition of water-wetted borings

and turnings in closed areas, such as ship hulls, has also been reported. Pure iron has

a melting point of 1,535 C (2,795 F). Ordinary structural steel has a melting point

of 1,430 C (2,606 F).

Pyrophoricity

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