Combustible Metal Agents and Application Techniques

PYROPHORIC METALS

DOE-HDBK-1081-94

Spontaneous Heating and Pyrophoricity

Extinguishing Uranium Fires

Uranium fires should be extinguished with the same techniques and precautions as

plutonium fires (see corresponding paragraph on plutonium).

Combustible Metal Agents and Application Techniques

A variety of metals burn, particularly those in finely divided form. Some metals burn when

heated to high temperatures by friction or exposure to external heat; others burn from

contact with moisture or in reaction with other materials. Because accidental fires may occur

during the transportation of these materials, it is important to understand the nature of the

various fires and the hazards involved.

The hazards involved in the control or complete extinguishing of metal fires include

extremely high temperatures, steam explosions, hydrogen explosions, toxic products of

combustion, explosive reaction with some common extinguishing agents, breakdowns of

some extinguishing agents with the liberation of combustible gases or toxic products of

combustion, and, in the case of certain nuclear materials, dangerous radiation. Some agents

displace oxygen, especially in confined spaces. Therefore, extinguishing agents and methods

for their specific application must be selected with care. Metal fires should not be approached

without suitable self-contained breathing apparatus and protective clothing, unless the fire is

enclosed in a glove box.

Numerous agents have been developed to extinguish combustible metal (Class D) fires, but a

given agent does not necessarily control or extinguish all metal fires. Although some agents

are valuable in working with several metals, other agents are useful in combating only one

type of metal fire. Despite their use in industry, some of these agents provide only partial

control and cannot be considered actual extinguishing agents. Certain agents that are suitable

for other classes of fires should be avoided for metal fires, because violent reactions may

result (e.g., water on sodium; vaporizing liquids on magnesium fires).

Certain combustible metal extinguishing agents have been used for years, and their success in

handling metal fires has led to the designations "approved extinguishing powder" and "dry

powder." These designations have appeared in codes and other publications where it was not

possible to employ the proprietary names of the powders. These terms have been accepted in

describing extinguishing agents for metal fires and should not be confused with the name "dry

chemical," which normally applies to an agent suitable for use on flammable liquid (Class B)

and live electrical equipment (Class C) fires. Class B extinguishing agents may not be safely

applied to come combustible metal (Class D) fires. Other extinguishing agents discussed

herein have been used only experimentally in limited areas or at specific installations, and

require much judgment in application.

The successful control or extinguishment of metal fires depends heavily upon the method of

application, training, and experience. Practice drills should be held on the particular

Pyrophoricity

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