Approved Combustible Metal Fire Extinguishing Agents

Spontaneous Heating and Pyrophoricity

DOE-HDBK-1081-94

PYROPHORIC METALS

combustible metals on which the agent is expected to be used. Prior knowledge of the

capabilities and limitations of agents and associated equipment is always useful in emergency

situations. Fire control or extinguishment will be difficult if the burning metal is in a place or

position where the extinguishing agent cannot be applied in the most effective manner. In

industrial plant locations where work is performed with combustible metals, public fire

departments and industrial fire brigades have the advantage of fire control drills conducted

under the guidance of knowledgeable individuals.

Approved Combustible Metal Fire Extinguishing Agents

A number of proprietary combustible metal extinguishing agents have been submitted

to testing agencies for approval or listing. Others have not, particularly those agents

developed for special metals in rather limited commercial use. Those extinguishing

agents described as follows have been approved or listed for use on fires involving

magnesium, aluminum, sodium, potassium, and sodium-potassium alloy. Information

on extinguishing agents was obtained from the 17th Edition of the NFPA Handbook.

G-1 Powder

"Pyrene" G-1 powder is composed of screened graphitized foundry coke to

which an organic phosphate has been added. A combination of particle sizes is

used to provide good packing characteristics when applied to a metal fire. The

graphite acts as a heat conductor and absorbs heat from the fire to lower the

metal temperature below the ignition point, which results in extinguishment.

The closely packed graphite also smothers the fire, and the organic material in

the agent breaks down with heat to yield a slightly smoky gas that penetrates

the spaces between the graphite particles, excluding air. The powder is

nontoxic and noncombustible.

G-1 powder is stored in cardboard tubes or metal pails, and can be stored for

long periods of time without deterioration or caking. It is applied to the metal

fire with a hand scoop or a shovel. The packing characteristics of the powder

prevent its discharge from a fire extinguisher.

The powder is applied by spreading it evenly over the surface of the fire to a

depth sufficient to smother the fire. A layer at least 12.5 mm (1/2 in.) deep is

recommended for fires involving fines of magnesium and magnesium alloys.

Larger chunks of metal require additional powder to cover the burning areas.

Where burning metal is on a combustible surface, the fire should be

extinguished by (a) first covering it with powder, (b) shoveling the burning

metal onto another 25 or 50 mm (1 or 2 in.) layer of powder that has been

spread out on a nearby noncombustible surface, and (c) adding more powder

as needed.

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Pyrophoricity