MetalGuard Powder

PYROPHORIC METALS

DOE-HDBK-1081-94

Spontaneous Heating and Pyrophoricity

G-1 powder is effective for fires in magnesium, sodium, potassium, titanium,

lithium, calcium, zirconium, and hafnium, and has been recommended for

special applications on powder fires in aluminum, zinc, and iron. It is listed by

Underwriters Laboratories Inc. (UL) for use only on magnesium and

magnesium alloys (dry fines and moist fines that are not moistened or wetted

with water or water soluble cutting oils) and is approved by the Factory

Mutual System (FM) for use on fires in magnesium, aluminum, sodium,

potassium, and sodium-potassium alloy. When plans call for use of G-1

powder on those metals mentioned, practice fire drills should be held in

advance. For fires of thorium, uranium, beryllium, or plutonium, G-1 powder

can be effective in covering the fire to prevent its spread, but will not

extinguish these fires. The products of combustion of thorium, uranium,

beryllium, and plutonium can be a health hazard, and precautions should be

observed consistent with the usual procedures in combating fires in

radioactive material.

MetalGuard Powder

MetalGuard powder is identical to G-1 powder in composition, and is simply

a trade name variation.

Met-L-X Powder

This dry powder, with its particle size controlled for optimum extinguishing

effectiveness, is composed of a sodium chloride base with additives. The

additives include tricalcium phosphate to improve flow characteristics and

metal stearates for water repellency. A thermoplastic material is added to bind

the sodium chloride particles into a solid mass under fire conditions.

Met-L-X powder is noncombustible, and secondary fires do not result from its

application to burning metal. No known health hazard results from the use of

this agent. It is nonabrasive and nonconductive.

Stored in sealed containers or extinguishers, Met-L-X powder is not subject to

decomposition or a change in properties. Periodic replacement of extinguisher

charges is unnecessary. Extinguishers range from 14-kg (30-lb) portable hand

units (carbon dioxide cartridge propellant), through 68- and 160-kg

(150- and 350-lb) wheeled units, to 900 kg (2,000 lb) for stationary or piped

systems. The wheeled units and piped systems employ nitrogen as the

propellant.

The powder is suitable for fires in solid chunks (such as castings) because of

its ability to cling to hot vertical surfaces. To control and then extinguish a

metal fire, the nozzle of the extinguisher is fully opened and, from a safe

distance (in order to prevent blowing the burning metal into other areas), a

Pyrophoricity

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