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4.6.2 Summary of Fire Suppression Methods - Cont'd .
d.
Carbon Dioxide. The carbon dioxide extinguisher holds liquid carbon dioxide under high pressure. Extinguishers
are made with both disk valves and seat valves. The disk valve type releases the entire contents of the cylinder when it
is opened. The seat valve type, which has a control valve, permits only the desired amount of gas to be discharged.
The stream should be directed at the base of the flames. The carbon dioxide extinguisher may be used on electrical
fires.
e.
Soda acid. The soda acid extinguisher contains a solution of water and sodium bicarbonate and, in a separate
bottle, an amount of sulfuric acid. When the extinguisher is turned upside down, the chemicals are mixed and expelled
under pressure through the hose. This extinguisher must not be used on electrical fires.
f.
Dry Chemical. The dry chemical extinguisher contains chemically processed bicarbonate of soda in a powder
form. Air or gas pressure contained either inside or outside of the extinguisher shell, is used to discharge the bicarbonate
of soda. In applying powder to flammable liquid fires, the stream should be so directed that the section of fire closest to
the operator is extinguished first. The operator should then gradually move forward, shifting the discharge nozzle from
side to side. Equipment should be cleaned after fire extinguishment because of the corrosive nature of dry powder
extinguishing agents. This extinguisher may be used on electrical fires.
g.
Inert Gas. An inert gas, such as nitrogen, can be used in a confined space to extinguish the fire by displacing the
oxygen. Personnel cannot be in the same space. Nitrogen may also be used to blanket a flammable liquid in a confined
space to prevent ignition due to the displacement of air (oxygen).
4-6.3 Fire Extinguishers Supplied with TPT
Each TPT is furnished with the fire suppression equipment defined in para. 2-4.13. It is noted that there are two types of
fire extinguishers:
a.
Nineteen (19) wheel-mounted combination dry chemical and foam extinguisher. The mixing and motive force of
the extinguisher is supplied from compressed nitrogen bottles carried on the equipment. The foam used in this
extinguisher is called aqueous film forming foam (AFFF). In general terms, the practice is to extinguish the fire with dry
chemicals and then prevent reignition with the AFFF which forms a film over the extinguished area. Details on the
operation of this equipment are contained in the U.S. Marine Corps technical manual in Appendix A.
b.
Ninety-five (95) 20 lb. capacity dry chemical, hand carried, fire extinguishers. These are intended for use in
extinguishing more minor fires.
4-6.4 Types of Fires and Suppression Action
a.
Electrical Fires. When an electrical fire occurs, the first action is to shut off the current at a point away from the
immediate switch controlling the equipment on fire. If wires must be cut, only qualified personnel, with proper equipment,
should be allowed to cut them. If the current cannot be shut off immediately, a carbon dioxide or dry chemical
extinguisher should be used to put out the fire. For large fires, water fog can be used provided care is taken to not cause
a solid stream of water under any conditions.
4-14
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