Chapter 7 Portable Fire Extinguishers Flashcards
Extinguishing agent
Material used to stop the combustion process
Incipient
Those that have not spread beyond the areas of origin
Advantages and Disadvantages of Portable Fire Extinguishers
- Portability, less time
2. Disadvantage is that its a “one-shot”
Class A Fire/extinguisher
Ordinary combustibles such as wood, paper, cloth, rubber, natural vegetation
Ex. water is the most commonly used extinguishing agent.
Class B Fires/extinguishers
flammable or combustible liquids (gasoline, oil-based paints, and some plastics.
Class C Fires/extinguishers
energized electrical equipment
ex. dry chemicals, or carbon dioxide
Class D Fires/extinguishers
combustible metals, magnesium, titanium, zirconium, sodium, lithium and potassium, must be selected properly because of possible violent reactions.
Class K Fires/extinguisher s
cooking oils and fats
ex.
Underwriters Laboratories, Inc.
the organization that developed the standards, classifications, and rating system for portable fire ext.
Class A Ext.
solid “A” in green triangle 1A- 1.25 gallons of water 2A- 2.5 gallons, 4A- has the ability to put out twice as much as the 2A rated extinguishers.
Class B Ext.
solid B in red square 10-B= capable of 10 square feet 40-B= 40 square feet of coverage 2-A,10-b,C works for ABC fires.
Class C Ext.
solid C in blue circle
Class D Ext.
solid D in yellow star
Class K Ext.
pictograph pan on fire
Standard for Portable Fire Extinguishers
NFPA 10
Fire Load
quantity of combustible materials present
Light/Low hazards locations
areas where the majority of material are noncombustible or arranged so that a fire is not likely to spread. Ex. Limited class A and class B materials, classrooms, churches hotel rooms
Ordinary (or moderate) hazard locations
contains more class A and class B materials than do light hazard locations. Ex. retail stores parking garage, research facilities and workshops
Extra (high) Hazard locations
contain more class A combustibles and or class B flammables than do ordinary hazard locations. Ex. wood working shops, service to repair facilities for cars, planes, deep fryers
Methods of Fire Extinguishment
- cooling the fuel
- cutting off the supply of oxygen
- interrupting the chain of reactions
Types of extinguishing agents
- water
- dry chemicals
- carbon dioxide
- foam
- wet chemicals
- halogenated agents
- dry powder
Water
efficient, plentiful and inexpensive. Used for class A fires
Loaded-stream fire extinguishers
can be used to counteract freezing by combining an alkali metal salt with water.
Dry chemicals
deliver a stream of very finely ground particles onto a fire. They interrupt chemical chain reactions and they absorb large quantities of heat effective class B, can be used class C (non conductive)