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15 Cards in this Set
- Front
- Back
The classes of fire are
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A, B, C, D and K
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Class A is
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ordinary combustible including wood, paper, plastic, etc.
» Use water or class A dry chemical to extinguish. » A picture symbol of a burning trash can the letter "A" , and a green triangle ∆. |
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Class B is
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flammable and combustible liquids.
» Extinguishment by use of dry chemical agents, halogenated agents, or foam. These fires are extinguish by blanketing and smothering or breaking the chain of reaction. » A picture symbol is the red square □ and the letter "B." |
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Class C is
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energized electrical equipment.
» Extinguished with nonconductive agents such as carbon dioxide, halon, and dry chemical. These fires are extinguish by turning off the energy to the unit of by a non conductive agent. » A picture symbol of a plug near an electrical outlet fire, a blue circle Ο and the letter "C." |
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Class D is
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combustible metals.
» Extinguish with agents that are a sodium chloride material which is used to cover the material. Donot use multipurpose extinguisher. » No picture just a yellow star and the letter "D." |
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Class K is
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fire involving cooking oil.
» Put out with is sometimes called media extinguishers. » Picture is a frying pan with flames and the letter "K." |
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Class A is rated
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» 1-A requires 1 and 1/4 gallons of water.
» 2-A will extinguish twice as much as 1-2 and so forth. |
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Class B is rated
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» The rating is based on the fire involving a 2 inch layer of n-heptane that a nonexpert operator can extinguish.
» Every 1-B rating corresponds to 1 square foot of flammable liquid. |
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The most common types of extinguishing agents are
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water, dry chemical, carbon dioxide, halogenated hydrocarbons, foam, and dry powder.
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Characteristics of water
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Physical:
Water is most commonly 2.5 gallons discharges 30 to 40feet for about 30 to 60 seconds, and uses pump or pressure to expel agent. Agent: A) Water freezes at 32 degrees F, has a high surface tension, and needs expellant force. » The agent for water removes heat to extinguish the fire, and is good on class A only. Advantages and limitations: A) » Advantages of water is that it absorbs a large amount of heat and can be used with specialized agents » Limitations is that it conducts electricity, freezes and has a high surface tension, and may react with certain chemicals. |
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Characteristics of dry chemical
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Physical:
B) Dry chemical can range from 2.5 pounds to 350 pounds, discharge 5 to 20 feet, and last 8 to 25 seconds, and uses cartride stored pressure to expel the agent. Agents: B) Many different agents the most common being Monammonium phosphate -multipurpose- Tri-class. » The extinguishing principle is breaking the chain of reaction. » Use on multi A,B, C and just B and C. Advantages and limitations: B) » Advantages of dry chemical is that it is nontoxic, nonconductive, and quick to knock down flame. » The Limitations is that causes breathing difficulties, insulating qualities, corrosive properties, not flash back resistive (no cooling), chemicals not interchangeable, and some are not compatible with foam. |
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Characteristics of carbon dioxide
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Physical:
C) Carbon dioxide can weight 2.5 pounds to 100 =, discharge 3 to 8 feet, and last 8 to 30 seconds, and uses it own pressure to expel agent. Agent: C) Carbon dioxide is agent is normally a gas, 1.5 times heavier than air, low in temperature, and can be stored as a liquid. » Extinguishes fires primary by smothering a layer of CO2 between the fuel and air. » Use for class B and C fires with limited effect on class A. Advantages and limitations: C) » Advantages are is that carbon dioxide is non-reactive, has its own discharge pressure, nonconductive, and has no residue. » Limitations are visibility, noise, short range, and dissipates rapidly, all while displacing oxygen. |
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Characteristics of halogenated hydrocarbons
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Physical:
D) Halogenated hydrocarbons (which was stopped in 94 due to its effect on ozone layer and is being weeded out) 2.5 pounds to 150, discharges 3 to 8 feet, lasting 8 to 30 seconds, and uses stored pressure to expel agent. Agent: D) Halon agent is stored as a liquid under pressure and is 2.5 times more effective than CO2. » Breaks chemical process. » Use on class B and C mostly with sensitive electrical equipment. Advantages and disadvantages: D) » Advantages of halon are high expansion ratio, needs no expellant, nonconductive, noncorrosive, and no residue. » Limitation is that halon can be toxic and create other toxic gases under fire conditions. |
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Characteristics of foam
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Physical:
Foam is 2.5 gallons and discharges 20 to 25 feet lasting 50 seconds, using stored pressure to expel agent. Agent:E) Foam agent is gas-filled bubbles, lighter than solution from which formed, floats on flammable liquids, and can be proportioned at various concentrations. » Extinguishes by smothering and some cooling. » For class A and B fires only, CLASS C WOULD GET U SHOCKED. Advantages and limitations: E) » Advantages of foam include being nontoxic and its flow capabilities. » Limitations be not compatible with some other agents, freezes, the discharge distance, it that it is conductive. |
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Characteristics of dry powder
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Physical:
F) Dry Powder weights 30 to 350 pounds, discharges 4 to 6 feet, lasting 19 to 30 seconds, using shovel of cartridge to expel the agent. Agent: F) Dry powder agent is fine powder, needs expellant force and no single agent is effective on all types of combustible metals. » Extinguish method is by smothering. » Design only for class D fires. Limitations: F) » Limitations of class D is that it can be packed, cannot be interchange with chemicals, is expensive, and may need large quantities in order to work. |