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15 Cards in this Set

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  • Back
The classes of fire are
A, B, C, D and K
Class A is
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 ∆.
Class B is
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."
Class C is
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."
Class D is
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."
Class K is
fire involving cooking oil.
» Put out with is sometimes called media extinguishers.
» Picture is a frying pan with flames and the letter "K."
Class A is rated
» 1-A requires 1 and 1/4 gallons of water.
» 2-A will extinguish twice as much as 1-2 and so forth.
Class B is rated
» 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.
The most common types of extinguishing agents are
water, dry chemical, carbon dioxide, halogenated hydrocarbons, foam, and dry powder.
Characteristics of water
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.
Characteristics of dry chemical
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.
Characteristics of carbon dioxide
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.
Characteristics of halogenated hydrocarbons
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.
Characteristics of foam
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.
Characteristics of dry powder
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.