How Fire Extinguishers Work

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How Fire Extinguishers Work

• Melanie Kirkpatrick

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FIRE

• The three essential elements of a fire are
• Heat
• Oxygen
• Fuel
• To put out a fire, you need to remove one of
  these elements.

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Inside the Fire Extinguisher
http//home.howstuffworks.com/fire-extinguisher1.h
tm
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Class A

• Ordinary combustible materials
• Air-Pressurized Water Extinguisher
• Class A Extinguishers have a rating such as 4-A.
• The number indicates how much water the
  extinguisher holds. One unit equals 1.25
  gallons. So a 4-A extinguisher holds 41.255
  gallons

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Class B

• Flammable Liquids
• Usually a Carbon Dioxide Extinguisher
• Has a number rating such as 10-B, which
  represents the area in square feet of a Class B
  fire the extinguisher can put out

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Class C

• Electrical Equipment
• Usually a Dry Chemical Extinguisher, but can also
  be Carbon Dioxide

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Class D

• Combustible Metals
• Different Metals have very different reactions to
  burning so there is no one type of agent approved
  for all Class D Fires

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Class K

• Kitchens and environments with a high probability
  of grease fires
• Wet potassium acetate based, low pH agent
• Class K extinguishers are rare because they have
  only existed since 1998
• Many kitchens still use Class B

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Carbon Dioxide Extinguishers

• Puts out fires by eliminating oxygen and
  replacing it with CO2
• Dry ice can sometimes come out
• Should only be used on Class BC Fires

Label of a CO2 Class BC extinguisher
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Dry Chemical Extinguishers

• Classified as ABC or BC
• Usually sodium bicarbonate, potassium
  bicarbonate, or monoammonium phosphate
• Coat fuel and smother fire

A Dry Chemical Potassium Bicarbonate Extinguisher
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Halon Fire Extinguishers

• Contains a gas which interrupts the chemical
  reaction when fuels burn
• Used to protect valuable electrical equipment
• Used on Class ABC fires
• Bromochlorodifluoromethane, halon 1211, used as
  its extinguishing agent

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Bibliography

• http//home.howstuffworks.com/fire-extinguisher.ht
  m
• http//www.fire-extinguisher101.com/index.html
• http//www.hanford.gov/fire/safety/extingrs.htm
• http//home.howstuffworks.com/question346.htm
• http//en.wikipedia.org/wiki/Fire_extinguishers
• http//www.osha.gov/SLTC/etools/evacuation/portabl
  e_about.html
• http//www.pp.okstate.edu/ehs/MODULES/exting/Trian
  gle.html
• http//www.uncg.edu/sft/extinguisher2A.html
• http//www.dcfp.navy.mil/equip/pkp.htm
• http//www.lhup.edu/ehs/FireSafetyPcy/Fire20Extin
  guisher20Info20Sheet.htm