ANSI Z308.1-2015 Standard Minimum Requirements  Workplace First Aid Kits and Supplies - Buy new ANSI Kits
ANSI Z308.1-2015 Standard Minimum Requirements Workplace First Aid Kits and Supplies - Buy new ANSI Kits

Types of Fire Extinguishers

Which type of Fire Extinguisher is right for the job? How do you know what type it is?

Most fire extinguishers will have a pictograph label telling which fuels the extinguisher is designed to fight.

Fire-ABC

Different types of fire extinguishers are designed to fight different classes of fire. The three most common types of fire extinguishers are:

  • Water (APW) Extinguishers
  • Carbon Dioxide Extinguisher, and
  • Dry Chemical Extinguishers

Water (APW) Extinguishers

APWs are designed for Class A (wood, paper, cloth) fires only.

Never use water to extinguish flammable liquid fires. Water is extremely ineffective at extinguishing this type of fire, and you may, in fact, spread the fire if you try to use water on it.

Never use water to extinguish an electrical fire. Water is a good conductor, and there is some concern for electrocution if you were to use water to extinguish an electrical fire. Electrical equipment must be unplugged and/or de-energized before using a water extinguisher on it.

APWs extinguish fire by taking away the "heat" element of the fire triangle. APWs are generally found in older buildings, particularly in public hallways.

Carbon Dioxide (CO2 ) Extinguishers

Carbon Dioxide extinguishers are filled with non-flammable carbon dioxide gas under extreme pressure. You can recognize a CO2 extinguisher by its hard horn and lack of pressure gauge. The pressure in the cylinder is so great that when you use one of these extinguishers, bits of dry ice may shoot out the horn.

CO2 cylinders are red and range in size from 5 lbs to 100 lbs or larger. In the larger sizes, the hard horn will be located on the end of a long, flexible hose.

CO2’s are designed for Class B and C
(flammable liquid and electrical) fires only
.

Carbon Dioxide is a non-flammable gas that extinguishes fire by displacing oxygen, or taking away the oxygen element of the fire triangle. The carbon dioxide is also very cold as it comes out of the extinguisher, so it cools the fuel as well. CO2’s may be ineffective at extinguishing Class A fires because they may not be able to displace enough oxygen to successfully put the fire out. Class A materials may also smolder and re-ignite. CO2’s will frequently be found in laboratories, mechanical rooms, kitchens, and flammable liquid storage areas.

FireExtinguisherABCDry Chemical Extinguishers

Dry Chemical Extinguishers come in a variety of types. You may see them labeled:

  • "DC" short for "dry chem"
  • "ABC" indicating that they are designed to extinguish class A,B,and C fires, or
  • "BC" indicating that they are designed to extinguish class B and C fires.

"ABC" fire extinguishers are filled with a fine yellow powder. The greatest portion of this powder is composed of mono-ammonium phosphate. Nitrogen is used to pressurize the extinguishers.

ABC extinguishers are red and range in size from 5 lbs. to 20 lbs.

It is extremely important to identify which types of dry chemical extinguishers are located in your area. Read the labels and know their locations! You don't want to mistakenly use a "BC" extinguisher on a Class A fire, thinking that it was an "ABC" extinguisher.

Dry chemical extinguishers put out fire by coating the fuel with a thin layer of dust, separating the fuel from the oxygen in the air. The powder also works to interrupt the chemical reaction of fire, so these extinguishers are extremely effective at putting out fire.

These extinguishers will be found in a variety of locations. New buildings will have them located in public hallways. They may also be found in laboratories, mechanical rooms, break rooms, chemical storage areas, offices, university vehicles, etc.

Dry chemical extinguishers with powder designed for Class B and C fires may be located in places such as commercial kitchens or areas with flammable liquids.

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