University of Southern Indiana

Fire Extinguisher Use

Elements of Fire
Before extinguishing a fire, it is important to understand the elements that make up a fire. In order for fire to occur, four elements must be present: oxygen, fuel, heat and a chemical chain reaction. This is represented by the Fire Tetrahedron. When any of the four elements are removed, the fire will go out. Fire extinguishers function by removing one of the four components of the Fire Tetrahedron.

Types of Fires
Fire extinguishers are rated based upon the types of fires they are designed to put out. These ratings are identified on the label of the fire extinguisher. Care should be taken to ensure the extinguisher chosen to put out a fire is proper for the type of fire. Listed below are the four main types of ratings.

  • Class A: Ordinary combustible materials, wood, paper, plastics and clothing
  • Class B: Flammable liquids and gases
  • Class C: Energized electrical equipment
  • Class D: Combustible metals

Types of Fire Extinguishers
The University uses the following types of fire extinguishers:

  • Water (Class A)
  • Carbon dioxide (Class BC)
  • Multipurpose dry chemical (Class ABC)
  • Dry powder (Class D)

More on Extinguishers

Follow the PASS procedure when operating any fire extinguisher:
P: Pull the pin.
A: Aim at the base of the fire.
S: Squeeze the handle or lever.
S: Sweep from side to side.

Rules for Extinguisher Usage

  • Be trained in extinguisher use
  • Use on small fires that are not spreading;
  • Know what type of fuel is burning;
  • Before extinguishing the fire, position yourself with the exit at your back;
  • Do not attempt to extinguish the fire if you are in jeopardy or feel uncomfortable doing so.

Missing or discharged fire extinguishers should be reported immediately to Emergency Minor Maintenance at 812-464-1700.

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