Laboratory-Specific Signage for Flammables

Fire Triangle

Three ingredients are essential to produce a fire. They are represented on each side of the fire triangle.

Fire Triangle showing three ingredients to produce a fire -- oxygen, heat, and fuel.

1. Enough oxygen to sustain combustion

2. Enough heat to raise the material to its ignition temperature

3. Some sort of fuel or combustible material

Source of Image: Wikimedia. Fire Triangle. http://upload.wikimedia.org/wikipedia/commons/thumb/2/20/Fire_triangle.svg/330px-Fire_triangle.svg.png (accessed June 19, 2015).


Fire Tetrahedron

When a chemical chain reaction is added to the fire triangle, it becomes a fire tetrahedron. Four items are necessary to produce a fire.

Fire Tetrahedron showing four items needed to produce a fire -- oxygen, heat, fuel, and chemical chain reaction.

1.  Oxygen

2. Heat

3. Fuel or combustible material

4. A chemical reaction

Source of Image: Wikimedia. Fire Tetrahedron. https://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Fire_tetrahedron.svg/220px-Fire_tetrahedron.svg.png (accessed June 19, 2015).

One of the four parts of the tetrahedron must be addressed to prevent or stop a fire.

  • Keep fuel and ignition sources separate.
  • Cut off oxygen to the fire by smothering.
  • Use an appropriate fire extinguisher to remove part of the fire tetrahedron.

Classes of Fires

Class Description Potential Harm
A Fires involving ordinary combustibles, such as wood, paper, and some plastics
B Fires involving flammable liquids, such as alcohols, lamp oils, or butane
C Fires involving electrical components
D Fires involving metals, such as aluminum or sodium
K Fires involving cooking or animal oils, such as frying foods

Source: OSHA. Fire Protection and Prevention, 2009. 


Types of Fire Extinguishers

Class Description
Dry chemical (multipurpose) A, B, C
Water only (will not work for other types of fires)
Foam only (will not work for other types of fires)
Carbon dioxide (not to be used in confined areas) B, C
Halon B, C
Metal D
Potassium acetate K

Note: In most cases, the high school laboratory will require a dry chemical extinguisher, but if you possess solid sodium or other reactive metals, a metal fire extinguisher is also recommended.

Source: OSHA. Fire Protection and Prevention, 2009. 

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