Basic Fire Fighting

Definition of a fire 

The state of combustion in which flammable materials burns, producing heat, flames and smoke.

Elements of a fire 

For fires to exist, the following four elements must be present at the same time: 

  • Enough OXYGEN to sustain combustion, 
  • Enough HEAT to raise the material to its ignition temperature, 
  • Some sort of FUEL or combustible material, and 
  • The chemical reaction that is fire. 

Classification of fire

Portable fire extinguishers are classified to indicate their ability to handle specific classes and sizes of fires. 

Labels on extinguishers indicate the class and relative size of fire that they can be expected to handle. 
Most fires that occur will fall into one or more of the following categories:

  
Class A: Fires involving ordinary combustible materials, such as 
paper, wood, and textile fibres, where a cooling, blanketing, or wetting extinguishing agent is needed.

  
Class B: Fires involving flammable liquids such as gasoline, thinners, oil-based paints and greases. Extinguishers for this type of fire include carbon dioxide, dry chemical and halogenated agent types. 

Class C: Fires involving energized electrical equipment, where a non-conducting gaseous clean agent or smothering agent is needed. The most common type of extinguisher for this class is a carbon dioxide extinguisher. 
 
Class D: Fires involving combustible metals such as magnesium, sodium, potassium, titanium, and aluminium. Special dry powder extinguishing agents are required for this class of fire, and must be tailored to the specific hazardous metal.  

Class F: Fires involving commercial cooking appliances with vegetable oils, animal oils, or fats at high temperatures. A wet potassium acetate, low pH-based agent is used for this class of fire. 
 
Conditions of a fire (conditions that you can expect)

  • Darkness 
  • Heat 
  • Smoke

Common sources of heat 

  • Electricity
  • Smoking
  • Friction
  • Cutting and welding
  • Spontaneous ignition
  • Static electricity
  • Chemical reaction

Transmission ways in which a fire spread 

  • Conduction
  • Convention
  • Radiation

The use of different types of fire extinguishers
There are five different types of fire extinguishers they are color coded and the instruction labels indicate on which type of fires we can use them. The pictogram indicates the use if the pictogram is crossed out it is not suitable for that class of fire.


Water Extinguisher

 
Signal: Red
Best for: Fires involving organic solid materials such as wood, cloth, paper, plastics, Coal etc. 

Dry Powder Extinguisher (Multi-Purpose)

 
Signal: Blue
Best for: Fires involving organic solid materials such as wood, cloth, paper, plastics, Coal etc.

Foam Extinguisher (AFFF)

Signal: Cream
Best for: Fires involving solids. Liquids such as grease, fats, oil, paint, petrol, etc. but not on domestic chip or fat pan fires. Can be used on class A fires but not recommended.

Carbon Di-Oxide Extinguisher

Signal: Black
Best for: Live electrical equipment when it is not possible to isolate the electric supply and flammable liquids such as grease, fats, oil paint, petrol etc. but not on domestic chip or fat pan fires.

Wet chemical

 
 
Signal: Canary Yellow
Best for: The specialist wet chemical extinguishers are ideal for Class “F” fires, involving cooking oils and fats, such as lard, olive oil, sunflower oil, maize oil and butter.

How to operate a fire extinguisher
It’s easy to remember how to use a fire extinguisher if you remember the acronym PASS.

  • Pull
  • Aim
  • Squeeze
  • Sweep

Fighting the fire 

  • Maintain a safe distance. 
  • Remember the effective extinguisher range. 
  • Ensure you know what is burning and what type of extinguisher to use. 
  • Switch off electricity. 
  • Know how to use the extinguisher. 
  • Never turn your back on the fire. 
  • Move around the perimeter of the fire to maximize coverage of the extinguisher agent.