The Fire Triangle

Three things must be present to occur a fire accident

        

•          Fuel

•         Oxygen

•         Heat

•         Enough OXYGEN to sustain combustion

•         Enough HEAT to reach ignition temperature

•         Some FUEL or combustible material

•         Fuel can be combustible material – Solid, liquid or gas.

•         Most solids and liquids become a vapor or gas before

they will burn

Fire Safety is based upon the principle of keeping fuel sources and ignition sources separate.

Quantity of Oxygen Required:-

The air we breathe contains about 21% oxygen. Fire only needs an atmosphere with at least 16% oxygen

Fire Tetrahedron

In the past, we learned that three elements, heat, fuel and oxygen were necessary for fire to start         and continue burning hence, the fire triangle concept

 they produce the CHEMICAL REACTION

In recent years this concept has been expanded to include fourth elements that of the chemical reaction thus 

Creating the fire tetrahedron.

Stages of combustion

There are four stage of combustion

•         Incipient Stage - At this stage, composition is occurring at the surface of the fuel due to the influence of some form of heat. 

•         Smoldering Stage - At this stage, up to 10% of the decomposing products released at the surface of the fuel are visible.

•         Flaming Stage - Vapors from the decomposing fuel have ignited and are at the stage where flames are self propagating.

•         Heat Stage - At this stage the burning has progressed to the point where the fire is still small but generating sufficient heat to warmthe air immediately around the fire, sending warm products of combustion upwards by convection.

•         The time required for afire to develop through the first two stages is usually quite long compared to the last two