Key Concepts of Fire
(Fire Triangle)

"At it's core,Fire can be understood through the Fire Triangle which comprises of 3 Elements that are necessary for a Fire or Ignite".

The 3 Elements are Heat,Oxygen and Fuel.

 

Elements of Combustion

 

                              Fuel

Any combustible material either solid,liquid or gas)that can burn.

Common fuels include wood, paper,gasoline,animal skin, clothes fabrics and various chemicals.

Fuel can be categorized in 7 main types:

Fossil Fuels:

Petroleum (gasoline,diesel,petrol,diesel,jet fuel) and other petrochemicals.

Natural Gas:

Primarily methane and propane used for heating,electricity generation,and as industrial fuels and for Electric Vehicles (EVS) as compressed Natural Gas(CNG).

Renewable Fuel:

Biofuels,Organic materials converted into energy including Ethanol used in gasoline blends.

Biodiesel:

Made from vegetable oils or animal fats used in diesel engines.

Biogas:

Produced from the anaerobic digestion of organic matter used for heating and electricity.

Wood and Biomass:

Used for heating and energy generation.

Nuclear Fuel:

Uranium and Plutonium used in nuclear reactors to produce energy through fission.

Hydrogen Fuel:

Hydrogen can used in Fuel cells to produce electricity emitting only water as a by-product.

Synthetic Fuel:

Fuels created through chemical processes that convert natural gas,coal,or biomass into liquid fuels(Fischer-Tropsch synthesis).

Alternate Fuel:

Electricity used in electric vehicle (EVS).

                         Oxygen 

Oxygen is a chemical element that is a colorless,odorless and tasteless gas at room temperature.

Fire requires an oxidizing agent typically oxygen found in the air.

Elemental Properties:

Oxygen is a non-metal and a member of the chalcogen group in the periodic table with two main isotopes 0-16(most abundant)and 0-18.

Combustion and Respiration:

Oxygen is vital for aerobic respiration(a process where cells extract energy from food) it is also necessary for combustion,enabling fire.

Occurance:

Oxygen is the most abundant element in the earth crust(about 21% of earth atmosphere).

Ozone:

In the upper atmosphere, oxygen can also exist as ozone(molecule composed of three oxygen atoms).

Ozone plays a critical role in protecting the earth from harmful ultraviolet(UV) radiation.

                            Heat

Heat is a form of energy that is transferrable between systems of objects with different temperatures,it flows from a warmer object to a cooler one until thermal equilibrium is reached(when both objects have same temperature)

Sufficient heat must be present to raise the material to it's ignition temperature.

This can come from various sources (matchsticks,friction, electrical sparks or chemical reactions)when any of the sources of heat is removed or insufficient,the fire will extinguish.

Heat can be transferred in 3 ways:

Conduction:

Direct transfer of heat through a material without any movement of the material itself it occurs when two objects in direct contact exchange energy.

Convection:

Transfer of heat through a fluid(gas or liquid) caused by the movement of the fluid.

Radiation:

The transfer of heat in the form of electromagnetic waves like infrared radiation through space,this process does not require any medium so heat can be transferred through a vacuum like the heat from the sun reaching the earth.

 Combustion Process 

When materials combust,a series of chemical reactions occur,primarily oxidation reaction where the fuel reacts with oxygen to produce heat,light,carbondioxide,and water vapor.

This process can be broken into:

Ignition

The moment the heat source raises the fuel to it's ignition temperature.

Flame Propagation 

As the fuel ignites the flames releases energy causing adjacent fuel to reach it's ignition temperature, allowing the fire to spread.