Element of Fire
There are three Elements which results Fire or Combustion
• Combustible material
• Oxygen, the fuel sources, and
• Ignition Source, the heat source.
Combustible Material
Combustible material is one which acts as a fuel source for fire, i.e., paper, wood, clothes, any solid combustible material like gasoline, kerosene, grease, tar, fingernail polish, magnesium, sodium, potassium, titanium or aluminum, cooking oil, vegetable oil, etc
Oxygen
Oxygen which is the most common factor and is available everywhere.
Ignition Source
Ignition source or heat source means flame, spark which ignites sufficient heat or Flame for a combustion or fire.
Here is an easy way to understand what is fire by fire triangle & by fire square (nuclear fire).
Fire Triangle
FIRE TRIANGLE it is an easy way to understand what is fire. It also gives a clear idea what the primary action is required against fire.
The Above Three Condition can be represented by a Triangle Known as “FIRE TRIANGLE”
So once any fuel Source like flame, small spark, any flickers, or any heat source come in contact of any combustible substance in the presence of oxygen combustion or fire takes place.
Condition Of Fire
Condition of fire depends on three things as we have previously read, i.e.
• presence of material that acts as fuel/combustible substance
• a source of heat/ignition
• the pressure of oxygen in the form of fire
Fire extinction in principle; consist in the limitation of one or more of these factors. The methods of extinguishing fire may be classified under the following headings:-
• Starving
• Smothering
• Cooling
• Inhibition or retarding of the combustion reaction
Starvation
Starvation is achieved by removal of the fuel burning in the fire. Sometimes combustible material can be removed by shutting off gas valves or fuel flows.
SMOTHERING
By excluding the oxygen in the surrounding atmosphere the fire will be extinguished.
COOLING
The most commonly used fire fighting medium is water. Water absorbs heat from the fire and cools the fuel to a temperature where it no longer produces flammable vapors.
STOP CHAIN REACTION
Stopping or interrupting the chain reaction between the fuel, heat, and oxygen will extinguish the fire. Specific methods of extinguishing fires often involve a combination of more than one of the four principles
Properties of Flammable Materials
Flammability
Flammability is the ability of a substance to burn. Vapors given off by a flammable material can burn when mixed with air in right proportion, in the presence of an ignition source.
Ignition Point
It is the lowest temperature to which a flammable substance must be heated for it to ignite.
Flash Point
It is the lowest temperature at which the vapors of a substance are available in sufficient quantity to produce a momentary flash when a flame is applied.
Fire Point
It is the temperature at which the heat from the combustion for burning vapour is capable of producing sufficient vapour to enable combustion continues.
Spontaneous Ignition Temperature
It is the lowest temperature, at which the substance will ignite spontaneously, i.e., the substance will burn without the introduction of a flame or other ignition sources.
Upper Flammable Limit
It is that concentration of flammable vapour in air below which there is insufficient flammable vapour to support and propagate combustion.
Auto Ignition
It is the ignition of a flammable material without the assistance of an external pilot source.
Flammable Range
It is the range of concentration of flammable vapour in air within which the vapour and air mixture is flammable.
Static Electricity
It is the electricity produces on dissimilar materials through physical contact and separation, for example, a sampling apparatus lowered in to a tank containing charged petroleum liquid.
Reactivity
It is the property of most materials to enter into a chemical reaction with each other. Combustion is a chemical reaction in which heat and light are involved. Fire from combustion is said to be the result of a rapid oxidation reaction at temperature above 730? C accompanied by the evolution of highly heated gaseous products of combustion and the emission of visible and invisible radiation.
The Following reaction is an example of combustion (reaction with atmospheric oxygen)
C+ O2= CO2 (carbon dioxide)
2C2+ O = 2CO (carbon monoxide)
2H2+ O2= 2H2O (water)
The diagram below shows the relation between oxygen and gases, and compares with lower flammable limit and upper flammable limit:
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