The substances which burn in air are called combustible.
Oxygen (in air) is essential for combustion.
During the process of combustion, heat and light are given out.
Ignition temperature is the lowest temperature at which a combustible substance catches fire. Inflammable substances have very low ignition temperature.
Fire can be controlled by removing one or more requirements essential for producing fire.
Water is commonly used to control fires.
Water cannot be used to control fires involving electrical equipment or oils.
There are various types of combustions such as rapid combustion, spontaneous combustion, explosion, etc.
There are three different zones of a flame - dark zone, luminous zone and non-luminous zone. An ideal fuel is cheap, readily available, readily combustible and easy to transport. It has high calorific value. It does not produce gases or residues that pollute the environment. Ü Fuels differ in their efficiency and cost.
Fuel efficiency is expressed in terms of its calorific value which is expressed in units of kilojoule per kg.
Unburnt carbon particles in air are dangerous pollutants causing respiratory problems. Incomplete combustion of a fuel gives poisonous carbon monoxide gas.
Increased percentage of carbon dioxide in air has been linked to global warming.
Oxides of sulphur and nitrogen produced by the burning of coal, diesel and petrol cause acid rain which is harmful for crops, buildings and soil.
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