Fire Engineering

1. Fire Extinguishing Method i) Cooling Heat may be removed and brought below the ignition point of the substance involved by pouring water that is called cooling. ii) Starvation The fire may be extinguished by removing the combustible material from the scene of the fire that is called starvation. iii) Smothering (Blanketing) The fire may be extinguished by removing oxygen or stopped oxygen supply that is call smothering. 2. Branching of Chemical Chain Reaction The chemical reactions in a flame take place very quickly at a very high temperature, and in a very small volume. All flame reactions depend largely on the activities of stray bits of molecules of the reacting substances. These little fragment are very reactive, very unstable, and can exist for a fraction of a second; also, these molecules are extremely mobile. For example:- 2H 2 + O 2 = 2H 2 O   In this reaction, hydrogen atoms(H), oxygen atoms(O) and hydroxyl radicals (OH) r...

1) Definition of Fire A process in which substances combine chemically with oxygen from the air and typically give out bright light, heat and smoke that is call of FIRE. 2) Triangle of Fire 3) Tetrahedron of Fire In a fire there are two different phase in which combustion proceeds, ‘surface combustion mode and flaming mode’. The surface combustion mode incorporates the three essential elements of fire as represented by the triangle of fire – Heat, Oxygen and combustible material. The flaming mode incorporates four basic requirement- heat, oxygen, combustible material and uninhibited chain reaction of combustion process. This is called the tetrahedron of fire. 4) Classification of Fire Class ‘A’- Solid Fire Example: Paper, Wood, Cloth, etc Class ‘B’- Liquid Fire Example: Oils, Paints, Chemicals, Wax, etc. Class ‘C’- Gases Fire Examples: L.P.G., Acetylene, Hydrogen, Methane, Natural Gas, etc Class ‘D’- Metal Fire Examples: M...

1. Flame and its type A flame is zone in which chemical reaction takes place between gases with the evolution of heat and light accompanied by vigorous combustion. i) Luminous flame- Producing heat and light, e.g. the flame of a burning oil, an oil lamp, a candle. ii) Non-Luminous flame- Producing heat and very little light, e.g. burning hydrogen or burning of carbon monoxide. 2. Diffusion Flames All combustion processes are vapour – phase reaction and the happen when the mixture of fuel vapour and air is within the limits of flammability. In an ordinary fire, the fuel vapour and air meet and are mixed by the process called diffusion within the reaction zone. At high temperature, the mixing of the fuel with air takes place quickly and the mixing within the reaction zone is very efficient. Flames in which the reactants are mixed by diffusion in this way are called diffusion flames. 3. Premixed Flames Unlike the diffusion flame, where the flame fl...

1. Combustion Ordinary combustion is a chemical reaction between a fuel and oxygen in presence of heat. Or it may be stated that three things are essential for combustion which can be represented by the tree arms of a triangle, viz. heat, combustible substance and oxygen. 2. Type of Combustion i) Slow or incipient combustion One in which the amount of heat and light emitted is feeble. ii) Rapid Combustion One in which a considerable amount of heat and light are emitted within a short time. iii) Deflagration Combustion A case of combustion which takes place with considerable rapidity evolving heat and light. iv) Explosive Combustion A very rapid combustion accompanied by a loud report within an extremely short time, with generation of very high pressure and temperature. 3. Oxygen content in air by weight and volume Consider we have 100 g of air. Mass of oxygen (O ₂ ) in 100 g of air = 23 g Mass of nitrogen (N ₂ ) in 100 g of air =...

A. Classification of Flammable Material Class- A Ordinary combustible solids. Example: Paper, Wood, Cloth, etc Class-B Combustible liquids or liquefiable solids.    Example: Oils, Paints, Chemicals, Wax, etc. Class-C                         Combustible gases.    Examples: L.P.G., Acetylene, Hydrogen, Methane, Natural Gas, etc Class-D                        Combustible metals.                           Examples: Magnesium, Sodium, Uranium, Thorium, etc                                                 ...