MECHANICAL ENGG DEPTT, SLIET 1

SANT LONGOWAL INSTITUTE OF ENGG. TECHNOLOGY,SANGRUR

PUNJAB

PRESENTED BYRAJESH KUMARPG/WLF/116115

GUIDED BY Er.HARISH KUMAR ARYAASST. PROFESSORMECHANICAL ENGG. DEPTT. SLIET

FIRE AND FIRE HAZARDS

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Introduction Chemistry of fire Fire triangle Types of fire Fire initiator Principle of fire spread Modes of fire spread Fire hazards

CONTENTS

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Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products.

The flame is the visible portion of the fire and consists of glowing hot gases. If hot enough, the gases may become ionized to produce plasma.Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different

INTRODUCTION

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Chemistry of fireFIRE:-Chemical reaction brought about by the combining of fuel and oxygen and the application of sufficient heat to cause ignition.FUEL:-can be either solid, liquid or a gaseous state.HEAT:-Amount of heat required to release a vapour which allow combustion to take place will depend fuel state.e.g.-a block of wood require a higher heat than petrol.COMBUSTION :-A chemical reaction or series of reaction in which heat and light are evolved.

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Fire TriangleThe fire triangle or combustion triangle is a simple model for understanding the ingredients necessary for most fires.The triangle illustrates a fire requires three elements: heat, fuel, and an oxidizing agent (usually oxygen). The fire is prevented or extinguished by removing any one of them. A fire naturally occurs when the elements are combined in the right mixture.

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Types Of Fire…..

Class A fire means a fire involving ordinary combustible materials such as paper, wood, cloth, and some rubber and plastic materials.

Class B fire means a fire involving flammable or combustible liquids, flammable gases, greases and similar materials, and some rubber and plastic materials.

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Class C fire means a fire involving energized electrical equipment where safety to the employee requires the use of electrically nonconductive extinguishing media.

Class D fire means a fire involving combustible metals such as magnesium, titanium, zirconium, sodium, lithium and potassium.

Class F fire means a fire involving cookers and cooking equipment. e.g. Cooking Oils and Fats.

continue…

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Smoker’s material Cigarette lighters Matches Cooking appliances Space heating appliances Central and water heating devices Blow lamps Welding and cutting equipment Electrical appliances Candles etc

Fire Initiators.

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Convection Conduction Radiation

Principles of fire spread…

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Conduction – Spread of heat energy through solids; Convection – Heat transfer through a fluid or gas, involving

expansion and movement; Radiation – Emission of heat energy through electromagnetic

radiation in the infra-red part of the spectrum, which is then absorbed by matter to varying degrees.

MODES OF FIRE SPREAD

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Convection process begins when combustible materials are subject to excessive level of heat and they give off a vapour which in turn ignites.when these vapours are heated they expand and become less dense than air.

convection

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Conduction is the movement of heat through a material.

Ability of conductors to transfer heat varies considerably according to type of material e.g. metal is a much better conductor than brick.

Thermal conductivity is a key element in building design.

Conduction

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Radiation is the transfer of heat energy as electromagnetic waves,which heat solid and liquid encountered in its path.

Fire radiatoin path do not require any contact between bodies and move independently.

If these radiation do not absorbed by any fire resistant material the electromagnetic radiation can radiate through glazing causes fire to spread.

Radiation

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Fire hazards can be categorized into three major groups

Light Hazard Light hazard occupancies are locations where the

total amount of Class A combustible materials, including furnishings, decorations and contents, are of minor quantity. This may include some buildings or rooms occupied as offices, classrooms, assembly halls, etc.

Fire hazards

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Ordinary hazard Occupancies are locations where the total

amount of Class A combustibles and Class B flammables are present in greater amounts than expected under Light (Low) Hazard Occupancies. These occupancies could consist of offices, classrooms, mercantile shops and allied storage, light manufacturing halls, research operations centers, auto showrooms, parking garages,workshops or support service areas of Light (Low) Hazard Occupancies.

Fire hazard continue….

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Extra (High) Hazard Extra hazard occupancies are locations where the

total amount of Class A combustibles and Class B flammables present, in storage, production, use, and/or finished product is over and above those

expected and classed as ordinary (moderate) hazards. These occupancies could consist of woodworking, vehicle repair, aircraft and boat servicing, individual product display showrooms, product convention center displays, storage and manufacturing processes such as painting, dipping, coating, including flammable liquid handling refineries, petrochemical gas treating plants and stations

Fire hazards continue…

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THANKS