THEORY OF FIRE-II

Fuel, Heat, and Oxygen

The three ingredients that cause fires are heat, oxygen, and combustible material. When all three components are present, combustion takes place.
• Combustible material (Fuel).
• Ignition Source (Heat).
• Oxygen.

Fuel
Fuel or combustible material, which acts as a fuel source for fire, i.e., paper, wood, clothes, any solid combustible material, fiber, textile fiber, gasoline, kerosene, grease, tar, fingernail polish, magnesium, sodium, potassium, titanium or aluminum, cooking oil, vegetable oil, etc.

Heat
Ignition source or heat source means flame, spark which ignites sufficient heat, or flame for combustion or fire.

Oxygen
Oxygen which is the most common factor and is available everywhere in the form of air.

An explosion is defined as the process in which combustion occurs and spreads rapidly so as to create a high pressure. In this case, the fire expands from a source of ignition and develops high pressure when restricted in an area.

Explosions have lower and upper limits (of dust concentration). A lower limit of explosion indicates that the concentration of dust particles is below the lower limit of explosion. Below this level, the dust concentration will not explode even on ignition. This happens because the heat produced under such circumstances is not sufficient to affect other dust particles. Alternatively, there could be a dust concentration of explosive levels but there may not be enough oxygen to start the fire. To counter the hazards of fire and explosions, it is necessary to know the characteristics of the dust. For example, fine aluminum dust explodes at very low limits of explosion whereas coarse aluminum dust does not catch fire even under the influence of another source of heat.

Fire Hazards

Fire hazard is a situation in which there is a risk of harm to people or property due to fire. Fire hazards can take the form of various ways that fires can easily start, such as a blocked cooling vent or overloaded electrical system, ways fires can spread rapidly, such as an insufficiently protected fuel store or areas with high oxygen concentrations, or things which, in a fire, pose a hazard to people, such as materials that produce toxic fumes when heated or blocked fire exits.

The Indian Fire Protection Association reports 85% of fire deaths occur in the home, making fire prevention a top priority in every home.


Electrical hazards
• Damaged wiring.
• Damaged plugs.
• Damp or wet wires.
• Overloaded motors.
• Broken switches, outlets, or sockets.
• Problems with lighting fixtures.
• Faulty heating elements.
• Overloaded circuits.
• Liquids near computers.
• Computers without surge protectors.


Housekeeping hazards
• Piles of scrap, waste materials, and trash.
• Sawdust, metal or plastic powder that can form an explosive mixture with air.
• Obstructed aisles.
• Blocked emergency exits.
• Material covering up fire extinguishers, exit signs, and alarms.
• Blocked sprinkler heads.


Friction hazards
• Hot bearings.
• Misaligned or broken machine parts.
• Choking or jamming materials.
• Poor adjustment of moving parts.
• Inadequate lubrication.


Process or operation-related hazards
• Cutting and welding operations, which use open flames and produce sparks.
• Molten metal, which can ignite combustibles or fall into cracks and start a fire that might not erupt until after the work is done.
• Processes that heat materials to high temperatures.
• Drying operations where materials in dryers can overheat.
• Grinding operations that produce sparks and dust.
• Processes in which flammable vapors are released.


Storage hazards
• Material stacked too high blocking sprinkler heads (need 18-inches clearance from head).
• Flammable or combustible material stored too close to heat sources.
• Flammable materials not stored in special containers and cabinets. Inadequate ventilation in storage areas.
• Material that might react with one another stored together.
• Material stored in damaged containers
• Material stored in unlabeled containers
• Containers not tightly sealed


Smoking hazards
• Ignoring "No Smoking" signs.
• Smoking around flammable or combustible materials.
• Throwing matches and cigarettes or cigars on tables or workbenches.
• Tossing butts on the floor or grass without properly extinguishing them in an ashtray or ash can.
• Tossing lighted butts or matches out windows or doors.
• Smoking in bed.
• Leaving a cigarette/cigar unattended.
• Smoking in areas where there is an accumulation of sawdust, plastic or metal powders that may become explosive.

Description of Each Class of Fire and Applicable Extinguishers

Class A Fire
Class A fire contains carbonaceous material (carbon contaminated material), like wood, fibrous materials, paper, furnishing materials etc.
So the suitable extinguishing agent for Class A fire is water and only water, so the person on the spot has to follow the following procedure: -

First:
If a person encounters Class A fire the first thing he is should do is anyhow inform his office mates, friends or any person who is available in that location by any medium.

Second:
Inform the nearest fire brigade or fire fighting team, meanwhile the person in charge can make a team and try to cut off the fuel supply (burning material) or provide a sufficient amount of water against the fire as soon as, and in sufficient amount.


Class B Fire
Class B fire has different categories: -

For volatile petroleum fire:
Volatile petroleum means whose flash point (flash point 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.) is below 60? C, like petrol, oil, solvents, paint and waxes. So suitable extinguishing agent for such kind of fire is foam extinguisher, CO2 or dry powder extinguishers and hence the person on the spot has to follow the following procedure: -

First:
If a person encounters class B fire the first thing he should do is anyhow inform his mates, friends or the any person who is available in that location by any medium.

Second:
Inform the nearest fire brigade or fire fighting team, meanwhile the person in charge can make a team and try to make a boundary for burning liquid and if there is CO2 or Dry Powder or foam extinguishers then he can utilize extinguishers in a proper manner against the fire.


For Nonvolatile petroleum Fires:
Nonvolatile petroleum means whose flash point is below 60? C and above, like alcohol.

Suitable extinguishing agents for such kind of fire are Foam extinguisher, CO2 or dry powder extinguishers and the person on the spot has to follow the procedure similar to the case of volatile fire.


For Chemicals or Paint Fires:
This kind of fires contains very light flash point.
Suitable extinguishing agents for such kind of fire are foam extinguisher, CO2 or dry powder extinguishers and the person on the spot has to follow the above described procedure.


Class C Fires:
A class C fire is one of the most common fires in industries, offices, and households, etc, .i.e., electrical fires. This kind of fire occurs due to short circuit, circuits switch board, radio or electrical equipment or due to overloading, spark etc. It involves energized electrical equipment, where a nonconducting gaseous (clean agent or smothering) agent is needed. Once the electrical power is taken away, the fire goes back to class A or B fire. Electrical fires are not considered to constitute a fire class on their own, as electricity is a source of ignition that will feed the fire until removed, when the electrical supply has been isolated the fire can be treated generally. However, we should always isolate the electrical supply before fighting the fire. If this is not possible then a nonelectrical conducting extinguishing agent is to be used regardless of the power status on all occasions.

Some electrical equipment can store, in capacitors, lethal voltage, even if their power supply has been isolated, we have to always use extinguishers containing nonelectrical equipment such as CO2, dry powder firefighting extinguishers.


Class D Fire:
Class D fire involves combustible metals such as magnesium, sodium, potassium, titanium, and aluminum. In such cases water is generally ineffective or even dangerous.

This type of fire occurs in chemical industries, laboratory etc. Special dry powder is produced for class D fire, particularly those involving alkali metal such as sodium and potassium. These dry powders extinguish metal fires by flushing the powder to form a crust, which excludes oxygen from surface of the molten. A specific agent is added to prevent from sinking into the surface of the molten material.


Class E Fire:
Class E fire involves in commercial cooking appliances with vegetable oils, animal oils, or fats at high temperatures. This kind of fire occurs in large catering kitchens, restaurants and takeaway establishments, etc. This fire is difficult to extinguish because of high auto ignition temperature.
Conventional extinguishers are not effective for cooking oil fires, as they do not cool sufficiently or may even cause flash back, thereby putting the operator at risk. This fire needs extinguishers containing a specially formulated wet chemical, which when applied to the burning liquid cools and emulsifies the oil, extinguishing the flame, sealing the surface and preventing re-ignition.

THEORY OF FIRES- I

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.

Fire Square:

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:

INTRODUCTION TO FIRE

Nowadays Fire is a common and Frequent Hazard in Daily Life, because a fire which starts unseen as small flickers of flame may grow at such a pace that it can quickly get out of hand.
This is due to carelessness, Ignorance, Lack of Knowledge, Stupidity, Unavailability of Proper fire fighting extinguishers.

This course is prepared in such a manner a Person can easily understand:
What is Fire?, How to detect a fire?, What is the exact procedure to fight against of fire?, What is correct procedure to use fire extinguishers?, What is fire prevention? and more.

Introduction:

Fire is the most common hazard which we face in industries, homes, and office premises. While complete and proper procedure of training and awareness can minimize the chances of an accidental fire to almost safe considerations, we must still be very much prepared to deal with a fire emergency in case it occurs. This document aims to teaches the basics about fire fighting techniques and equipments -- proper types, how to use them, when and where to use them and when not to use them, as along with the proper procedures to follow if a fire occurs.


HISTORY OF FIRE FIGHTING:

The American Fire Control Board fire fighting team is exists from the first century B.C. Ancient Rome too had a fire department with close to 7000 paid fire fighters. The fire brigades responded and fought not only fires, but also patrolled the cities with the power to impose punishment upon those violating fire-prevention codes. The first fire pump was invented in 200 B.C. by inventor Ctesibius of Alexandria.

In 1648 Governor Peter Stuyvesant of New Amsterdam (New York City) was appointed as a fire inspector with the power to impose fines for fire code of conduct. In 1672 leather hose and couplings for joining lengths of pipe together were produced, leather hose had to be sewn like a fine boot.

Boston (MA) imported the first fire engine in America in 1679. Inventor Thomas Lote of New York City built the first fire engine made in America in 1743. A steam fire engine was built in London in 1829.

Fabric and rubber-treated hose did not come into general use until 1870. But the fire companies of the day were very slow to accept these rapid advances in the field.

Modern equipments are usually diesel powered and many variations of the basic fire engine have enabled firefighters to respond to many types of emergency situation, prevalent in these industrial times.

Definition of Fire:

Fire can be defined as an external sign of chemical reaction, usually with the combination of hydrocarbons with oxygen, resulting in the release of energy. To start the action it is necessary to apply a flame or a spark, having a certain amount of energy value, to a material that has been raised to a certain threshold temperature sufficient to release inflammable gases, which conduct the continuation of fire; or else to raise the substance to its auto ignition temperature or the temperature where spontaneous combustion of the liberated gases occurs.

Once the fire has started, the heat energy released is available to raise the temperature of a greater amount of the substance to that of combustion, so the amount of gases liberated from the burning material increase and fire spreads more rapidly. If the temperature is close to self-ignition, less amount of energy is required to cause the combustion, and fire will appear to break out at points at some distance from the main fire.

However the air/fuel ratio limits the rate at which different substances will burn and limitation of air will cause long tongues of flame to reach out searching for the air required, once given a good start and plenty of combustible material. Incomplete combustion can result in the formation of gas pockets, which may explode in case air suddenly becomes available, whilst heated hydrocarbon, if lacking air, will decompose and form sooty particles characteristic of thick, black smoke. It can be seen that there are three elements required for the propagation of fire.

There are three things that result in fire or combustion:
1. Combustible material
2. Oxygen the fuel sources, and
3. Ignition Source, the heat source.

Priniciple of Fire Fighting:

The fire fighting principle rests on the basis of the removal of one of the sides of the fire triangle, fire tetrahedron or fire square.

For example: -
Fire starts when paper or wood comes in contact of flame or heat in presence of oxygen, a fuel source.

We have to take the following steps to control this fire:
1. Remove the source of fuel by marking a boundary or removing the fuel itself.
2. Remove oxygen by obstructing the air or oxygen supply.
3. Remove heat or flame by supplying water or fire extinguisher against fire.

Fire stands for:
FIND the fire, the location, and its size.

INFORM person in charge.
• If there is a general alarm system then raise the alarm.
• Make a call to the nearest fire control party.
• Activate emergency firefighting equipment.

RESTRICT the fire.
• De-energize electrical systems in the affected space.
• Set fire boundaries to confine the fire.
• Shut-off ventilation.
• Prior to activating fixed extinguishing system, ensure evacuation from the area.

EXTINGUISH the fire.
• Determine the class of fire (explained later), appropriate equipment and extinguishing agent to be used and plan the method of extinguishing.

If unable to control fire, prepare to abandon the location.

Fire Prevention and Fire Safety:

Fire Prevention Tips
Fires and burns are the third leading cause of unintentional home injury and related deaths. Fire safety and survival begins with everyone being prepared. Following the below mentioned safety measures reduces the chance of fire:


Fire Safety At Home
Safe fire practice and awareness at home are a part of a fire protection plan and it is also critical to be prepared to react quickly in case a fire occurs at home.


Safe Fire Fighting and Practice
• An hour of planning may save years of life. Practice fire.

• Make sure the home/office has at least one smoke alarm on every floor. They will give time to escape in case of fire.

• Make sure everyone knows the ways out of each room.

• A window can be used as an exit. Make sure windows and screens can be easily removed from inside, in case you need to escape a fire.

• Folding escape ladders may be needed in higher buildings. In an emergency, take caution when escaping down a stairway. It might become a chimney for smoke, hot gas, and fire.

• Don’t jump in panic from a high window. Stay in the room with the door closed and the window slightly open. Hang a sheet out the window to show rescuers your location. Sit on the floor to avoid breathing in smoke.

• A hot door is a warning. Feel the door before opening it and look to keep the room, kitchen, and basement doors closed at night to act as a barrier, in case of fire.

• Never go back into a burning building for any reason!


FIRE FIGHTING STRATEGY:

Inspect and review:
1. The scene of fire as rapidly as possible.

2. Assess the nature of fire by determining its intensity and extent.

3. The type and abundance of fuel.

4. The danger of entering the fire area.

5. Most effective techniques for extinguishing the fire.

6. Location and rescuing endangered person.

7. Containing the fire and protecting adjacent areas.

8. Ventilation of the fire area to allow for the escape of heat and toxic gases.

9. Finally extinguishing the fire.

In case your clothing is on fire (and the floor is not), drop and roll on the ground to extinguish the flames. If you are within a few feet of a safety shower or a fire blanket, use these instead, but do not try to run if you are on fire. If one of your coworkers catches fire and runs down the hallway in panic, tackle them and extinguish the fire in their clothing.

Hi friends..
well this blog is for those who are intersted in fighting fire...
i will be posting many topics on how to fight with fire..basically fire fighting...keep in touch