What is FIRE ?
Fire is a chemical reaction that includes the rapid oxidation of flammable
The fires usually start on a small scale because most of them originate from
small sparks because of the neglect of fire prevention methods
risk to the lives of individuals for
injuries, suffocation and possibly
destruction of buildings and
structures due to the fire.
risks that Threats to nearby sites ,
There is no requirement for direct
contact between the fire and the
building at risk.
Fire is often associated with
catastrophic environmental damage,
especially in oil installations.
Combustion gases are the most
common causes of death during fire,
and inhalation leads to rapid
suffocation, especially if these gases
are toxic, hot or oxygen free.
The temperature is responsible for the
speed of ignition and the spread of fire,
and its effects on human dryness of the
skin and difficulty breathing, as well as
its destructive effects on the buildings.
The flame is the light accompanying
Smoke is the result of incomplete
ignition of materials, a combination of
small components of non-burnt solids
with resulting gases and condensate
8. Combustion Theory
What burn is the vapors of fuel ( liquid ), and this vapors if combined with the air in
the right ratio of each material and found a source of ignition to burn.
1. Solid ( wood, cloth, paper).
2. Liquid ( petroleum liquids (oil, benzene, kerosene, solar, etc…).
3. Gas ( petroleum gases (natural gas, butane, acetylene, hydrogen).
9. Combustion Theory
All the materials need Oxygen to burn, the ratio of oxygen in the atmosphere is
about 21%, and the ratio of oxygen should not be less than 16% until the fire
10. Combustion Theory
Heat (Sources of Ignition)
Heat is a form of energy that reflects the movement of atoms within an object,
which is invisible but can be felt around us.
• Ignition Point
Is the lowest temperature where the flammable material releases sufficient amount of
vapors or gases to be with the air sufficiently mixed to ignite and continue to ignite even
after removing the source of ignition
• Flash Point
Is the lowest temperature in which the flammable liquid releases a quantity of vapors to
be mixed with air and ignites in a flashy image when exposed to a heat source that ends
when this source is removed.
11. Combustion Theory
Many sources of Ignition:
Electrical power is one of the essentials of any production site and this danger is
present in electrical connections.
2. Do not connect wires properly
3. Damage to electrical wiring or damage to its insulation.
Smoking comes in second place after electricity, and most of these fires occur due to the
fall of cigarettes or Residues of burning cigarettes .
12. Combustion Theory
Many sources of Ignition:
Fires occur due to hot works such as cutting and welding in places containing flammable
materials due to sparks.
It is the heat generated from the surfaces of furnaces, boilers, hot pipes and electric lamps.
Static electricity is produced as a result of friction between two things, one fixed and the other
moving, such as the movement of petroleum materials in pipes, resulting in electrical charges so
it’s necessary to earthing all equipment.
In the event of friction between the parts of the engines, there may be a rise in temperature that
may cause the ignition of flammable materials close to these equipment and machines.
13. Combustion Theory
Chain Chemical Reaction:
The fire continues to ignite as long as the three elements ( material, heat and oxygen)
are present in the correct proportions, the reaction of these elements produce free
radicals Which make the continuation of the fire.
• The ignition / explosion limits are the percentage of the volume of flammable
/explosive gases in the air
Lower Explosive/Flammability Limit(LEL)
• Is the lowest proportion of flammable fumes that combine with the air to form an
explosive / flammable mixture ignites when exposed to ignition source.When there is
a mixture between the air and flammable material below the lower flammability of that
substance, it does not ignite ( poor Mixture ).
■ Upper Explosive/Flammability Limit (UEL)
• Is the highest percentage of flammable fumes that combine with the air to form an
explosive / flammable mixture ignites when exposed to a source of ignition. When
there is a mixture between the air and flammable material that is greater than the
maximum flammability of that substance, it does not ignite ( Rich Mixture ).
The higher the range between LEL & UEL, the greater the
risk of the material.
15. Fire Classes
There are five classes of fires according to the US classification depend on the type
Fire in solid materials such as wood, paper, clothing, rubber and some plastics.
Fires that occur in liquid and gaseous substances such as oil and petroleum gases.
Fire originated in equipment, appliances and electrical equipment.
Fire originated in active minerals such as sodium, potassium and magnesium.
Fires that occur at kitchens
17. Fire Stages
At this stage the combustible materials are combined with oxygen and heat (ignition source)
in a chain chemical reaction as a result of generating free radicals.
The fire begins to appear as smoke, and may develop rapidly at this stage or slowly over a
period of time that may not exceed a few minutes.
At this stage no heat or flame is observed, and the fire can be controlled using handheld fire
Some substances, such as gases, may not pass through this stage and there is a sudden
explosion as soon as there is a source of ignition.
Fire Growth stage
The flame begins to appear as a source of heat. More flammable materials are burned.
Convection and radiation currents start to heat more surfaces to reach the ignition point .
18. Fire Stages
Fully Developed stage
At this stage, the fire is fully developed and reaches its peak, and all the flammable
materials available are burned with extreme temperatures, which can result in serious
damage to the place with the rapid consumption of oxygen.
Decay/ Burn out stage
At this point, the fire reduces or loses flammable or oxygen content. The fire then decreases and the
temperatures begin to drop. The fire begins to eat itself until
it is extinguished and turned into ash.
The heat is transferred by direct contact or through the
conductor, as with hot hand contact with hot water. The
heat passes from the container to the hand through the
Heat travels in liquids and gases due to variations in
density depending on temperature changes. Moved by
convection currents and moving from bottom to top
Note : Convection currents happen only in liquids and
gases, not in solid objects.
Heat radiation from hot objects to other less heat
through the air moves in straight lines that propagate in
all directions in the form of heat waves .
20. To extinguish any type of fire, one
of the four factors that cause fire
( fuel, oxygen, heat and Chemical
chain reaction ) must be
21. Fire Fighting Mechanism
Starving the fire is by depriving it of flammable materials that are fuel for the fire by :
1. Transportation of goods and materials available in the fire place away from the effect of heat
2. Close gas line valves
The fire is smothering by prevent air oxygen from reaching it .
1. Close outlets and ventilation openings in the fire place
2. Cover flammable materials by chemical foams
3. Replace oxygen with water vapor, carbon dioxide, dry chemical powder, or halogen vapors
4. Fire can be extinguished using explosives such as dynamite. This was the way to extinguish
the oil well fires in the past .
22. Combustion Theory
Its purpose is to reduce the temperature of flammable materials by using water .
Chain Reaction Stopping
For some fire extinguishers estimated to stop the chemical reaction of the fire
sequence, these substances include dry powder and halons. Powder particles absorb