Unit 1.

THEORIES OF
COMBUSTION
Introduction:

IN order to fire an engine properly the fireman need not necessarily know anything
about the theory of combustion. He may have learned to apply the principles without knowing
the reason for so doing. In fact, many first-rate firemen do not understand anything about
these principles. There are, however, certain fundamental facts that should be borne in mind
when endeavouring to explain to firemen the necessity of doing certain things to get proper
results.

Combustion is a chemical combination or reacting that produces heat, and heat is a

form of energy due to molecular vibration or motion.

To understand this, we must try and get a mental vision of the processes of chemical
combination and we must be able to picture a structure of matter that is capable of molecular
vibration. We will endeavour to do this as simply as possible.

Let us begin!

Learning Outcomes:

1. Describe accurately the products of combustion.

2. Explain comprehensively the fire suppression, Control, Extinguishment & Extinguishing
Agents.
3. Discuss and demonstrated how to use the fire extinguishers.
4. Recognize the difference between flammable materials and hazardous materials

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

 Before we discuss about the lesson 1 of this module. We will discuss first the
introduction of the subject and the early means of producing fire and theories of
combustion.

Introduction:

IN order to fire an engine properly the fireman need not necessarily know anything
about the theory of combustion. He may have learned to apply the principles without knowing
the reason for so doing. In fact, many first-rate firemen do not understand anything about
these principles. There are, however, certain fundamental facts that should be borne in mind
when endeavouring to explain to firemen the necessity of doing certain things to get proper
results.

Combustion is a chemical combination or reacting that produces heat, and heat is a

form of energy due to molecular vibration or motion.

To understand this, we must try and get a mental vision of the processes of chemical
combination and we must be able to picture a structure of matter that is capable of molecular
vibration. We will endeavour to do this as simply as possible.

We can only guess that pre historic people may have gained knowledge about fire from
observing things in nature, so the origin of fire before dawn civilization maybe traces to an
erupting volcanoes or forest fires and lightning. No one really knows where on earth surface or
what stage of early history man learned how to start a fire and how to make use of it. Yet
today man has had fire as;
1.source of warm and light.
2. protection against enemies
3. cause chemical changes to foodstuffs to be digested to suits man’s body structure.
4. provides processes for modifying chemicals into medicines.
5. provide heat to convert wood, metals and bones into domestic tools or instruments
for aggressions.

While the application of fire has served man’s needs. Its careless and wanton use exacts
an enormous and careful tool from society in life and property. Hence man’s understanding of
fire would enable him to develop the technology of prevention and control to a considerable
advance state.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

EARLY MEANS OF PRODUCING FIRE

1. Bow Drill

2. Weighted Bow Drill

3. Hand Drill

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 4. Striking Flint

5. Magnifying Glass

Theories of Combustion

Fire Triangle Theory – The graphical representation of the three elements of fire
namely: Oxygen, Heat and Fuel.

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 Using the same theory, there are three ways to extinguish fire:
1. Remove the fuel
2. Cut – off the oxygen
3. Reduce the temperature (cooling)

Elements of Fire
1. Heat – a form of energy generated by the transmission of some other form of
energy, as in combustion or burning.

Heat Sources:
1. Open flame
2. Electrical circuit
3. Sparks
4. Hot surfaces
5. Friction
6. All sources of ignition

2. Oxygen – a colorless, odorless gas and one of the compositions of air which is
approximately 21% by volume.

Oxygen sources: Oxygen Requirements:

1. 21% of normal oxygen 1. 12% - no fire

2. 78% of nitrogen 2. 14% - flash point
3. 1% of other gases 3. 21% - fire point

3. Fuel – any substance which reacts chemically with oxygen and produces flames.

Fuel Sources:
1. Solid – molecules are closely packed together
2. Liquid – molecules are loosely packed
3. Gas – molecules are free to moved

Common types of solids:

a. Bulky b. Finely divided c. Dust
1. Coal 1. Plastic 1. Saw dust
2. Wood 2. Paper 2. Sugar
3. Wax 3. Cork 3. Grain
4. Grease 4. Leather 4. Others

Common types of Gases:

1. Natural Gases 4. Hydrogen
2. Propane 5. Acetylene
3. Butane 6. Carbon monoxide and others
4. Hydrogen

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Common types of liquid:
1. Gasoline 6. Paint
2. Kerosene 7. Varnish
3. Turpentine 8. Lacquer
4. Alcohol 9. Olive oil
5. Cod liver oil

Fire Tetrahedron
For combustion to occur, four elements are necessary:
1. Oxygen (oxidizing agent)
2. Fuel
3. Heat
4. Self- sustaining chemical reaction

Combustion Reaction/Process:
 Causes pyrolysis or vaporization of solid and liquid fuels and the production of ignitable
vapors or gases;
 Provides the energy necessary for ignition;
 Causes the continuous production and ignition of fuel vapors or gases to continue the
combustion reaction.

Types of Energy: (Common Sources of Heat)

1. Chemical energy – it is the most common source of heat in combustion reactions.

2. Electrical energy – can generate temperatures high enough to ignite any combustible
materials near the heated area.
Factors involving Electrical Heating:
 Current flow through a resistance
 Overcurrent or overload
 Arcing

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 Example of arcing
 Sparking
 Static
 Lightning
3. Nuclear energy – is generated when atoms either spilt apart or combine.
Examples:
a. Fission heats water to drive steam turbines and produce electricity
b. The solar energy is a product of a fusion reaction (a form of nuclear energy).
4. Mechanical energy – an energy generated by friction and compression.
 Heat of friction – is the movement of two surfaces against each other. This movement
produced sparks being generated.

 Heat of compression – heat is generated when a gas is compressed in a container or

cylinder.

Combustion
Fire and combustion are terms that are often used interchangeably. Technically
speaking, fire is a form of combustion. Fire is a rapid, self-sustaining oxidation process
accompanied by the release of heat and light of different intensities.

Acquire New Knowledge

Here is your first lesson – Read and learn

Lesson 1. Products of Combustion

Four categories of products of combustion:

1. Fire gases – are those that remain when other products of combustion cool to
normal temperature.

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 Type of poisonous gases:
1. Hydrogen sulphide (H2S) – a fire gas formed during fires involving organic
material containing sulfur. It is colorless, highly toxic gas with the strong odor of
rotten eggs. Exposure for even a short time is dangerous.
2. Hydrogen Cyanide (HCN) – a toxic fire gas found in oxygen-starve fires involving
nitrogen-containing materials such as wool, silk, urethane, polymides and
acrylics. This gas is also used as a fumigant which can pose serious danger to
firefighters working in recently fumigated building. Hydrogen cyanide smells like
bitter almonds which may not be easily detected.
3. Hydrogen Chloride (HCL) – a gas which can be fatal after only a few breaths is
produced in fires involving chloride-containing plastic.
2. Flames Defined – it is a luminous body of a burning gas which gets hotter and less
luminous when mixed with more oxygen.
Types of flames:
A. According to color and completeness of combustions.
1. Luminous flame – a reddish-orange in color; it deposits soot because it is
a product of incomplete combustion; it has a lower temperature.
2. Non-luminous flame – bluish in color; it does not deposit soot because it
is a product of complete combustion; it has a higher temperature than
luminous flame.

B. According to burning fuel and air mixture:

1. Premixed flame – example of a Bunsen burner.
2. Diffusion flame – example of flame of the oxyacetylene torch (diffused –
dispersed; widely spread).

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 C. Based on smoothness:
1. Laminar flame – (smooth flame) flame is laminar when a particle follows
a smooth path through a gaseous flame.
2. Turbulent flame – (rough flame) those having unsteady, irregular swirls
and eddies.

Nature of fire
Pyrolysis – it refers to the chemical process whereby fire consumes the most solid part
of the fuel. It is the thermal decomposition of a solid fuel through the action of heat.

The process of pyrolysis involves the following:

1. The fuel is heated until its temperature reaches its fire point;
2. Decomposition takes place – moisture in the fuel is converted to vapor.
3. Decomposition produces combustible vapors that rise to the surface of the fuel.
These combustible vapors are technically termed as free radicals;
4. 4. Free – radicals undergo combustion if proper amount of oxygen is present.

3. Heat defined – a form of energy measured in degree of temperature, it is

the product of combustion that spread the fire. It causes burns and other
injuries such as dehydration, heat exhaustion, and respiratory tract
injuries.
4. Smoke defined – it is the visible product of incomplete combustion,
usually a mixture of oxygen, nitrogen, carbon dioxide, carbon monoxide,
finely divides particle of soot and carbon, and miscellaneous assortment
of product released from the burning material.
Properties of fire:
A. Physical properties:
1. Specific gravity – the ratio of the weight of a solid or substance to the weight of an
equal volume of water.
2. Vapor density – the weight of a volume of pure gas compared to the weight of a
volume of dry air at the same temperature nad pressure.
3. Vapor pressure – the force exerted by the molecules on the surface of the liquid at
equilibrium.
4. Temperature – the measure of thermal degree of the agitation of molecules of a
given substance; the measure of the molecular activity within a substance.
5. Boiling point – the constant temperature at which the vapor pressure of the liquid is
equal to the atmospheric pressure.
6. Ignition temperature or kindling temperature – the minimum temperature to the
which the substance in the air must be heated in order to initiate or cause self-
contained combustion without the addition of heat from outside sources.

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 7. Fire point – the temperature at which the material will give off ample vapors to keep
burning.
8. Flashpoint – the temperature at which a material is not hot enough to keep burning,
but still gives off enough vapors to cause a flame to flash across the surface.
B. Chemical properties :
1. Endothermic reaction – are changes whereby energy is absorbed or is added before
the reaction takes place.
2. Exothermic reaction – reactions changes that release or give off energy thus they
produce substances with less energy than the reactants.
3. Oxidation – a chemical change in which combustible material and an oxidizing agent
react.
4. Combustion/flame – the manifestation of fire when the fire is in its gas-phased
combustion. A matter that is produced by fire.

The following chart lists the Vapor Density (air = 1) for some of the more common flammable
materials:
Materials Vapor Density
Acetylene 0.9
Butane 2.0
Gasoline 3-4
Hydrogen 0.1
JP-4 3.0
Kerosene 3.0
Propane 1.6

Phases of Burning/The Three Stages of Fire:

Factors to be considered in determining phases of burning:

1. The amount of time the fire has burned;
2. The ventilation characteristics of the confining structure;
3. The amount and type of combustibles present

Fires generally have three (3) progressive stages based on the above factors:

1. Incipient/Beginning phase – it Is the initial stage of fire.

Characteristics:
a. Normal room temperature
b. Oxygen plentiful

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 c. Thermal updraft rise accumulates at higher point
d. Flame temperature of 1000 degrees F
e. Producing pyrolysis products: (CO2, CO, SO2, water vapor, & other
gases)

2. Free-Burning Phase – the second phase of burning in which materials or structures

are burning in the presence of adequate oxygen.
Characteristics:
a. Fire has involved more fuel
b. Oxygen supply is depleted
c. Heat accumulates at upper area
d. Temperature exceeds 1,300 degrees F (705 degrees C)
e. Area is fully involved

3. Smoldering Phase – the final phase of burning wherein flame ceases but dense
smoke and heat completely fill the confined room
Characteristics:
a. Flames may die and leave only glowing embers or super-heated fuel
under pressure with little oxygen
b. Intense heat will vaporize lighter fuel components, such as hydrogen
and methane, increasing the hazard
c. Temperature throughout the building is very high and normal
breathing is not possible
d. Oxygen deficiency may cause backdraft

Backdraft – any action taken during fire fighting operations that allows air mix with these hot
gases can result in an explosive ignition

Conditions that indicate the danger for backdraft

a. Pressurized smoke exiting small openings
b. Black smoke becoming dense gray yellow
c. Confinement and excessive heat
d. Little or no visible flame
e. Smoke leaving the building in puffs or at intervals
f. Smoke stained windows
Flashovers – occurs when a room or other area is heated enough that flames sweep over the
entire surface

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Classification of Fire

A. Based on Cause:
1. Natural fire
2. Accidental fire
3. Intentional fire
B. Based on Burning Fuel
Four Classes of Fire
1. Class A – Materials involving vegetable fibers, wood, paper straw, grain, and
grass; combustible minerals such as coal and coke.

2. Class B – Materials including petroleum products

3. Class C – involves electrical motors, electrical appliances and apparatus

4. Class D – These are materials involving combustible metals, alloys, or metal

compounds either in a solid, semi solid or liquid state

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 5. Class K – materials involved in the kitchen fires

Spontaneous Heating

Spontaneous heating and spontaneous ignition start as a result of a chemical reaction

within the material – a reaction independent of any outside source of heat.

Propagation of fire

Propagation of fire simply means the fire spread of fire. As a substance burns,
propagation will be increased by the transmission of heat by nearby materials.

Types of Heat Transmission:

1. Conduction – it is the transmission of heat through an object/medium or conductor,

such as pipe, metal, hot air duct, wire even wall
2. Radiation – the transmission through the discharge and spread of heat from a
heated or burning source
3. Convection – it is the transmission of heat by the moving currents of liquid or gas
4. Flame Contact – Heat may be conducted from one body to another by direct contact

Intensity of fire
Intensity of fire means simply “how hot the fire is burning”. Some types of fuels
naturally burn hotter (more intensely) that others. For example, a gasoline fire burns hotter
than a wood fire, while an acetylene flames is hotter than a gasoline flame.

Factors to determine the intensity of fire:

1. Type of fuel
2. Percentage of oxygen present

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Explosives Limits
The term “explosives limits” means the amount (expressed in percent) of fuel vapor that
can be mixed with air to form and explosive or flammable mixture.

Magnitude of Fire
The Magnitude of fire means the size of a fire, and it is governed by the surface area of
fuel exposed to the air.

Flashpoint
The temperature at which the material is not hot enough to keep burning, but still gives
off vapors to cause a flame to “flash” across the surface.

Firepoint
The temperature at which the material will give off ample vapors to keep burning.

Ignition Temperature – the degree of heat necessary to ignite flammable vapors

The following are explosive limits (percent by volume in air) for some of the more common
fuels:

FUEL LOWER LIMIT UPPER LIMIT

Acetylene 2.5% 80.0%
Butane 1.9% 8.5%
Gasoline 1.4% to 1.5% 7.4% to 7.6%
Hydrogen 4.0% 75.0%
JP-4 1.3% 6.5%
Propane 2.2% 9.5%

The following are the Flashpoint and Ignition Temperatures for some of the more common fuels

FUEL FLASHPOINT IGNITION TEMPERATURE

Gasoline 60 to 80 Octane-45 degrees 536-700 degrees F
F
JP-4 30 degrees F 468 degrees F
Kerosene 100 degrees F 444 degrees F
Cleaning Solvents 100-110 degrees F 450 degrees F
Paper Approx. 250-300 F Approx. 475 F
Wood Approx. 350-400 F Approx. 750 F

Oxidation
In nearly all fires, oxidation takes place by using the oxygen that is present in the
atmosphere.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

 Acquire New Knowledge

Here is your second lesson – Read and learn

Lesson 2. Fire Suppression, Control, Extinguishment & Extinguishing Agents

Four Methods of Fire Extinguishment and how it Works

1. Cooling – the cooling process uses an extinguishing agent whose primary characteristic
is heat absorption
2. Smothering – excludes the oxygen from the fuel so that the gases or vapors of the fuel
cannot ignite or continue the combustion
3. Separation – the removal of fuel, as in the example of turning off a valve in a gas line
prevents the fuel and oxygen from coming together
4. Chemical Chain Reaction – known as the inhibition or the interruption of chemical
reaction.

Extinguishing Agents

The following are the most common extinguishing agents, the class of fire they used, and the
extinguishing methods used:

1. Water – used only on Class A fires. Water is the most effective in cooling the burning
material below its ignition temperature. It is the most commonly used agent in fire
fighting.

Usage – water is generally used on Class A fires. Water may also be used to extinguish Class C
and Class D fires in some cases.

2. Carbon Dioxide (CO2)

Usage: due to its non-conductivity, CO2 is very effective for use on Class C fires. It is also used
on Class B fires.

Effects: it covers or blankets the burning materials and reduces the oxygen content to below
levels needed for combustion.

3. Dry Chemical – the dry chemical extinguishing agents in use today are mixtures of
powders and various additives that improve the storage, flow, and water repellence
of the powders.
Usage:
There are two basic types of Dry Chemical:
b. Ordinary and Regular Dry Chemical – generally refer to those powders that are
intended for use on Class B or Class C fires.
c. Multi-purpose Dry Chemical – refers to powders listed for use on Class A, B, C
fires.

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 4. Dry Powder – is a generally term for agents used to extinguish combustible metal
fires.

Usage: Dry powder is used primarily on Class D fires and should not be used on other types of
fire, due to its limited value on these fires.
5. AFFF – Aqueous Film Forming Foam has replaced protein foam for all around fire
fighting purposes.
Effects:
Quick “knock-down” and “heat reduction”.

Usage: it is used primarily to extinguish on Class B fires. It may be used on Class A fires but
may be less effective than plain water.

6. Halons (Halogenated Agents) – these agents have been used for over 50 years.

Effects: halogenated agents work as chemically to extinguish fire. They stop combustion
process by breaking the fire chain reaction and prevent further fire propagation.

Usage: Halogenated agents are very effective on Class B and Class C fires and have some
effects or success on Class A fires.

Acquire New Knowledge

Here is your third lesson – Read and learn

Lesson 3. Fire Extinguishers

Fire Extinguishers – it is a mechanical device usually made of metal, containing

chemicals, fluids, or gases for stopping fires, the means for application of its contents for the
purpose of putting out fire (particularly small fire) before it propagates, and is capable of being
readily moved from place to place.
It is a portable device used to put out fires of limited size.

Portable fire extinguishers offer the greatest potentials for immediately controlling workplace
fire.

Classification and ratings

Different type of fire extinguishers is designed to extinguish fire involving different types
of fuels. Extinguishers are classified as Class A, B, C, and D or combination depending on the
fire against their agents is effective.

Class A type of extinguisher is used on fires involving ordinary combustible materials

such as wood, clothes, and paper.
Class B extinguisher is used on fires involving liquids, grease and gases.
Class C extinguishers are used on fires involving energized electrical equipment.

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 Class D extinguisher is used on fires involving combustible metals such as titanium,
magnesium, zirconium, Sodium and potassium.

Information Indicated on the Extinguisher

1. Date of original filling
2. Chemical contents
3. Type of extinguisher
4. Operating instruction and safety procedure in usage
5. Name and address of the manufacturer
6. Name and address of the dealer

Fire Extinguisher Ratings

Class A and B extinguishers carry a numerical rating indicate how large a fire
experienced person can put out with the use of and extinguisher.

Class A Ratings
An extinguisher for Class A fires could have any one of the following ratings. The
numerical rating for this class of fire extinguisher refers to the amount of water the fire
extinguisher holds and the amount of fire it will extinguish.
1-A 6-A
2-A 10-A
3-A 20-A
4-A 30-A
5-A 40-A

An extinguisher for Class B fires could have any one of the following ratings. The
numerical rating for this type of extinguisher states the approximate number of square feet of
flammable liquid fire that a non-expert individual can expect to extinguish.
1-B 20-B
2-B 30-B
5-B 40-B
10-B and up to 640-B

Parts of Pressurized Water Extinguishers

1. Shell
2. Discharge valve
3. Pick-up tube
4. Hose
5. Nozzle
6. Pressure gauge

Parts of Dry Chemical Fire Extinguishers

1. Carrying handle
2. Nozzle
3. Cap
4. Shell

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 5. Cartridge puncturing lever
6. Hose
7. CO2 Cartridge

1. Dry Chemicals: Dry Chemical extinguishers are usually rated for multi-purpose use.
It contains an extinguishing agent and uses a compressed, non-flammable gas as a
propellant.

Types:

a. Regular or ordinary used only on Class B or Class C fires

b. Multi-purpose dry chemicals used on Class A, Class B, and Class C.

2. Carbon Dioxide – used on Class B and Class c fires. CO2 extinguishes fire by
smothering; reducing the oxygen level below that supports combustion.
3. Foam – used only on Class A and Class B fires. Foams remove fuel by forming a
layer over a burning liquid and preventing flammable vapors from escaping.
4. Halons – used on Class B and Class C fires. These liquefied gases are most effective
in interrupting the chain reaction, but they also have slight smothering and cooling
effects. These types of extinguishers are often used to protect valuable electrical
equipment since they leave no residue to clean up unlike CO2.
5. Metal/Sand Extinguishers – These types of extinguishers are primarily used for
flammable metals (Class D) and have the characteristics of a blanketing effect
(smothering) on the fire.

The following are the different types of Metal/Sand Extinguishing Agents:

 Sodium chloride – used for metal fires involving magnesium, sodium, potassium,
sodium/potassium alloys, uranium and powdered aluminium. Heat from the fire causes
the agent to harden and form a crust that excludes the air and dissipates heat.
 Powdered Copper Metal (Cu metal) – used for fires involving lithium and lithium alloys.
It is the only known lithium fire fighting agent which will cling to a vertical surface thus
making it the preferred agent used on three dimensional and flowing fires.
 Graphite – based powders – these are designed for use on lithium fires. It is also
effective on fires involving high melting metals such as zirconium and titanium.
 Specially – designed sodium bicarbonate – based dry agents – used to suppress fires
with most metal alkyls, pyrophoric liquids which ignite on contact with air, such as
triethylaluminum.
 Sodium carbonate-based dry powders – can be used with most Class D fires involving
sodium, potassium or sodium/potassium alloys. This agent is recommended where
stress corrosion of stainless steel must be kept to an absolute minimum.

6. Halotron I extinguishers – these extinguishers are intended for use on class B and
Class C fires. Halotron I is ozone – friendly replacement for halon 1211. These
properties make it ideal for computer rooms, clean rooms, telecommunications
equipment, and electronics, and it is expensive.
7. FE – 36 – (Hydrofluorocarbon – 236a or known as HFC – 236afa) – it is a DuPont-
Manufactured Halon 1211 replacement. This agent is less toxic than both Halon

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 1211 and Halotron I. it has a zero ozone-depleting effect or potential. FE-36 is no
scheduled for phase out whereas Halotron I production is slated to cease in 2015.
8. Water Mist Extinguishers – ideal used for Class A fires where a potential Class C
hazard exist. Unlike an ordinary water extinguisher, the misting nozzle provides
safety from electric shock and reduces scattering of burning materials.

Steps in using portable fire extinguishers:

1. Pull the pin at the top of the extinguisher.
2. Point the nozzle or outlet toward the base of the fire.
3. Press the handle above the carrying handle to discharge the agent.
4. Sweep the nozzle in side to side motion before the flames to spread the
extinguishing agents

Semi – Portable/Wheeled Extinguisher – these types of extinguishers provide a way of getting a

sizeable amount of extinguishing agent to a fire rapidly. These units are designed for in plant
protection and offer a considerably longer agent discharge period and greater fire fighting
power capacities range from 100 to 350 Ibs. of dry chemical agent.

Steps to operate a wheeled type extinguisher:

1. Open the compressed gas cylinder to pressurize the agent;
2. Free the hose from its reel and move toward the fire;
3. Point the nozzle toward the base of the fire;
4. Squeeze the nozzle to discharge the agent. To stop discharging, release the nozzle
action.

The more common types of extinguishers that you may come in contact with are the following:
1. Water
2. Carbon Dioxide
3. Dry Chemical
4. Dry Powder

Procedures for Inspecting Various Types of Extinguishers:

1. Check accessibility and proper location;
2. Check for tag for date of last recharge or inspection;
3. Check nozzle for obstruction and operations;
4. Examine for corrosion or mechanical damage;
5. Check lock pin and seal;
6. Determine if full
7. Examine condition of hose and hose coupling;
8. Check horns for cracks, dirt, or grease accumulations;
9. Date of inspection and initials of inspector.

Pressurized and Stored-Pressure Water Extinguishers

Most of these extinguishers are 2 ½ gallons in capacity

The different parts of the extinguisher are the following:

1. Shell

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 2. Discharge valve
3. Pick-up tube
4. Hose
5. Nozzle
6. Pressure gauge
7. CO2 cartridge

Inspection:
1. Check the seal attached to the safety pin for damage;
2. Check the air pressure gauge for correct pressure reading of 100 psi and condition of
pressure gauge;
3. Examine the hose and nozzle for foreign objects and damage, and overall condition
of the extinguishers.

No semi-annual inspection is required for these types of extinguishers except for the CO2
cartridge-operated type. With this type, weigh the cartridge every 6 months to check for any
leakage. At the annual inspection, agent must be discharged, clean the extinguisher completely,
and recharge it with the proper agents.

Carbon Dioxide Extinguishers

CO2 is an inert gas that extinguishes fires by smothering rather than by cooling. The
heat absorbing capacity of CO2 is very limited being only 10% that of water.

All CO2 extinguishers must be provided with the following seals:

1. A seal attached to the valve handle or wheel to hold the valve locking pin in place;
2. A plastic hood or cap placed over the safety valve to cover the frangible pressure-
release disk.

Inspection:
1. Check pin seal on the extinguisher to insure that it is intact;
2. Check the plastic seal to make sure that the seal is in place over the safety disk;
3. Check the extinguisher location to make sure that it is not subjected to high
temperatures or in the direct exposure to the rays of the sun;
4. Check the hose for deterioration or weaknesses;
5. Check the horn for damage.

The annual inspections of CO2 extinguishers should include weighing the shell to insure a
full charge. Lubricate also the running gears on wheel type extinguishers. It should be
recharge if less than 90% of its capacity is present.

Dry Chemical Extinguishers

This also helps prevent packing of the chemical while stored inside the extinguisher.
These dry chemical extinguishers maybe found in different sizes which range from 2 ½ to
30 pounds. The extinguishers maybe cartridge-operated or maybe stored-pressure type.

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 Inspection:
The inspection includes checking of the hose, nozzle, and shell for leaks, cracks, and
corrosion. Check cartridge if screwed tightly in position and that the seal is firmly attached
and in place.

Semi-annual inspection, the cartridge must be weighed to determine if there has been a
loss of not more than 10% of the excellent gas from cartridge. If more than 10% loss has
occurred, the cartridge must be replaced and/or recharge.

Annual inspection includes all of the previous checks and inspections, plus a complete
operational test, cleaning and checking.

Dry- Powder Extinguishers

These types of extinguishers are designed for use on class D fires. Their sizes may vary
from the small 1 lb to the 350 pound wheeled type extinguishers. The 30-pound type is the
most common type used in the U. S. Air Force. The agents used I the extinguishers may be
in powder or in granule form. Using these agents on the wrong type of metal fire may result
in a serious explosion, release of toxic gases, or both, thus endangering the users and
others.

Inspection:
The inspection procedures for these extinguishers are identical to those for dry-chemical
extinguishers. One exception to this is certain dry-powder agents have no “extinguisher” but
are always stored in the container used for shipping.

Damaged Extinguishers:
Leaked, corroded, or otherwise damaged extinguisher shells or cylinders should be
discarded or returned to the manufacturer for repair. CAUTION: Never Try To Repair The
Shell or Cylinder Subjected to Pressure.

Testing Extinguishers:
1. Service test – a service test of an extinguisher is an operational test of the
extinguisher to see to it that it is operating properly.
2. Hydrostatic test – hydrostatic test is internal pressures check of an extinguisher
cylinder or shell to detect possible failure under pressure.

The following are extinguishers recommended for testing every 5 years:

1. Cartridge operated water extinguishers
2. Stored pressure water extinguishers
3. Dry chemical with soldered brass or stainless-steel shell
4. Carbon dioxide

Types of extinguisher to be tested every 12 years:

1. Halon 1211
2. Halon 1301
3. Cartridge operated dry powder
4. Stored pressure dry chemical with aluminium, brazed, brass or mold steel shells
5. Cartridge operated dry chemical with mild steel shells

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Conditions which allow the destruction of an extinguishers:
1. When the shell or cylinder threads are damaged
2. When the extinguisher has been burnt in a fire
3. Pitting exist due to corrosions

Category of Fire Extinguishers According to their contents and classes:

Type mechanism effectiveness discharge Class of fire

H2O Reduces 30-40 ft 60 sec A
temperature
CO2 Displaces 3-8 ft 8-30 sec B&C
Oxygen
Dry Chem Blinds Oxygen 5-20 ft 10-40 sec A BC
Chemical Halon Blinds Oxygen 4-10 ft 4-10 sec B&C
Met L-X Smother N/A N/A D

The following are declared prohibited acts concerning the use of fire extinguishers:

1. Removal of inspection tag attached to fire extinguishers

2. Refilling a discharged extinguisher with extinguishing agents other than what the
unit was designed to contain.
3. Selling extinguishers prohibited by Rule 37, section 104 of PD 1185.
4. Selling defective or substandard extinguishers.
5. Using/installing two or more thematic special hazard vaporizing liquid units in rooms
with volume greater than the normal capacity of one unit.
6. Installing pressure gauges in fire extinguishers which do not indicate the actual
pressure of the interior of vessel such as but not limited to, use of un-calibrated
gauges, not providing or blocking the connection between the gauge and the
interior, or fixing the indicator/needle to indicate a certain pressure.

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 Parts of fire Extinguisher

Types of Fire Extinguisher

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION
 Acquire New Knowledge

Here is your fourth lesson – Read and learn

Lesson 4. Flammable Materials and hazardous materials

The specific differences in the properties are known as characteristics, and all flammable
materials have characteristics peculiar to themselves. All matter, including flammable materials
will exist in at least once of three states.

These states-or groups are known as:

1. Liquids
2. Gases
3. Solids

As firefighters, you should know the contents of a container to determine the pressure
build-up when the container is near a fire. Too high a pressure is liable to burst the tank
or otherwise endanger life or lives.

Liquids defined

Liquids are fluids that do not generate more than 40 psia when heated to 100 degrees F

To determine whether a fluid should be classed as a gas or a liquid, it is tested.

Procedures in Testing

1. Placed the fluid in a closed container equipped with pressure gauge, then raised the
temperature of the container and contents to 100 degrees F. As the fluid vaporizes
and creates a pressure, the gauge will show it.
2. Add the gauge reading to the atmospheric pressure, an absolute pressure reading is
obtained.

Types of Liquids

A. Flammable liquids – these are liquids with a flashpoint below 100 degrees F and a
vapor pressure not over 40 psia at 100 F. they called Class I liquids, which are
subdivided into the following classes:
 Class IA – any liquid that has a flashpoint below 73 F, and a boiling point below
100 F.
 Class IB – any liquid that has flashpoint below 73 F, and a boiling point at or
above 100 F.
 Class IC – any liquid that has a flashpoint below 100 F, but not below 73 F.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

 B. Combustible Liquids – liquids that have a flashpoint at or above 100 F. they are
subdivided into the following categories:
 Class II – any liquid having a flashpoint at or above 100 F and below 140 F.
 Class IIIA – any liquid having a flashpoint at or below 140 F and below F.
 Class IIIB – any liquid having a flashpoint at or above 200 F.

Gases

Gases are classified by their chemical, physical properties, and usage.

A. Chemical properties – chemical properties of gases are of prime interest to

firefighters, as they reflect the ability of the gas to react within it or with other
materials. The chemical properties of gases, maybe broken down as follows:

1. Flammable gases – any gas that which burn in normal concentrations of oxygen in
the air.
2. Non-flammable gases – any gases that will not burn in air.
3. Reactive gases – any gases that will react within itself or with other materials under
conditions other than fire.
4. Toxic gases – any gases that may complicate firefighting efforts due to its serious
life hazards.

B. Physical properties – is the physical behavior of a gas both outside and inside its
container and when accidentally released, these are of prime interest to firefighters.

The Physical Classification are the following:

1. Compressed gases – matter which is solely in a gaseous state in its container with a
lower pressure limit of 25 psig (pounds per square inch gauge) at normal
temperature of 70 F to 100 F.
2. Liquified gases – matter which exist partly as a gas and partly as a liquid at normal
temperatures inside the container and remain under pressure as long as any liquid is
in the container.
3. Cryogenic gases – gas which remains as liquified gas in its container at temperature
far below normal temperature.

C. Usage – classification of gases is made by their usages. However, there will be much
overlapping in these usages.

1. Fuel gases – gases which burn with air to produce heat, power, or light.
2. Industrial gases – gases used in industrial processes such as: water treatment,
welding and cutting, refrigeration, and etc.
3. Medical gases – gases used for medical purposes such therapy and anaesthesia.

Solid

Combustible solids are those which ignite burn and change chemically when subjected
to heat or fire. The heat must be approximately 350 F or higher.

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Combustible Metals – most of the combustible metals are chemical elements which are part of
earth’s composition.

Some of the combustible metals are the following:

1. Sodium
2. Titanium
3. Uranium
4. Zirconium
5. Magnesium
6. Potassium
7. Lithium
8. Sodium- potassium alloys

Fire effects on Building Materials

Building materials have varying degrees of resistance to fire, depending on their

composition, arrangement, and the amount of heat generated in the fire. There is no such thing
as “fireproof”, since all building materials are affected by fire. Other factors, such as density,
thickness, building protective devices and surface treatment, result in differing effects on
building materials under fire conditions.

Effects of fire on Various Materials:

1. Wood – wood turns with an open flame and it chars depending upon its type,
condition, thickness.
2. Steel – in its usual form is non0combustible, however, steel wool and filings can be
ignited under certain conditions. In a burning building, structural steel may heat
rapidly, lose its strength, and deform.
3. Masonry – in general, brick, stone, and concrete are considered fire resistant.
4. Miscellaneous construction materials – in addition to the three most common
building materials, there are number of other materials that are used in all types of
buildings. These types of materials are normally used for interior finishes, roofing, or
decorative purposes.
 Plastic sheeting – a translucent, corrugated, plastic-impregnated fiberglass
panels used for natural illumination of structures. Their combustibility varies
according to the type of plastic used as a binder. Most types are slightly less
combustible than wood, but still burn readily.
 Glass – while glass is non-combustible, its normal brittleness is increased by
sudden cooling. This causes it to crack and shatter.
 Asphalt -asbestos siding, roofing, and shingles – all these are combustible to
a degree, depending on the relative amounts of asphalt and inert material
compounds in their make-up.
 Clay tile – these are used for floor covering, partitions, flues, etc., tile can be
generally classed with masonry as noncombustible.
 Fiber board – fiberboards of vegetable or animal materials are generally
combustible, while those of mineral origin are not.
 Gypsum board – widely used as an interior finish for partitions, walls, and
ceilings, it is regarded as noncombustible.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

  Plastics and synthesis resins – to date more types and forms of plastics and
synthetic resins are commonly used as building materials, and for related
purposes.

Fire Retardant Treatment

Two general types of fire-retardant:

1. Surface coating – is usually used in combination with a paint, decompose at the
point of contact of a flame or other heat source to form a blister filled with an
infinite number of tiny bubbles.
2. Impregnation – it is usually done at a processing plant or factory by forcing solutions
of fire -retardant chemicals, under pressure, into the pores of the materials to be
protected.

Hazard Classification

In the year 1976, the U.S Department of Defense (DoD) used a hazard classification and
identification system all its own for explosives and other dangerous materials.

After many years of study, the DoD implemented the present classification system based
on a system recommended for international use by the United Nations Organization (UNO).

Below are the listings of all nine UNO classes of |Dangerous Materials.

Class 1 – Explosives

Class 1 is divided into four divisions which indicate the type of hazards expected.

A. Class Division 1.1 Class 1.

Mass detonating explosives comparable to Quantity-Distance (Q-D) class 7 and M
designated items

Assigned to this class are principally blast hazards. They may be expected to
mass detonate when a small portion is initiated by any means, such as fire,
severe conclusion or impact impulse of an initiating agent.

B. Class Division 1.2

Non-mass detonating, fragment producing explosives. These items for which the
principal hazards may be fragments, toxicity, or blast.

C. Class Division 1.3

It includes explosives that present a mass fire hazard. Items assigned to this
class usually burn vigorously with little or no possibility of extinguishing fires that
have gained headway in storage situations.

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 D. Class Division 1.4
It includes explosives with a moderate fire hazard, but no blast hazard. Items assigned
to this class primarily present fire hazards producing no blast and virtually no
fragmentation or toxic hazards beyond the normal fire hazard distance.

Class 2 – Gases: Compressed, liquified or dissolved under pressure.

Class 3 – flammable liquids

Class 4 – flammable solids

Class 5 – oxidizing substances and organic peroxides

Class 6 – poisonous (toxic) and infectious substance

The Department of Transportation (DOT) labelling system is perhaps the most widely
used. New, and more descriptive placards and labels have been selected that permit fire
fighters and emergency service people all over the world to visually understand the hazards
they face at the scene of an emergency.

Some of the more common labels and placards are described here and should be
explored depth.

Color Scheme for New Cards

PLACARDS COLORS
DANGEROUS Upper and lower triangles in red; Inscription
in black and white
Explosives A and Explosives B Orange background; symbol and Inscription
in black
Non-Flammable Ga Green background; symbol and inscription
white
Oxygen, Oxidizer and Organic Peroxide Yellow background; symbol and inscription in
black
Poison Gas, Poison and Chlorine White background; symbol Borderline, and
inscription in black
Flammable and Combustible Red background; symbol and inscription
white
Flammable solid White background with seven vertical red
stripes; symbol and inscription in black
Radioactive Top portion yellow with black symbol lower
portion white with black inscription
Corrosive Center and lower areas black; inscription in
white; symbol in black and white.

Note: the word “Gasoline” may be used in place of “Flammable” for highway transportation of
gasoline. The words “Fuel oil” may be used in place of “Combustible” for highway transportation
of fuel oil that is not classed as a “flammable liquid”.

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HAZARDOUS MATERIALS PLACRADING REQUIREMENTS

HAZARD NEW PLACARD

Class C explosives flammable

Non- flammable Gas Non- Flammable Gas

Non-flammable-Chlorine Non-Flammable Gas Chlorine

Non-Flammable gas-Oxygen Oxygen

Combustible liquid- Packages with rated capacity Combustible of 110 gallons or more, cargo
tanks or tank car

Flammable Liquid Flammable

Flammable Solid Flammable Solid

Oxidizer Oxidizer

Organic Peroxide Organic Peroxide

Class B Poison Poison

Corrosive Material Corrosives

Irritating Dangerous

EMERGENCY ACTION GUIDE FOR HAZARDOUS MATERIALS

CHLORINE:
(Non-flammable gas, Poisonous)

Potential Hazards

 Fire: -cannot catch fire – may ignite combustible

 Explosion: - container may explode due to heat fire.
 Health: - contact may cause burns to skin eyes
 Vapors may be fatal if inhaled
 Runoff may pollute water supply.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION

Immediate Action

 Get help and notify local authorities

 If possible, wear self-contained breathing apparatus and full protective clothing
 Keep upwind and estimate immediate danger area
 Evacuate according to evacuate table

Immediate Follow-up Action

Fire:
- Move containers from fire area if without risk
- Cool containers with water from maximum distance until fire is out
- Do not get water inside containers
- Do not use water on leaking container
- Stay away from ends of tanks

Spill or leak:

- Do not touch spilled liquid

- Stop leak if without risk
- Use water spray to reduce vapors
- Isolate area until gas has dispersed
- Do not get water inside container

First Aid:

- Bring victim to fresh air and open area. Call for emergency medical care.
Effects of contact or inhalation may be delayed.
- If victim is not breathing, give artificial respiration, if breathing difficult, give
oxygen
- If victim contacted the material, immediately flush skin or eyes with running
water for atleast 15 minutes.
- Remove contaminated clothes
- Keep victim warm and quiet.

Evacuation Table – Based on Prevailing Wind of 6-12mph

Approximate Size of Spill Distance to Evacuate From For minimum safety,

immediate Danger Area Downwind Evacuation area
should be:
200 square feet 160 yards (192 paces) 1 mile long, ½ mile wide
400 square feet 240 yards (288 paces) 11/2 miles long, 1 mile wide
600 square feet 300 yards (360 paces) 11/2 miles long, 1 mile wide
800 square feet 340 yards (408 paces) 2 miles long, 1 ½ miles wide
In the event of an explosion, the minimum safe distance from flying fragments is 2, 000 feet
in all directions.

CDI 216 – FIRE PROTECTION & ARSON INVESTIGATION