Industrial Safety-Mod-1-till fire safety.pdf

INDUSTRIAL SAFETY
ENGINEERING
By: Asst. Prof. Anjan Kumar Mishra
DEPARTMENT OF MECHANICAL ENGINEERING
PARALA MAHARAJA ENGINEERING COLLEGE, SITALAPALLI,
BERHAMPUR

COURSE STRUCTURE
2
Module-I : Introduction to Industrial Safety, mechanical and electrical
hazards, Factories act 1948.
Module-II : Fundamentals of maintenance engineering, Types of
maintenance and tools used for maintenance, Maintenance cost
and its relation with replacement economy.
Module-III : Wear and Corrosion and their prevention, Types of wear,
Lubrication methods and corrosion prevention methods.
Module-IV : Fault tracing and decision tree concept, decision tree for
problems in various machine tools.
Module-V : Periodic inspection concept, Steps for periodic and preventive
maintenance of machines, Repair cycle concept
Mechanical Engineering Department, PMEC Berhampur, Odisha-761003 Email:anjan.me@pmec.ac.in

HOW UNSAFE ARE INDIAN WORKPLACES?
3
The accident statistics appeared under this title by Mr. N. Vidyasagar in the
‘Business Times’ supplement of the Times of India.
➢ Around 125 workers die every day.
➢ 50,000 are injured every day.
➢India accounts for 32% of global mishaps and 37% of occupational injuries.
This is a grave situation which should alarm us — as progressive thinkers —
and push us to investigate, in-depth, the causative factors responsible for the
present day situation.

ACCORDING TO SIR BRIAN APPLETON;
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“Safety is not an intellectual exercise to keep us in work rather it is a matter of
life and death. It is the sum of our contributions to safety management that
determines whether the people we work with live or die”
• Coined after the Piper Alpha mishap on 6 July 1988, killing 167 people

BHOPAL GAS TRAGEDY
5
➢ The Union Carbide Corporation of USA established their Indian
subsidiary, Union Carbide India Ltd. (UCIL) and a plant at Bhopal in 1934 to
manufacture carbaryl.
Monomethylamine (MMC) + Phosgene
Methyl Isocyanate (MIC) + Alpha-Naphthol
Methyl Isocyanate (MIC)
Carbaryl
➢ All over Europe the maximum permissible storage limit for MIC is observed
as half a ton.
• The U.S. management forced the managers of their Indian subsidiary to
keep the MIC storage capacity hazardously high at over 90 tons.
• MIC was thus stored in three large tanks at the Bhopal plant. This led to its
discharge in vapour and liquid form through the safety valve.

BHOPAL GAS TRAGEDY : THE MISHAP
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➢ 10:15 pm: The shift supervisor asked an operator to wash the piping
around one of the three MIC storage, suspecting a leak in the tank valve.
• The valve on the tank was blinded off to prevent ingress of water, entry
of which would initiate a highly exothermic polymerization reaction.
➢ 11:00 pm: The night shift operator noticed a pressure rise in the tank. He
ignored it on the assumption that it was pressurized in the previous shift
for the purpose of transferring the contents to the next pesticide unit.
➢ 11:30 pm: the operators sensed irritation in their eyes. They knew that it
was due to a small leak of MIC. Again, that was not an unusual
phenomenon to them, so they ignored it.
• Temperature and pressure continued to build in the MIC tank to several
times the permissible limit, irrespective of water being sprayed over.

BHOPAL GAS TRAGEDY : ACTIVITIES LED TO TRAGEDY
7
➢ The catastrophe actually began when the storage tank of MIC became
contaminated with water and a runaway reaction occurred. The
temperature and pressure rose, the relief valve lifted and MIC vapour was
discharged into the atmosphere.
➢ The protective equipment, which should have prevented or at least
minimized the discharge, was out of action or not in full working order.
➢ The refrigeration system, which should have cooled the storage tank, was
shut down.
➢ The scrubbing system, which should have absorbed the vapour, was not
immediately available.
➢ The flare system, which should have burnt any vapour which got past the
scrubbing system, was out of use.

BHOPAL GAS TRAGEDY : THE DISASTER
8
➢ At midnight, the undue pressure build-up in the tank burst the safety valve,
and MIC gas rushed straight through an atmospheric vent line out into
Bhopal’s cool night air in the early hours of Monday, December 3, 1984,
affecting innocent citizens and animals.
➢ Many people died in their sleep because of the heavy gas cloud, others
woke up to intense irritation in their eyes, choking and suffocating
sensation in their throats and lungs. They rushed out onto the streets,
grasping for fresh air, only to make matters worse for themselves.
➢ Over 8000 people died in the immediate aftermath. About 250,000 were
left with permanent disabilities.
➢ Since then 10 to 15 persons die every month and over 120,000 continue to
suffer acutely from exposure-related diseases and their complications.

BHOPAL GAS TRAGEDY : THE ERRORS COMMITTED
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1. Adequate in-built safety systems were not provided and those provided
were not checked and maintained as scheduled.
2. In all, five safety systems; Vent gas scrubber, Flare stack, Water curtain,
Refrigeration system and a spare storage tank were provided in the plant.
But none of these ever worked or came to the rescue in the emergency.
3. Safe operating procedures were not laid down and followed under strict
supervision.
4. Total lack of ‘on-site’ and ‘offsite’ emergency control measures.
5. No hazard and operability study (HAZOP) was carried out on the design and
no follow-up by any risk analysis.
6. Evacuation drills for fire and release of toxic gases were never held and
practised.

BHOPAL GAS TRAGEDY : THE ERRORS COMMITTED
10
7. The community living in the vicinity of the plant had never been alerted and
warned about the dangers.
8. The local authorities had never been informed of the hazards so that they
would know what to do in the event of such an emergency.
9. It was the responsibility of both the local as well as central authorities to
request the management to disclose all the relevant information with
regard to the major hazard installations and their control procedures,
identifying key personnel responsible for taking the appropriate measures
in emergency as per the provisions under the Factories Act, 1948.
10.Danger signals and warnings were not observed and followed.

BHOPAL GAS TRAGEDY : LESSONS TO BE LEARNT
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1. Wherever and whenever possible, we should reduce or eliminate
inventories of hazardous materials, in process and in storage.
2. An alternative to intermediate storage is substitution, i.e., using a safer
material or route, especially when reducing inventories, or intensification
as it is called, is not practicable.
3. Just as “materials which are not there cannot leak” (Dr. Trevor Kletz),
“people who are not there cannot be killed”.
4. For major hazard installations like the Bhopal plant, hazard and operability
study (HAZOP) should be carried out on the design for identifying routes
by which contamination and other unwanted deviations can occur.
5. Keep protective equipment in working order and size it correctly, even
when the plant is shut down.

BHOPAL GAS TRAGEDY : LESSONS TO BE LEARNT
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6. Safe Operating Procedures are to be maintained on regular schedule.
7. Training in Loss Prevention.
8. Handling ‘on-site’ and ‘offsite’ emergencies

INDUSTRIAL ACCIDENT
13
➢ According to the Factories Act, 1948: “It is an occurrence in an
industrial establishment causing bodily injury to a person that
makes them unfit to resume their duties in the next 48 hours”.
➢ In other words, accident is an unexpected event in the course of
employment which is neither anticipated nor designed to occur.
Thus, an accident is an unplanned and uncontrolled event in which
an action or reaction of an object, a substance, a person, or a
radiation results in personal injury.
➢ It is important to note that self-inflicted injuries cannot be regarded
as accidents.

WHY DO ACCIDENTS OCCUR?
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➢ Lack of risk awareness.
➢ Lack of knowledge on the activity being undertaken.
➢ Lack of safety aspects in design.
➢ Lack of commitment to safety.
➢ Lack of control.
➢ Lack of education, training and motivation.
➢ Lack of team-work and safety culture.
➢ Lack of discipline.
➢ Lack of social responsibility in general and personal responsibility
and accountability to safety.
➢ Failure to learn from past experiences of similar incidents.
➢ Failure to inspect safety gadgets and devices and maintain them in
order regularly and adequately.
Mechanical Engineering Department, PMEC Berhampur, Odisha-761003 Email: anjan.me@pmec.ac.in

WHY DO ACCIDENTS OCCUR?
15
➢ No efforts to prevent hazards by employing safer designs or by
adopting control methods.
➢ Failure to identify critical components and comply with the
preventive maintenance requirements of the installation.
➢ Failure to sponsor candidates who are qualified, deserving and are
interested in making safety profession as their.
➢ Lack of instituting safety in the organization. Out of all the various
management functions, safety function remains the most neglected
function — apparently, considered non-profitable.
➢ Safety profession is, at the most, given a subordinate position in the
management hierarchy. It generally falls to the middle management
level which is not aware of even the basic principles of safety.

STAGES TO AN ACCIDENT
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A detailed analysis of an
accident will normally
reveal three cause levels:
1. Basic
2. Indirect
3. Direct
Figure source: Industrial Safety
Management: Hazard Identification and
Risk Control by L. M. Deshmukh

HOW EFFECTIVE IS THE LEGISLATION/MANAGEMENT?
17
➢ India has state-of-the art regulations, but they are not implemented. The
basic reason for this is the total indifference towards safety by everyone
— the Government, the Management and the Workers’ Unions.
➢ Statutory provisions are becoming more stringent day by day, but they
aren’t effective; they remain only in the books of statute. Those who are
responsible for implementation of the industrial legislation hardly
know of or are aware of the same.
➢ Bureaucratic corruption has reached an extent that it is easy and
convenient for any management to evade the law. Both the
management offering and the authorities accepting the bribe to ignore
the unlawful and unsafe condition are to be blamed for neglecting
safety in an industry.

HOW EFFECTIVE IS THE LEGISLATION/MANAGEMENT?
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➢ The top management should ensure that it remains committed to the
safety and health of its employees throughout their term with them.
➢ A commitment to safety by the management on paper, in a safety manual
declaring the company’s safety policy, has no meaning. It should be put
into action.
➢ Safety practice should be made a core culture of the organisation. The
decision makers in the organisation need to have a thorough knowledge
of various norms and systems in safety.
• Environmental Factors: These causes arise out of unsafe situational and
climatic conditions. These may include excessive noise, very high
temperature, humid conditions, bad working conditions, unhealthy
environment, slippery floors, excessive glare, dust and fume, arrogant
behaviour of domineering supervisors, etc.

UNSAFE ACTIONS
19
Industrial accidents occur due to certain acts on the part of workers.
These acts may be the result of lack of knowledge or skill on the part of
the worker, certain bodily defects and wrong attitude. Examples;
Operating without authority.
Failure to use safe attire or personal protective equipment’s,
Careless throwing of material at the work place.
Working at unsafe speed, i.e., too fast or too low.
Using unsafe equipment, or using equipment’s unsafely.
Removing safety devices.
Taking unsafe position under suspended loads.
Distracting, teasing, abusing, quarrelling, day-dreaming, horseplay
One’s own accident prone personality and behaviour.

UNSAFE CONDITIONS
20
➢Unsafe working conditions are the biggest cause of accidents. These
are associated with defective plants, tools, equipment, machines, and
materials. Such causes are known as ‘technical causes’.
➢They arise when there are improper guarded or defective equipment,
faulty layout and location of plant, inadequate lighting arrangements
and ventilation, unsafe storage, inadequate safety devices, etc.
➢Besides, the psychological reasons; working over time, monotony,
fatigue, tiredness, frustration and anxiety are also cause accidents.
➢Safety experts identify that there are some high danger zones in an
industry. These are, hand lift trucks, wheel-barrows, gears and pulleys,
saws and hand rails, chisels and screw drivers, electric drop lights, etc.,
where about one-third of industrial accidents occur.

UNSAFE CONDITIONS
21
Figure source: Google Images

MAJOR EFFECTS/RESULTS OF ACCIDENTS
22
➢Recent studies and researches made in accidents revealed that the
industrial establishment suffers not only in the amount of
compensation to be paid by it as a legal liability but also the real loss is
many times more than it. The workers, the consumer, and the society
at large are also the sufferers due to the occurrence of accidents.
1. Loss to Industry:
• Expenditure to be made on the medical treatment of the workers.
• Wages to be paid to the worker for the period when they are not able
to join the work due to the injuries caused to them due to the accident.
• Expenses to be made for the services of machines and tools on which
the worker was working.

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Loss to Industry Contt….:
• Expenses to be made for inspection and repairs of the machines and
tools.
• Expenses to be incurred on recruitment and training of new worker
who has been employed in place of an injured or deceased worker.
• The cost of the period during which other workers to stop working
out of fear or out of sympathy with the worker injured by an accident.
• More wages than the normal ones are to be paid on overtime, in case
the production work is held up, for honoring the orders of customer
in time.
• An accident has also its effect on the other workers. There is a
likelihood of occurrence of other accidents out of fear or nervousness.

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2. Loss to the Workers:
• An industry suffers a lot on account of accidents. It affects severely
the workers too. In fact the workers’ losses are far more worse than
the loss of others.
• Beside the economic loss, workers have to suffer badly in case of their
death, if there is no one to help their family.
• If some one is unable to work after the accident, they becomes a
burden for their family.
• Some time the family losses the source of income and also have to
bear excessive expenses of their treatment.

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3. Loss to the Consumers:
• The cost of industrial accident is included in the production cost and
therefore, the accidents make an increase in the production cost.
• This again leads to an increase in the prices of commodities and
consumer will not be able to buy according to his need which will
also affect the standard of living of the consumers.
4. Loss to the Society:
• If the worker dies or disabled on account of the accident and the
worker’s family become helpless, the society has to come to its rescue.
• The family of such worker has to depend upon the aid of the
donation given by the different organisations and it is also a burden
on the society.

ACCIDENT CAUSE AND EFFECT SMBO
MODEL
26
Figure source:
Industrial Safety
Management: Hazard
Identification and Risk
Control by L. M.
Deshmukh

CONTROL OF ACCIDENTS
27

MECHANICAL HAZARDS
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➢Mechanical hazards are hazards created by the use of or exposure
to either powered or manually operated equipment, machinery and
plant.
➢Mechanical hazards arise from relative movements between parts
of the human body and objects such as work equipment or objects,
which lead to their contact. The result of this contact can lead to
accidents and injuries.
➢Part of the machinery that could be hazardous to workers
include sharp edges, hot surfaces, moving parts, flywheel,
pulley, belt, etc.
➢Accidents caused by contact with parts moving in controlled or
uncontrolled manner and with dangerous surfaces, as well as
accidents caused by falling, slipping, tripping and twisting, each
account for the highest proportion of all occupational accidents,

COMMON MECHANICAL INJURIES
29
➢Fracture: Fracture is the medical term for a broken bone. It can
be classified as simple, compound or complete fracture.
➢Puncturing/Stabbing: Puncturing results when an object
penetrates straight into the body and pulls straight out, creating
a wound in the shape of the penetrating object.
➢Straining and spraining: A strain results when muscles are
overstretched or torn. Strains and sprains can cause swelling
and intense pain.
➢Impact: Being hit by ejected parts of the machinery or equipment
➢Friction and abrasion: A section of the skin being rub away by
the machine.

COMMON MECHANICAL
INJURIES
30
➢Entrapment: Being caught in a moving part of a machine
or equipment or plant.
➢Crushing: Collision of plant with a person can result to crushing.
➢Shear: Can be two moving parts (sharp or otherwise)
moving across one another.
➢High pressure injection: This is an injury caused by high-pressure
injection of oil, grease, diesel fuel, gasoline, solvents, water, or
even air, into the body.
➢Cut: Severing of a human body part by a cutting motion
e.g. amputation

CAUSES OF MECHANICAL HAZARDS
31

32

33
Table source: Federal Institute for Occupational Safety and Health, Germany

PREVENTION OF MECHANICAL HAZARDS
34
➢All hazards associated with the use of machinery can be managed
by adopting safe work procedures and the application of appropriate
safeguards.
1. Safeguarding helps to minimize the risk of accidents from machine by
forming a barrier which protect the operator or other persons from
the equipment hazards point/danger area. Most guards are used at
the point of operation.
Types of Machine Guards:
There are four types of machine guards are there, namely
Fixed, Interlocked, Adjustable, and Self-adjusting guards.

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a) Fixed Machine Guards
Fixed guard is a permanent part of the machine. It is not dependent upon
moving parts to function. It may be constructed of sheet metal, screen,
wire cloth, bars, plastic, or any other material that is substantial enough to
withstand whatever impact it may receive and to endure prolonged use.
Image source:
Google Images

36
b) Interlocked Machine Guards
Shut down the machine when the guard is not securely in place or is
disengaged. The main advantage of this type of guard is that it allows safe
access to the machine
Image
source:
Google
Images

37
c) Adjustable Machine Guards
Provide a barrier against a variety of different hazards associated with
different production operations. They have the advantage of flexibility.
However, they are not dependable barrier as other guards, and they
require frequent maintenance and careful adjustment.
Image
source:
Google
Images

38
c) Self-Adjusting Machine Guards
The openings of these barriers are determined by the movement of the
stock. As the operator moves the stock into the danger area, the guard is
pushed away, providing an opening which is only large enough to admit
the stock. After the stock is removed, the guard returns to the rest
position. This guard protects the operator by placing a barrier between the
danger area and the operator.
2. Safe work procedure must not be left out in the context of prevention of
mechanical hazards. The safe work procedures covers:
• Adopting safe system of work
• Equipment inspection and maintenance
• Adequate training and Supervision.

ELECTRICAL HAZARDS
39
➢The electrical hazards occur when a person makes contact with a
conductor carrying electricity simultaneously in contact with the ground.
The Electrocutions/shocks are one of the greatest electrical hazards.
➢The quantity and the path of the passing current decides the level of
damage to the person.
Current level Probable effect on human body
1 mA Slight tingling
5 mA Slight shock: not painful but disturbing
6-30 mA Painful shock, muscular control lost
50-150 mA Extremely painful, respiratory arrest, severe muscular contraction,
death is possible
1000-4300 mA Nerve damage, death is most likely
10000 mA Cardiac arrest, severe burn, probable death

CAUSES OF ELECTRICAL HAZARDS
40
• Improper grounding
• Exposed electrical
parts
• Inadequate wiring
• Overhead power lines
• Damaged insulation
• Overloaded circuits
• Wet conditions
• Damaged tools and
equipment
The following is a list of a common causes of electrical hazards
found on industrial sites
N.B.: The material and figure source in this section is OSHA
(Occupational Safety and Health Administration), USA

CAUSES AND PREVENTION OF ELECTRICAL HAZARDS
41
1. Improper Grounding
⦁ Grounding is the process used to
eliminate unwanted voltage.
⦁ A ground is a physical electrical
connection to the earth.
⦁ Grounding reduces the risk of
being shocked or electrocuted.
⦁ The ground pin safely returns
leakage current to ground.
⦁ Never remove the ground pin.
⦁ Removing the ground pin removes
an important safety feature.

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2. Exposed Electrical
Parts
⦁ Exposed wires
or terminals are
hazardous.
⦁ Never use a panel that
has exposed wires and
missing circuit
breakers.
⦁ All openings must
be closed.
⦁ Outer insulation on
electrical cords must be

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2. Exposed Electrical Parts
⦁ On construction sites, temporary lighting must be properly guarded
and protected to avoid contact with broken bulbs and avoid potential
shocks.

44
3. Inadequate Wiring
⦁ Use properly rated extension cords.
⦁ Make sure the power tools are being
used with a properly rated extension
cord.

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5. Damaged Insulation
⦁ Defective or inadequate insulation causes
hazard.
⦁ Insulation prevents conductors from
contacting each other or you.
⦁ Never attempt to repair a damaged cord
with tape.
⦁ Never use tools or extension cords with
damaged insulation.
⦁ Do not run extension cords through doors
or windows.
⦁ Never hang extension cords from nails or
sharp objects.

46
6. Overloaded Circuits
⦁ Overloaded circuits can cause fires.
⦁ Use proper circuit breakers.
⦁ Never overload an outlet.
⦁ Do not use power strips or surge
protectors on construction sites

47
7. Damaged Tools and Equipment
⦁ Do not use electric tools that are
damaged.
⦁ You may receive a shock or be
electrocuted.
⦁ Use double insulated tools.
⦁ It will be marked “Double Insulated”.

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8. Wet Conditions
⦁ Wet conditions are hazardous.
⦁ Damaged insulation increases the
hazard.
⦁ Always avoid using tools in wet
locations.
⦁ Water increases the risk of electric
shock.

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9. Overhead Power Lines
⦁ Overhead power lines
are very dangerous.
⦁ Never store materials or
equipment under
overhead power lines.
⦁ Maintain a distance of at
least 10’ between equipment
and overhead power lines.
⦁ Maintain safe distances
between scaffolding
and overhead power
lines. Mechanical Engineering Department, PMEC Berhampur, Odisha-761003 Email: anjan.me@pmec.ac.in

50
10. General Electrical Hazard Prevention
Methods
⦁ Always consider these safety
precautions: Personal protective
equipment (PPE), Inspect tools,
Ground fault circuit interrupters
(GFCIs), Lock-out/tag-out.
1. PPE for electrical hazards
include: Hardhats
Rubber or insulating
gloves Insulating clothing

51
e
Methods
2. Inspect tools and cords completely
befor using for;
▪ Cracks
▪ damaged insulation
▪ broken ground pins
▪ frayed line cord
▪ loose parts
▪ any other damage

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Methods
3. Ground fault circuit interrupters (GFCIs)
▪ A GFCI is a fast-acting circuit breaker.
▪ It senses small imbalances in the
circuit caused by current leakage to
ground.
▪ It continually matches the amount of
current coming and going to an
electrical device
▪ The GFCI looks for a difference
of approximately 5 milliamps.

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10. General Electrical Hazard Prevention Methods
4. Lock-out/Tag-out
▪ Workers must ensure electricity is off and
“locked- out” before work is performed.
▪ The switch must be tagged.
▪ The tag lets others know why the switch is off.
▪ Workers must be trained in lock-out/tag-out
procedures.

INDUSTRIAL FIRE HAZARDS
A state, process, or instance of combustion in which fuel
or other material is ignited and combined with oxygen,
giving off light, heat, and flame.
Department of Mechanical Engineering
54

55
⦁ For a fire to occur, fuel, oxygen, heat, and a chemical
chain reaction must join in a symbiotic relationship.
⦁ A fire can be classified into two general forms or
modes: flame fire and surface fire.
⦁ Flame fires directly burn gaseous or vaporized fuel and
include deflagrations. The rate of burning is usually
high, and a high temperature is produced.
⦁ Surface fires occur on the surfaces of a solid fuel.
⦁ A surface fire can be represented by a triangle
composed of heat, fuel, and air.
Source: Accident Prevention manual
for Business and Industry by P.E.
Hagan , J.F. Montgomery and
J.T.O’Reilly

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Knowing how and why a fire burns suggests ways to control
and extinguish it.
⦁ Heat can be taken away by cooling.
⦁ Oxygen can be taken away by excluding the air.
⦁ Fuel can be removed to an area where there is not enough heat
for ignition.
⦁ The chemical reaction of the flame fire can be interrupted by
inhibiting the rapid oxidation of the fuel and the concomitant
production of free radicals, the lifeblood of the flame’s reaction.

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1.Cooling a Fire
To extinguish a fire by cooling, remove heat at a greater rate than the total heat that
is being produced by the fire. The most common and practical extinguishing agent is
water applied in a solid stream or spray, or incorporated in foam.
2. Removing Fuel from a Fire
⦁ Storage tanks for flammable liquids may be arranged so that their contents
can be pumped to an isolated, empty tank in case of fire.
⦁ When flammable gases catch fire as they are flowing from a pipe, the fire will
go out if the fuel supply can be shut off.
⦁ In any mixture of fuel gases in air, adding excess of air dilutes the fuel’s
concentration below the minimum combustible concentration point.

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3. Limiting Oxygen in a Fire
➢ Limit air, or oxygen, from a fire by smothering the burning area with
a noncombustible material, as by covering it with a wet blanket,
throwing sand on the fire, smothering it with inert gas, or covering it
with a chemical or mechanical foam.
4. Interrupting the Chain Reaction in a Fire
⦁ Analyzing the anatomy of a fire reveals that the original fuel
molecules combine with oxygen in a series of successive intermediate
stages, called branched chain reactions. Then the end product,
combustion, occurs. The intermediate stages are responsible for the
evolution of flames.

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⦁ As molecules break up in these branched-chain reactions, unstable
intermediate products called free radicals are formed. The
concentration of free radicals determines the speed of flames. The life of
the free hydroxyl radical (-OH) is very short (0.001 second), but long
enough to be crucial in the combustion of fuel gases. The almost
simultaneous formation and consumption of free radicals is the lifeblood
of the chain reaction.
⦁ Extinguishing agents, such as dry chemicals (sodium or potassium
bicarbonate–base, and ammonium phosphate–base) and halogenated
hydrocarbons, remove the free radicals in these reactions from their
normal function as a chain carrier. Potassium bicarbonate dry
chemical is the most effective because of the large size of the
potassium ion.

CLASSIFICATION OF
FIRES
60
Four general
classifications of fires
have been adopted by the
NFPA (National Fire
Protection Association),
USA. These classifications
are based on types of
combustibles and the
extinguishing agent
needed to combat each.
Source: QRFS(Quick
Response Fire Supply),
Virginia Mechanical Engineering Department, PMEC Berhampur, Odisha-761003 Email: anjan.me@pmec.ac.in

RECOMMENDED FIRE EXTINGUISHERS
61
Source: NFPA,
USA

CAUSES OF INDUSTRIAL FIRES
62
➢ Electrical equipment, smoking, friction, open flames, and poor
housekeeping are some common causes of industrial fire.
1. Electrical Equipment
➢ Overheating of electrical equipment and arcs resulting from short circuits
in improperly installed or maintained electrical equipment are two of the
leading causes of fire in buildings.
➢ Temporary or makeshift wiring, particularly if defective or overloaded, is
a very common cause of electrical fires.
➢ Ground or double-insulate all electrical equipment, use waterproof
cords and sockets in damp places, and use explosion-proof fixtures
and lamps in the presence of highly flammable gases and vapours.
➢ Periodically inspect and test electrical installations and all electrical
equipment.

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2. Smoking
➢ Carelessly discarded cigarettes, pipe embers, and cigars are a
major source of fire.
➢ Prohibit smoking, especially in woodworking shops, textile mills,
flour mills, grain elevators, and places where flammable liquids or
combustible products are manufactured, stored, or used.
➢ Although it might be desirable to eliminate smoking completely in
a plant, such a rule is difficult to enforce. Instead, allow smoking at
specified times and in a safe place where supervision can be
maintained.
➢ Mark NO-SMOKING areas with conspicuous signs.
➢ Prohibit carrying matches into the plant and provide special lighters
Smoking room.

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3.Friction
➢ Excessive heat generated by friction causes a very high percentage of
industrial fires. Inadequate lubrication, misaligned bearings, or broken or
bent equipment—all sources of friction.
➢ Fires frequently result from overheated power transmission bearings
and shafting in buildings such as grain elevators, cereal, textile, and
woodworking mills, and plastics and metalworking plants, where dust
and lint accumulate.
➢ Keep the accumulation of flammable dust or lint to a minimum. Provide
drip pans beneath bearings, and clean them frequently to prevent oil from
dripping to the floor or on combustible material below. Keep oil holes of
bearings covered to prevent dust and gritty substances from entering the
bearings.

65
4. Foreign Objects or Tramp Metal
➢ Take every precaution to keep foreign objects from entering
machines or processes. They might strike sparks where there are
flammable dusts, gases, or vapors, or combustible material, such as
cotton lint or metal powder.
➢ For this purpose, use screens or magnetic separators such as
are used in textile mills, grain elevators, and other operations
where explosive mixtures of dusts are present.
5. Open Flames
➢ Open flames are probably the most obvious source of ignition for
ordinary combustibles. Heating equipment, torches, and welding
and cutting operations are principal offenders.

66
6. Spontaneous Ignition
❑ Spontaneous ignition results from a chemical reaction in which there
is a slow generation of heat from oxidation of organic compounds.
❑ Spontaneous ignition usually occurs around quantities of bulk
material packed loosely enough for a large amount of surface to be
exposed to oxidation yet without adequate air circulation to dissipate
heat.
❑ These materials include vegetable and animal oils and fats, coal,
charcoal, and some finely divided metals. Rags or wastes saturated
with linseed oil or paint often cause fires too.
❑ The best preventives against SI are either total exclusion of air or
good ventilation. With small quantities of material, the former method
is practical. With large quantities of material, such as storage piles of
bituminous coal, both methods have been used with success.
65

67
7. Housekeeping
• Poor housekeeping contributes to industrial fires. Properly
collecting and storing combustibles and disposing of rubbish, as well
as maintaining locker rooms, will prevent fire hazards.
• Many industrial fires are the result of accumulations of oil-soaked and
paint-saturated clothing, rags, waste, excelsior, and combustible
refuse.
• Do not store such material or allow it to accumulate in air, elevator,
or stair shafts; in tunnels; in out-of-the way corners; near electric
motors or machinery; against steam pipes; or within 10 ft (3 m) of any
stove, furnace, or boiler.
• Locker rooms in which oil-soaked clothing, waste, or newspapers are
kept are always a serious fire hazard. Take every precaution to
prevent such combustible materials from accumulating.

INDUSTRIAL FIRE PREVENTION
68
The fire prevention technique comprises of three major
steps;
1. Fire Detection
2. Alarm Systems
3. Fire Extinguishing
• Portable Fire Extinguisher
• Sprinklers and Water-Spray Systems
• Special Systems and Agents

INDUSTRIAL FIRE PREVENTION
69
Fire Detection
• Human Observer
• Automatic Fire-Detection System
• Thermal/Heat Detectors
• Fixed-Temperature Detectors
• Rate-Compensated Thermal Detectors
• Rate-of-Rise Thermal Detectors
• Line Thermal Detectors
• Eutectic-Salt-Line Thermal Detectors
• Bulb Detection Systems
• Smoke Detectors
• Beam Photoelectric Detectors
• Reflected-Beam Photoelectric Detectors
• Products-of-Combustion (Ionization) Detectors
• Single-Chamber Ionization Detectors
• Dual-Chamber Ionization Detectors
• Low-Voltage Ionization Detectors
• Flame Detectors
• Infrared Detectors
• Ultraviolet Detectors
• Combustion-Gas Detector
Alarm Systems
• Local Alarm
System
• Auxiliary Alarm
Systems
• Central Station
System
Fire Extinguishing
• Portable Fire Extinguisher
• Water Solution Extinguishers
• Dry-Chemical Extinguishers
• Carbon Dioxide Extinguishers
• Dry-Powder Extinguishers
• Sprinklers and Water-Spray Systems
• wet-pipe
• dry-pipe
• preaction
• deluge
• combined dry-pipe and preaction,
• limited water-supply systems.
• Special Systems andAgents
• Foam systems
• Fixed CO2 systems
• Dry-chemical piped systems
• steam jet systems
• Inert gas systems
• Prevention of explosion
• explosion-suppression system

1. FIRE DETECTION
70
▪ Losses can be reduced if the rising fire is detected so it could be
extinguished. Thus, fire-detection devices must be a part of every fire
protection system. There really are no fire detectors, but rather heat / smoke
/ flame detectors.
▪ Means of detection could be a human observer or an automatic fire-
detection system.
1.1. Human Observer
▪ A human observer is a good fire-detection system for the following
reason: He or she can take immediate action in a flexible way, whether
calling the fire department or putting out a fire with an extinguisher. Be
sure that employees report any fire that they have put out.
▪ Human observers should also report malfunctioning fire alarm systems.
False alarms have a negative effect: if an actual fire occurs, the sounding
alarm may be dismissed as just another false alarm.

1. FIRE DETECTION
71
1.2.Automatic Fire-Detection System
▪ There are many types of fire detectors to handle various situations and to detect
various states of the beginning of a fire. Most manufacturers and distributors offer
several or all of the commonly used types. They can also engineer a combination of
equipment to meet the special needs of a plant.
1.2.1 Thermal/Heat Detectors
• Thermal detectors detect the heat from a fire. There are several kinds of thermal
detectors, each with a specific use. However, they can only detect the heat of a fire,
which usually will not build up to significant levels until the last stage of a fire.
• Many fires start slowly, with little heat generated at the beginning, and will be well
under way by the time a thermal detector comes into operation. They are generally
used where no life hazard is involved and some loss can be tolerated.

1. FIRE DETECTION
72
1.2.1.1 Fixed-Temperature Detectors
• These thermal detectors are based on a
bimetallic element. They are made of two
metals that have different coefficients of
expansion. When heated, the element will
bend to close a circuit, initiating the alarm.
• A thermal detector may also use a fusible,
spring-loaded element, that melts at a certain
temperature, releasing an arm to close a
circuit.
• Fixed-temperature detectors are simple,
inexpensive, and require a low-voltage

1. FIRE DETECTION
73
1.2.1.2 Rate-Compensated Thermal Detectors
• These detectors work by the expansion
characteristics of a hollow tubular shell
containing two curved expansion struts
under compression.
• When subjected to a rapid rise of heat, the
shell expands and lengthens at a faster rate
than the struts, thus permitting the
contacts to close. When heated slowly,
both the shell and the struts lengthen at
about the same rate until the struts are
fully extended, thus making contact at a
pre-set temperature point.

1. FIRE DETECTION
74
1.2.1.3 Rate-of-Rise Thermal Detectors
• These detectors use an enclosed,
vented hemispherical chamber
containing air at atmospheric pressure,
with a small pressure-sensitive
diaphragm on top. With a normal rise
in temperature, the excess pressure is
relieved through small vents.
• However, a rapid rise in temperature
will deflect the diaphragm faster than
the vents can operate, thus triggering
an alarm. This unit responds quickly
to a rapid rise in temperature.

1. FIRE DETECTION
75
1.2.1.4 Line Thermal Detectors
• These detectors use a length of small-diameter tubing that can be as long as
1,000 ft (305 m). When exposed to the heat of a fire, air inside the tube expands,
sending a pressure wave to expand a diaphragm at the end, which in turn triggers
an alarm.
• This is an unobtrusive, inexpensive
detector. For example, it can be run
along the ceiling molding, where it
is nearly invisible. No maintenance
is needed. It can be painted over,
and it will even work with the
tubing broken, if the temperature
rises fast enough.

1. FIRE
DETECTION
76
1.2.1.5 Eutectic-Salt-Line Thermal Detectors
• These detectors consist of pliant metal tubing containing a eutectic salt in which
a wire is embedded. At a preselected temperature, the salt creates a short-circuit
between the internal wire and the outside tubing, there by triggering an alarm.
• The pliant tubing can be wound around and
shaped to the various components of the
engines to signal any increase in
temperature that might be the result of a fire
caused by leaking oil, hydraulic fluid, etc.
• These line detectors are also used in
conveyor-belt systems where the bearings
supporting a rubberized belt may ignite
because of friction and lack of lubrication.
Mechanical Engineering Department, PMEC Berhampur, Odisha-761003 Email: anjan.me@pmec.ac.in 75

1. FIRE DETECTION
• These detectors are completely mechanical.They are especially desirable in
locations where the explosive nature of the fire hazard makes it wise or essential
to avoid t use of electricity.
• These systems involve a number of bulbs containing air at atmospheric pressure.
One or more of these bulbs are installed along the ceiling of the
77
1.2.1.6 Bulb Detection Systems
he
hazardous area, all connected back to
a diaphragm at the control center.
• When a rise in temperature strikes one or
more of the bulbs, it deflects the
diaphragm, and a mechanical
extinguishing system can be activated.
This system is used as a release
mechanism for CO2 fire extinguishers in
marine and industrial applications.

1. FIRE DETECTION
78
1.2.2 Smoke Detectors
• Smoke detectors respond to the particles of combustion, both visible
(smoke) and invisible. A conventional smoke detector operates on a light
principle: It can be triggered by either a decrease or an increase in light.
• When smoke enters a light beam, it either absorbs light so the receiver end of
the circuit registers less light, or it scatters light so that a terminal, normally
bypassed by the light beam, now receives part of the light.
• The more sophisticated smoke detectors are responsive both to gas or
products of combustion and to smoke. These products-of-combustion
detectors are capable of detecting the beginning of a fire long before there
is visible smoke or flame.

1. FIRE DETECTION
79
1.2.2.1 Beam Photoelectric Detectors
• These detectors are triggered with less
light. A long beam is directed at a
photocell. Rising smoke tends to obscure
the beam, decreasing light transmission
and sounding an alarm.
• These detectors are an inexpensive way to
cover large spaces, such as warehouses.
Beam photoelectric detectors are, however,
sensitive to voltage variations, to dirt on the
lamp or lens, and also to flying insects or
spiders, which sometimes congregate near
the lamp, seeking warmth.

1. FIRE DETECTION
80
ct
1.2.2.2 Reflected-Beam Photoelectric
Detectors
• These detectors use a beam of light in a
chamber, with the photocell normally in
darkness.
• Should visible smoke particles enter the
chamber, they scatter the light and refle
it onto the cell, causing a change in
electric conductivity that results in an
alarm.

1. FIRE DETECTION
81
rs
al
1.2.2.3 Products-of-Combustion (Ionization) Detecto
• These detectors sense both visible and invisible
products of combustion suspended in the air. They
consist of a chamber with positive and negative
plates and a minute amount of radioactive materi
that ionizes air in the chamber. The potential
between the two plates causes ions to move across
the chamber, setting up a small current.
• When aerosols from incipient fires enter the chamber, they cling to masses of
moving ions. This slows the ions’ movement and increases the voltage necessary
for the ions to make contact. This voltage imbalance, amplified by electrical
circuitry, triggers an alarm.
• If excessive dust is present, however, the device will give a false alarm.

1. FIRE DETECTION
82
1.2.2.4 Single-Chamber Ionization Detectors
• These detectors are most economical. The chamber of these detectors is open to
the atmosphere. Current flows between two poles and gets an increased voltage
from combustion aerosols. This closes the contact and sends an alarm through
the relay.
1.2.2.5 Dual-Chamber Ionization Detectors
• These detectors have two identical sources of radiation: one is a sealed chamber,
the other is open to the atmosphere. The inner ionization chamber monitors the
surrounding conditions and compensates for the effect on the ionization rate of
barometric pressure, temperature, and relative humidity.
• This construction accepts a wider range of atmospheric variations without giving
false alarms.

1. FIRE DETECTION
83
1.2.2.6 Low-Voltage Ionization Detectors
• These detectors are relatively new. While the conventional type needs 120 v, a
low-voltage detector needs only 24 v. Theoretically, an installation would cost
less.
• Low-energy, nonarmored cable is less expensive and easier to install, with
essentially no danger of short-circuits or electrical shock.
• Most large cities, however, require armored conduit for low-voltage detectors so
the savings may be less than expected.
• Nevertheless, most systems specified today are low-voltage, as the low-profile
detector heads are less obtrusive, while being equally sensitive and reliable.

1. FIRE DETECTION
84
1.2.3 Flame Detectors
• Flame detectors respond to the optical radiant energy of combustibles. Flame
detectors sense light from the flames. Sometimes they work at the ultraviolet
end of the visible spectrum, but more often they work at the infrared end.
• To avoid false alarms from surrounding light sources, flame detectors are set
to detect the typical flicker of a flame, perhaps at 5 to 30 Hz. Or there may be
a few seconds delay before the alarm in order to eliminate false alarms from
transient flickering light sources, such as flashlights or headlights.
• Flame detectors have some very important applications, such as in large
aircraft hangars and for guarding against fires in fuel and lubricant drips. In
general, however, by the time flame is visible, a fire has a good foothold.
Either an infrared or an ultraviolet detector can be used to sense the flame.

1. FIRE DETECTION
85
1.2.3.1 Infrared Detectors
• These flame detectors sense a portion of the radiant infrared energy of flames.
• They are often used in operations requiring an extremely fast response—for
example, where flammable liquids are stored or used.
1.2.3.2 Ultraviolet Detectors
• These flame detectors react only to actual
flame. They do not respond to glowing
embers or incandescent radiation. Also,
these units are insensitive to heat, infrared
radiation, and ordinary illumination.

1. FIRE DETECTION
86
1.2.3.3 Combustion-Gas Detector
• These detectors are closest to being general-purpose detectors. Combustion-gas
detectors do not rely on heat. In effect, they “smell” a potential fire by measuring
the percent of gas present. Also, they do not wait for the dangerous condition of
flames to occur before they sound an alarm. Most fires detected by combustion-
gas detectors can be extinguished by workers on the site.
• Combustion-gas detectors can usually be set to automatically sound an alarm or
to set off extinguishing equipment. Some conditions may require periodic
maintenance and calibration.
• There are areas, however, where combustion-gas detectors cannot be used. For
example, in an area where a certain level of combustion gases may be tolerated
at times because a particular process emits them, flash fires from nearby
flammable liquids may be anticipated.

2. ALARM SYSTEMS
87
• Alarm systems can be divided
into four groups: local,
auxiliary, central station, and
proprietary.All types of alarm
systems should be equipped
with a signal system that clearly
communicates to all persons in
the building, plant, or
laboratory.
• Whenever an alarm is sounded
in any portion of the building or
area, all employees must know
what the sound means.
• Table shows the relative sensitivity of fire
detectors when means of detection is
matched to the class of fire

2. ALARM SYSTEMS
88
2.1 LocalAlarm Systems
• A local alarm consists simply of bells,
horns, lights, sirens, or other warning
devices right in the building.
• Local alarms are generally used for
life protection—that is, to evacuate
everyone and thereby limit injury or
loss of life from the fire.
• Local alarm systems are inexpensive,
available from a wide range of
suppliers, and easy to install. By
themselves, however, they do not
provide much protection.

2. ALARM SYSTEMS
89
2.2AuxiliaryAlarm Systems
• Auxiliary alarm systems are
even less expensive than
local alarm systems. Such a
system simply ties a fire
detector to a nearby fire call
box. In effect, it becomes a
relay station triggered by fire
detectors inside the building.

2. ALARM SYSTEMS
90
2.3 Central Station Systems
• Central station systems are available in most major cities around the country.
• Operated by trained personnel, a central station continually monitors a number
of establishments and, in case of an alarm, calls a nearby fire station and alerts
the building’s personnel.
• Central station devices are virtually always leased. The central station company
installs fire detectors throughout the building, then ties them to an alarm board
back at the central station, usually through leased phone lines.
• In rare cases, the central station may be connected directly to the fire department.
Generally, however, when the attendant at the central station gets an alarm signal
from a subscriber, he or she telephones the fire department.
• Central station personnel are competent and expensive.

2. ALARM SYSTEMS
91
This console is part of a
comprehensive proprietary
system capable of detecting fire,
burglary, and any unwanted
fluctuations in industrial process
conditions.
The system incorporates closed-
circuit television, portable radio
communication equipment, and
other instruments to handle
indoor and outdoor security
needs of a building or a group
of buildings. Source: ADT—American District Telegraph Company

3. FIRE
EXTINGUISHING
92
3.1 Portable Fire Extinguishers
• The term portable is applied to manual equipment used on small, beginning fires
or used between the discovery of a fire and the functioning of automatic
equipment or the arrival of professional fire fighters.
• Portable extinguishers are classified to indicate their ability to handle specific
classes and sizes of fires.
1. Use ClassAextinguishers for ordinary combustibles, such as wood, paper, some
plastics, and textiles, where a quenching-cooling effect is required.
2. Use Class B extinguishers for flammable liquid and gas fires, such as oil,
gasoline, paint, and grease fires, where oxygen exclusion or a flame interrupting
effect is essential.

3. FIRE EXTINGUISHING
93
3. Use Class C extinguishers for fires involving electrical wiring and equipment
where the dielectric non conductivity of the extinguishing agent is of first
importance. These units are not classified by a numeral, because Class C fires
are essentially either Class A or Class B but also involve energized electrical
wiring and equipment. Therefore, choose the coverage of the extinguisher for
the burning fuel.
4. Use Class D extinguishers for fires in combustible metals, such as magnesium,
potassium, powdered aluminum, zinc, sodium, titanium, zirconium, and lithium.
Persons working in areas where Class D fire hazards exist must be aware of the
dangers in using Class A, B, or C extinguishers on a Class D fire. Of course they
should also know the correct way to extinguish Class D fires. These units are not
classified by a numerical system and are intended for special hazard protection
only.

94
Types of Portable Extinguishers
➢ The following types of portable extinguishers are recommended for various
types of fires: water solution, dry-chemical, CO2, and dry-powder extinguishers.
➢ Water Solution Extinguishers
• Fire extinguishers that use water or water solutions include pump tank, stored
pressure, and AFFF(Aqueous Film Forming Foams). These extinguishers are
effective against Class A fires because of the quenching and cooling effect of
water. These units cannot be used on fires in or near electrical equipment, since
they can present a shock hazard to the operator.
➢ Dry-Chemical Extinguishers
• The dry-chemical extinguisher is one of the most versatile units available. It
extinguishes by interrupting the chemical flame’s chain reaction. Do not confuse
it with a dry-powder extinguisher.

95
➢ Carbon Dioxide Extinguishers
• CO2 extinguishers put out fires by displacing the available oxygen. They do not
leave a residue.
➢ Dry-Powder Extinguishers
• Because the use of combustible metals, such as sodium, titanium, uranium,
zirconium, lithium, magnesium, sodium-potassium alloys (NaK), and other less-
common metals, has increased, have dry-powder extinguishers available to fight
such fires.
• G-1 Powder : a graphite organic-phosphate compound.
• Met-L-X
• Lith-X
• Met-L-Kyl
: composed of a sodium chloride base with additives.
: composed of a special graphite base with additive.
: a bicarbonate-base dry chemical and an activated absorbent.

96
3.2 Sprinkler and Water-Spray Systems
➢ There are many types of sprinklers and water-spray systems for extinguishing
fires. The type of building, operations performed in it, and materials used will
help determine the type of sprinkler or water-spray system used. Automatic
sprinklers are the most extensively used and most effective installations of fixed
fire-extinguishing systems.
➢ There are six basic types of automatic sprinkler systems: wet-pipe, dry-pipe,
preaction, deluge, combined dry-pipe and preaction, and limited water-supply
systems.
➢ In the wet-pipe system, which represents the greatest percentage of sprinkler
installations, all parts of the system’s piping are filled up to the sprinkler heads
with water under pressure. Then, when heat actuates the sprinkler, water is
immediately sprayed over the area below

97
➢ The dry-pipe system generally substitutes for a wet-pipe system in areas where
piping is exposed to freezing temperatures. A good rule of thumb is to use a dry-
pipe system when more than 20 sprinklers are involved.
➢ Preaction systems are similar to dry-pipe systems. However, they react faster
and hence minimize water damage in case of fire or mechanical damage to
sprinklers or piping.
➢ The deluge system wets down an entire area by admitting water to sprinklers
that are open at all times. Deluge valves that control the water supply to the
system are actuated by a fire-detection system located in the same area as the
sprinklers. This type of system is primarily designed for extra hazard buildings
where great quantities of water may have to be applied immediately over large
areas.

98
➢ The combination dry-pipe and preaction systems are used on installations
that are larger than can be accommodated by one dry-pipe valve.
➢ The limited water-supply system is used for installations that do not have
access to a continual or large supply of water.
Water-Spray Systems
➢ Water spray is effective on all types of fires where there is no hazardous
chemical reaction between the water and the materials that are burning.
➢ Water-spray systems can be designed effectively for any one, or any
combination, of the following purposes:
•extinguishing fire • controlling fire where extinguishment is not desirable, such as
gas leaks • exposure protection; that is, absorbing heat transferred from equipment
by the spray • preventing fire by having water spray dissolve, dilute, disperse, or
cool flammable materials.

99
3.3 Special Systems andAgents
These systems are usually installed to supplement rather than replace the automatic
sprinkler system.
➢ Foam systems are often used to protect dip tanks, oil and paint storage rooms,
and asphalt coating tanks. Foam systems also have been developed to put out
tank fires by subsurface injection of foam. Foam can also be used to extinguish
fires in laboratories.
➢ Fixed CO2 systems are often installed for the protection of rooms that contain
electrical equipment, flammable liquid or gas processes, dry-cleaning
machinery, and other exposures. CO2 is useful where a fire can be extinguished
by displacing the oxygen content of the air or where water must not be used
because of electrical hazard or the nature of the product.

100
➢ Dry-chemical piped systems have been developed for situations where quick
extinguishment is needed, either in a confined area or for localized application,
and where reignition is unlikely. These systems are adaptable to flammable
liquid and electrical hazards. They can be operated manually or automatically, or
be activated at the system or by remote control.
➢ Automatic or manually controlled steam jet systems can be used to smother fires
in closed containers or in small rooms, such as heaters, drying kilns, smoke
ovens, asphalt-mixing tanks, and dry-cleaning tumbler dryers. However, such
systems are practical only where a large supply of steam is continuously
available.
• However, steam has not been found effective on deep-seated fires that may form
glowing embers, or in enclosures where the normal operating temperature is not
considerably higher than air temperatures.

101
➢ Inert gas systems can prevent fires and explosions by replacing the oxygen in
the air with an inert gas, such as CO2, nitrogen, flue gas, or other
noncombustible gases, until it reaches a level (or percentage) where combustion
will not take place.
➢ Preventing the development of explosive mixtures is the best defense against
explosions. Equipment for handling and storing flammable gases should be
designed, constructed, inspected, and maintained so that the danger of leakage
and of explosive mixture formation is reduced to a minimum.
➢ An explosion-suppression system can be used to reduce the destructive pressure
of an explosion. These systems are designed to detect an explosion as it is
starting and to actuate devices that suppress, vent, or take other action to prevent
the full explosive force.

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