Fire and explosion hazards

FIRE AND
EXPLOSION
PREPARED BY-
SANJAY KUMAR PUROHIT
M.PHARM(Q.A)

INTRODUCTION
 FIRE:
- it is the rapid oxidation of a material in the exothermic
chemical process of combustion , releasing heat , light &
various reaction products .
- Fire prevention in the workplace starts out with knowledge of
knowing different types of fires & how to control them in the
case of emergency.
- There are four different types of fires .each of which have
different fire extinguishers to be used .
 Types Of Fires :
1) Class A Fires :
2) Class B fires :
3) Class C fires :
4) Class D fires :
2

1) Class A Fire :
- These are fires in ordinary combustible materials such as wood , cloth ,paper etc.
Those produce glowing ember .
2 ) Class B Fire :
- These are the fires of flammable petroleum , liquids , gases & greases
etc..
3

3) Class C Fire :
-These fires involved energized electrical equipment .
-These fires are the one that come from equipment such as power lines &
transformers .
4) Class D Fire :
-These are fires in combustible metals.
-In this type of fire where metal used in the workplace is unstable & catch on fire . Or
the metal could be stationary & because of certain environment conditions & its
chemical compound it could immediately react & combust .
Ex. – aluminium , titanium ,magnesium .
4

 CHARACTERISTICS OF FIRE :
1) Fire can cause large losses ( human & materials)
2) Chemical reaction requires three components : Fuel , Oxygen ,
Ignition source [ Fire triangle ].
3) Ignition can be caused by convection , conduction & radiation .
4) Several type of combustion process depending on the combustion
rate.
A) Slow combustion ( no flames , very low temp )
B) Normal combustion ( controlled combustion rate )
C) Explosion ( very quickly )
D) Detonation ( very quickly & propagates very quickly ) chrome
5

Influencing factors
1) Flash
point
(Minimu
m
ignition
temp.)
2) Auto ignition
temp.
3)Concentration
of gas
4) Density of gas 5) Catalysts
6) Oxidizing
substances.
Factors influencing fire :
6

 Sources of fire hazards :
1) Hot surfaces
2) Combustible & flammable liquids
3) Heat utilization equipments ( over heating )
4) chemical process equipments
5) Gas cylinders
6) Ovens & surfaces
7) Reactor
8) welding & cutting
9) spark from metal to metal contacts
10) carelessness
7

EXPLOSION
8
• An explosion is a rapid increase in volume & release of energy in an extreme
manner , usually with generation of high temp. & the release of gases.
•Supersonic explosion created by high explosives are known as Detonations &
travel via supersonic shock waves.
•Subsonic explosions are created by low explosives through a slow burning
process known as Deflagration.
•There are several types of explosion that can happen , some more common in
the workplace than others . Most of which are not even possible to occur in
everyday circumstances .
•Difference between fire & explosion is the rate at which energy is released . In
fire it is at slow rate & in explosion it is at high rate & sudden release.

9
Types of explosion :
1) Natural explosion :
- These are the explosions that occur in nature such as volcanic
eruptions & explosions , during forest fires from the igniting of
oils in three tops.
2) Chemical explosion :
- These are the most common explosion that occur, mostly in the
areas that use it during the job operation such as ammunition
testing areas.
- These type including explosion such as gun powder , TNT, &
dynamite.

10
3) Nuclear explosion :
-This is an explosion derived from fission & fusion in a nuclear reaction , even
the smallest nuclear weapon is powerful enough to destroy an entire city ,
making them deadly hazard.
4) Electrical explosion :
-Excessive magnetic pressure within an ultra – strong electromagnet can
cause a magnetic explosion .
- A lightning bolt is another form of electric explosion .
5) Astronomical explosion :
- It is biggest type of explosion & are also the least possible to occur in normal
circumstances.

11
6) Mechanical explosion :
- These are completely physical , mechanical , occur when a tightly sealed
container under pressure encounter a break , at which it release its gases or
liquids rapidly causing an explosion.
Astronomical explosion

12
INDUSTRIAL PROCESSES & HAZARD POTENTIAL
 Hazard : it is situation possesses a level of threat life , health , property or
environment .
Industrial hazard : it may be defined as any condition produced by
industries that may cause injury or death to personnel or loss of product or
property .
Safety : it defined in simple terms means freedom from occurrence of risk or
injury or loss.
Industrial safety : it refers to the protection of workers from the danger of
industrial accidents .
Types of hazards :
1) Mechanical hazard :
2) Electrical hazard:
3) Thermal hazard:
4) Process hazard :

13
 Mechanical hazard :
-It is any hazard involving a machine or process .
-Motor vehicle , aircrafts & air bags , pose mechanical hazard . Compressed gases or
liquids can be considered a mechanical hazard.
Source of mechanical hazard :
- it occurs when machine is a malfunctioning .
- machines may run either manually or automatically .
-A few machines are cutting , shearing , crushing & breaking .
-Large number of equipments
-Crowded workplace conditions .
-Failure of SOP
-Dangerous parts
-Improper maintenance of equipments .
-Electrical or power supply.
Factors responsible for mechanical hazards are :
a) Physical factors : physical capabilities of worker may not meet the job
requirements.
b) physiological factors : The various physiological factors that affect the
mechanical hazards are age , sex, time & experiences .

14
Prevention of mechanical hazards :
-Requirements for safeguards - safeguard must meet these requirements :
1) Prevent contact :
- It prevent hands , arms or any part of worker’s body from making
Contact with dangerous moving parts .
2) Secure :
- Workers should not be able to easily remove with the safeguards. Guards & safety
device made up of durable material that will withstand the conditions of normal
use.
3)Protect from falling objects :
- The safeguard must ensure that no objects can fall into the moving objects . A small
tool which dropped in a cylinder machine could easily become a projectile that
could strike & injure someone.
4) Create no new hazards :
- The edges of guards must be rolled or rounded in such way that eliminates sharp
edges & prevent unwanted injuries.

15
5 ) Create no interferences :
-Proper safeguarding can enhances efficiency , since worker will not afraid of injuries
then.
-6) Allow safe lubrication :
-If possible , one should able to lubricate the machine without removing the
safeguards. Locating oil reservoirs outside of the guard, with a line leading to the
lubrication point.
- it will reduce the need of operator or maintenance worker to enter the hazardous
area.

16
 Electrical hazards :
-It is a dangerous conditions where a worker could make electrical contact with
energized equipment or a conductor , & from which the person sustain an injury from
shock .
-These is a potential for the worker to receive a arc flush burn, thermal burn, or blast
injury.
Improper use & maintenance of
apparatus
Improper use of electrical outlets
Overloaded circuit
Improper joint of two wires
Worker touch the phase having wet cloth
& high humidity .
Worker touches another person receiving
shock.
Worker receives shock from electrical
components not grounded properly .
Worker touches two wires at different
voltages at same time.

17
Prevention of electrical hazard :
A) ELECTRICAL SAFETY POLICY :
- Power equipment should be plugged into wall receptacles with power
switches in the off positions.
- Electrical equipment should be unplugged by grasping the plug & pulling.
Never pull or jerk the cord to unplug the equipment.
- Cracked , exposed wiring on equipment cords must be corrected .
- Temporary or permanent storage of material must nor allowed within the
3 feet of electrical equipment .
- Any electrical equipment causing shocks or which has high leakage
potential must be tagged with DANGER – DO NOT USE label or
equipment.

18
B . Responsibilities of individual employee :
1)Training & education :
- Employees should be trained in electrical safety work practices & equipment
operation .
2)Hazardous conditioning reporting :
- Employees should always report unsafe equipment conditions or procedure .
3)Work practices :
- Employees always follows safe work practices , procedures & policy.
4)Housekeeping :
- Good housekeeping requires all employees to observes activities that could cause
electrical shock hazards .
Ex . Electrical equipment that is not properly grounded in the areas that have water
on the floor can create shock hazards .
- cleaning tools & electrical equipment with solvents can create health & physical
safety problems .

Fire (Thermal) Hazards
 Fire is an exothermic chemical reaction between
oxygen and fuel.
 Combustion Slow combustion eg: cotton waste
burning Rapid combustion
 eg: petroleum product Spontaneous combustion eg:
paint, scrap
 The effect of fire on people take the form of skin burns
Fire can take several different forms including jet fires
pool fires and boiling liquid expanding vapour
explosion.
19

Sources of fire hazards :-
1) Hot surfaces
2) Combustible & flammable liquids
3) Heat utilization equipments ( over heating )
4) chemical process equipments
5) Gas cylinders
6) Ovens & surfaces
7) Reactor
8) welding & cutting
9) spark from metal to metal contacts
10) carelessness
20

Steps to be taken
 Don't panic
 Raise the alarm
 Evacuate the premises
 Turn off the gas supply
 Attack the fire with extinguisher
 vacate the place
 In case of fire safe methods to be followed
 Stair cases only to be used for evacuation
 Exit doors should be closed after getting out
 Go down the stair case to the ground
 Walk do not run
21

4. Process hazards:-
 Process hazard due to dust, sticky material, and previous
contamination of other products.
 Sources of dust hazards:-
 grinding or milling of drugs,excipients.
 during weighing dusts may flot on air.
 during powder mixing dusts may be generated.
 during coating operation dust are generated.
 during capsule filling and tablet punching dusts
may be generated.
23

Prevention of dust hazards:-
2. Filtration
24
1.Inerital
separation
3.Electrostatic
separator

Types of extinguisher:-
 Water based
 Dry powder based ( ABC extinguisher)
 Foam based
 Wet chemicals and water additive based
 Carbon dioxide based
25

 The hazard management process:
i. Identification of the hazards.
ii. Determination whether the hazard can be eliminated or
isolated.
iii. Assessing the remaining hazard to determine whether they are
principle hazard or significant hazard.
iv. Developing and introducing principal hazard management
plans for principal hazards.
v. Developing and introducing principal control plan for all
principal control mechanisms.
vi. For remaining hazard where they can not be eliminated or
isolated , conducting a risk assessment to minimize the
likelihood of the hazard
vii. Participation of workers in the identification , assessment and
control hazard
27

• Procedure:-
1. Identification of hazard
This is a fundamental step in hazard management.
Some ways of identifying the hazard:
Workplace inspection
Incident reporting
Consultation with employees
Feedback from employs
28

2. Risk assessment
After identification of hazard need to assess the risk created by each
hazard will cause, injury , illness or disease.
3. Hazard control
It is not enough to just find and rate the hazard’s.
After find the hazard is important to eliminate or control the hazard before
the injury or illness of people due to hazard
4. Evaluate , monitor and review
It is important to know if your risk assessment was complete and accurate
, it is also essential to be sure that changes in the workplace have not
introduced new hazards.
29

EXPLOSION
 An explosion is a rapid increase in volume and release of energy in
an extreme manner, usually with the generation of high
temperatures and the release of gases.
 There are three fundamental types
 Mechanical
 Nuclear
 Chemical.
A mechanical explosive is one that depends on a physical reaction.
such as overloading a container with compressed air.
31

 A nuclear explosive is one in which a sustained nuclear reaction
can be made to take place with almost instant rapidity,
releasing large amounts of energy.
 Chemical explosives are of two types:
 (1) Detonating, or high, explosives and
 (2) Deflagrating, or low, explosives.
 Detonating explosives, such as TNT and dynamite, are
characterized by extremely rapid decomposition and
development of high pressure, whereas deflagrating explosives,
such as black and smokeless powders, involve merely fast
burning and produce relatively low pressures. Under certain
conditions, such as the use of large quantities and a high
degree of confinement, some normally deflagrating explosives
can be caused to detonate.
32

 For example, at high temperatures (> 2000 °C) a
mixture of nitrogen and oxygen can be made to react
rapidly and yield the gaseous product nitric oxide; yet
the mixture is not an explosive since it does not
evolve heat, but rather absorbs heat.
 N₂ +0,2 NO-43,200 calories (or 180 kJ) per mole of N
33

MECHANICAL EXPLOSION
 A physical process, as opposed to chemical or nuclear, e.g.. the
bursting of a sealed or partially sealed container under internal
I pressure is often referred to as a mechanical explosion.
Examples include an overheated boiler or a simple tin can of
beans tossed into a fire
 A mechanical explosion may be illustrated by the gradual
buildup of pressure in a steam boiler or pressure cooker. As
heat is applied to the water inside the boiler, steam is
generated.
 If the boiler is not equipped with some type of safety valve, the
mounting pressure will eventually reach a point at which it will
overcome the structural or material resistance of its container
and an explosion will occur. Such a mechanical explosion will be
accompanied by high temperatures. a rapid escape of gases or
steam and a loud noise.
34

CHEMICAL EXPLOSION
A chemical explosive is a compound or mixture which,
upon the application of heat or shock, decomposes or
rearranges with extreme rapidity, yielding much gas and
heat.For a chemical to be an explosive, it must exhibit all
of the following:
Rapid expansion (i.e., rapid production of gases or rapid
heating of surroundings)
 Evolution of heat
 Rapidity of reaction
 Initiation of reaction
36

 There are many chemical reactions that will release energy. These are
known as exothermic reactions. If the reaction proceeds slowly, the
released energy will be dissipated and there will be few noticeable
effects other than an increase in temperature.
 On the other hand, if the reaction proceeds very rapidly, then the
energy will not be dissipated. Thus, a great quantity of energy can be
deposited into a relatively small volume, then manifest itself by a rapid
expansion of hot gases, which in turn can create a shock wave or propel
fragments outwards at high speed.
 Chemical explosions may be distinguished from other exothermic
reactions by the extreme rapidity of their reactions. In addition to the
violent release of energy, chemical explosions must provide a means to
transfer the energy into mechanical work. This is accomplished by
expanding product gases from the reaction. If no gases are produced,
then the energy will remain in the products as heat.
37

MULTIPHASE REACTIONS
 A multiphase reaction refers to reactions
involving components in different phases,
and is a combination of simultaneous phase
change and conversion of some materials
into others.
 Multiphase reaction and reactor are in
chemical allied industry have great economic
and ecological importance.
38

Classification based on number of phases:
• Gas-solid catalytic
• Gas-solid non catalytic
• Gas-liquid solid catalytic
• Gas-liquid solid reaction
• Liquid-liquid
• Gas-liquid-liquid-solids
39

Multiphase catalytic
reactions -
40

Multiphase reaction
technology areas:-
41

Conti..
Multiphase reactions are very common in the
pharmaceutical industry and include.
e.g., hydrogenations, oxidations, halogenations and
phase-transfer catalysis reactions. They involve
combination of two or more immiscible phases (e.g.,
liquid. liquid, solid-liquid or gas-liquid reactions).
42

Conti..
 When mass transfer from one phase to the other is the
rate-determining step, it crucial to maximize the
interfacial area. In batch, the interfacial area is low and
poorly defines, thus, leading to prolonged reaction
times.
 Due to the small characteristic dimensions of micro
reactors, large and well defined interfacial areas are
observed, typically orders of magnitudes higher than
in traditional batch environments. These large
interfacial areas lead to efficient mass transfer between
the two phases.
43

Strategies of selection of
multiphase reaction:
44

Conti..
 Continuous flow (micro) reactor technology therefore
offers the unique possibility to perform multiphase
reactions, in particular gas-liquid chemistry, with
unparalleled efficiency and process safety. Gases can be
dosed into the flow system with precise stochiometry
using mass flow controllers and intense mixing of the
gaseous and liquid phase can be achieved.
 Furthermore, high pressure operation increases the
concentration of the gas in the liquid phase. Combustion
and explosion hazard are reduced in channels of small
diameter and, consequently, reactions can be performed
under unusually harsh process conditions in a safe and
controllable manner
45

TRANSPORT EFFECTS
 Dangerous goods can be transported without causing
unnecessary properly and with care hazards if inhaled.
1 WHAT ARE DANGEROUS GOODS?
 Dangerous goods can be explosive, flammable, toxic,
radioactive, corrosive or harmful in some other way to
humans, animals, or the environment. 50% of
transported goods are dangerous.
46

Conti..
 United Nations statistics show that half of all goods
transported belong to the category of dangerous
goods. Petroleum products transported by tankers
form a large proportion of all transported goods, but
road and railway transport is also significant. For
example, 85% of chlorine, which is one of the very
dangerous chemicals, is transported by rail.
 Large amounts of other highly dangerous goods, such
as hydrochloric acid, sulphuric acid, sulphuric dioxide,
nitric acid, phenol and methanol are transported
regularly. Major accidents caused extensive damage
but that is not all.
47

Conti..
 We forget easily that small amounts of oil, gasoline,
battery acids and refrigerator fluids are released to
environment daily. Even small but frequent wastes
from ships. households, cars or agriculture increase the
load to the environment.
48

 For example: one litre of oil can, under unfavourable
circumstances, spoil 100000 litres of drinking water. A
spill of hydraulic fluid from a truck can lead to
environmental damages.
49

2 DANGEROUS SITUATIONS
• There is always a risk of spillage during the transport of
hazardous goods. When incompatible substances mix
with each other there is a possibility of chemical reaction.
which can produce enough heat to cause fire or explosion
and can release dangerous gases.
50

Conti..
For example, toxic nitrous oxides are formed when
ammonium nitrate (in fertilizers) decomposes in a fire.
Another example is the toxic gases which fume off when a
spillage of concentrated sulphuric acid is absorbed in
sawdust.
• Special conditions can increase the risks A chemical
substance or preparation may be hazardous in itself when it
comes into contact with other chemicals including air, water
or humidity. For example, when calcium carbide (used in the
production of acetylene and pyrotechnics) comes to contact
with water, it releases the extremely flammable gas acetylene
(used in welding flame) and creates an explosion hazard.
51

VEHICLE REQUIREMENTS
 Transport by road may take place as bulk materials, or
in containers and tanks. The detailed technical
requirements for different transport methods are
usually given in national regulations.
52

• Declaration that the packing and labelling is properly done.
• Transport emergency card (instructions in writing in case of accident
or emergency
that may occur during transport)
• Certificate of approval given by technical inspection for the tank and
vehicle.
• Labels and placards for the vehicle.
• Driver's training certificate
The transporter
should check that the
following documents
are attached Transport
document (letter of
consignment)
53

Global rates
 Global chemical industry generate more then 2 trillion USD gross
income
 They are larger contributor to GDP
 Distribution
54

Accident Statistics
 Fire and explosion contribute substantially to the risk
associated with chemical plant.
55

PREVENTIVE AND PROTECTIVE
MANAGEMENT FROM FIRES AND
EXPLOSION

Electricity passivation:
• Passivation includes the creation of an outer layer of
guard/ shield material that is applied as a micro-coating
in semi-conductor devices of metallization films to reduce
the environmental effects.
• Passivation layers can be both organic and inorganic in
nature, among organic passivation layers, PI materials
have been widely used in electronic devices due to their
goo high temperature resistance, excellent mechanical
and electrical properties, and high chemical stability.
58

Ventilation
 The purpose of ventilation is to dilute the
explosive vapours with air to prevent
explosion and to confine the hazardous
flammable mixtures. Always provide
adequate ventilation to reduce the potential
for ignition of flammable vapours.
 Open Air Plants: Average wind velocities are
high enough to safely dilute volatile
chemical leaks which may exist within a
plant.
 Plant Inside Buildings
59

Types of ventilation:
a. Local exhaust ventilation: Local exhaust ventilation systems
remove the contaminant before it spreads through the
workplace. They are most useful for controlling toxic
materials when their airborne concentrations could exceed
legislated standards.
b. Dilution/general ventilation General (dilution) ventilation
systems supply clean air that mixes with the air in the
workplace, diluting the concentrations of the contaminant. It
is not suitable to control exposure to toxic substances
because these systems actually spread the contaminant
throughout the workplace before exhausting it
60

Sprinkler system:
 The system consists of an array of sprinkler heads connected to a water
supply. The heads are mounted in a high location (usually near ceilings) and
disperse a fine spray of water over an area when activated. The control point
is connected to an array of heat/or smoke detectors that start the sprinklers
when an abnormal condition is detected. It a fire is detected, the entire
sprinkler array within an area is activated, possible in area not areas not even
affected by the fire.
61

Proofing
All electrical devices are inherent ignition sources. Most safety
practices for electrical installations are based on the National Electric
Code (NEC). Process areas are divided into two major types of
environments/area Explosion Proof (XP) Flammable materials
(particularly vapours) might be present at certain times Non-
Explosion Proof abnormal conditions.(non-XP: Flammable materials
are not present even under
62

Relief Valves
 A relief valve or pressure relief valve (PRV) is a type of
safety valve, used to control or limit the pressure in a
system; pressure might otherwise build up and create a
process upset, instrument or equipment failure, or fire.
 Process plant can be subjected to excessive overpressure
or under pressure due to External fire
 Process abnormality or mal-operation
 Equipment or service/utility failure
 Changes in ambient conditions
 Excess chemical reaction
63

Causes of safety relieve valve overpressure are:
 Blocked discharge
 Exposure to external fire, often referred to as "Fire Case’’
 Thermal expansion Chemical reaction
 Heat exchanger tube rupture
Uses of relief valves: The primary function of safety relief valves is
the protection of life, property and environment. A safety relied
valve is a device designed to protect a pressurised vessel or system
against over-pressure should all other safety system fails.
64

Flare:
 A flare, also sometimes called a fuse, is a type of
pyrotechnic that produces a bright light or intense heat
without an explosion. Flare is used for distress signalling,
illumination, or defensive countermeasures in civilian and
military applications. Flares may be ground pyrotechnics,
projectile pyrotechnics, or parachute-suspended to
provide maximum illumination time over a large area.
 A gas flare, alternatively, known as a "llare stack", is a gas
combustion device used in industrial plants such as
petroleum refineries, chemical plants and natural gas
processing plants. They are also common at oil or gas
extraction sites having oil wells, gas wells, offshore oil and
gas rigs and landfills.
65

 Gas flares burn up the flammable gases released by
pressure relief valves when flammable gases are
emitted by different types of plant equipment. This
prevents these excess gases, which may be harmful,
from leaking into the area immediately surrounding
the equipment. Flaring most often occurs during start-
up and shut down, when large amounts of excess gas
are built up.
66

Scrubbers:
 Scrubbers are air pollution control devices that use
liquid to remove particulate matter or gases from an
industrial exhaust or flue has stream. This atomized
liquid (typically water) entrains particles and
pollutant gases in order to effectively be them out
of the gas flow.
 They are also capable of handling explosive and
flammable gases safely. However, scrubbers suffer
from high levels of corrosion and produce slurry
waste streams which are less convenient for
recycling and disposal.
67

The major types of industrial
scrubbers are
a. Wet scrubbers: One of the most basic of the various
industrial scrubbers is the wet industrial scrubber. In its most
basic form, water is encapsulated in a metal or composite
container. Contaminated gas is passed through the water,
and the water absorbs the contaminants. Other liquids can
be used to effectively remove varied contaminates. These
liquids differ in the chemical composition and the overall
charge
b. Dry scrubbers: A dry industrial scrubber is composed of a
reaction centre where the sorbent or dry reaction material
that absorbs contaminants is mixed with the polluted gas.
Also within the system is material component that aids in the
removal of the reaction product, which is the dry sorbent
bound to the pollutant. Dry scrubbers are used primarily to
remove acids found within gasses.
68

C Electrostatic precipitators:
 Electrostatic precipitators function uniquely from the
different types of industrial scrubbers by using charged to
remove dust and other contaminants from a gas. It is
important to match the polarity and type of charge to
bind to and remove the pollutants from the gas. An
example of the design of an electrostatic precipitator is a
plate precipitator. The plate is a sheet of metal that is
charged with a specific type of charge. These plated are
designed to run parallel with the piping so that the gas
will pass through by the plate and the plated will remove
the dust or contaminate.
69

Fire and explosion hazards

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