Ch.

E-104 Health and Safety at

Workplace

Ms.Sobia Anwar
Fire

❖ Fire is the rapid oxidation of a combustible material releasing heat, light,

and various reaction products such as carbon dioxide and water.
❖ Fire is one of the most common hazard
❖ Fire in oil and gas industry

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Fire Triangle

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 Fire Triangle
❖ Fuels:
• Oxidizers ❑ Liquids
❑ Gases
➢ gasoline, acetone,
➢ Oxygen, fluorine, ether, pentane
chlorine
➢ hydrogen ❑ Solids
peroxide, nitric ➢ plastics, wood dust,
acid, perchloric fibers, metal particles
acid
❑ Gases
❑ Solids
➢ acetylene, propane,
➢ Metal peroxides, carbon monoxide,
ammonium
nitrate hydrogen
❖ Ignition sources
❑ Sparks, flames, static
electricity, heat

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How to extinguish fire????
Cooling (Remove heat)
Starvation (Cut fuel supply)
Smothering (Stop Air supply/contact)

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Types of fires

❖ Fire is generally divided into five major classes based on the type of fuel.
1. Class A-Ordinary combustible materials
2. Class B- Flammable liquids
3. Class C- Flammable gases
4. Class D- Metal fires
5. Class E- Electrical Fires
And in some cases, Class F - Cooking oil fires

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 Class A-Ordinary combustible fires

❖ Probably the most common type of fire.

❖ Occur when materials become heated to their ignition temperature and
will continue to burn if there is heat, oxygen and fuel to burn.
❖ Materials involved in these types of fires include
❑ Paper, wood, textiles, rubber,
❑ Some plastics and
❑ Other organic carbon-based compounds.

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 Class A-Ordinary combustible fires

❖ Class A fires are probably the easiest to extinguish

❑ Spraying them with water will cool the fire, removing the heat supply which is
essential for the fire to burn.
❑ Water based or foam-based fire extinguishers are most appropriate for putting
out ordinary combustible fires.

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 Class B- Flammable liquids

❖ Flammable liquids are those that have an ignition temperature of less than
100°C.
❖ These liquids also have a low flashpoint, which means that can burn easily.
❖ These liquids can however burn at any temperature if a source of ignition,
such as a spark or naked flame is supplied.

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 Class B- Flammable liquids

❖ Examples of flammable liquids are

❑ Petrol,
❑ Kerosene,
❑ Alcohol,
❑ Solvents and
❑ Paints.

❖ Fires involving these liquids give off a lot of heat

and tend to spread very quickly.
❖ Also produce thick, black toxic smoke.

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 Class B- Flammable liquids

❖ The best approach for extinguishing a Class B fire is to use a foam fire
extinguisher to smother(to extinguish fire by covering to cut off from air) the
flames.
❖ Using water causes the fuel to scatter therefore spreading out the fire.

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Class C- Flammable gases

❖ Flammable gases have the potential to create an explosion, if triggered by a

single spark.
❖ These include
❖ Butane,
❖ Propane and
❖ Petroleum gases
❖ Secure storage in sealed containers is needed
for these gases.
❖ The lower flammable limit states the lowest
concentration of flammable gas that will burn in
air. It is usually around 5%.

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Class C- Flammable gases

❖ Class C fire is the most dangerous types of fire to fight.

❖ Before attempting to put the fire out, you should make sure that the gas
supply is isolated first.
❖ For this type dry powder extinguishers are suitable.

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Class D-Metal fires

❖ Certain metals can burn if ignited.

❖ It requires a lot of heat to ignite most metals, as they are good conductors
and transfer heat away quickly to their surroundings.
❖ Powdered metals are easier to ignite than solid lumps of metal

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Class D-Metal fires

❖ Alkali metals can burn when in contact with air and water. These include
❑ Potassium,
❑ Magnesium,
❑ Aluminum and
❑ Sodium

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Class D-Metal fires

❖ If a metal fire is determined early , specialist type D powder fire extinguishers

can be effective,
❖ It should be ensured that the specific dry powder type extinguishers are
suitable only for use on metal fires.
❖ In many cases with industrial fires where there are large amounts of burning
metal, the safest approach is usually to let the fire burn itself out. As Class D
fires tend to produce a lot of ash, this builds up and eventually
starves(discontinue) the fire’s oxygen supply.

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Class E-Electrical Fires
❖ Electrical fires are not strictly a fire class of their own, as electricity is a
source of ignition as opposed to a fuel.
❖ Important to mention due to special fire safety requirements.
❖ Short circuits, overloaded switchboards, faulty equipment and damaged
wiring can all cause electrical fires.

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 Class E-Electrical Fires

❖ Before dealing with an electrical fire, the supply of electricity must be

isolated as quickly as possible.
❖ Foam and water-based extinguishers should not be used to put out the
fire.
❖ Carbon dioxide and dry powder fire extinguishers are the only types of fire
extinguishers recommended for safely tackling electrical fires.

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Types of fire extinguishers
Water and Foam

Carbon Dioxide

Dry Chemical

Dry Powder

Wet Chemical
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Water and Foam

❖ The Water extinguisher eliminates a fire by allowing water to take away the
heat component of a fire
❖ Foam extinguisher eliminates a fire by separating oxygen from the fire.
❖ Water extinguisher only suitable for Class A fires.
❖ Foam extinguisher can only be used on Class A and Class B fires only.

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 What is foam???
❖ A fire fighting foam is simply a stable mass of small air-filled bubbles, which
have a lower density than oil, gasoline or water.
❖ Foam is made up of three ingredients - water, foam concentrate and air.
❖ When mixed in the correct proportions, these three ingredients form a
homogeneous foam blanket.

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 Carbon Dioxide
❖ This type of fire extinguisher takes away the oxygen from a fire and removes
the heat with a cold discharge.
❖ Suitable for fires caused by electricity and liquid combustibles.

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 Carbon Dioxide
❖ Carbon dioxide has a higher density. It surrounds the fire and cut off the air
supply.

❖ Carbon dioxide does not conduct electricity.

❖ It covers the flammable liquid and cut off the air supply.

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Dry Chemical
The Dry Chemical Extinguisher removes the chemical reaction of a fire.
In this category the multi-purpose Dry Chemical extinguisher is the most
used fire extinguisher of all extinguishers.
It is effective on Class A, Class B and Class C fires.

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Dry Powder
Similar to the dry chemical extinguisher, dry powder separates fuel from
oxygen or removes the heat element of a fire.
Dry powder extinguishers are used on Class D fire.

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 Fire Prevention Goals
❖ Life safety
❑ The primary goal of fire safety efforts is to prevent loss of life.

❖ Property protection
❑ The secondary goal of fire safety is to prevent property damage.

❖ Protection of operations
❑ By preventing fires and limiting damage we can assure that work
operations will continue.

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 Fire Protection
❖Alarms
❑Know WHERE the nearest fire alarm box is located.

❑Know HOW to turn on an alarm.

❑Know how the alarm sounds and the proper EVACUATION ROUTE

❖Extinguishers
❑Know where the nearest fire extinguisher is located.

❑Know how to operate it.

❑Know the type of fire it should be used on.

❖Refueling
❑Equipment shall not be refueled while running or hot.

❖Smoking
❑Smoking is permitted only in approved smoking areas.
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 Fire Protection Systems
❖ Active fire protection systems means active all the time for protection.
❖ Active fire protection systems such as water sprinkler, spray systems, and
smoke ventilation systems are widely used in the process industries for
protection of storage vessels, process plant, loading and installations.
❖ The duty of the fire protection system may be to extinguish the fire, control
the fire, or provide exposure protection to prevent dominant effects.

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 Fire Protection Systems
❖Passive fire protection System means it will be active when required but
not all the time e. g., fire resistant walls and floor and fire stopping fire doors,
❖Passive fire protection can provide an effective alternative to active systems
for protecting against vessel failure. This generally consists of a coating of
fire-resistant insulating media applied to a vessel or steel surface.
❖ It is often used where water or other active protection media supplies are
inadequate, such as in remote locations, or where there are difficulties with
handling fire water run-off.
❖Fire walls are another form of passive fire protection that are used to prevent
the spread of fire and the exposure of adjacent equipment to thermal radiation.
❖An important criterion in deciding which system is most appropriate for fire
exposure protection is the likely duration of the exposure to fire as passive fire
protection is only effective for short duration exposure (1-2 hours).

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Fire alarm systems

Automatic fire sprinklers

Fire escapes
(A fire escape is a special kind of emergency exit, usually
mounted to the outside of a building or occasionally inside but
separate from the main areas of the building.)

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Fire extinguisher cabinets

Fire extinguisher cylinders

Fire extinguishing blankets

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Fire extinguishing compounds

Fire fighting foam

Fire hose(pipe) nozzles

Fire resistant curtains

Fire protection systems

Standpipes
Flame retardants
(to slow down flame)
Asbestos, aluminum hydroxide,
magnesium hydroxide, boron
compounds, red phosphorus, various
hydrates.