NEBOSH International General Certificate

in Occupational Safety and Health

Unit IG2

Element 10: Fire

Learning Objectives

• Describe the principles of fire initiation, classification and spread.

• Describe the basic principles of fire prevention and the prevention
of fire spread in buildings.
• Describe the appropriate fire alarm system and fire-fighting
arrangements for a simple workplace.
• Describe the factors which should be considered when
implementing a successful fire evacuation of a workplace.
10.1 Fire Initiation, Classification and
Spread

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Fire Triangle
Fuel:
A combustible material or
substance consumed during the
combustion process.
Oxygen:
From the air (which is 21% oxygen)
or oxygen-rich substances (oxidising
agents).
Heat or ignition source:
Energy to start the combustion
process.
Principles of Fire

Fire is a rapid chemical process in which

oxygen combines with another substance
(‘fuel’) in the presence of a source of heat.
This reaction is called combustion.
During this reaction, heat, flames and
smoke are produced.
Classification of Fire

This is the EU system.

There is no formal Class E. ‘Electrical fires’ is used for electrical equipment.

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Principles of Heat Transmission and Fire Spread

• Direct burning.
• Conduction.
• Convection.
• Radiation.
Principles of Heat Transmission and Fire Spread
Conduction

Convection

Radiation

8
Causes

• Electrical equipment.
• Deliberate ignition (arson).
• Hot work.
• Smoking.
• Cooking appliances.
• Heating appliances.
• Unsafe use and storage of flammable
liquids and gases.
• Mechanical heat.
• Chemical reactions.
Consequences

• People killed and injured.

• Damage to buildings and
contents including smoke
damage.
• Environmental damage, e.g.
water run-off.
10.2 Preventing Fire and Fire Spread

11
Control Measures to Minimise the Risk of Fire in a Workplace
Control combustible and flammable materials:
• Solids, liquids, gases.
Control ignition sources:
• Systems of work, smoking, arson.
Use of electrical equipment in flammable
atmospheres:
• Hazardous area classification.
Systems of work:
• Hot processes, machinery, electrical equipment.
Good housekeeping:
• General tidiness, waste control and disposal.
Control of Combustible and Flammable Materials

• Eliminate use altogether.

• Substitute for lower risk.
• Minimise quantities:
 Stock control, housekeeping, waste
management.
• Safe use and storage in protected,
dedicated buildings.
Control of Combustible and Flammable Materials
• Should be stored outside.
• Storage area should be fenced with secure,
lockable gate.
• Warning signs displayed.
• Ignition sources eliminated.
• Bottles chained upright.
• Separate from other buildings.
• Empty and full bottles separated.
• Oxygen bottles not be stored with LPG.
• Return to store immediately after use.
Control of Ignition Sources

• Electrical equipment.
• Hot work.
• Smoking.
• Cooking and heating
appliances.
• Mechanical heat.
• Deliberate ignition.
Use of Electrical Equipment in Flammable Atmospheres

• Flammable gas/vapour/dust mixed with

air can be explosive.
• Electrical equipment can ignite the
mixture.
• National legislation controls use of
electrical equipment:
 In EU, the ATEX Directives.
 In UK, transposed as the Dangerous
Substances and Explosive
Atmospheres Regulations 2002.
Use of Electrical Equipment in Flammable Atmospheres
• Zone 0 - a place in which an explosive
atmosphere is present continuously, or for long
periods, or frequently.
• Zone 1 - a place in which an explosive
atmosphere is likely to occur in normal
operation occasionally.
• Zone 2 - a place in which an explosive
atmosphere is not likely to occur in normal
operation but, if it does occur, will persist for a
short period only.

There are corresponding standards for dust

explosion hazards - these are called Zone 20, Zone
21 and Zone 22.
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Use of Electrical Equipment for in Flammable Atmospheres

Electrical Equipment Zone

Category 1 Zone 0 or Zone 20

Category 2 Zone 1 or Zone 21

Category 3 Zone 2 or Zone 22

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Systems of Work

Permit to work for control of hot work:

• Remove flammable materials from
the area.
• Cover items that can’t be removed.
• Sweep the floor.
• Damp down wooden floors.
• Provide suitable fire extinguishers.
• Ensure ‘fire-watcher’ present in the
area.
• Check area after work has finished.
Good Housekeeping

• Waste-free.
• Tidy.
• Well-ordered.
• Pedestrian routes clear.
Flash Point

The flash point - the lowest temperature at

which a liquid can form an ignitable
mixture in air (the vapour can be ignited by
an external ignition source but combustion
is not sustained).
The lower the flash point, the easier it is to
ignite the material.
Liquids are classified as:
• Flammable.
• Highly flammable.
• Extremely flammable.
Classification of Flammable Liquids
• Category 3: ‘Flammable liquids’:
 Flash point 23oC - 60oC.

 Easily ignited with a heat source, e.g. a match.

 Maximum storage in work area: <250 litres.

• Category 2: ‘Highly flammable liquids’:

 Flash point <23°C.

 Boiling point >35°C.

 Maximum storage in work area: <50 litres.

• Category 1: ‘Extremely flammable liquids’:

 Flash point <23°C.

 Boiling point <35°C.

 Very easy to ignite at room temperature.

Storage of Flammable Liquids

• Use the minimum volume of liquid

required.
• Liquid should be in a properly labelled
container.
• Ideally, the container will be metal with a
self-closing lid.
• Use a metal tray to catch spills and have
absorbent material available.
• Use away from heat and ignition sources.
• Ensure that workspace is well-ventilated.
• Return containers to safe storage after use.
Small quantities storage of Flammable Liquids

• Use minimal quantities.

• Store sealed (lids on, or self-closing lid).
• Flammable cabinet:
 Fire resistant (metal).
 Lockable lid/doors.
 Clearly signed.
 Spill tray.
• Away from ignition sources.
Larger quantities storage of Flammable Liquids
• Purpose-built, single-storey flammables store, segregated
chemicals.
• Built of non-combustible materials, lightweight roof for
explosion relief.
• Built outdoors away from other buildings or having firewall
protection.
• The store suitably fenced in a secure area.
• All electrical systems intrinsically safe, all other ignition
sources eliminated.
• Store being well-ventilated at high and low levels.
• All access doors lockable with sill to contain spillages.
• Adequate fire-fighting equipment, suitable fire safety signs.
• Regular checks for security, safe storage of substances.
• Clear, safe access for fire service, adequate means of escape.
Compartmentation

• Keeping fire and smoke in or out of area

of building.
• Creating enclosed/sealed boxes using fire-
resistant materials.
• Fire is contained in one part of the
building.
• Only fully effective if openings in the
compartment walls are sealed.
• Local building regulations play a major
part in applying high standards of
compartmentation to workplaces.
Characteristics of fire door

• Able to withstand fire for a set time (e.g.

30 mins).
• Fitted with self-closing devices.
• Fitted with intumescent strip (expands
when hot).
• Fitted with a cold smoke seal.
• Have vision panels of fire-resistant glass
(typical).
• Clearly labelled.
Properties of Common Building Materials

Concrete: Usually performs well in a fire.

Steel: Severely affected by high temperatures.
Brick: Usually very resistant.
Thin timber will burn quite quickly; thick timber
Timber:
will survive for longer.

Surface treatment can improve fire performance:

• Encasing steel in concrete.
• Intumescent paint.
• Insulation.
• Wall coverings.
Properties of Common Building Materials

Insulation:
• Must be fire retardant.
Wall coverings:
• Can be flammable so
need to be carefully
selected.
Protection of Openings and Voids
Openings:
• E.g. service conduits, air handling
ducts.
Voids:
• E.g. stairwells, voids between floors,
roof voids.
Protection:
• Self-closing shutters.
• Fire break walls.
• Procedure to seal any new openings,
e.g. with fire-retardant foam.
10.3 Fire Alarm Systems and Fire-
Fighting

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Fire Detection and Alarm Systems
• Simplest system:
 Someone shouts ‘Fire!’
• Simple with more noise:
 Hand bell, whistle or air horn.
• Manually operated fire alarm:
 Manual call points.
• Interlinked smoke alarm:
 Links normally unoccupied rooms to interlinked smoke
alarms.
• Automatic fire detection and alarm:
 Automatic detectors, manual call points, linked to
sounders/lights.
The sophistication will depend on the complexity of workplace.
Fire Detection and Alarm Systems
Smoke detectors:
• Detect small smoke particles.
• Very sensitive, early warning.
• Two main types: ionising and optical.
• Can give rise to false alarms.
Heat detectors:
• Detect excess heat generated by a fire.
• Less sensitive, later warning.
• Two main types: rate of rise and fixed
temperature.
• May not detect fires that are giving off smoke but
not much heat.
Portable Fire-Fighting Equipment

• Fire extinguisher.
• Fire blankets:
 Physically smother fires, e.g. fat
fires in kitchens.
• Hose reels:
 Used in large buildings for fire
teams.
• Sprinkler systems:
 Sited in buildings and warehouses.
 Automatically dowses the fire.
Extinguishing Media

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Fire Extinguisher Siting

• On fire exit routes.

• Close to exit doors.
• Close to specific hazards.
• Fixed to the wall or on
stand/trolley.
• Clearly visible.
• Signed.
• Unobstructed access.
Fire Extinguisher Inspection & Maintenance
Inspection:
• Regular and frequent to ensure they
are:
 In place (firing pin).
 In good working order.
Maintenance:
• Ensure they remain in safe working
order.
• Once a year.
• Certificated engineer.
• Inspection, testing, dismantling.
Fire Extinguisher Training

• Theory training.
• Types of extinguisher.
• Hands-on experience.
• Records kept in line
with local regulations.
Access for Fire and Rescue Services
The requirements for vehicle access differ
depending on the:
• Presence of fire mains.
• Size of the building.
• Type of fire appliance to be used.
• For small buildings without a fire main, access
for a pump appliance should be provided to 15%
of the perimeter.
• For large, high-rise buildings, the entire
perimeter will need to be accessible.
• Site should have an emergency plan including
liaison with fire service.
• Familiarisation visits may be carried out.
10.4 Fire Evacuation

40
Means of Escape
• Available to every person in the
workplace.
• Does not require use of lifts (expect
in special cases).
• Must take person to a place of safety.
• Two or more separate routes may be
required.
• Travel distance should be short.
• Adequate width.
• Clearly signed.
• Appropriately lit.
• Emergency lighting.
• No obstructions.
Means of Escape
Travel Distances depends on:
• Number of people occupying a room.
• Travel distance to nearest available:
 Final exit - to a place of total
safety.
 Storey exit - into protected
stairway.
 Separate fire compartment -
containing final exit.
• Fire risk.
• Number of alternative escape routes
available.
Means of Escape

Stairs and Passageways:

• Fire-resistant protection.
• Adequate width:
 Consider wheelchair users.
• Unobstructed.
• No storage of materials or
equipment.
Doors

• Easy to operate.
• Adequate width.
• Open in direction of
travel.
• Not locked.
Emergency (Escape) Lighting

• At night or where there is no

natural light.
• To indicate escape routes.
• To indicate call points and fire-
fighting equipment.
• Regular maintenance.
• Routine inspection/testing.
Exit and Directional Signs

• Standard shape.
• Standard colour.
• Pictogram.
• Easy to interpret.
• Clearly visible.
Assembly Points

• Safe distance from building.

• Safe location.
• Further escape possible if
needed.
• Must not impede fire-fighters.
• Clearly signed.
• 'Refuges' for disabled workers.
Emergency Evacuation Procedures

Emphasis is on personal safety:

• Sound the alarm.
• Get out of the building.
• Stay out of the building.
More complex procedures needed
for some workplaces, e.g. hospitals.
Fire Marshals

Typical duties:
• Check all areas are evacuated.
• Assist disabled/infirm
workers.
• Ensure fire escape routes are
kept clear.
• Ensure windows and doors
are closed.
• Conduct roll call at assembly
point.
Roll Call

• Ensure all persons

accounted for.
• May not be practical, e.g.
supermarkets.
Provision for the Infirm and Disabled

• Staff with disabilities may need

personal evacuation plans:
 Assist with travel
downstairs.
 Alert those with hearing
impairment.
• May need to consider temporary
disabilities, e.g. use of crutches.
• Consider also evacuation of
young/elderly.
Building Plans and Emergency Escapes

Fire plans should include:

• Who is likely to be in premises.
• Action to be taken on discovering
fire.
• Escape routes.
• Fire-fighting equipment.
• Action to be taken after evacuation.
• Training.
Training and Information

Information on fire safety procedures

for:
• Employees.
• Contractors.
• Visitors and the public.
Training for staff:
• Who use portable extinguishers.
• Fire marshals.
• Assist disabled or infirm people.
• Members of the fire team.
Fire Drills

• Usually once or twice a

year.
• Allows staff to practise
procedures.
• Allows for testing of those
procedures.
• Records kept.
Summary

In this element, we have:

• Outlined some of the basic principles of fire safety such as: the fire
triangle, the five classes of fire, the methods by which fire can
spread and some of the common causes of workplace fires.
• Explained how fire and the spread of fire can be prevented by
controlling potential fuel sources and potential ignition sources.
• Outlined the structural measures that exist to contain fire and smoke
in the event of a fire starting, and the use of self-closing fire doors.
Summary

• Described the general principles of fire detection and alarm

systems.
• Discussed types of fire extinguisher commonly used, such as
water, carbon dioxide, foam, dry powder and wet chemical, and
the strengths and limitations of each type.
• Outlined the principal characteristics of a means of escape.
• Described basic requirements for evacuation procedures, fire
marshals, training and information, the capabilities of employees,
fire drills and special procedures for the infirm or disabled, and
the inclusion of escape routes in building plans.