Fire

Fire initiation, classification and spread

The Fire Triangle

Heat (source of ignition) - Sources of Ignition

Fuel - Sources of fuel

Oxygen - Sources of Oxygen

Naked flames

Fixed or portable heaters

Hot processes (e.g. welding)

Cooking

Electrical equipment

Machinery

Static electricity

Lighting

Discarded cigarettes or matches

Flammable liquids (e.g. petrol)

Flammable gases (e.g. Hydrogen)

Flammable chemicals (e.g. solvents)

Wood

Plastics, rubber and foam (e.g. furniture)

Paper and card (e.g. waste paper)

Insulating materials (e.g. wall and partition components)

Ambient air (most common source for fire)

In buildings, forced air ventilation

Leaks from oxygen cylinders

Oxidising materials (agents e.g. Hydrogen peroxide and Halogens)

Usual source of oxygen is ambient air

However, some materials known as oxidising agents can supply combustible materials with a source of oxygen which does not come from air

Oxidising agents speed up development of a fire and make combustion more intense

Very dangerous in oxygen deficient atmosphere, for example confined space entry

Classification of fires

Class A - fires involving solids (organic)

Class B - fires involving flammable liquids or liquefied solids

Class C - fires involving flammable gases (petrol, methane)

Class D - fires caused by burning metals

Class F - fires involving cooking oils and fats

Note; Electrical fires - strictly a 'class' but often a source of ignition

Principles of heat transmission and fire spread

Convection - Movement of hot gases rising from the source of fire

Conduction - Heat transfer through solid materials such as metal

Radiation - Transfer of infra-red radiation waves through air

Direct burning - Combustible materials in direct contact with a naked flame

Causes of fire

Unsafe act (e.g. welding near combustible material)

Misuse of equipment (e.g. overloaded electrical sockets)

Defective machinery or equipment (causing arcing)

Mechanical heat (friction from machinery)

Chemicals reactions (self-combustion of substances)

Poor control of hot work

Deliberate Ignition (arson)

Inadequately maintained machinery

Consequences of fire HEEL

Human

Environment

Economic

Legal

Fire Risk Assessment

Reasons for carrying out a fire risk assessment

To identify where a fire could start

To identify those persons who could be at risk

To reduce risks to an acceptable level

To comply with the law

Moral obligation

Financial reasons

Factors to consider when carrying out a fire assessment

Step 1 Identify the hazards

Sources of Heat/Ignition

Sources of Fuel

Sources of Oxygen

Step 2 Decide who might be harmed and how

People in the workplace

Consider how fire, heat or smoke may spread

Identify locations of people at risk

Identify vulnerable groups at risk (elderly, disabled)

Consider how people will be warned

Consider members of the fire response service

Step 3 Evaluate the risks and decide on precautions

Risk reduction by prevention

Reduce sources of ignition

Minimise potential fuel for fire

Reduce oxygen sources

Inspection of areas

Safe systems

Risk reduction by protection

Prevention of fire spread

Fire detection and alarm

Fire-fighting equipment

Means of escape

Roles & responsibilities

Evacuation training via fire drills

Maintenance on fire equipment

Sprinkler system

Step 4 Record, Plan, Inform, Instruct & Train

Record significant findings

Emergency plan (develop and communicate)

Fire management plan

Step 5 Review & Monitor

Change in legislation

Change to work processes

Change to layout and structure of workplace

Change to the number and type of people present

A near miss or fire occurs

Poor fire drill evacuation

Improvement notice

Temporary workplace & changes to workplaces

Particular attention must be paid to:

Accumulation of flammable waste & building materials

Obstruction or loss of exits and exit routes i.e. change of emergency lighting must follow

Fire doors propped open or removed

Openings created in fire-resisting structures

Isolation of fire detection or fixed lighting systems

Introduction of additional electrical equipment or other sources of ignition

Use of hot work processes

Introduction of flammable products e.g. adhesives or flammable gases

Certain works only to be carried out when the building is not at full capacity to reduce risk

How contractor manages their waste

Is residual risk manageable

Factors to review in fire risk assessment

Escape routes / Suitable of fire safety signage

Access & availability of firefighting equipment

Need for & suitability of escape lighting

Fire protection / fire resistant structures with building

Introduction of new fire hazards (e.g. hot works)

Correct storage / use of flammable materials

Site security / arson prevention

Fire prevention and prevention of fire spread

Control measures to minimise the risk of fire in a workplace

Use & storage of flammable & combustible materials

Eliminate if possible

If not possible to eliminate, reduce quantity

Substitute with less dangerous alternative

Storage should consider:

Storage area locked to prevent unauthorised access

Warning signs displayed

Flammable liquids & gases kept in suitable containers & labelled

Storage area kept well-ventilated

Lids kept on containers at all times (self-closing lids preferred)

Fire-fighting measures in place near the storage area

Control of ignition source

Hot work (welding)

Only use competent, trained welders

Regulators should be of a recognised standard

Colour code hoses (blue for oxygen, red for acetylene, orange for propane)

Non-return valves on blowpipe / touch

Flashback arrestors incorporating cut off valves

User of crimped hose connections not jubilee clips

Check equipment visually before use

Ensure work area is well-ventilated

Secure cylinders in an upright position, never drag cylinders

Keep hose lengths to a minimum

Permit-to-work system

Fire-watch - depending on temperatures raised determines cool down period

Smoking

Outside in designated area away from fuels

No smoking at least 30 mins before work stops

Arson

Secure access points

Security guards

Lighting (deterrent)

CCTV (deterrent)

Siting of waste skips away from building - on impermeable surface

Accumulation of waste to a minimum

Good perimeter fencing / barriers

Removal to store of any combustible material and keep locked shut

Other controls for sources of ignition

Mechanical heat (friction) - ensure lubrication of machine parts

Electricity - inspection, testing (Pac) and maintenance

Cooking and heating appliances - not left unattended; inspection, testing and maintenance

Safe Person, Safe Environment, Safe Materials, Safe Equipment (PEME)

Safe Person

How to raise the alarm

How to evacuate

Safe Environment

Information on fire compartments in the event of emergency

Information on escape routes

Information on the need to keep means of escape clear at all times

Lighting

Safe Materials

How to handle, use and store flammable liquid correctly

Information on logging out substances from store

Information regarding ignition temperatures of substances

Safe Equipment

Information on how to use equipment correctly

Information on intervals for inspection and maintenance

Information on how to switch off electrical equipment when not in use

Storage of flammable liquids

General principles

Ventilation

Ignition

Containment

Exchange

Separation

Storage of flammable liquids in workrooms

Store minimum volumes only

Storage of containers in purpose built flammable cabinet with lockable doors and drip tray

Good levels of ventilation

Ignition source not in vicinity of workroom

Flammable warning signs

Workrooms should not contain any other material

Workroom constructed to a 30 minute fire-resistance standard

Storage of flammable liquids in outside location

Storage area away from potential ignition sources

Storage area on impervious concrete with sumps for spills

Bonded kerbs to prevent liquid spread

Located away from other buildings

Secure fence and gate (2 metres)

Flammable warning signs

Protection from sunlight

Flame-proof lighting

Fire extinguishers located nearby

Full & empty containers stored separately

Storage area free of general waste

Prevention of the spread of fire and smoke - properties of common building materials

Brickwork

Resistant to fire because of exposure to high temperatures in kiln

Resistance of between 30 minutes and 2 hours

Steelwork

Severely affected by high temperatures; steel may twist and warp

Twist and warp can lead to building collapse

Timber

Performs well in fires when of sufficient size

Outside becomes charred which slows combustion process

Glass

Performs poorly unless fire-resistant

At high temperatures glass will melt and sag

Concrete

Highly resistant to fire

Heat will make concrete spall (small sections break away)

Prevention of the spread of fire and smoke - structural measures

Use of fire-resisting materials

Division of workplace into discrete fire resistant zones (compartmentation)

Stairwell compartmentation

Fire-resistant doors (smoke & intumescent seals)

Fire-resistant windows

Seal voids e.g fire curtains

Fire dampers in duct work

Fixed sprinkler systems in buildings

Use of venting systems to allow smoke and toxic fumes to escape

Prevention of the spread of fire and smoke - protection of openings and voids

Openings and voids include lift shafts, service ducts, voids between floors, roof voids

Controls include:

Fire shutters

Cavity barriers

Fire curtain

Sealing holes in walls

Use of suitable electrical equipment in flammable atmospheres

Classification of areas where explosive atmospheres may occur

3 zones for gases and vapours

Zone 0 - Flammable atmosphere highly likely to be present; may be present for long periods or even continuously

Zone 1 - Flammable atmosphere possible but unlikely to be present for long periods

Zone 2 - Flammable atmosphere unlikely to be present except for short periods of time; typically as a result of a process fault condition

3 zones for dust

Zone 20 - Dust cloud likely to be present continuously or for long periods

Zone 21 - Dust cloud likely to be present occasionally in normal operation

Zone 22 - Dust cloud unlikely to occur in normal operations but, if it does, will only exist for a short period

Depending on zone where work is being done, the correct selection of equipment must be made:

'Intrinsically safe' - cannot produce a spark with sufficient energy to cause ignition - symbol Ex ia (suitable for zones 0, 1, 2 & 20, 21, 22)

'Flameproof' - ingress of explosive atmosphere is controlled and any ignition is contained in the equipment - symbol Ex d (suitable for zones 1, 2 & 21, 22)

'Increased safety' equipment - does not produce sparks or hot surfaces - symbol Ex e (suitable for zones 1, 2)

Fire alarm system & firefighting arrangements

Types of fire detection

Heat detection

Radiation detection

Smoke detection

Flammable gas detection

Types of alarm system

Voice

Hand-operated

Call points with sounders (and lights)

Automatic

Factors to consider when siting extinguishers

Position them along escape routes

Make them accessible

Make them visible

Place in designated holders

Within reasonable distance

Same position on different levels of building

Away from source of extreme heat, cold, dirt or dust - so far as is reasonably practicable

Maintenance of fire extinguishers

Servicing must be carried out by a competent person

Full servicing involves inspection (internal & external), refilling & re-pressurisation

Monthly checks

Training requirements for use of portable fire extinguishers

Understanding of the principles of combustion

Identification of the various types of extinguisher

How to identify whether extinguisher is appropriate to use

Principles of use & limitations of extinguishers

Considerations for personal safety when using extinguishers

How to tackle fires correctly

Any specific issues relating to the workplace

Extinguishing media - general (portable extinguishers)

Water - colour code red - suitable for Class A fires

Foam - colour code cream - suitable for Class B fires

Dry powder - colour code blue - suitable for Class A, B, C, D fires

Carbon dioxide - colour code black - suitable for Class B fires (early stages)

Limitations of extinguishing media

Water - not suitable for Class B, C, F, or electrical fires

Carbon dioxide - generally not suitable for Class D metals, & ineffective in an outdoor environment

Dry powder - can be used on Class A, but effective protection time is short & powder can cause mess

Access for fire and rescue services

Vehicles

Access requirements depend on building height, floor area & whether fire main is fitted

Access to a minimum of 15% of the perimeter or within 45m of every point of building

Buildings with floor levels over 18m or basements more than 10m below ground level must allow rescue service vehicle access

Fire-fighting

Low rise buildings - no special requirements

High rise buildings - facilities such as firefighting lifts & firefighting stairs

Evacuation of a workplace

Requirements for suitable means of escape

Travel distances

Minimise distance to be travelled to a safe point (usually outside in the open air)

More than one route of escape from any point in the building

Stairs

Part of the escape route & particularly important

Should be within a fire-resistant structure

Fitted with fire doors

Wide enough to handle the numbers of people likely to use them

Non-slip

Adequately lit

Passageways / corridors

Routes wide enough to handle the numbers of people likely to use them

No combustible material stored on the route or on walls (noticeboards)

No obstructions (e.g. vending machines)

Adequately lit

Fire doors

Doors to open in direction of travel

Should be easy to operate (ergonomics)

Not locked

Not wedged open at any time

Fitted with vision panel

Fitted with smoke seals or intumescent strips around frame

Emergency lighting

Alarm, call points & firefighting equipment

Exit doors

Escape routes

Signs

Exit & directional signs

Green safe condition signs

At each point requiring a change of direction

Clearly located & easy to understand

Not relent on language only

Assembly point

Final destination at the end of the means of escape

Should be outside in the open air away from danger

More than one assembly point depending on number of people and site layout

Means of communication between assembly points

Clearly signed

Nominated person in charge

Emergency evacuation procedure

Should be documented

Should specify action to take on discovering a fire

Action to take individual on hearing the alarm

Action to take individual when evacuating

Nominated staff with responsibilities to be performed in the event of a fire

Detail foreseeable emergencies

Responsibilities of fire marshals

Assisting / directing people towards emergency exits

Conducting 'sweeps' to ensure building is empty

Assisting the vulnerable to escape safely

Checking that escape routes are clear on a daily basis

Liaising with the fire service in the event of an emergency

Assisting in internal reviews once emergency is over

Fire drills

Purpose

Familiarise people with evacuation procedure

Test adequacy of means of escape

Allow those with responsibilities to practice them

Roll call

Method of accounting for all personnel

Where public have access. 'sweeps' by fire marshals must be conducted

Various roll call systems linked to access and egress methods in building

Provisions for disabled persons

Staff with disabilities must be specifically accommodated for in emergency plan

Wheelchairs users need access to an evacuation chair if situated above the ground floor with nominated persons to provide assistance

Workers who are deaf should have access to alarms that emit light rather than sound