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