It is important to use the correct type of fire extinguisher on a particular type of fireAutomatic fire detection
The prime purpose of a fire detection system is to provide an early warning of fire to the occupants of a building so that they may escape to safety.
Fire detectors are designed to detect one or more of the three characteristics of a fire: Smoke, Heat or Flame. No one type of detector is the most suitable for all applications and the final choice has to depend on individual circumstances.
Heat Detectors operate by the use of physical properties of:
- Expansion of metals.
- Melting of solids.
- Expansion of liquid or gases.
- Changes in electrical characteristics of materials.
Smoke Detectors are of two general types:
- Ionisation detectors.
- Optical beam-type detectors.
Flame Detectors are of two general types:
- Infra-red detectors.
- Ultra-violet detectors.
Automatic fire detection equipment is regularly inspected, tested and maintained in an efficient operating condition strictly in accordance with BS 5839: Part 1 1988, under the terms of University maintenance agreements with reputable fire alarm companies.
Fire warning systems
An audible fire warning system is provided in every University building as the first link in the chain of fire safety precautions. This is to ensure that all occupants are warned quickly of any outbreak of fire, so that they can leave the building without delay.
There are three main types of warning systems:
- Electrically energised sounders (usually bells) - activated manually from one or more call points and which, upon operation, will continue to sound automatically.
- Electrically energised sounders activated by an automatic detector. (These may also be incorporated in the system described above).
- Hand operated rotary gongs or sounders sited at suitable points in the building. These should only be used in smaller, low risk premises. Although needing little maintenance, they have the disadvantage that a warning, once given, should be continued until everyone is outside the building.
Where there may be difficulty in hearing an alarm due to noisy equipment, or in soundproof rooms, etc., flashing lights (strobes) have been installed.
Escape lighting
It is important that premises are provided with an adequate degree of illumination, either by natural means or otherwise, in order that the occupants can see to move around.
1. Premises which are occupied during the hours of darkness or have areas in which the natural lighting is restricted, e.g. a basement, windowless accommodation etc, should be provided not only with normal lighting but also with escape lighting, so that in the event of the normal lighting failing, either through a fire or otherwise, the escape lighting will automatically come on and remain on to provide illumination throughout the escape route for safe movement to a place of safety.
2. The normal and escape lighting should both be capable of illuminating the internal and external escape routes, exit signs, door fastenings, fire alarm call points and fire extinguishers.
3. There are two basic types of fixed escape lighting systems:
- A central power supply (batteries trickle charged from the mains) connected to luminaires throughout the premises. This system either operates automatically on failure of the normal lighting circuit or is on at all material times.
- A number of independent luminaires, each containing a lamp, battery and trickle-charger, and connected to an adjacent lighting circuit. Each luminaire operates automatically on failure of the lighting circuit to which it is connected or may be on at all material times.
4. Escape lighting may be required to be kept switched on throughout the time that the premises are in use (maintained lighting) or may need only to come into operation if the normal lighting should fail (non-maintained lighting).
The minimum period for which the escape lighting is required to function will depend upon the use of the building and will be for one, two or three hours.
Escape lighting should conform to BS 5266: PART 1: 1988.
Escape lighting systems and associated equipment shall be maintained only by suitably qualified engineers nominated by Buildings & Estate Division.
Signs
Any exit which is not a normal route of travel from a building should be indicated by a notice bearing a “running man” symbol and, if appropriate, the words “Fire Exit” in conspicuous lettering of appropriate size. The notice should , if possible, be sited above the exit opening.
Where an exit cannot be seen or where a person escaping might be in doubt as to the location of an exit. ‘Fire Exit’ notices to include a directional arrow, should be provided at suitable and conspicuous positions along the escape route.
Signs which are necessary to indicate actions that should be taken are ‘mandatory’ signs. These signs are circular, with white lettering on a blue background. The most common of this type is the “Fire Door - Keep Shut”.
All fire safety signs, notices and graphic symbols should conform to the Health and Safety (Safety Signs and Signal) Regulations (1996).
Means of escape
Even if a fire certificate is not required, the management in places where people work have a statutory duty (under the Fire Precautions Act (1971) to provide a means of escape.
Fire fighting equipment
Even if a fire certificate is not required, the management in places where people work have a statutory duty (under the Fire Precautions Act (1971) to;
- provide suitable fire fighting equipment,
- ensure that it is properly maintained,
- ensure that staff are trained in its use.
(Apart from legal requirements, there may be contractual obligations to the University insurers to provide fire fighting equipment).
Above all, it is a common sense precaution to provide this equipment.
Portable fire extinguishers are the equipment generally provided, backed up in many cases with hose reels.
Older extinguishers should comply with B.S. 5423, 1987, new extinguishers with BSEN3 and BS7863 specification for portable fire extinguishers.
Types of fire extinguisher
There are four main types of extinguisher in use in the U.K. The ground-colour of all extinguishers is RED, labelled with a code-colour which identifies the contents, in accordance with the chart below:
| Type | Colour of label | Use |
|---|---|---|
| Water | Red, with white text | Suitable for most fires. But not those involving flammable liquids or live electrical equipment. |
| Foam | Pale cream | Suitable for burning liquids. |
| Carbon Dioxide gas | Black | Suitable for burning liquids or fires involving electricity. |
| Powder | French blue | Suitable for burning liquids or fires involving electricity. |
Note that older extinguishers (BS 5423) will have the entire body-colour of the extinguisher corresponding with the above code-colours. Such extinguishers will continue alongside the new (BS EN3 and BS7683) extinguishers, and will be gradually replaced by them.
Occasionally emerald-green extinguishers may be encountered. These contain HALON, a halogenated hydrocarbon which was an excellent fire-fighting medium, but whose manufacture and use was discontinued on environmental grounds in 1994. It is expected that such extinguishers will be withdrawn from use in 2002. Care should be exercised in the use of halon extinguishers, as the vapour is toxic.
Choice of extinguishing agent
Class 'A' fires
Water is by far the most effective agent. It can be conveniently provided in the following ways:
a) Portable extinguishers from which the water is expelled in the form of a jet or spray.
There are two main types:
- Gas cartridge type, from which the water is expelled by pressure released from a gas cartridge.
- Stored Pressure type, from which the water is expelled by the release of pressure stored within the body.
b) Hose Reels which are permanently connected to the mains water supply and fitted with hand controlled nozzles. Note - With manual type hose reels, it may be necessary to operate a valve before the hose is run out.
c) Aqueous Film Forming Foam (AFFF). Similar to water type extinguishers when used for class ‘A’ fires.
Class 'B' fires
In fires of this class the smothering effect of the agent is most important. The following are the agents most widely used.
Foam
There are two main types;
- Gas cartridge type, from which foam is expelled by pressure released from a gas cartridge; and
- Stored pressure type, from which foam is expelled by the release of pressure stored within the body.
N.B. - Special foams must be used on liquids which mix with water, e.g. alcohol, acetone, glycerine and glycols, etc.
Aqueous Film Forming Foam (AFFF)
Similar to water type extinguishers, but with additives making the media suitable for Class ‘B’ fires.
Carbon Dioxide
This is stored in liquid state under high pressure in the extinguisher and released as a gas. It should not be used if the risk of re-ignition is high.
Powder
This is a very effective agent when applied promptly, but it has limitations when the risk of re-ignition is high.
Halon Halogenated hydrocarbons
Soon to be withdrawn. Effective but toxic.
Fire Blanket
Or other means of covering, such as a lid on a fixed vessel.
Dry Sand kept in buckets
Not very effective as an extinguishing agent, but can be usefully applied to limit the spread of burning liquids.
Class 'C' and Class 'D' fires
It is not recommended that extinguishers be provided for these classes of fire for use by untrained persons. With gas leak fires, the only action recommended is the closure of the valve or plugging of the leak (but only if safe to do so). No attempt should be made to extinguish the flame in any other way.
Fire routine procedure and staff instruction
- University fire routine procedures should be strictly adhered to, and all members of staff be aware of their responsibilities in the event of fire.
- Regular staff instruction must be carried out by a nominated person and an appropriate entry made in the buildings’ Fire Precautions Log Book.
- Particular attention should be given to any new or temporary members of staff.
- In addition to instructions contained in the fire routine procedure, all staff should know that it is vital a 999 telephone call be made irrespective of any automatic method of transmitting an alarm, and that when the Service has been called, the fire alarm system must not be re-set until authorised by a Fire Officer.
- Fire evacuation drill must be performed at least once every 12 months (more in buildings with a high occupancy turnover) and an appropriate entry made in the building’s Fire Precautions Log Book.
- If further advice is desired on the foregoing, or any other matter relating to fire, please do not hesitate to contact the University Health, Safety and Environment Office (Ext 3049).
