Page 364 - IGC BOOK

10.3 Fire Alarms and Fire Fighting

Fire Detection and Alarm System

In workplaces where a fire is unlikely to cut off the means of escape, for example open
areas and single-storey buildings, where all exits are visible and the distances to be travelled
are small, it is likely that any fire will be quickly detected by the people present. A shout of
"Fire" may be all that is needed.

In larger workplaces, particularly multi-storey buildings, an electrical fire warning system with
manually operated initiation points is likely to be the minimum facility needed. Automatic fire
detection will be necessary in normally unoccupied areas, where a fire could start and develop
to the extent that escape routes may become affected, before it is discovered/
Manual Systems

Manual systems are suitable for small workplaces and involve the use of the following basic
devices:

• Rotary gongs – which are sounded by turning a handle around the rim of the gong.
• Hand strikers – for example, iron triangles suspended from a wall accompanied by a
metal bar which is used to strike the triangle manually.
• Hand bells.
• Whistles.
• Air-horns.

These devices are normally located on the walls of corridors, entrance halls and staircase
landings, etc., where they are readily available to anyone who may have to raise an alarm.

Electric Systems
These are systems which, although set in motion manually, operate as part of an electrical
alarm circuit. When an alarm call point is activated, the alarm signal is automatically sounded
throughout the premises (or a particular part of them). The alarm system may also sound an
alarm outside the building and possibly relay an alert to the fire brigade.

The call points in a manual/electric system are usually small red wall-mounted boxes which
are designed to operate either automatically when the glass front is broken or when the glass
front is broken and a button pressed. Most available models are designed to operate
immediately the glass front is broken.

ENSIGN | Unit IG2 – Element 10 –Fire 19