What is Fire Alarm and Detection Systems?

Most Fire Alarm and Detection Systems work on the same basic principles. If a fire is detected, then an alarm is on. This warns building managers and resident that there may be a fire and that evacuation may be essential. Some systems include remote signalling equipment which can caution the fire brigade or a remote monitoring centre.

Fire can be detected by; flame detectors, heat detectors, carbon monoxide detectors, smoke detectors and multi sensor detectors, or an alarm can be on at manual call points. Alarms may consist of bells, sirens, lights, horns or a combination these. Two power supplies are required, generally a mains supply and batteries providing 24 hours for the back up.

It is important that a total assessment of need is undertaken before a fire detection and alarm system is designed or purchased.

In the India, fire alarm systems are categorised as:

L, (L1 to L5): automatic systems intention for the protection of life.

M: manual systems, fitted with sounders and call points.

P, (P1 and P2): automatic systems intention for the protection of property.

Fire detection and alarm systems can be split into a number of general types:

• Conventional systems.
• Addressable systems.
• Analogue addressable systems.
• Wireless systems.
• Self-contained units.

Conventional systems commonly consist of a series of detectors and call points wired to a control panel which drives the detectors and a minimum of two sounder circuits, incorporate LED indicators and allows de-activation and resetting. Typically, separate circuits will be provided for each fire 'zone'. This partition into zones means that the approximate location of the fire is known and so the suitable response can be instigated. It also allows for simple diagnosis of faults.

Addressable systems are identical to conventional systems, but the central control panel can identify strictly which detector or call point triggered the alarm, or whether communication has been lost with a detector. In this system the circuit is wired in a loop, with a number of detectors or call points on each loop. The loop can be powered from both ends, so that it sustain to function even if there is a break in the loop.

The control panel can be programmed to display specific information, or trigger specific responses for different detectors within the system. Addressable systems are commonly used for larger or more complex installations because of the benefits of more perfect detection, and so fault finding, and the reduced wiring requirement.

Analogue addressable systems, or intelligent systems can include an analytical capability in each detector which can assess local parameters to establish whether there is a fire, a fault or a maintenance requirement. This can be useful in stop the occurrence of false alarms. A pre-alarm warning may be informed if a detector is approaching a trigger condition.

Wireless fire alarm systems attached detectors and call-points to the control panel through wireless signals.

Self-contained fire alarm units are commonly only suitable for small installations. They consist of a single unit, including break glass contact, sounder, power supply, battery and charger.

It is important that Fire Alarm and Detection Systems are regularly tested and serviced, and fire drills may be held to assure occupants are familiar with fire and evacuation procedures.

The paper proposed that education could contribute significantly to decreasing false alarms and that the imprive use of multi-sensor detectors is a cost effective way of averting false alarms from common causes such as cooking fumes and steam.