Detectors | Sounders/ Beacon (Light) | Manual Call Points | Cables & Wiring

There are number of reasons for installing fire detection and alarms systems. Each systems is designed to fulfil specific needs. The following are recognized functions:

• To notify occupants of a facility to take necessary evasive action to escape the dangers of a hostile fire.

• To summon organize assistance to initiate or to assist in fire control activities.

• To initiate automatic fire control and suppression systems and to sound an alarm.

• To supervise fire control and suppression systems to assure that operational status is maintained.

• To initiate wide variety of auxiliary functions involving environmental, utility and process controls.

Since the response of an automatic detection system does not depend on the presence or action of people, automatic detection is likely to give a better guarantee of success than manual detection. However Manual Call Points should always be provided since people can often give an earlier Alarm of fire when they are present.

Detectors

A Fire detector installation is intended to enable a fire to be detected at a sufficiently early stage for it to be easily extinguished without extensive damage to property.

In general people are the most sensitive fire detectors, but they are not always present or alert; there may be parts of the property that are not normally attended during day time or working hours; there may be parts of the property that are not normally attended during certain period of the night or completely unoccupied during non working hours. The use of detectors then can significantly reduce the property loss provided that suitable provision has been made for the necessary subsequent action. When fire start in un occupied areas (the period of inoccupation) they may grow if undetected to a stage where they cannot be easily extinguished; since any area may be un occupied at sometime for maximum protection, total coverage of the premises should be provided.

Sounders/ Beacon (Light)

The primary purpose of systems installed for the property, and life protection is to summon the occupants of the fire squad and other staffs. The number of alarm sounders installed through out the resort/building should meet the requirements to alert the occupants. The type, number and location of Fire Alarm Sounders should be such that the Alarm Sound is distinct from the background noise. The note of the Fire Alarm Sounders should be distinct from any other sounder likely to be heard.

In areas where a normal type of sounder may be ineffective, e.g.: where the background noise is excessive, where the occupants are deaf or where heavy protection is likely to be worn, visual signals should be used.

Manual Call Points

It is important that Manual Call Points are clearly identifiable and simple to use without the need for instructions as to their method of operation. The method of operation of all Manual Call Points in all installations should be identical unless there is a special reason for differentiation. A person operating a Manual Call Point should not be left in doubt as to the success of operation. The delay between operation of a Call Point and the giving of the general Alarm should therefore not exceed 5 seconds.

Cables & Wiring

The satisfactory operation of a Fire Alarm System depends very much on the interconnections between its components. Unless these connections operate correctly when required a system will not fulfill its function.
It is essential that connections between detectors or call points and the control equipment are functioning correctly when a fire occurs. The control equipment should be able to maintain the Alarm without a continued signal from the detection or call point, i.e. destruction of the connection after the initial operation would not affect the sounding of the alarm.

Most connection to detectors or call points will be required to function correctly for significant periods during a fire. Such connections include those by which power is supplied to the control equipment to the audio visual Alarm or other such devices connected to fulfill the function of the system designed for Fire protection where heat resistance cable are used for the interconnection in fire Alarm circuits.
In practice no system can have total reliability, but one of the objectives of a good design is to reduce the probability of the system being in operation in the area of a Fire when the fire starts.