Fire Alarm System

A fire alarm system has a number of devices working together to detect and warn people through visual and audio appliances when smoke, fire, carbon monoxide or other emergencies are present. These alarms may be activated automatically from smoke detectors, and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium and high, depending on the country and manufacturer of the device.

Magnetic smoke door holders/retainers: wall or floor mounted solenoids or electromagnets controlled by a fire alarm system or detection component that magnetically secures spring-loaded self-closing smoke tight doors in the open position. Designed to de-magnetize to allow automatic closure of the door on command from the fire control or upon failure of the power source, interconnection or controlling element. Stored energy in the form of a spring or gravity can then close the door to restrict the passage of smoke from one space to another in an effort to maintain a tenable atmosphere on either side of the door during evacuation and fire fighting efforts in buildings. Electromagnetic fire door holders can be hard-wired into the fire panel, radio controlled triggered by radio waves from a central controller connected to a fire panel, or, acoustic, which learn the sound of the fire alarm and release the door upon hearing this exact sound.

Duct mounted smoke detection: smoke detection mounted in such a manner as to sample the airflow through duct work and other plenums specifically fabricated for the transport of environmental air into conditioned spaces. Interconnection to the fan motor control circuits is intended to stop air movement, close dampers and generally prevent the recirculation of toxic smoke and fumes produced by fire into occupiable spaces.

Emergency elevator service: activation of automatic initiating devices associated with elevator operation are used to initiate emergency elevator functions, such as recall of associated elevator cab(s). The recall will cause the elevator cabs to return to the ground level for use by fire service response teams and to ensure that cabs do not return to the floor of fire incidence, in addition to prevent people from becoming trapped in the elevators. Phases of operation include primary recall (typically the ground level), alternate/secondary recall (typically a floor adjacent to the ground level – used when the initiation occurred on the primary level), illumination of the “fire hat” indicator when an alarm occurs in the elevator hoistway or associated control room, and in some cases shunt trip (disconnect) of elevator power (generally used where the control room or hoistway is protected by fire sprinklers).

Public address rack (PAR): an audio public address rack shall be interfaced with fire alarm system, by adding signaling control relay module to either rack power supply unit, or to the main amplifier driving this rack. The purpose is to “mute” the BGM (background music) of this rack in case of emergency in case of a fire initiating the true alarm.