In general, a fire alarm system is classified
as either automatically activated, manually activated, or both.
Automatic fire alarm systems are intended to notify the building
occupants to evacuate in the event of a fire or other emergency,
report the event to an off-premises location in order to summon
emergency services, and to prepare the structure and associated
systems to control the spread of fire and smoke.
Automatically activated devices can
take many forms intended to respond to any number of detectable
physical changes associated with fire:-
Convected thermal energy -
Products of combustion -
Radiant energy - flame detector,
Combustion gasses - carbon