A fire alarm system is a building system designed to detect, alert occupants, and alert emergency forces of the presence of fire, smoke, carbon monoxide, or other fire-related emergencies. Fire alarm systems are required in most commercial buildings. They may include smoke detectors, heat detectors, and manual fire alarm activation devices. All components of a fire alarm system are connected to a fire alarm control panel. Fire alarm control panels are usually found in an electrical or panel room. Fire alarm systems generally use visual and audio signalization to warn the occupants of the building. Some fire alarm systems may also disable elevators, which are unsafe to use during a fire under most circumstances.
A fire alarm horn strobe, pull station, and remote annunciator connected together in a fire alarm system
A fire alarm notification appliance as widely used under North American standards
A fire alarm control panel
Fire alarm speaker and pull station
A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors/Alarms are usually housed in plastic enclosures, typically shaped like a disk about 150 millimetres (6 in) in diameter and 25 millimetres (1 in) thick, but shape and size vary. Smoke can be detected either optically (photoelectric) or by physical process (ionization). Detectors may use one or both sensing methods. Sensitive alarms can be used to detect and deter smoking in banned areas. Smoke detectors in large commercial and industrial buildings are usually connected to a central fire alarm system.
Smoke detector mounted on a ceiling
Optical smoke detector with the cover removed; the angled plastic in an arc across the top is a light baffle
Inside a basic ionization smoke detector. The black, round structure at the right is the ionization chamber. The white, round structure at the upper left is the piezoelectric horn that produces the alarm sound.
An americium container from a smoke detector