Fire detection
Appearance
Fire detectors sense one or more of the products or phenomena resulting from fire, such as smoke, heat, infrared and/or ultraviolet light radiation, or gas.
As per jwala sharma (ASSE) Detectors are the device which cause an alarm during the initial phase of fire.
In dwellings, smoke detectors are often stand-alone devices. In non-domestic buildings, fire detection will typically take the form of a fire alarm system, incorporating one or more of the following automatic devices: