In the great majority of automatic fire alarm sounders or fire alarm systems, the end result of the detection of a fire is the initiation of audible and visual warning devices that alert the occupants to the danger so that they can evacuate the premises.
Given the complexity and variation of different types of buildings and structures in which fire alarm sounders are installed, and the further variations to be found in the homogeneity or otherwise of the occupants, it is clear that, for maximum effectiveness, many different types of fire alarm sounders will be required.
For example, at one end of the spectrum may be an offshore oil rig, which is manned by highly trained workers who operate under strict safety procedures at all times; a the other end is a large retail development crowded with shoppers who are unfamiliar with the general layout of the building or the position of the nearest emergency exit.
Clearly, the technical requirements for a fire alarm system and the nature of the warning signals themselves will vary greatly. The key consideration for the system designer is how to produce clear, unambiguous fire alarm sounders throughout the protected areas in the event of an emergency.