Every year, thousands of people die in home and commercial building fires, but far more are saved as a result of fire alarm systems that provide them with sufficient notice to evacuate the premises. In the distant past, fire alarm systems consisted of men and sometimes animals, but more recently, increasingly sophisticated systems have been developed that form an essential part of the concentric layers of building defense. To identify current trends in this field, this paper provides a review of the relevant peer-reviewed and scholarly literature concerning automatic fire alarm systems in general, as well as their composition and working principle in particular, including their design, basic configuration, and the types of notification devices that are typically used, as well as the detectors and emergency voice and other alarm communication systems that are currently deployed with respect to the Americans with Disabilities Act Accessibility Guidelines for fire alarm systems. Finally, a summary of the research and important findings are presented in the paper's conclusion.
Review and Discussion
Fire alarm systems form an important part of what has been conceptualized as a series of concentric rings that are used to defend a building and its occupants by providing them with sufficient notice to evacuate the premises and reach a place of safety while awaiting the arrival of firefighting personnel (Liston, 1999). For instance, according to Liston, "Protection managers use alarms that detect fires to evacuate people quickly and to call a firefighting service to extinguish the fire. Managers often connect these alerts directly to a public fire service organization to bring firefighting assistance as soon as possible" (1999, p. 204). Although every building is unique in some fashion and the fire alarm systems that are used will therefore differ in some respects, the types of alarms that are used by these systems are typically tailored to the needs of their occupants. For instance, in buildings with general alarm notification requirements, an audible siren, bell or alarm might be used to notify building occupants. In this regard, Liston advises, "Alarms produce an emergency or urgent sound that everyone in the building hears and recognizes to be a fire alert" (1999, p. 204). In most settings that have access to reliable sources of electrical power, electronic bells or horns are used to alert occupants and in the case of commercial properties, institutional staff and firefighting personnel as well. For instance, Liston advises that, "Automatic fire alarm systems are electrical systems of noise-making mechanisms such as bells or horns. This alerts the institution staff and the public to evacuate and firefighting staff to respond to extinguish the fire. The alarm system might send the signal outside the building to alert another fire service or security organization" (1999, p. 205).
Automatic fire alarm systems operate by detecting changes in environmental conditions that are indicative of a fire such as heat levels or airborne particulate matter or other type of emergency conditions that are being monitored (Mork, 2002). The automation involved in fire alarm systems extends beyond simply notifying building occupants, but includes notifying institutional and firefighting staff, initiating automatic sprinkler and other deluge systems, together with appropriate notification and warning systems (Liston, 1999). According to Liston, automatic fire alarm systems are optimally tied to networks that can provide minimal response time, which will vary from setting to setting but good systems can initiate fire suppression systems and notify appropriate personnel within 3 minutes, but the best systems will have persons on the site as part of the response so that immediate steps can be taken to alert building occupants (Liston, 1999).
In those cases where there are occupants with special needs such as the hearing or visually impaired, alternative notification methods have been devised in response to the Americans with Disabilities Act Accessibility Guidelines (ADAAG) issued in July 1991, which stipulate what types of building components and construction features define accessibility. According to Valente (1999), one of the provisions of the ADAAG mandates that all fire alarm systems are accessible to building occupants, with the various elements of a fire detection and alarm system that must be considered including the manual fire alarm stations (pull stations), audible warning devices (horns and speakers), and visual warning devices (strobe lights) which are described further in Table…