A fire alarm system is designed to detect the presence of fire by monitoring environmental changes associated with combustion.
In general, a fire alarm system is classified as either automatically actuated, manually actuated, or both. Automatic fire alarm systems are intended to inform people of dangerous, life-threatening situations, and to prepare the structure and associated systems to control the spread of fire and smoke.
The Fire Alarm Control Panel
The fire alarm control panel can be considered “the brain” in fire alarm systems. The panel processes inputs from initiation devices, and triggers notification devices when it has determined that an alarm condition is warranted. The most commonly used control panels are either conventional or addressable systems.
A conventional fire alarm panel consists of one or more circuits, with detectors connected in parallel. An alarm signal is received at the fire panel when the current on a circuit increases due to the alarm operation of one of the detectors on that circuit. The main drawback with conventional panels is that one cannot tell which device has been activated within a circuit. The fire may be in one small room, but as far as emergency responders can tell, a fire could exist anywhere within a zone.
Conventional panels are cost effective for small facilities where a few zones can provide sufficient alarm annunciation.
An addressable fire alarm panel is more advanced than their conventional counterparts, with a higher degree of programming flexibility and single point detection. Unlike conventional alarm methods, these systems monitor and control the capabilities of each alarm initiating and signaling device through microprocessors and system software. In effect, each intelligent fire alarm system is a small computer overseeing and operating a series of input and output devices. When the conditions for an alarm signal are satisfied at the detector, an alarm signal is transmitted via the circuit to the fire indicator panel. In an addressable system, each detector has the ability to identify itself and its current status. There are many advantages of addressable systems including the stability of the system, ease of modification (add or delete detection devices), and the ability to identify the precise location of a detector and its current condition.
A manual pull station is a wall mounted device meant to be pulled by a building occupant to signal to the building fire alarm system that a fire emergency exists. When pulled, it activates the building fire alarm system and all emergency functions connected to that system.
Manual pull stations are required in virtually all full fire alarm systems. Usually they are located on the inside wall adjacent to each exit from a building or from a floor.
An initiating device is one that initiates an alarm, supervisory, or trouble signal. Heat, smoke, gas, and light are the most common means of early detection.
The Acclimate® 2251TMB photoelectric detector includes thermal detection at 135°F. It uses advanced onboard software to combine the signals from the photo and thermal elements to create a true multi-criteria detector capable of rejecting nuisance sources, but still responding quickly to real fires. Separate photo and thermal elements also allow the Acclimate detector to provide different responses to smoke or heat. In addition, the Acclimate detector can adjust its sensitivity according to its environment.
The BEAM200 and BEAM200S single-ended reflected beam smoke detectors are uniquely suited for protecting open areas with high ceilings where other methods of smoke detection are difficult to install and maintain. Listed for operation from –22°F to 131°F, the BEAM200 detector can be used in open area applications to provide early warning in environments where temperature extremes exceed the capability of other types of smoke detection.
The FS20X detector integrates infrared and ultraviolet sensing technologies. It is a Multi-Spectrum and UV/Dual IR/VIS fire and flame detector with a proven UV solar-blind sensor. The FS20X exhibits faster false-alarm free response to fires over a wider temperature range and with a much longer detection range compared to conventional UV/IR detectors.
FireVu is an advanced Video Smoke Detection serverbased system designed to operate over an IP network. Using mathematical algorithms, it is capable of detecting the presence of smoke within each of its four available camera inputs. Building operators can be alerted of any activity either remotely over the system’s network or local to the Fire Alarm Control Panel via relay outputs. FireVu uses standard CCTV cameras combined with advanced software to pinpoint flame and smoke signatures during incipient fire stages.
Upon receiving an alarm notification, the fire alarm control panel must now alert someone that an emergency is underway. Fire alarm systems utilize a variety of devices to alert building occupants and fire authorities within the protected area as well as outside that an event or fault has occurred. Notification appliances usually consist of audible (horns, chimes, etc.) and visual (strobes) alarms or a combination of both.