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Fire Protection Glossary - A


Accessible (as applied to equipment). Admitting close approach; not guarded by locked doors, elevation, or other effective means.

Accessible (as applied to wiring methods). Capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building.

Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth.

Accessible Area of Refuge. An area of refuge that complies with the accessible route requirements of CABO/ANSI A117.1, American National Standard for Accessible and Usable Buildings and Facilities.

Accessible Means of Egress. A path of travel, usable by a person with a severe mobility impairment, that leads to a public way or an area of refuge.

Acknowledge. To confirm that a message or signal has been received such as by the pressing of a button or the selection of a software command.

Active Multiplex System. A multiplexing system in which signaling devices such as transponders are employed to transmit status signals of each initiating device or initiating device circuit within a prescribed time interval so that lack of receipt of such signal may be interpreted as a trouble signal.

Addition. An extension or increase in floor area or height of a building or structure.

Addressable Device. A fire alarm system component with discrete identification that can have its status individually identified or that is used to individually control other functions.

Addressable Control Device. A signaling system output device which, when operating with a compatible control unit, is used to control individual preselected electrical circuits such as audible or visual alarm signaling appliances, fan circuits, or door release circuits.

Addressable Intelligent Device. A signaling system data input device which, when communicating with a compatible control unit, may have its status individually identified by the control unit.

Addressable System. A system, which uses a signaling technique that, allows a control unit to identify a specific initiating device or group of devices by location.

Addressable System Smoke Detector. A smoke detector, which, in addition to providing alarm and trouble outputs to a control unit, may be uniquely identified by location to the main control unit.

Adverse Condition. Any condition occurring in a communications or transmission channel that interferes with the proper transmission or interpretation, or both, of status change signals at the supervising station. See also Trouble Signal.

Agent Release. The release of a chemical substance (i.e., Halon, FM200) capable of producing a chemical reaction, which will extinguish a fire. Agent release is most often used in areas where water release would cause damage to electrical equipment.

Agglomerate. To gather into a ball, mass, or cluster.

Air Sampling-Type Detector. A detector that consists of a piping or tubing distribution network that runs from the detector to the area(s) to be protected. An aspiration fan in the detector housing draws air from the protected area back to the detector through air sampling ports, piping, or tubing. At the detector, the air is analyzed for fire products.

Alarm. A warning of fire danger.

Alarm Initiating Device. A device which when actuated, initiates an alarm. Such devices, dependant upon their type, may be operated manually or automatically. Automatic initiating devices may respond to smoke, heat, or waterflow, for example.

Alarm Service. Service required following the receipt of an alarm.

Alarm Signal. A signal, indicating an emergency requiring immediate action, such as a signal indicative of fire.

Alarm System. A combination of compatible initiating devices, control panels, and indicating appliances, designed and installed to produce an alarm signal in the event of fire.

Alarm Verification Feature. A feature of automatic fire detection and alarm systems to reduce unwanted alarms wherein smoke detectors report alarm conditions for a minimum period of time, or confirm alarm conditions within a given time period after being reset, in order to be accepted as a valid alarm initiation signal.

Alert Tone. An attention-getting signal to alert occupants of the pending transmission of a voice message.

All-Call Mode. A selector switch on the fire alarm control unit which allows all speaker circuits to be used for an "All-Call Page" transmission.

Analog Initiating Device (Sensor). An initiating device that transmits a signal indicting varying degrees of conditions as contrasted with a conventional initiating device, which can only indicate an on/off condition.

Analog Intelligent Control Panel. An addressable, programmable fire alarm control unit which determines when and whether a device or system is in alarm.

Analog System. A fire alarm system which measures how much of a substance exists at an automatic initiating device contrasted with a conventional system, which can only determine whether the initiating device is on or off (in alarm or not in alarm). Measurements may include smoke density (percent obscuration), temperature, water level, air pressure, etc.

Analog Smoke Detector. A system smoke detector capable of communicating information regarding measured smoke level to a control unit. This type of detector is capable of sending signals to the control unit, which indicate the analog level of smoke within the detector. An analog smoke detector is typically used as part of an addressable system but differs from the Addressable Smoke Detector in that it is capable of communicating the level of smoke as well as its discrete address and its alarm and/or trouble condition.

Annunciator. A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means in which indication provides status information about a circuit, condition, or location.

ANSI. American National Standards Institute, 1430 Broadway, New York, NY 10018.

Approved. Acceptable to the authority having jurisdiction. The National Fire Protection Association does not approve, inspect, or certify any installations, procedures, equipment, or materials; nor does it approve or evaluate testing laboratories. In determining the acceptability of installations, procedures, equipment, or materials, the authority having jurisdiction may base acceptance on compliance with NFPA or other appropriate standards. In the absence of such standards, said authority may require evidence of proper installation, procedure, or use. The authority having jurisdiction of an organization concerned with product evaluations that are in a position to determine compliance with appropriate standards for the current production of listed items.

Assembly Occupancy. Assembly occupancies include, but are not limited to, all buildings or portions of buildings used for gatherings of 50 or more persons for such purposes as deliberation, worship, entertainment, eating, drinking, amusement, or awaiting transportation. Assembly occupancies also include special amusement buildings regardless of occupant load. Assembly occupancies include armories, libraries, assembly halls, mortuary chapels, auditoriums, motion picture theaters, bowling lanes, museums, clubrooms, passenger stations and terminals of air, surface, underground, and marine public transportation facilities, college and university classrooms, 50 persons and over, conference rooms, places of religious worship, courtrooms, pool rooms, dance halls, recreation piers, drinking establishments, restaurants, exhibition halls, skating rinks, gymnasiums, and theaters.

ASTM. American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

Atrium. A floor opening or series of floor openings connecting two or more stories that is covered at the top of the series of openings and is used for purposes other than an enclosed stairway; elevator hoistway; escalator opening; or utility shaft used for plumbing, electrical, air conditioning, or communication facilities.

Audible Signal. The sound made by one or more audible notification appliances such as bells, chimes, horns, and speakers, which respond to the operation of an initiating device.

Audio Voice Link (AVL). Allows the fire alarm control unit to play a single channel of different voice messages from a library of words.

Authority Having Jurisdiction (AHJ). The organization, office, or individual responsible for approving equipment, an installation, or a procedure. The phrase "authority having jurisdiction" is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department, or individual such as a fire chief; fire marshal, chief of a fire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction, In many circumstances, the property owner or his or her designated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction.

Automatic. Providing a function without the necessity of human intervention.

Automatic Extinguishing System Supervisory Device. A device that responds to abnormal conditions that could affect the proper operation of an automatic sprinkler system or other fire extinguishing system(s) or suppression system(s) including, but not limited to, control valves; pressure levels; liquid agent levels and temperatures; pump power and running; engine temperature and overspeed; and room temperature.

Automatic Extinguishing or Suppression System Operation Detector. A device that automatically detects the operation of a fire extinguishing or suppression system by means appropriate to the system employed.

Automatic Fire Detector. A device designed to detect the presence of a fire signature and to initiate action. For the purpose of this code, automatic fire detectors are classified as follows:

Fire-Gas Detector. A device that detects gases produced by a fire.

Heat Detector. A fire detector that senses heat produced by burning substances. Heat is the energy produced by combustion that causes substances to rise in temperature.

Other Fire Detectors. Devices that detect a phenomenon other than heat, smoke, flame, or gases produced by a flame.

Radiant Energy-Sensing Fire Detector. A device that detects radiant energy (such as ultraviolet, visible, or infrared) that is emitted as a product of combustion reaction and obeys the laws of optics.

Smoke Detector. A device that detects visible or invisible particles of combustion.

Automatic Fire Alarm System. A system in which all or some of the circuits are actuated by automatic devices, such as fire detectors, smoke detectors, heat detectors, and flame detectors.

Automatic Float Charger. Provides secondary (standby) power for temporary operation of the control unit following the loss of primary (main) power. The float charger keeps the secondary (standby) batteries charged during normal operation.

Auxiliary Box. A fire alarm box that can be operated from one or more remote actuating devices.

Auxiliary Fire Alarm System. A system connected to a municipal fire alarm system for transmitting an alarm of fire to the public fire service communications center. Fire alarms from an auxiliary fire alarm system are received at the public fire service communications center on the same equipment and by the same methods as alarms transmitted manually from municipal fire alarm boxes located on streets.

Local Energy Type. An auxiliary system that employs a locally complete arrangement of parts, initiating devices, relays, power supply, and associated components to automatically trip a municipal transmitter or master box over electrical circuits that are electrically isolated from the municipal system circuits.

Parallel Telephone Type. An auxiliary system connected by a municipally controlled individual circuit to the protected property to interconnect the initiating devices at the protected premises and the municipal fire alarm switchboard.

Shunt Auxiliary Type. An auxiliary system electrically connected to an integral part of the municipal alarm system extending the municipal circuit into the protected premises to interconnect the initiating devices, which, when operated, open the municipal circuit shunted around the trip coil of the municipal transmitter or mater box, which is thereupon energized to start transmission without any assistance whatsoever form a local source of power.

Auxiliary Trip Relay. A relay used to operate a municipal master box from an auxiliarized control panel.

Average Ambient Sound Level. The root mean square, A-weighted sound pressure level measured over a 24-hour period.
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Some information may be found within this web site that is reprinted with permission from one or more of the following: NFPA 70 National Electrical Code®,NFPA 72® National Fire Alarm Code®, & NFPA 101® Life Safety Code®, Copyright© NFPA, Quincy, MA 02269.

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