GLOSSARY
Our handbook of terms for the most common language and terminology of the Fire Alarm and Access Control Systems industry.
Terms and Definitions
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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.
WA 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.
A fire alarm system component with discrete identification that can have its status individually identified or that is used to individually control other functions.
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)
A detector that consists of a piping or tubing distribution net- work 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.
A device which, when actuated initiates an alarm. Such devices, depending on their type, can be operated manually or actuated automatically in response to smoke, flame, heat, or water flow.
A signal indicating an emergency requiring immediate action, such as an alarm for fire from a manual station, a water flow alarm, or an alarm from an automatic fire alarm system.
A combination of compatible initiating devices, control panels, and notification 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 automatic smoke detectors must report alarm conditions for a minimum period of time, or confirm alarm conditions within a given period of time after being reset, to be accepted as a valid alarm initiation signal.
An attention-getting signal to alert occupants of the pending transmission of a voice message.
Analog Initiating Device (Sensor). An initiating device that transmits a signal indicating varying degrees of condition as contrasted with a conventional initiating device, which can only indicate an on/off condition.
A unit containing two or more indicator lamps, alphanumeric displays, or other equivalent means in which each indication identifies the circuit, or location to be annunciated.
Acceptable to the authority having jurisdiction.
The organization, office, or individual responsible for approving equipment, an installation, or a procedure.
A connection to the municipal fire alarm system to transmit an alarm of fire to the municipal communications center. Fire alarms from an auxiliary alarm system are received at the municipal communications center on the same equipment and by the same alerting methods as alarms transmitted by municipal fire alarm boxes located on streets.
The root mean square, A-weighted sound pressure level mea- sured over a 24-hour period.
A single stroke or vibrating type audible notification appliance which has a bell tone.
(Also see “manual fire alarm box”) a. Noncoded. A manually operated device which, when operated, closes or opens one or more sets of contacts and generally locks the contacts in the operated position until the box is reset.
b. Coded. A manually operated device in which the act of pulling a lever causes the transmission of not less than three rounds of coded alarm signals. Similar to the non- coded type, except that instead of a manually operated switch, a mechanism to rotate a code wheel is utilized. Rotation of the code wheel, in turn, causes an electrical circuit to be alternately opened and closed, or closed and opened, thus transmitting a coded alarm signal which identifies the location of the box. The code wheel is cut for the individual code to be transmitted by the device and can operate by clockwork or an electric motor. Clockwork transmitters can be pre-wound or can be wound by the pulling of the alarm lever. Usually the box is designed to repeat its code four times and automatically come to rest. Pre-wound transmitters must sound a trouble signal when they require rewind- ing. Solid state, electronic coding devices are also used in conjunction with the fire alarm control unit to produce a coded sounding of the system’s audible notification appliances.
A fire alarm box in which it is necessary to break a special element in order to operate the box.
The upper surface of a space, regardless of height. Areas with a suspended ceiling would have two ceilings, one visible from the floor and the one above the suspended ceiling.
The height from the continuous floor of a room to the continuous ceiling of a room or space.
Ceiling surfaces referred to in conjunction with the locations of initiating devices are defined as follows:
Beam Construction. Ceilings having solid structural or solid nonstructural members projecting down from the ceiling surface more than 4 in. (100 mm) and spaced more than 36 in. (910 mm), center to center.
Girder. A support for beams or joists that runs at right angels to the beams or joists. If the top of girders is within 4 in. (100 mm) of the ceiling, the girder is a factor in deter- mining the number of detectors and is to be considered a beam. If the top of the girder is more than 4 in. (100 mm) from the ceiling, the girder is not a factor in detector location.
Solid Joist Construction. Ceilings that have solid structural or solid nonstructural members projecting down from the ceil- ing surface for a distance of more than 4 in. (100mm) and spaced at intervals of 36 in (910 mm) or less, center to center.
A system or group of systems in which the operations of circuits and devices are transmitted automatically to, recorded in, maintained by, and supervised from a listed central station having competent and experienced servers and operators who, upon receipt of a signal, take such action as required by this code. Such service is to be controlled and operated by a person, firm, or corporation whose business is the furnishing, maintaining, or monitoring of supervised fire alarm systems.
The use of a system or a group of systems in which the operations of circuits and devices at a protected property are signaled to, recorded in, and supervised from a listed central station having competent and experienced operators who, upon receipt of a signal, take such action as required by this code. Related activities at the protected property such as equipment installation, inspection, testing, maintenance, and runner service are the responsibility of the central station or a listed fire alarm service local company. Central station service is controlled and operated by a person, firm, or corporation whose business is the furnishing of such contracted services or whose properties are the protected premises.
A systematic program using randomly selected follow-up inspections of the Certificated systems installed under the program, which allows the listing organization to verify that a fire alarm system complies with all the requirements of this code. A system installed under such a program is identified by the issuance of a certificate and is designated as a certificated system.
Unit volume of flow of a gaseous substance (such as air) measured in cubic feet per minute.
A single-stroke or vibrating type audible notification appliance which has a xylophone-type striking bar and / or tone.
A circuit component that interfaces initiating devices or control circuits, or both, notification appliances or circuits, or both, system control outputs, and other signaling line circuits to a signaling line circuit.
An audible or visible signal conveying several discrete bits or units of information. Notification signal examples are numbered strokes of an impact-type appliance and numbered flashes of a visible appliance.
A device that either (a) responds to more than one of the fire signatures or (b) employs more than one operating principle to sense any one of these signatures. Typical examples are (a) combination of a heat detector with a smoke detector, or (b) a combination rate- of-rise and fixed temperature heat detector.
A manually operated box for separately transmitting a fire alarm signal and a distinctive guard patrol tour supervisory signal.
A protected premises fire alarm system for fire alarm, supervisory or watchman service whose components can be used in whole or part in common with a non-fire-emergency signaling system, such as a paging system, a musical program system, HVAC control system, or a process monitoring system, without degradation of, or hazard to, the fire alarm system.
A device with the control circuits necessary to (1) furnish power to a fire alarm system; (2) receive signals from alarm initiating devices and transmit them to audible indicating appliances and accessory equipment; and (3) monitor the integrity of the system installation wiring and primary (main) power. The control unit can be contained in one or more cabinets in adjacent or remote locations.
A circuit or path connecting a subsidiary station (s) to a supervising station (s) over which signals are carried.
A specific listing process that applies only to two-wire devices (such as smoke detectors) that are designed to operate with certain control equipment.
Equipment that interfaces mechanically or electrically together as manufactured and without field modification.
A single-owner or single-user protected premises on a continuous plot of ground, including any buildings thereon, that is not separated by a public thoroughfare, transportation right-of-way, property owned or used by others, or body of water not under the same ownership.
A valve or plate regulating the flow of air or other fluid.
A system component located in the supervising station that will accept and display signals from the DACT’s sent over the public switched telephone system.
A system in which signals are transmitted from a Digital Alarm Communicator Transmitter (DACT) located at the protected premises through the public switched telephone network to a Digital Alarm Communicator Receiver (DACR) located at the supervising station.
A system component at the protected premises to which initiating devices or groups of devices are connected. The DACT will seize the connected telephone line, dial a preselected number to connect to a DACR in the supervising station, and transmit signals indicating a status change of the initiating device.
A passageway made of sheet metal or other suitable material not necessarily leak-tight, used for conveying air or other gas at low pressures.
A device located within a duct, protruding into a duct, or located outside a duct that will detect visible or invisible particles of combustion flowing within the duct. Actuation of the device may allow operation of certain control functions.
A device such as a resistor or diode placed at the end of a circuit to maintain monitoring fire integrity.
Device used to supervise power (usually for four wire smoke detectors) and installed within or near the last device on the circuit.
A smoke detector which initiates an alarm condition on a circuit separate from the circuit that supplies operating power to the device.
A term usually applied to the simultaneous operation of all the audible and visible alarm notification appliances on a system to indicate the need for evacuation of a building.
A device that detects abnormally high temperature or rate-of-temperature rise.
A circuit to which automatic or manual signal initiating devices are connected where the signal received does not normally identify the individual device operated.
An ionization smoke detector has a small amount of radioactive material which ionizes the air in the sensing chamber, thus rendering it conductive and permitting a current to flow between two charged electrodes. This gives the sensing chamber an effective electrical conductance. When smoke particles enter the sensing chamber, they de- crease the conductance. When the conductance is less than a predetermined lever, the detector actuates.
Internet Protocol or packet data.
Equipment or materials to which has been attached a label, symbol, or other identify- ing mark of an organization acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of the production of such labeled equipment or materials and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
The action of light being reflected and/or refracted off particles of combustion, as in a light scattering photoelectric smoke detector.
Equipment or materials included in a list published by an organization acceptable to the authority having jurisdiction and concerned with evaluation of products and services, that maintains periodic inspection of listed equipment or materials or periodic evaluation of services and whose listing states either that the equipment, material or service meets identified standards or has been tested and found suitable for a specified purpose.
A physical facilities-based network capable of transmitting real time signals with formats unchanged that is managed, operated, and maintained by the service provider to ensure service quality and reliability from the subscriber location to public switched telephone network (PSTN) interconnection points or other MFVN peer networks.
The ability to detect a fault condition in the installation wiring which would prevent normal operation of the fire alarm system.
NFPA administers the development of and published codes, standards, and other materials concerning all phases of fire safety.
A fire alarm system component such as a bell, horn, speaker, light, or text display that provides audible, tactile, or visible outputs, or any combination thereof.
A notification appliance that alerts by the sense of hearing.
A notification appliance that conveys a stream of audible information. An example of an audible textual appliance is a speaker that reproduces a voice message.
A notification appliance that alerts by the sense of smell.
A notification appliance that alerts by the sense of touch or vibration.
A notification appliance that alerts by the sense of sight.
A notification appliance that conveys a stream of visible information. An example of a visible textual appliance is a screen or monitor that displays an alphanumeric or pictorial message.
An area covered by notification appliances that are activated simultaneously.
National Recognized Testing laboratory, such as Underwriters Laboratories, FMRC and Intertek.
Any alarm caused by mechanical failure, malfunction, improper installation, or lack of proper maintenance, or any alarm activated by a cause that cannot be determined.
Audible or visible signaling only to those persons directly concerned with the implementation and direction of emergency action in the area protected by the fire alarm system.
Audible or visible signaling to occupants or inhabitants of the area protected by the fire alarm system.
In the photo- electric light scattering smoke detector, a light source and a photosensitive sensor are so arranged that the rays from the light source do not normally fall on the photosensitive sensor. When smoke particles enter the light path, some of the light is scattered by reflection and refraction onto the sensor, causing the sensor to respond.
In a projected beam photoelectric smoke detector, the amount of light transmitted between a light source and a photosensitive sensor is monitored. When smoke particles are introduced in the light path, some of the light is scattered and some absorbed, thereby reducing the light reaching the receiver, causing the detector to respond.
A system that sounds an alarm at the protected premises as the result of the manual operation of a fire alarm box or the operation of protection equipment or systems such as water flowing in a sprinkler system, the discharge of carbon dioxide or Halon 1301, or the detection of smoke, heat or flame.
An assembly of communications equipment and telephone service providers that utilize managed facilities-based voice networks (MFVN) to provide the general public with the ability to establish communications channels via discrete dialing codes.
A device which will respond when the temperature rises at a rate exceeding a predetermined amount.
A system that connects alarm initiating devices or a control unit in a protected premises to signal receiving equipment at a Remote Supervising Station, such as fire or police headquarters or other places acceptable to the authority having jurisdiction.
A device whose detecting element is concentrated at a particular location. Typical examples are bimetallic detectors, fusible alloy detectors, certain pneumatic rate-of-rise detectors, certain smoke detectors and thermo- electric effect detectors.
An effect that occurs when heated air containing smoke particles or gaseous combustion products rises until it reaches a level at which there is no longer a difference in temperature between it and the surrounding air. Stratification can also be caused by powered ventilation that develops an opposing airflow.
A signal indicating the need for action in connection with the supervision of guard tours, automatic sprinkler or other extinguishing systems or equipment, or the maintenance features of other protective systems.
The time it takes for the operating element of a heat detector to absorb hear from the surrounding air. Thus, when a fixed temperature device operates, the temperature of the surrounding air will always be higher than the operating temperature of the device itself.
An audible signal indicating trouble of any nature, such as a circuit open or ground occurring in the device or wiring, or with a power supply associated with a fire alarm system.
A smoke detector which initiates an alarm condition on the same circuit that also supply power to the detector.
A listed so constructed and installed that any flow of water from a sprinkler system equal to or greater than that from a single automatic sprinkler head will result in actuation of this switch and subsequently indicate an alarm condition.
A designated area of a building. Commonly, zones within a building are annunciated remotely to enable the emergency responders to rapidly locate a fire. The term can also indicate an area served by detectors.