FIRE DIVISION - Glossary
ADI-GARDINER's Fire Division is able to meet your needs in every area of fire detection, nursecall or emergency lighting. This specialist part of our business has grown to provide nationwide field sales support, gaining a reputation for superior products and service along the way.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
ADDRESSABLE SYSTEM SMOKE DETECTOR - System smoke detectors, which, in addition to providing alarm and trouble indications to a control unit, are capable of communicating a unique identification (address).
AIR SAMPLING-TYPE DETECTOR - A sampling-type detector consists of piping or tubing distribution from the detector unit to the area(s) to be protected. An air pump draws air from the protected area back to the detector through the air sampling ports and piping or tubing. At the detector, the air is analyzed for fire particulate.
ALARM (SIGNAL) NOTIFICATION APPLIANCE - An electromechanical appliance that converts energy into audible or visible signal for perception as an alarm signal.
ALARM SIGNAL - A signal indicating an emergency requiring immediate action, such as an alarm for fire from a manual box, a waterflow alarm, or an alarm from an automatic fire alarm system, or other emergency signal.
ALARM VERIFICATION FEATURE - A feature of automatic fire detection and alarm systems to reduce unwanted alarms, wherein automatic fire detectors must report alarm conditions for a minimum period of time or confirm alarm conditions within a given time period, after being reset, to be accepted as a valid alarm initiation signal.
ANALOGUE - Physical characteristics - such as voltage, pressure, or shaft rotations - expressed in numerical form.
ANALOGUE DEVICE OR METER - A device that measures the relative strength of a specific item or force and translates that measurement into a corresponding voltage using a needle indicator vs. a digital display as compared to a conventional device that only indicates an on or off condition.
ANALOGUE SIGNAL - A control signal that varies over a range (e.g., temperature of a room).
ANNUNCIATION - A visible and/or audible indication of system status.
ANNUNCIATOR - A device which gives a visible or audible indication of the condition or status, such as normal, trouble, or alarm, of a smoke detector or system.
AUTOMATIC FIRE ALARM SYSTEM - A system of controls, initiating devices and alarm signals in which all or some of the initiating circuits are activated by automatic devices such as smoke detectors.
AUTOMATIC GAIN CONTROL (AGC) - The ability of a beam smoke detector to compensate for light signal degradation due to dust or dirt. Rate of compensation is limited to insure that the detector is still sensitive to slow, smouldering fires.
AVERAGE AMBIENT SOUND - The average sound level measured in a given area over the period of occupancy.
BEAM SMOKE DETECTOR (PROJECTED BEAM SMOKE DETECTOR) - A device that senses smoke or smoke and heat by projecting a light beam from a transmitter across the protected area to a receiver that monitors the light signal. Smoke and/or heat entering the beam path will decrease the light signal causing an alarm.
BEAM RANGE - The distance between the transmitter and receiver. Where mirrors are used to direct the beam, the total beam range includes the distance between the mirrors and the transmitter and receiver.
CANDELA (CD) - Unit of light intensity.
CLASS A CIRCUIT (LOOP) - An arrangement of supervised initiating device, signalling line, or indicating appliance circuits that prevents a single open or ground on the installation wiring of these circuits from causing loss of the system's intended function.
CLASS B CIRCUIT (LOOP) - An arrangement of supervised initiating device, signalling line, or indicating appliance circuits, which does not prevent a single open or ground on the installation wiring of these circuits from causing loss of the system's intended function.
COMBINATION SMOKE DETECTOR - A smoke detector that combines two or more smoke or fire sensing technologies.
CUMULATIVE OBSCURATION - is a combination of the density of light blocking particles per foot and the linear distance that these particles occupy, i.e., smoke density times the linear distance of the smoke field.
DETECTOR COVERAGE - The recommended maximum distance between adjacent detectors or the area that a detector is designated to protect. Also, the area in which a smoke detector or heat detector is considered to effectively sense smoke and/or heat. This area is limited by applicable listings and codes.
DIGITAL ALARM COMMUNICATOR RECEIVER (DACR) - A component that receives signals from a communication transmitter (DACT). These signals contain information pertaining to the condition of the alarm system.
DIGITAL ALARM TRANSMITTER (DACT) - A component that transmits signals to a communication receiver (DACR). These signals contain information pertaining to the condition of the alarm system.
DIODE - A device that allows the current to flow in only 1 direction. When a detector head is removed from its base it still passes the current. Internal connections then short it out when the detector head is back in place.
DRIFT COMPENSATION - The capability of a detector to automatically adjust its alarm sensitivity to compensate for any changes over time in the factory settings for smoke and/or fire detection. In analogue systems, this may be done by the panel.
END OF LINE - A device such as a resistor or diode placed at the end of a Class B wire loop to maintain supervision.
END OF LINE RELAY - Device used to supervise power (for four-wire smoke detectors) and installed after the last device on the loop.
FALSE ALARMS - An unwanted alarm caused by non-smoke contaminants such as dust or insects.
FIRE - A chemical reaction between oxygen and a combustible material where rapid oxidation results in the release of heat, light, flame and/or smoke.
FIRE ALARM CONTROL PANEL - A component that receives inputs form initiating devices and sends outputs to notification appliances. This unit also supplies partial or all power to system components. This unit may incorporate a DACT to transmit signals to a DACR.
FLAME DETECTOR - A device that detects the infrared, ultraviolet, or visible radiation produced by a fire.
FOOTCANDLE - Illuminance of a 1-candela source measured 1 foot away from the source.
FOUR-WIRE SMOKE DETECTOR - A smoke detector which initiates an alarm condition on two separate wires (initiating loop) apart from the two power leads.
HEAT DETECTOR - A device that detects abnormally high temperature or rate-of-temperature rise.
INITIATING CIRCUIT - A circuit which transmits an alarm signal initiated manually or automatically, such as a fire alarm box, smoke, heat, or flame sensing device, sprinkler waterflow alarm switch or similar device or equipment to a control panel or any similar device or equipment which, when activated, causes an alarm to be indicated or retransmitted. An Initiating Device Circuit (Loop) is a circuit to which automatic or manual signal initiating devices are connected where the signal received does not identify the individual device operated.
INITIATING DEVICE - Any manually operated or automatically operated equipment which, when activated, initiates an alarm through an alarm signalling device.
INTELLIGENT (ANALOG, SMART) SYSTEM SMOKE DETECTOR - A system smoke detector capable of communicating information about smoke conditions at its location to a control unit. This type of detector typically communicates a unique identification (address) along with an analogue (data) signal, which indicates the level of smoke at its location.
IONIZATION SMOKE DETECTOR - An ionization smoke detector has a small amount of radioactive material that 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 particles of combustion enter the ionization area, they decrease the conductance of the air by attaching themselves to the ions, causing a reduction in mobility. When the conductance is less than a predetermined level, the detector responds in a fire alarm condition.
ISOLATOR - A device designed to protect the loop circuitry in the event of a short circuit, by disconnecting the part of the loop where the short has occurred. It re-connects once the fault has been rectified.
LIGHT SCATTERING - The action of light being reflected and/or refracted by smoke particles for detection by a photoelectric smoke detector. The action of light being refracted or reflected.
LISTED - Equipment or materials included in a list published by an organization (e.g., Underwriters Laboratories) acceptable to the "authority having jurisdiction" andconcerned with product evaluation, that maintains periodic inspection of listed equipment or materials and whose listing states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner. Note: The means for identifying listed equipment may vary for each organization concerned with product evaluation, some of which do not recognize equipment as listed unless it is also labelled.
LUMEN - Amount of light emitted by a 1-candela source passing through a specified area in space.
MAINTENANCE CONDITION - Method of providing annunciation of a smoke detector that it is out of its listed sensitivity range.
NOTIFICATION APPLIANCE - A component such as a horn or strobe that provides audible and/or visible alarm outputs.
NOTIFICATION APPLIANCE CIRCUIT - A circuit to which notification appliances are connected.
NUISANCE ALARM - An unwanted alarm caused by smoke from cooking or cigarettes.
OBSCURATION - A reduction in the atmospheric transparency caused by smoke usually expressed in percent per foot.
OHM'S LAW - Voltage = Current x Resistance
"ON AXIS" - A way of describing the "plane" of or uni-directional light generated from a strobe light. Often used to describe certain UL Standard 1638 strobe lights that send their light out primarily in front of the device.
PARTICLES OF COMBUSTION - Substances (products that either remain at the site of burning such as ash, or scatter as volatile products) resulting from the chemical process of a fire.
PHOTOELECTRIC SMOKE DETECTOR - In a photoelectric 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 detector to respond.
POLAR - Way of describing light output in 2-dimensional space. Plotted as output in candela vs. angle.
PRIVATE MODE - Applications where the signal is known to be in place and where someone is trained to take additional action upon notification from the signal.
PROJECTED BEAM SMOKE DETECTOR - In a projected beam detector the amount of light transmitted between a light source and a photosensitive sensor is monitored. When smoke particles are introduced into the light path, some of the light is scattered and some absorbed, thereby reducing the light reaching the receiver, causing the detector to respond.
PUBLIC MODE - The mode of operation for both visible and audible where the signal is intended to alert anyone in the protected area whether aware or unaware of its presence.
RATE-OF-RISE HEAT DETECTOR - A device that will respond when the temperature rises at a rate exceeding a predetermined amount, usually 15° per minute.
RECEIVER - The device, in a projected beam smoke detector system, which monitors the signal level of the light that is sent by the transmitter.
RESISTOR - A device used to control Voltage and Current. It determines how much current will flow through a component.
SENSITIVITY - The ability of a smoke detector to respond to a given level of smoke.
SMOKE COLOR - The relative lightness or darkness of smoke, ranging from invisible to white to gray to black.
SMOKE DENSITY - The relative quantity of solid and gaseous airborne products of combustion in a given volume.
SMOKE DETECTOR - A device that detects the visible or invisible particles of combustion.
SMOOTHING ALGORITHMS - A method of "smoothing out" a detector's interpretation of sudden, short-duration increases in obscuration within the sensing chamber, intended to reduce the occurrence of nuisance alarms.
SPOT (POINT) DETECTOR - 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, most smoke detectors and thermoelectric detectors. Spot-type detectors have a defined area of coverage.
STRATIFICATION - An effect that occurs when air containing smoke particles or gaseous combustion products is heated by smouldering or burning material and, becoming less dense than the surrounding cooler air, 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 forced ventilation.
SUPERVISORY SIGNAL - A signal that indicates the need for maintenance pertaining to certain components in the system.
TRANSMITTER (PROJECTOR) - The device in a projected beam smoke detector that projects the light across the protected area.
TRANSPARENCIES (FILTERS) - A panel of glass or plastic having a known level of obscuration, which can be used to test the proper sensitivity level of a beam smoke detector.
THERMAL LAG - When a fixed temperature device operates, the temperature of the surrounding air will always be higher than the operating temperature of the device itself. This difference between the operating temperature of the device and the actual air temperature is commonly spoken of as thermal lag, and is proportional to the rate at which the temperature is rising.
TROUBLE CONDITION - The status of a device or system that impairs its proper operation, i.e. open circuit on an initiation loop. The notification of a trouble condition indicated on a control panel or annunciator is a "TROUBLE" SIGNAL.
TROUBLE SUPERVISION - The ability of a fire alarm control unit (FACU) to detect a fault condition in the installation wiring, which would prevent normal operation of the fire alarm system.
TWO-WIRE SMOKE DETECTOR - A smoke detector that initiates an alarm condition on the same two wires that also supply power to the detector.
UNWANTED ALARM - Any false alarm or nuisance alarm.
VOLTAGE DROP - The decrease in voltage from the beginning of a circuit to the end of a circuit due to resistance.
WIRELESS SMOKE DETECTOR - A smoke detector that contains an internal battery or batteries that supply power to both the smoke detector and integral radio frequency transmitter. The internal power source is supervised and degradation of the power source is communicated to the control panel. On stimuli, the detector transmits a radio signal to a repeater or Fire Alarm Control Unit (FACU) that in turn generates a signal or status condition.
ZONE - A specific area within protected premises that defines the type of alarm and/or location.