Updated Monday June 30, 2008

Firefighter Dictionary: T

The following is common terminology to structural fire firefighters. There are additional definitions for emergency medical terminology, building construction, arson investigation and hazardous materials and more. Please note that some definitions have more than one meaning but are spelled the same. Click on a letter to take you to that index.   

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 

T
Tachometer	An instrument, dashboard or pump panel gauge that measures the engine speed in revolutions per minute (rpm).
T & G, tongue and groove	A joint made by a tongue (a rib on one edge of a board) that fits into a corresponding groove in the edge of another board to make a tight flush joint. Typically, the subfloor plywood is T & G.
T bar	Ribbed, "T" shaped bars with a flat metal plate at the bottom that are driven into the earth. Normally used chain link fence poles, and to mark locations of a water meter pit.
Tab	The exposed portion of strip shingles defined by cutouts.
Tactical Direction	Direction given by the Operations Section Chief that includes the tactics required to implement the selected strategy, the selection and assignment of resources to carry out the tactics, directions for tactics implementation, and performance monitoring for each operational period.
Tactical objectives	The specific operations that must be accomplished to achieve strategic goals. Tactical objectives must be both specific and measurable. Tactical level officers are Division / Group / Sector.
Tactics	Deploying and directing resources on an incident to accomplish incident strategy and objectives.
Tail beam	A relatively short beam or joist supported in a wall on one end and by a header at the other.
Tailboard	The back step of fire apparatus.
Tandem	Two-axle suspension.
Tandem pumping	Short relay operation in which the pumper taking water from the supply source pumps into the intake of the second pumper. The second pumper boosts the pressure of the water even higher; this method is used when pressures higher than the capability of a single pump are required.
Tanker	A fire truck  that is used primarily for carrying water to a fire scene, normally in excess of 1,500 gallons.  Tankers can be in size from 3000 gallons to 10,000 gallons. These are most often employed in rural areas where access to fire hydrants is sometimes more difficult than in more built up areas or in areas where it is not feasible to lay large amounts of hose due to both friction and elevation loss. Not a Tanker/Pumper; this apparatus does not have a pump. See Mobile Water Supply Fire Apparatus; in ICS terms, tanker refers to a water-transporting fixed-wing aircraft.
Tanker shuttle operations	Method of water supply by which tenders/tankers continuously transport water between a fill site and the dumpsite located near the emergency scene. See Water Shuttle Operation.
Tanker / Pumper	A mobile water supply apparatus equipped with a fire pump. In some jurisdictions, this term is used to differentiate a fire pump equipped mobile water supply apparatus whose main purpose is to shuttle water.
Tar	A dark heavy oil used in roofing and roof surfacing.
Target hazard	The major hazard associated with a chemical substance, such as corrosive hazard, fire hazard, or an explosion hazard.
Task Force	A combination of single resources assembled for a particular tactical need with common communications and a Leader.
Team	See Single Resource.
Technical assistance	Personnel, agencies, or printed materials that provide advanced technical information on the handling of specific technologies such as hazardous materials, engineering, ordinance handling, etc..
Technical Specialists	Personnel with special skills that can be used anywhere within the ICS organization. Trained, certified, qualified individuals who provide specific expertise to the Incident Commander. They may represent the shipper, manufacturer, or be otherwise familiar with the problems involved in the emergency.
Teco	Metal straps that are nailed and secure the roof rafters and trusses to the top horizontal wall plate. Sometimes called a hurricane clip.
Tee	A "T" shaped plumbing fitting.
Telecommunicator (Dispatcher)	One who answers 9-1-1 calls and dispatches emergency equipment over the radio.
Telescoping aerial platform apparatus	Type of aerial apparatus equipped with an elevating platform; also equipped with piping systems and nozzles for elevated master stream operations; are not meant to be climbed and are equipped with a small ladder that is to be used only for escape from the platform in emergency situations.
Telescoping boom	Aerial device raised and extended via sections that slide within each other.
Temperature	The intensity of  heat measured by a thermometer or similar instrument. The lowest possible temperature is absolute zero on the Kelvin temperature scale (-273 degrees on the Celsius scale). At absolute zero it is impossible to release any energy.
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Temperature rise	The temperatures increase over ambient due to load.
Tempered	Strengthened tempered glass will not shatter nor create shards, but will "pelletize" like an automobile window. Required in tub and shower enclosures and locations, entry door glass and sidelight glass, and in a windows when the window sill is less than 16" to the floor.
Tender	A vehicle used primarily to serve in conjunction with engine companies or fireboats to provide additional hose or other equipment; term used within ICS for a mobile piece of apparatus that has the primary function of supporting another operation. Examples include a water tender that supplies water to pumpers, a fuel tender that supplies fuel to other vehicles, etc. Also see Tanker and Mobile Water Supply Apparatus.
Tensile strength	The force required to rupture a material by pulling on it. A physical test applied to materials (ranging from plastics to steel) to determine when they will tear, break, snap, or rupture.
Termination	That portion of incident management where personnel are involved in documenting safety procedures, site operations, hazards faced, and lessons learned from the incident. Termination is divided into three phases: Debriefing, Post-Incident Analysis, and Critique.  See Post-Incident Analysis.
Terrorism	Under the Homeland Security Act of 2002, terrorism is defined as activity that involves an act dangerous to human life or potentially destructive of critical infrastructure or key resources and is a violation of the criminal laws of the United States or of any State or other subdivision of the United States in which it occurs and is intended to intimidate or coerce the civilian population or influence a government or affect the conduct of a government by mass destruction, assassination, or kidnapping. See Section 2 (15), Homeland Security Act of 2002, Pub. L. 107-296, 116 Stat. 213 5 (2002).
Tertiary decontamination	A third phase of decontamination usually accomplished at a medical facility to remove remaining minute quantities of contaminant.
Tetrahedron	A four-sided, solid geometric figure that resembles a pyramid, with one of the sides forming the base. The fire service has used this geometric form to demonstrate that to have a fire occur it will need four things, heat, fuel, oxygen and a chemical reaction. If one or more is eliminated, the fire will not occur or if already active; the fire will be extinguished. See Fire Tetrahedron and Fire Triangle
Thermal burn	Pertaining to or characterized by heat.
Thermal column	Heated column of smoke and gases moving upward from a fire while cooler airflows toward the base of the fire; the magnitude and the intensity of a fire can often be judged by observing the thermal column. See Plume.
Thermal conductor	Material capable of transmitting heat.
Thermal cracking	A refining process, which decomposes, rearranges, or combines hydrocarbon molecules by the application of heat without the aid of catalysts.
Thermal expansion	The proportional increase in length, volume, or superficial area of a body with rise in temperature. The amount of this increase per degree temperature, called the coefficient of thermal expansion, is different for different substances.
Thermal Imaging Camera (TIC)	As the name implies these cameras are able to measure the differences in temperatures between different surfaces and display this on a small screen as what looks like a black and white picture. This allows fire personnel to "see" inside of a wall, floor, or ceiling to check for areas of abnormal heat without having to open the area up for visual inspection. Newer models can display even more information than the earlier models. As an example, some cameras provide color images, codes and temperature scales. Some models transmit these images to a receiver outside of the immediate fire area.
Thermal inertia	The properties of a material that characterize its rate of surface temperature rise when exposed to heat. Thermal inertia is related to the product of the material's thermal conductivity.
Thermocouple	A device for measuring temperature, in which two electrical conductors of dissimilar metals (such as copper and iron) are joined at the point where heat is to be applied. Most commonly used in heating appliances such as furnaces and hot water heaters.
Thermoplastic	Plastic materials that soften and melt under exposure to heat and can reach a flowable state.
Thermoply ™	Exterior laminated sheathing nailed to the exterior side of the exterior walls. Normally ¼ " thick, 4 X 8 or 4 x 10 sheets with an aluminumized surface.
Three phase	Consists of 4 wires and is used in industrial and commercial applications. This system is suitable for installations requiring large motors. It consists of three hot wires and one ground wire. The voltage in each hot wire is out of phase with the others by 1/3 of a cycle, as if produced by 3 different generators.
Three-dimensional shingles	Laminated shingles. Shingles that have added dimensionality because of extra layers or tabs, giving a shake-like appearance. May also be called "architectural shingles".
Threshold	The bottom metal or wood plate of an exterior door frame. Generally they are adjustable to keep a tight fit with the door slab.
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Threshold Limit Value (TLV)	The concentration of a toxic substance that can be tolerated with no ill effects. For an airborne toxic material, the Threshold Limit Value is used as a guide in the control of health hazards and represents the concentration to which nearly all workers may be exposed eight hours per day over extended periods of time without adverse effects.
Threshold Limit Value / Short Term Exposure Limit  (TLV/STEL)	The 15-minute, time-weighted average exposure which should not be exceeded at any time, nor repeated more than four times daily with a 60-minute rest period required between each STEL exposure. The lower the value, the more toxic the substance. The contaminant concentration to which research indicates workers can be exposed for a short time period without suffering from irritation, injury, or adverse health effects (assuming the TLV-TWA is not exceeded) Limit published by the ACGIH. The concentration to which workers can be exposed continuously for a short period of time without suffering from 1) irritation, 2) chronic or irreversible tissue damage or 3) narcosis if sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency and provided that the TLV-TWA is not exceeded. Usually this is a 15-minute time period that is to occur no more than 4 times daily with at least one hour breaks between exposures.
Threshold Limit Value / skin	Indicates a possible and significant contribution to overall exposure to a material by absorption through the skin, mucous membranes, and eyes by direct or airborne contact.
Threshold Limit Value / Time Weighted Average (TLV/TWA)	The airborne concentration of a material to which an average, healthy person may be exposed repeatedly for 8 hours each day, 40 hours per week, without suffering adverse effects. The young, old, ill, and naturally susceptible will have lower tolerances and will need to take additional precautions. TLVs are based upon current available information and are adjusted on an annual basis by organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH). As TLVs are time-weighted averages over an eight-hour exposure, they are difficult to correlate to emergency response operations. The lower the value, the more toxic the substance.
Threshold limit value-ceiling (TLV-C)	The contaminant concentration that should not be exceeded for any length of time during a work shift
Through the roof	A visual indication that the fire has gained sufficient headway so as to vent itself by burning a hole through the roof of a structure.
Throwing salvage covers	To spread salvage covers over items by throwing them in a specified manner that unfolds the cover and drapes the furnishings to be protected against the elements of fire and suppression operations. See salvage cover
Tie in	Securing oneself to a ladder by the use of a rope, hose tool, belt, or by inserting one leg between the rungs of a ladder.
TIER I	Inventory form for reporting Hazardous Chemicals (Sec. 312) and extremely Hazardous Substances (Sec. 302).
TIER II	A form similar to the Tier I form but which describes in more detail the chemical quantity and location(s) within the facility. These forms must be filled out and sent to the LEPC and the local fire department.
Tiller	A type of ladder truck with a second cab at the rear of the truck where a firefighter will steer the rear wheels. Because tiller trucks can steer in the front and the back, they are able to navigate turns that other ladder trucks could not. The rear steering wheel on a large aerial ladder truck or other vehicle requiring two separate steering mechanisms.
Tillerman	The person who operates the rear wheel and steering mechanism of a large aerial ladder.
Timber	Lumber with a cross section larger than 4"x6", for posts, sills, and girders.
Time Line	Graphical representation of the events in the fire incident displayed in chronological order.
Time Unit	Functional Unit within the Finance/Administration Section responsible for recording time for incident personnel and hired equipment.
Time temperature curve	A graph curve showing the rise or fall in temperature at stated intervals in relation to the elapsed time and the fire resistance or combustibility of various materials.
TJI or TJ	Manufactured structural building component resembling the letter "I". Used as floor joists and rafters. I-joists include two key parts: flanges and webs. The flange or from of the I joist may be made of laminated veneer lumber or dimensional lumber, usually formed into a 1 ½" width. The web or center of the I-joist is commonly made of plywood or oriented strand board (OSB). Large holes can be cut in the web to accommodate duct work and plumbing waste lines. I-joists are available in lengths up to 60'' long.
TNT	Abbreviation for Trinitrotoluene.
Toenailing	To drive a nail in at a slant. Method used to secure floor joists to the plate.
Top chord	The upper or top member of a truss.
Top lap	The shortest distance in inches from the lower edge of an overlapping shingle to the upper edge of the lapped unit in the first course below, that is the width of the shingle minus the exposure.
Top plate	Top horizontal member of a frame wall supporting ceiling joists, rafters, or other members.
Torch	A person hired to set fires for fraudulent purposes.
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Torching fire	Fire burning principally as a surface fire that intermittently ignites the crowns of trees or shrubs as it advances.
Tormentor poles	Poles attached to long extension ladders for the purpose of steadying the ladder during the raising and lowering operations.
Total pressure	Total amount of pressure loss in a hose assembly due to friction loss in the hose and appliances, elevation losses, or any other factors.
Total stopping distance	Sum of the driver/operator reaction distance and the vehicle braking distance.
Touch off	To set a fire or to describe a fire that firefighters believe has been purposely set.
Tower	See Drill Tower.
Tower ladder	Term used to describe a telescoping aerial platform fire apparatus.
Toxic materials	Substances that can be poisonous if inhaled, swallowed, or absorbed into the body through cuts or breaks in the skin.
Toxic products of combustion	The toxic by-products of the combustion process. Depending upon the materials burning, higher levels of personal protective clothing and equipment may be required.
Toxicity	The ability of a substance to produce injury once it reaches a susceptible site in or on the body; a measure of the harmful effect produced by a given amount of toxin on a living organism; the relative toxicity of an agent can be expressed in milligrams of toxin needed per kilogram of body weight to kill experimental animals; the property a material possesses which enables it to injure the physiological mechanism of an organism by chemical means, with the maximum effect being incapacitation or death.
Tractor tiller aerial ladder	Aerial ladder apparatus that consists of a tractor power unit and trailer (tiller) section that contains the aerial ladder, ground ladders, and equipment storage areas; the trailer section is steered independently of the tractor by a person called the tiller operator/tillerman.
Traffic control device	Mechanical device that automatically changes traffic signal lights to favor the path of responding emergency apparatus.
Trailers	Trails of fast-burning materials used by arsonists as fuses to rapidly spread a fire throughout a structure.
Transfer valve	A valve used for placing multistage centrifugal pumps in either volume or pressure operation. (also change over valve)
Transmission of heat	The Law of Heat Flow through conduction, convection, and radiation.
Transom window	A narrow horizontal window above a window or door, named for the cross bar on which it rests.
Transverse hose bed	Hose bed that lies across the pumper body at a right angle to the main hose bed; designed to deploy pre-connected attack hose to the sides of the pumper.
Trap	A plumbing fitting that holds water to prevent air, gas, and vermin from backing up into a fixture.
Trash Line	Same as jump line, although not necessarily carried on the front bumper. Small diameter, pre-connected hose line intended to be used for trash or other small, exterior fires.
Tray ceiling	A recessed ceiling resembling an upside-down tray; also referred to as a stepped ceiling.
Tread	The walking surface board in a stairway on which the foot is placed.
Treated lumber	A wood product which has been impregnated with chemical pesticides such as CCA (Chromated Copper Arsenate) to reduce damage from wood rot or insects. Often used for the portions of a structure which are likely to be in contact with soil and water. Wood may also be treated with a fire retardant.
Triage	Sorting; a technique of establishing rescue, decontamination, treatment and transportation priorities in any event where the number of casualties overwhelms the resources of the emergency response organizations.
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Trim- Interior	The finish materials in a building, such as moldings applied around openings (window trim, door trim) or at the floor and ceiling of rooms (baseboard, cornice, and other moldings). Also, the physical work of installing interior doors and interior woodwork, to include all handrails, guardrails, stair way balustrades, mantles, light boxes, base, door casings, cabinets, countertops, shelves, window sills and aprons, etc. Exterior- The finish materials on the exterior a building, such as moldings applied around openings (window trim, door trim), siding, windows, exterior doors, attic vents, crawl space vents, shutters, etc. Also, the physical work of installing these materials
Trimmer	The longer floor or ceiling-framing member around a rectangular opening into which headers are joined; both headers and trimmers are doubled.
Trimmer	The vertical stud that supports a header at a door, window, or other opening.
Triple hydrant	A fire hydrant having three outlets, usually two 21/2-inch outlets and one larger outlet.
Triple combination pumper	A fire department pumper that carries a fire pump, hose, and a water tank.
Truck	A ladder truck that carries a complement of ladders, tools, and equipment.
Truck Company	A truck company is a combination of a fire truck with an aerial ladder, an assortment of ground ladders and forced entry tools and the manpower used to staff it. Trucks can have straight aerial ladders as short as 65 feet or longer ladders with platforms (buckets) on the end. In many department's truck companies are responsible for ventilation and forcible entry duties. A standard truck company will include an officer, driver/operator and two firefighters on a ladder truck. See Ladder Company.
Trumpets	Symbolic insignia or rank used throughout the fire service dating back to the time when fire officers gave commands through speaking trumpets.
Truss	Structural unit of members fastened in triangular  or combinations of triangles for added strength, arrangements to form a rigid framework for support over long spans. An engineered and manufactured roof support member with "zig-zag" framing members. Does the same job as a rafter but is designed to have a longer span than a rafter. Known to weaken by the effects of fire.
Truss blocks	The blocks used to separate the beams of a truss beam ladder. Also called Beam Blocks or Rung Blocks.
Truss rafter	Truss spaced close enough (usually 24" o.c.) to eliminate the need for purlins.
Turnout clothing	A name given to bunker, or protective, clothing.
Turnouts	Protective clothing worn when turning out (responding) to an alarm or fire. Usually consists of boots and pants, coat and helmet.
Turntable	A rotating platform at the base of an aerial ladder, usually containing the operator's panel.
Turret	A vehicle-mounted master stream device; a heavy stream nozzle mounted on other equipment and connected by piping to the pump; also called Turret Gun, Monitor, Deck Gun, Heavy Stream Device.
Turret (construction)	A small tower usually on the corner of a building, most common in Victorian-style homes.
Two stage centrifugal pump	A centrifugal pump with two impellers.
Type	A classification of resources in the ICS that refers to capability. Type 1 is generally considered to be more capable than Types 2, 3, or 4, respectively, because of size, power, capacity, or, in the case of incident management teams, experience and qualifications.
Types of roofs	Gable, Flat, Gambrel, Deck, Mansard, Shed, Butterfly