NFPA 1700 Guide for Structural Fire Fighting

Abandoned Building

A building that is unoccupied/ unused with no intention of re-occupying and reusing.


An unplanned event that interrupts an activ­ity and sometimes causes injury or damage or a chance occur­rence arising from unknown causes; an unexpected happening due to carelessness, ignorance, and the like.

Aerial Fire Apparatus

A vehicle equipped with an aerial ladder, elevating platform, or water tower that is designed and equipped to support firefighting and rescue operations by positioning personnel, handling materials, providing continu­ous egress, or discharging water at positions elevated from the ground.


Someone’s or something’s surroundings, espe­cially as they pertain to the local environment; for example, ambient air and ambient temperature.

Atmospheric Pressure

The pressure of the weight of air on the surface of the earth, approximately 14.7 pounds per square inch (psia) (101 kPa absolute) at sea level.


A deflagration resulting from the sudden introduction of air into a confined space containing oxygen- deficient products of incomplete combustion.


Any story of a building wholly or partly below grade plane that is not considered the first story above grade plane.

Bidirectional Vent

A building opening that serves as both an intake and exhaust vent of a flow path at the same time.


Boiling liquid expanding vapor explosion.

Blitz Attack

A coordinated fire attack from the exte­rior with a master stream (300+ gpm).


Powered fans that are used to push air into a structure to increase the pressure of the gases inside a structure to move the gases to an area of lower pressure, usually the exte­rior.

British Thermal Unit (Btu).

The quantity of heat required to raise the temperature of one pound of water 1°F at the pressure of 1 atmosphere and temperature of 60°F; a British thermal unit is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories


The tendency or capacity to remain afloat in a liquid. (2) The upward force of a fluid upon a float­ing object.


The amount of heat necessary to raise 1 gram of water 1°C at the pressure of 1 atmosphere and temperature of 15°C; a calorie is 4.184 joules, and there are 252.15 calories in a British thermal unit (Btu).


A cancer-causing substance that is identified in one of several published lists, including, but not limited to, those prepared by the U.S. National Toxicology Program, the International Agency for Research on Cancer (IARC), the National Institute for Occupational Safety and Health (NIOSH), and the American Conference of Govern­mental Industrial Hygienists (ACGIH).

Ceiling Jet

A relatively thin layer of flowing hot gases that develops under a horizontal surface (e.g., ceiling) as a result of plume impingement and the flowing gas being forced to move horizontally.

Ceiling Layer

A buoyant layer of hot gases and smoke produced by a fire in a compartment.


Carbonaceous material that has been burned or pyrolyzed and has a blackened appearance.


Capable of undergoing combustion.

Combustible Liquid



A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame.

Combustion Products

The heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion.

Command Post

The location where the incident commander and associated staff are located during an emer­gency incident.


The basic fire-fighting organizational unit staffed by various grades of fire fighters under the supervision of an officer and assigned to one or more specific pieces of apparatus.

Engine Company

A piece of fire apparatus along with fire fighters that have the primary responsibility to deliver a fire stream or streams to extinguish the fire in coordination with ventilation (truck company) and rescue operations.

Rescue Company

A piece of fire apparatus along with fire fighters that are generally utilized for search and rescue at fire incidents.

Truck (Ladder) Company

A group of fire fighters who work as a unit and are equipped with one or more pieces of aerial fire apparatus.


The interposing of a physical barrier that is not required to be fire or explosion resistant in order to limit combustible particulate solid migration and hence to control the size of a hazard area.

Concealed Space

That portion(s) of a building behind walls, over suspended ceilings, in pipe chases, and in attics whose size might normally range from 44.45 mm (1:K, in.) stud spaces to 2.44 m (8 ft.) interstitial truss spaces and that might contain combustible materials such as building struc­tural members, thermal and/or electrical insulation, and duct­ing.


Heat transfer to another body or within a body by direct contact.

Conductive and Compressive Heat Resistance (CCHR) Test

A test used to evaluate the properties of the garment shoulder and knee areas, which are more likely to become compressed, because thermal insulation is reduced under compression.

Construction Type

The combination of materials used in the construction of a building or structure, based on the varying degrees of fire resistance and combustibility.


Smoke, fumes, and particulates depos­ited on personnel, PPE, apparatus, tools, and equipment.


Heat transfer by circulation within a medium such as a gas or a liquid.

Changing Technology

Technology is constantly chang­ing the world around us as well as changing how we work and live. This is true for the fire service as well. Research that has a direct impact on the fire service comes from a wide range of disciplines — engineering, textile science, the military, and many others. For example, the development of thermal imagers by the military enabled the use of thermal imagers for the fire service.

Changes in the Fire Fighters’ Work Environment

Over the past 50 years, changes in construction materials, construc­tion methods, insulation, and furnishings have changed the means and the speed of fire growth within a structure. Both research experiments and line-of-duty death (LODD) and line- of


In the 1950s a wide range of synthetic materials called polymers became available for use in clothing, furniture, interior finish, and insulation.

Fire-Fighting Equipment Enables Changes in Fire- Fighting Tactics.

During the same 50-year period, the tactics fire fighters use on the fireground have also changed. The reliance on indi­rect, or exterior, attack prior to entry changed to a focus on interior, direct fire control.

Decay Stage

The stage of fire development within a structure characterized by either a decrease in the fuel load or available oxygen to support combustion, resulting in lower temperatures and lower pressure in the fire area.


The process of removing contami­nants such as soot, particulate, and fireground chemicals to clean fireground tools and equipment and prevent the spread of contamination to other persons or equipment.

Dry Decontamination

Utilizing forced airflow or brushing off of personnel, PPE, apparatus, tools, and equip­ment to reduce contaminants.

Gross Decontamination

The initial phase of the decontamination process during which the amount of surface contaminant is significantly reduced by removing bulk contaminants and substances from the surface of the equipment or tools using some form of brushing, wetting agent, and/or detergents.

Wet Decontamination

Utilizing water or a water and soap solution to reduce contaminants on personnel, PPE, apparatus, tools, and equipment.

Defensive Strategy

The plan for the actions or move­ments of fire department units to protect exposures and contain the main body of fire to the already affected areas.


Propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted medium.


The mass of a substance per unit volume, usually specified at standard temperature and pressure. The density of water is approximately 1 gram per cubic centimeter. The density of air is approximately 1.275 grams per cubic meter.


Sensing the existence of a fire, espe­cially by a detector from one or more products of the fire, such as smoke, heat, infrared radiation, and the like. (2) The act or process of discovering and locating a fire.


Propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium.

Differential Pressure

The difference between pres­sures at different points along a flow path that creates a flow of gases or fluids from an area of higher pressure to an area of lower pressure.

Diffuse Fuel

A gas, vapor, dust, particulate, aerosol, mist, fog, or hybrid mixture of these, suspended in the atmos­phere, which is capable of being ignited and propagating a flame front.

Diffusion Flame

A flame in which fuel and air mix or diffuse together at the region of combustion.

Direct Application

Fire-fighting operations involving the application of extinguishing agents directly onto the burn­ing fuel surface.


The process of properly removing a member’s PPE and respiratory protection to limit additional contamina­tion and exposure.


The process of properly dressing in full PPE, ensuring all exposed skin and airway are protected.

Door Control

Using a door to limit the amount of air available to the fire, or to isolate a part of the building from the flow path.

Drop Down

The spread of fire by the dropping or fall­ing of burning materials. Synonymous with “fall down.”

Dry Decontamination


Dynamic Flow

A unidirectional or bidirectional flow of smoke/air that presents irregular stratification and shape or alternates in direction (i.e., pulsations).

Energy Storage System (ESS)

One or more compo­nents assembled together capable of storing energy and provid­ing electrical energy into the premises wiring system or an electric power production and distribution network.

Engine Company



The process of air or gases being drawn into a fire, plume, or jet.

Exclusion Zone


Exhaust Vent

The outlet of a flow path that allows the gases to move out of the structure.


The sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the produc­tion and release of gases under pressure, or the release of gas under pressure. These high-pressure gases then do mechanical work such as moving, changing, or shattering nearby materials.


Any chemical compound, mixture, or device that functions by explosion.

Exposure — Personnel

The process by which people, animals, and equipment are subjected to or come in contact with a hazardous environment or material.

Exposure — Structure

The side of a structural assem­bly or separate part of the fireground that is directly exposed to the fire to which the fire could spread.

Exposure Protection

Using an extinguishing agent to coat the exposure, and/or remove the fuel(s), to prevent fire spread.


To cause to cease burning.


Distortion, breakage, deterioration, or other fault in an item, component, system, assembly, or structure that results in unsatisfactory performance of the function for which it was designed.

Fire. A rapid oxidation process, which is a gas phase chemical reaction resulting in the evolution of light and heat in varying intensities.

Fire Alarm System.

A system or portion of a combina­tion system that consists of components and circuits arranged to monitor and annunciate the status of fire alarm or supervi­sory signal-initiating devices and to initiate the appropriate response to those signals.

Fire Apparatus

A vehicle designed to be used under emergency conditions to transport personnel and equipment or to support the suppression of fires or mitigation of other hazardous situations.

Fire Command Center

The principal attended or unattended room or area where the status of the detection, alarm communications, control systems, and other emergency systems is displayed and from which the system(s) can be manually controlled.

Fire Control

The coordinated tasks of delivering an extinguishing agent (e.g., water) to fire and heat and manag­ing the flow of air, smoke, heat, and fuel(s).

Fire Department Connection (FDC)

A connection through which the fire department can pump supplemental water into the sprinkler system, standpipe, or other water-based fire protection systems, furnishing water for fire extinguish­ment to supplement existing water supplies.

Fire Dynamics

The detailed study of how chemistry, fire science, and the engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior.

Fire Propagation

See 3.3.73, Fire Spread.

Fire Resistive Construction

Construction designed to provide reasonable protection against fire.

Fire Science

The body of knowledge concerning the study of fire and related subjects (such as combustion, flame, products of combustion, heat release, heat transfer, fire and explosion chemistry, fire and explosion dynamics, thermody­namics, kinetics, fluid mechanics, fire safety) and their interac­tion with people, structures, and the environment.

Fire Spread

The movement of fire from one place to another.


A body or stream of gaseous material involved in the combustion process and emitting radiant energy at specific wavelength bands determined by the combustion chemistry of the fuel. In most cases, some portion of the emit­ted radiant energy is visible to the human eye.

Flame Front

The flaming leading edge of a propagat­ing combustion reaction zone.


The condition where unburned fuel from a fire has accumulated in the ceiling layer to a sufficient concentration (i.e., at or above the lower flammable limit) that it ignites and burns; can occur without ignition of, or prior to, the ignition of other fuels separate from the origin.


Capable of burning with a flame.

Flammable Gas

A material that is a gas at 68°F (20°C) or less at an absolute pressure of 14.7 psi (101.3 kPa), that is ignitable at an absolute pressure of 14.7 psi (101.3 kPa) when in a mixture of 13 percent or less by volume with air, or that has a flammable range at an absolute pressure of 14.7 psi (101.3 kPa) with air of at least 12 percent, regardless of the lower limit.

Flammable Limit

The upper or lower concentration limit at a specified temperature and pressure of a flammable gas or a vapor of an ignitible liquid and air, expressed as a percentage of fuel by volume that can be ignited.

Flammable Liquid


Flammable Range

The range of concentrations between the lower and upper flammable limits.

Flash Fire

A fire that spreads by means of a flame front rapidly through a diffuse fuel, such as dust, gas, or the vapors of an ignitible liquid, without the production of damag­ing pressure.

Flash Point of a Liquid

The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momen­tary flame across its surface.


A transition phase in the development of a compartment fire in which surfaces exposed to thermal radia­tion reach ignition temperature more or less simultaneously and fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space.

Flow Path

The route followed by smoke, air, heat, or flame toward or away from an opening; typically, a window, door, or other leakage points, due to differences in pressure.

Flow Path Control

The tactic of controlling or closing ventilation points to limit additional oxygen into the space thereby limiting fire development, heat release rate, and smoke production, and to control the movement of the heat and smoke conditions out of the fire area to the exterior and to other areas within the building.

Fog Stream.



A material that will maintain combustion under specified environmental conditions.

Fuel Gas

Natural gas, manufactured gas, LP-Gas, and similar gases commonly used for commercial or residential purposes such as heating, cooling, or cooking.

Fuel Load

The total quantity of combustible contents of a building, space, or fire area, including interior finish and trim, expressed in heat units or the equivalent weight in wood.

Fuel Package

A single item of fuel.

Fuel-Limited Fire

A fire in which the heat release rate and growth rate are controlled by the characteristics of the fuel, such as quantity and geometry, and in which adequate air for combustion is available.

Fully Developed Stage

The stage of fire development where heat release rate has reached its peak within a compart­ment based on available fuel or ventilation.


The physical state of a substance that has no shape or volume of its own and will expand to take the shape and volume of the container or enclosure it occupies.

Glowing Combustion

Luminous burning of solid material without a visible flame.

Gross Contamination


Growth Stage

The stage of fire development where the heat release rate from an incipient fire has increased to the point where heat transferred from the fire and the combustion products are pyrolyzing adjacent fuel sources and the fire begins to spread across the ceiling of the fire compartment (rollover).


Any arrangement of materials that presents the potential for harm.

Hazard Control Zones

The physical or conceptual demarcation of an emergency scene according to levels of risk and the associated personal protective equipment (PPE) usage that identifies the exclusion, hot, warm, and cold zones are all zones within the “hazard control zone” classification.

Cold Zone

A hazard-free area where PPE is not required and that is suitable for locating command, rehabili­tation, medical functions, and public access.


Exclusion Zone

An area where no personnel may enter due to imminent hazard(s), where issued PPE will not protect against the hazard, or where there is a need to protect potential evidence.

Hot Zone

The primary incident hazard area deemed immediately dangerous to life and health (IDLH) and where personnel wear PPE suitable for the hazards encountered.

Warm Zone

A limited-access area for personnel directly aiding or in support of operations in the hot zone where personnel wear PPE suitable for the hazards present.


A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.

Heat and Flame Vector.

An arrow used in a fire scene drawing to show the direction of heat, smoke, or flame flow.

Heat Flux.

The measure of the rate of heat transfer to a surface or an area, typically expressed in kW/m2, or W/cm2.

Heat of Combustion.

The total amount of thermal energy that could be generated by a fuel if it were to burn completely and which is typically measured in kilojoules per gram (kj/g) or mega joules per kilogram (MJ/kg).

Heat of Ignition.

The heat energy that brings about ignition.

Heat Release Rate (HRR).

The rate at which heat energy is generated by burning.

Heat Transfer.

The exchange of thermal energy from the source to the fuel by the mechanisms of conduction, convection, or radiation, or all three.

High-Pressure Side or Upwind Side

The side of the building that the wind is impacting on.

High-Rise Building.

A building where the floor of an occupiable story is greater than 75 ft (23 m) above the lowest level of fire department vehicle access.

Horizontal Ventilation

A method of utilizing natural ventilation currents to manage the flow of heat and smoke from the interior to the exterior while entraining fresh air from an intake on the same level of the structure.


A hose extended from fire apparatus or a standpipe system designed to flow between 90 gpm and 300 gpm.

Hot Zone


Hydraulic Ventilation

Use of a water stream to remove gases from a compartment through an exhaust vent while entraining fresh air from an intake.

FfVAC Ventilation

Air flows due to fixed building heating ventilation and air conditioning systems.

Ignitible Liquid

Any liquid or the liquid phase of any material that is capable of fueling a fire, including a flammable liquid, combustible liquid, or any other material that can be liquefied and burned.


The process of initiating self-sustained combustion.

Ignition Energy

The quantity of heat energy that should be absorbed by a substance to ignite and burn.

Ignition Temperature

Minimum temperature a substance should attain in order to ignite under specific test conditions.

Ignition Time

The time between the application of an ignition source to a material and the onset of self-sustained combustion.

Immediately Dangerous to Life or Health (IDLH).

Any condition that would pose an immediate or delayed threat to life, cause irreversible adverse health effects, or interfere with an individual’s ability to escape unaided from a hazardous environment.

Incendiary Fire

A fire that is intentionally ignited in an area or under circumstances where and when there should not be a fire.

Incident Action Plan

The correct actions that match, take control of, and mitigate the incident hazards within the overall incident strategy.

Incident Command System (ICS)

A component of an incident management system (IMS) designed to enable effec­tive and efficient on-scene incident management by integrating organizational functions, tactical operations, incident plan­ning, incident logistics, and administrative tasks within a common organizational structure.

Incident Commander (IC)

The individual responsi­ble for all incident activities, including the development of strategies and tactics and the ordering and the release of resources.

Incipient Stage

The early stage of fire development where the fire’s progression is limited to a fuel source and the thermal hazard is localized to the area of the burning material.

Independent Service Provider (ISP)

See 3.3.243, Verified Independent Service Provider (ISP).

Indirect Attack

Fire-fighting operations involving the application of extinguishing agents to reduce the buildup of heat released from a fire with the intention of suppressing the fire without applying the agent directly onto the burning surface.

Intake Vent

An inlet of a flow path that allows fresh air to move into the structure.


The preferred SI unit of heat, energy, or work. A joule is the heat produced when one ampere is passed through a resistance of one ohm for one second, or it is the work required to move a distance of one meter against a force of one newton. There are 4.184 joules in a calorie and 1055 joules in a British thermal unit (Btu). A watt is a joule/second.

Knee Wall

A short wall, typically under 3 ft (1 m) in height, used to create a room, such as a living space within an attic, and whose creation results in a void space behind the knee wall and the underside of the roof.


The reduction of flame and heat to a point where further extension of a fire has been abated and the overhaul stage can begin.

Latent Heat

The energy that causes a change in state of matter of an object.


The systematic process of removing debris from the top down and observing the relative location of arti­facts at the fire scene.

Life Safety

The protection of human life, including all persons within a structure, civilians, and fire-fighting person­nel.

Lightweight Construction

Structures that have framework made out of wood or other lightweight materials.


Any material that (1) has a fluidity greater than that of 300 penetration asphalt when tested in accordance with ASTM D5, Standard Test Method for Penetration of Bituminous Materials, or (2) is a viscous substance for which a specific melt­ing point cannot be determined but that is determined to be a liquid in accordance with ASTM D4359, Standard Test for Deter­mining Whether a Material is a Liquid or a Solid.

Low Explosive

An explosive that has a reaction veloc­ity of less than 1000 m/sec (3000 ft/sec).

Low-Pressure Side or Downwind Side

The side of the building opposite the side of the building that the wind is impacting on.

Lower Explosive Limit or Lower Flammable Limit

The minimum concentration of combustible vapor or combus­tible gas in a mixture of the vapor or gas and gaseous oxidant above which propagation of flame will occur on contact with an ignition source.

Master Stream


Material First Ignited

The fuel that is first set on fire by the heat of ignition; to be meaningful, both a type of mate­rial and a form of material should be identified.

Mechanical Ventilation

The use of powered blowers, fans, smoke ejectors, or hydraulic ventilation to exchange gases inside the structure with fresh air.

Natural Ventilation

The use of convection currents and winds to ventilate a structure without the use of powered blowers, fans, smoke ejectors, or hose streams.

Negative-Pressure Ventilation

The use of powered blowers, fans, or smoke ejectors to remove gases from a compartment through an exhaust vent while entraining fresh air from an intake.

Neutral Plane

Marks the level at a bi-directional vent, such as a doorway or window opening, between the hot gas (smoke) flowing out of a fire compartment and the cool air flowing into the compartment.

Noncombustible Material

A material that, in the form in which it is used and under the condition anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat.


Not readily capable of burning with a flame. (2) Not liable to ignite and burn when exposed to flame. Its antonym is flammable,

Nozzle Penetrating Nozzle

A nozzle that is designed to penetrate a building membrane such as a roof, wall, or floor to deliver a water stream from one area to another area.

Spray Nozzle

A nozzle intended for connection to a hose line or monitor to discharge water in either a spray pattern or a straight stream pattern as selected by the opera­tor.

Straight Tip Nozzle. A smooth-bore nozzle for producing a solid stream.

Nozzle Pressure

The pressure at the point where water flows from a nozzle and is described in pounds per square inch (psi).

Offensive Strategy

The plan for the actions and movements of arriving fire department units to control the fire, effect rescues, start searches for occupants, and extinguish the fire with the intent to commence operations inside the fire building.


The general location where a fire or explo­sion began.


A fire-fighting term involving the process of final extinguishment after the main body of the fire has been knocked down. All traces of fire must be extinguished at this time.


Operation of equipment in excess of normal, full-load rating or of a conductor in excess of rated ampacity that, where it persists for a sufficient length of time would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.


Any solid or liquid material that readily yields oxygen or other oxidizing gas or that readily reacts to promote or initiate combustion of combustible materials and that can, under some circumstances undergo a vigorous self- sustained decomposition due to contamination or heat expo­sure. [400,2019|

Oxygen Deficiency

Insufficiency of oxygen to support combustion. {See also 3.3.240, Ventilation-Controlled Fire.)

Penetrating Nozzle


Personal Protective Equipment (PPE)

Protective equipment tested and approved for fire fighting, including, but not limited to, coat, pants, gloves, boots, hood, helmet, and self-contained breathing apparatus.

Photovoltaic (PV) System

The total components, circuits, and equipment up to and including the PV system disconnecting means that, in combination, convert solar energy into electric energy.


Any of a wide range of natural or synthetic organic materials of high molecular weight that can be formed by pressure, heat, extrusion, and other methods into desired shapes.


The column of hot gases, flames, and smoke rising above a fire; also called convection column, thermal updraft, or thermal column.

Positive Pressure Attack

The utilization of powered blowers or fans, prior to fire control, as a means to control and reduce the heat in the intake portion of the flow path and exhaust heat and smoke from the fire area.

Positive Pressure Isolation

The utilization of powered blowers or fans to pressurize sections of buildings or exposures adjacent to the fire area with the intent to prevent smoke and fire spread into the pressurized sections.

Positive Pressure Ventilation

The utilization of powered blowers or fans, post-fire control, to exhaust heat and smoke from the fire area.


Application or use of measures to prevent damage, change or alteration, or deterioration.


A measure of force per unit area, given in pounds per square inch (psi) or Pascals (Pa), exerted on a surface at 90 degrees to that surface.

Products of Combustion

See 3.3.24, Combustion Products.


A process in which material is decomposed, or broken down, into simpler molecular compounds by the effects of heat alone; pyrolysis often precedes combustion.

Radiant Heat

Heat energy carried by electro mag­netic waves that are longer than light waves and shorter than radio waves; radiant heat (electromagnetic radiation) increases the temperature of any substance capable of absorbing the radiation, especially solid and opaque objects.


Heat transfer by way of electromagnetic energy.

Rapid Fire Development

A transient phase in fire behavior accompanied by a rapid increase in heat release rate of the fire and temperature in the environment, sometimes accompanied by the generation of over-pressure.

Rapid Intervention Crew (RIC)

A dedicated crew of at least one officer and three members, positioned outside the IDLH, trained and equipped as specified in NFPA 1407, who are assigned for rapid deployment to rescue lost or trapped members.

Rate of Heat Release

See 3.3.105, Heat Release Rate (HRR).

Recirculation. Ineffective ventilation where smoke continues to circulate within the structure instead of being exhausted from the structure.


A return to flaming combustion after appa­rent but incomplete extinguishment.


The process of searching, evacuating, and removing occupants from the fire building and providing emergency medical care.

Rescue Company



The degree of peril; the possible harm that might occur that is represented by the statistical probability or quantitative estimate of the frequency or severity of injury or loss.


See 3.3.76, Flameover.


The process of protecting the contents within a building during and following the fire incident.


The general physical location where an emer­gency is occurring.

Self-Contained Breathing Apparatus (SCBA)

Protec­tive equipment that consists of an air supply, a facepiece, and a regulator.

Sensible Heat

The energy that causes a change in the temperature of an object.

Size Up

The ongoing observation and evaluation of factors that are used to develop strategic goals and tactical objectives.


The airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion, together with the quantity of air that is entrained or otherwise mixed into the mass.

Smoke Condensate

The condensed residue of suspended vapors and liquid products of incomplete combus­tion.

Smoke Cooling

Fire-fighting operations involving the application of extinguishing agents to reduce the flammability of the smoke.

Smoke Ejectors

A powered fan that is designed to remove gases from the interior of a structure using negative pressure.

Smoke Explosion

A rapid fire development that occurs when a smoke-air mixture falls within its flammable range, either external or internal to the room of origin, and is ignited, resulting in a significant pressure front.

Smoke Ignition

The ignition of the products of pyrolysis and incomplete combustion interior or exterior to the fire compartment due to the accumulated smoke layer falling within its flammability range and either autoigniting or igniting due to an ignition source.


Combustion without flame, usually with incandescence and smoke.


Black particles of carbon produced in a flame.


Chipping or pitting of concrete or masonry surfaces.

Special Amusement Building

A building that is temporary, permanent, or mobile and contains a device or system that conveys passengers or provides a walkway along, around, or over a course in any direction as a form of amuse­ment arranged so that the egress path is not readily apparent due to visual or audio distractions or an intentionally confoun­ded egress path, or is not readily available due to the mode of conveyance through the building or structure.

Specific Gravity (air) (vapor density)

The ratio of the average molecular weight of a gas or vapor to the average molecular weight of air.

Specific Gravity (of a liquid or solid)

The ratio of the mass of a given volume of a substance to the mass of an equal volume of water at a temperature of 4°C.

Spontaneous Heating

Process whereby a material increases in temperature without drawing heat from its surroundings.

Spontaneous Ignition

Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.

Sprinkler System

A system, commonly activated by heat from a fire and discharges water over the fire area, that consists of an integrated network of piping designed in accord­ance with fire protection engineering standards that includes a water supply source, a water control valve, a waterflow alarm, and a drain. The portion of the sprinkler system aboveground is a network of specially sized or hydraulically designed piping installed in a building, structure, or area, generally overhead, and to which sprinklers are attached in a system pattern.

Stack Effect

The vertical airflow within buildings caused by the temperature-created density differences between the building interior and exterior or between two interior spaces.

Standard Operating Guideline (SOG)

A written directive that establishes recommended strategies/concepts of emergency response to an incident.

Standard Operating Procedure (SOP)

A written directive that established specific operation or administrative methods to be followed routinely for the performance of a task or for the use of equipment.

Steam Conversion

The physical event where water is delivered to the heat of a fire and the water is converted from a liquid to a vapor in the form of steam.

Straight Stream


Straight Tip Nozzle



The general plan or direction selected to accomplish incident objectives.

Stream – Broken Stream

A stream of water that has been broken into coarsely divided drops.

Fog Stream

A stream of water that is flowed in the form of small water droplets.

Master Stream

A ground or aerial device designed to flow in excess of 300 gpm.

Straight Stream

A water stream that flows from a solid bore nozzle or a stream that flows from a combination nozzle with the stream setting placed in the narrowest stream setting that is available.

Support Personnel

Any personnel on the fireground in support of fire operations to assist with rehabilitation, decon­tamination medical treatment, and monitoring.


The sum of all the work done to extin­guish a fire, beginning at the time of its discovery.


Compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid, and which can act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.


Deploying and directing resources on an inci­dent to accomplish the objectives designated by the strategy.

Target Fuel

A fuel that is subject to ignition by ther­mal radiation such as from a flame or a hot gas layer.


The degree of sensible heat of a body as measured by a thermometer or similar instrument.

Thermal Column

See 3.3.159, Plume.

Thermal Decomposition

A chemical decomposition caused by heat.

Thermal Expansion

The increase in length, volume, or surface area of a body with rise in temperature.

Thermal Inertia

The properties of a material that characterize its rate of surface temperature rise when exposed to heat; related to the product of the material’s thermal conductivity (k), its density (p), and its heat capacity (c).

Thermal Protective Performance (TPP)

A numerical value indicating the resistance of materials to a convective and radiant heat exposure.


The study of the science, methodol­ogy, and practice of temperature measurement


Plastic materials that soften and melt under exposure to heat and can reach a flowable state.

Thermoset Plastics

Plastic materials that are hard­ened into a permanent shape in the manufacturing process and are not commonly subject to softening when heated; typi­cally form char in a fire.

Time Line

Graphic representation of the events in a fire incident displayed in chronological order.

Total Burn

A fire scene where a fire continued to burn until most combustibles were consumed and the fire self1 extinguished due to a lack of fuel or was extinguished when the fuel load was reduced by burning and there was sufficient suppression agent application to extinguish the fire.

Transitional Attack

The application of a fire stream from the exterior of a structure to improve conditions prior to interior fire control.

Travel Distance

The length measured on the floor or other surface along the centerline of the natural path of travel.


Truck (Ladder) Company.


Turnout Components

The interval that begins when the emergency response facilities (ERFs) and emergency response units (ERUs) notification process begins by either an audible alarm or visual annunciation, or both, and ends at the beginning point of travel time.

Unidirectional Vent

A building opening that serves as either an intake and exhaust vent of a flow path at a given time.

Upper Layer

See 3.3.18, Ceiling Layer.


No furnishings or equipment present.


The gas phase of a substance, particularly of those that are normally liquids or solids at ordinary tempera­tures. (See also 3.3.94, Gas.)

Vapor Density

See 3.3.193, Specific Gravity (air) (vapor density).


Also known as vapourisation, is a phase transition of an element or compound from the liquid phase to vapor.


An opening for the passage of, or dissipation of, fluids, such as gases, fumes, smoke, and the like.

Vent Profile

The visual evaluation of the condition (stratification-neutral plane) presented at a specific ventilation opening relating to a unidirectional, bidirectional, or dynamic flow integrated with the four fire development assessment indi­cators (smoke, air, heat, and flame [SAHF1).


Circulation of air in any space by natural wind or convection or by fans blowing air into or exhausting air out of a building; a fire-fighting operation of removing smoke and heat from the structure by opening windows and doors or making holes in the roof.

Ventilation Control Device

Using an object to limit the amount of air available to the fire.

Ventilation for Extinguishment

The controlled and coordinated ventilation tactic that should coincide with the engine company extinguishment of the fire.

Ventilation for Search

The controlled and coordina­ted ventilation tactic performed to facilitate the movement of a firefighter into an area to conduct a search for victims.

Ventilation Induced Flashover

A flashover initiated by the introduction of oxygen into a preheated, fuel-rich (smoke filled), oxygen-deficient area.

Ventilation Profile

The visual evaluation of the entire fire building’s ventilation openings, indicating air movement into the structure as well as smoke, heat, or flame out of the structure.

Ventilation-Controlled Fire

A fire in which the heat release rate or growth is controlled by the amount of air availa­ble to the fire.

Ventilation-Limited Fire

A fire in which the heat release rate or growth is controlled by the amount of air (oxygen) available to the fire.


The escape of smoke and heat through openings in a building.

Verified Independent Service Provider (ISP).

An independent service provider verified by a third-party certifica­tion organization to conduct an advanced inspection, advanced cleaning and sanitization, basic repair, and advanced repair service.

Vertical Ventilation

A method of using buoyancy to permit smoke and convected heat to flow upward to be exhaus­ted from the building through vents above the fire while being replaced with intake air through other vents at the same level of the fire or lower.

Virgin Fuels

Fuel that is new and previously unused.

Void Space

Cofferdams and spaces not normally accessible or used for storage.

Water Supply

The amount of water described in terms of gallons per minute that is available at a fire incident for fire control.

Watt (W)

Unit of power, or rate of work, equal to one joule per second, or the rate of work represented by a current of one ampere under the potential of one volt.

Wet Decontamination


NFPA 1700 Guide for Structural Fire Fighting

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