Glossary

The act of removing or thinning out vegetation to reduce the available fuel for a potential fire. Fuel reduction strategies help minimize the intensity and spread of wildfires.

The study of materials that acted as fuel for a fire, used to determine how the fire started and spread. This analysis is an important part of fire investigations.

The components involved in storing and delivering fuel to an engine or device, such as tanks, lines, and valves. Malfunctions in the fuel system can lead to leaks and potential fire hazards.

A sudden and violent rupture of a fuel tank caused by overpressure or ignition of flammable vapors. Fuel tank explosions can result from accidents, overheating, or deliberate acts.

The specific kind of material that fuels a fire, such as wood, gasoline, or paper. Different fuel types have varying ignition points, burn rates, and heat outputs, influencing fire behavior.

The process by which flammable vapors from liquid fuel ignite when exposed to an ignition source. Fuel vapor ignition poses a significant risk in confined spaces or where fuel is stored improperly.

A fire where the availability of fuel limits its growth and intensity. In such fires, reducing the fuel load can effectively control and suppress the fire.

The stage of a fire where all combustible materials in a room are burning, typically resulting in high heat and rapid fire spread. This phase is also known as flashover.

A container housing fuses that protect an electrical system by breaking the circuit when excessive current flows through it. Overloaded or faulty fuses can lead to electrical fires if not properly managed.

A pyrotechnic device used in wildland firefighting to ignite controlled burns or backfires. Fusees burn at a high temperature and are a reliable tool for setting intentional fire lines.

A safety device designed to melt at a specific temperature, breaking a circuit or releasing a mechanism, such as closing a fire door. Fusible links help prevent fire spread by activating fire protection systems.

A fire that occurs within a gallery or tunnel-like space, often characterized by limited ventilation and high heat buildup. Gallery fires can be particularly challenging to control due to confined spaces.

The production of an electric current resulting from a chemical reaction between different metals or electrolytes. In fire investigations, galvanism can be relevant when analyzing electrical faults and corrosion.

A state of matter that is highly compressible and expands to fill any space it occupies. In fire contexts, certain gases, such as natural gas or propane, are significant fire hazards due to their flammability.

A laboratory technique used to separate and analyze compounds in a mixture, often applied in fire investigations to detect accelerants or other chemicals present at a fire scene.

A fire that results from the ignition of gasoline vapors, which are highly flammable and capable of rapid combustion. Gasoline fires are often associated with vehicle or fuel storage incidents.

The ignition of flammable vapors released by gasoline, which can ignite at relatively low temperatures when mixed with air and exposed to a spark or flame.

A device used to measure the volume or concentration of gases, which can be used in fire investigations to monitor combustible gas levels in enclosed spaces.

The broad zone where a fire is believed to have started, identified before narrowing down to a specific point of origin. Investigators use this area to begin more detailed analyses.

Key personnel in the Incident Command System (ICS) responsible for coordinating major sections of an emergency response, including operations, planning, logistics, and finance/administration.

A defined region used in fire management for planning, resource allocation, and coordination of firefighting efforts. Understanding the geographic area helps with strategic deployment and management of fire resources.

The shape, arrangement, and distribution of combustible materials in an area, which influence how a fire spreads. Irregular fuel geometry can create complex fire behavior patterns.

A stage of fire where burning occurs without flame, producing heat and light. Glowing combustion typically happens after active flaming has subsided and can reignite if conditions change.

A unit of mass in the metric system used to measure small quantities of substances, including potential accelerants or residues found in fire investigations.

The force that pulls objects toward the center of the Earth. In fire behavior, gravity influences how burning materials fall and where embers or sparks land, potentially igniting new fires.

An area of vegetation, such as grass or trees, surrounding an urban region that can act as a fuel source for fires. Properly managed green belts can help prevent or slow fire spread.

The electrical connection between a circuit or device and the earth, which helps prevent electrical shocks and fires. Faulty grounding can lead to dangerous arcing and fire risks.

An unintentional electrical path between a power source and a grounded surface, often causing current to flow outside its intended circuit. Ground faults can generate heat and ignite fires if not properly protected by circuit breakers or GFCIs (Ground Fault Circuit Interrupters).

Combustible materials that lie on or beneath the surface of the ground, such as roots, decomposed leaves, and duff. Ground fuels can contribute to smoldering fires that may persist for long periods and reignite under favorable conditions.

The movement of fire and smoke through a building's heating, ventilation, and air conditioning (HVAC) system. Proper design and maintenance of HVAC systems can help prevent fire spread and improve building safety.

A fire weather index used to assess the potential for wildfire growth based on atmospheric stability and dryness. A higher Haines Index indicates greater potential for large and intense fires.

A group of elements, including chlorine, fluorine, bromine, and iodine, that are often used in fire suppression systems due to their ability to inhibit combustion. Halogen-based fire extinguishers are effective for certain types of fires but may be phased out due to environmental concerns.

A fire control line constructed by hand using tools such as shovels, axes, and rakes. Hand lines are used to create breaks in vegetation to help prevent the spread of fire.

A person trained to work with specialized detection canines, such as those used in accelerant detection during fire investigations. Handlers guide and manage dogs to identify fire-related evidence.

Non-flammable features in landscaping, such as stone, concrete, and gravel. Hardscaping is used to create defensible space around structures and reduce fire risk.

The wood from broad-leaved trees, such as oak and maple. Hardwoods generally burn more slowly and produce less intense flames compared to softwoods, making them less likely to contribute to rapid fire spread.

Any condition or situation that poses a risk of fire ignition, spread, or danger to life and property. Hazards can be natural (e.g., dry vegetation) or man-made (e.g., faulty wiring).

The process of evaluating potential fire risks in a given area or structure and determining the necessary precautions and mitigation measures. This assessment helps prioritize fire prevention efforts.

The strategies and practices used to reduce or eliminate potential fire risks, such as removing flammable vegetation, installing fire-resistant materials, and maintaining electrical systems.

A location identified as having significant fire or explosion risks due to the presence of flammable or combustible materials, gases, or dust. Proper safety protocols and equipment are required in hazardous areas to prevent incidents.

Substances that pose a fire, explosion, or health risk when mishandled or improperly stored. Proper storage and handling of hazardous chemicals are crucial for fire prevention and safety.

The practice of removing or modifying flammable vegetation to lower the potential for wildfires. This includes activities such as controlled burns, pruning, and clearing underbrush.

Toxic or harmful gases released during combustion or chemical reactions that can pose a health risk. Firefighting and investigation efforts must take into account the presence of hazardous fumes to ensure safety.

Gases that are flammable, toxic, or explosive and can pose a significant fire risk if released into the environment. Monitoring and controlling the presence of hazardous gases is essential for fire prevention.

A substance or material that poses potential fire, explosion, chemical, or health hazards. Common hazardous materials include fuels, solvents, and chemicals used in industrial processes.

Various substances that pose fire, explosion, or chemical risks if not handled properly. Fire departments and hazmat teams are trained to respond to incidents involving hazardous materials to prevent or mitigate fire and environmental damage.

The leading and fastest-moving part of a wildfire or fire front, driven by wind and topography. The head of the fire is often the most intense and poses the greatest risk to firefighting efforts and nearby structures.

A form of energy that raises the temperature of materials and can lead to combustion when combined with fuel and oxygen. Heat transfer methods include conduction, convection, and radiation.

The physical and chemical changes that occur in materials exposed to high temperatures. Heat damage can include warping, discoloration, melting, and structural weakening, and is analyzed during fire investigations to understand fire behavior.

The process by which heat is spread or released from a material or system to the surrounding environment. Effective heat dissipation is crucial in preventing overheating that could lead to fires.

An event where a sudden release of stored thermal energy results in rapid expansion and damage. Heat explosions can occur when enclosed materials or gases are subjected to extreme heat and pressure.

The rate at which heat energy is transferred to or from a surface, typically measured in watts per square meter (W/m²). High heat flux can indicate the potential for ignition and fire spread in nearby materials.

The total amount of energy produced by a fire, measured over a given period. Heat release is an important metric for understanding fire intensity and its potential impact on structures and people.

The rate at which heat energy is generated by a fire, measured in kilowatts (kW) or megawatts (MW). HRR is used to evaluate fire growth and the effectiveness of fire suppression methods.

Devices that detect changes in temperature and alert occupants or trigger fire suppression systems. Heat sensors are used in various fire safety systems to provide early warning of fire conditions.

A phenomenon where an object blocks heat from reaching a surface, creating a pattern or area of less heat damage. Heat shadowing can help investigators determine the source and direction of a fire.

Protective barriers designed to reflect or absorb heat, protecting structures or equipment from high temperatures. Heat shields are used in various fire prevention systems and in firefighting gear.

Distinct thermal patterns produced by fire or heat-emitting objects, detectable by thermal imaging equipment. Heat signatures can be used to locate hotspots and track fire progression during firefighting efforts.

Objects or processes that generate heat, such as electrical appliances, machinery, or open flames. Identifying heat sources is essential in fire investigations to determine potential ignition points.

The movement of heat energy from one place or material to another through conduction, convection, or radiation. Heat transfer plays a key role in fire spread and behavior.

The directional flow of heat and flames, used to analyze how a fire spreads and what factors contribute to its movement. Understanding heat and flame vectors helps investigators determine the origin and behavior of a fire.

The total energy released as heat when a substance undergoes complete combustion. This value helps assess the intensity and potential energy output of a fire involving different fuels.

The minimum amount of heat energy required to initiate combustion in a specific material. Understanding the heat of ignition is crucial for assessing fire risks and prevention strategies.

Dense, larger-sized combustible materials such as logs, tree stumps, and large branches that burn more slowly but with greater intensity. Heavy fuels contribute to longer-lasting fires.

A fraction of petroleum that is denser and has a higher boiling point, used in products like diesel fuel and lubricants. Heavy petroleum distillates can pose fire risks due to their flammability.

A specific range of hydrocarbons found in heavier petroleum products. HPDs can be present as accelerants or fuel sources in fire investigations and require specialized analysis for detection.

The part of a fire perimeter opposite the head, typically burning more slowly. The heel is often considered a safer area for firefighters to work from when suppressing a fire.

A designated location used for managing and operating helicopters during firefighting operations. Helibases provide support for refueling, loading firefighting equipment, and coordinating aerial efforts.

A temporary or designated location where a helicopter can land, take off, and perform operations such as dropping water or fire retardant. Helispots are used for quick access in wildfire areas.

The use of helicopters to support firefighting operations, including water drops, transporting personnel, and delivering equipment. Helitack crews are specially trained to manage aerial firefighting activities.

A group of firefighters trained to conduct firefighting operations using helicopters. Helitack crews are responsible for initial attack efforts and rapid response in remote or hard-to-reach areas.

A type of explosive that detonates and produces a shock wave at supersonic speeds. High explosives are used in demolition and military applications and can pose significant risks if improperly handled or involved in a fire.

A comparison between high explosives, which produce a rapid detonation and shock wave, and a high order explosion, which refers to the complete and efficient detonation of an explosive material.

Severe destruction caused by an explosion that fully utilizes the energy of the explosive material. High-order damage is characterized by shattering and extensive structural impact.

Electrical cables designed to carry high-voltage electricity. Damaged or improperly installed high-voltage cabling can pose significant fire risks due to the potential for arcing and overheating.

Strategies used to maintain control of a fire's perimeter and prevent it from spreading while additional resources or tactics are deployed. Holding actions may include building fire lines and applying water or retardants.

Equipment and personnel used to sustain the containment of a fire once control lines are established. These resources ensure that fire does not breach containment and spread further.

The arrangement and deployment of fire hoses during firefighting operations to deliver water from a water source to the fire. Hose lays are essential for maintaining an effective water supply during suppression efforts.

An elite team of firefighters specifically trained for rapid and aggressive wildfire suppression. Hotshot crews are highly skilled in creating fire lines, conducting backburns, and working in difficult terrain.

An area within or near a fire perimeter where smoldering or active flames continue to burn. Hotspots must be monitored and extinguished to prevent the fire from reigniting or spreading.

The process of identifying and extinguishing hotspots to ensure that a fire does not reignite or spread beyond containment lines. This is a critical part of mopping up after a fire.

Damage to the hull of a vessel, which can occur as a result of a fire on board. Hull damage assessment is important for maritime fire investigations to determine the cause and impact of the fire.

The structural soundness of a vessel’s hull, which can be compromised during a fire due to heat and flame exposure. Maintaining hull integrity is crucial for the safety and buoyancy of the vessel.

The amount of water vapor in the air, which affects fire behavior. Low humidity levels can lead to dry conditions that increase the likelihood of fire ignition and rapid spread.

A combination of different materials or fuel types that can affect fire behavior. Hybrid mixtures may involve combinations of gases, solids, or liquids that influence ignition and combustion characteristics.

A water source connection point used by firefighters to access water for fire suppression. Hydrants are commonly located along streets and in residential areas to provide a reliable supply of water for firefighting.

The ignition of hydraulic fluid when exposed to a heat source or open flame. Hydraulic fluid can be flammable, and leaks or ruptures in hydraulic systems pose fire hazards, especially in industrial and mechanical settings.

An organic compound made up of hydrogen and carbon atoms, often found in fuels such as gasoline, propane, and natural gas. Hydrocarbons are highly flammable and are key components in fire behavior and risk analysis.

A highly flammable gas that can be a byproduct of chemical reactions or used as a fuel. Hydrogen fires burn with an almost invisible flame and require specific detection and suppression methods.

The release of hydrogen fluoride gas, which can be toxic and pose serious health risks. Hydrogen fluoride can be released during certain chemical fires and requires specialized response measures.

A type of material or fuel that ignites spontaneously when it comes into contact with an oxidizer. Hypergolic materials are commonly used in rocket propulsion but pose significant fire risks due to their reactive nature.

An abnormally high body temperature that can result from exposure to excessive heat, such as during a fire. Hyperthermia is a medical emergency that can lead to heat exhaustion, heat stroke, and severe health complications.

A condition in which the body or a region of the body is deprived of adequate oxygen supply. Hypoxia can occur during a fire due to high levels of smoke or reduced oxygen in the environment and poses significant risks to both occupants and responders.

A term used to describe the interface zone where urban development meets wildland areas, creating a higher risk for wildfires that can impact homes and infrastructure.

The International Association of Arson Investigators, an organization that provides training, certification, and resources for professionals involved in fire investigation. The IAAI sets standards for conducting thorough and accurate fire investigations.

Specially trained dogs used to detect the presence of ignitable liquids at fire scenes. These canines assist investigators in locating potential accelerants that may indicate arson.

The process of starting a fire by applying sufficient heat to a fuel source. Ignition can be natural, accidental, or intentional and is a critical focus in fire investigations.

The specific location where a fire first started. Determining the ignition area is essential for understanding the fire's cause and origin.

The minimum amount of energy required to initiate combustion in a particular material. Ignition energy varies by material and environmental conditions, and understanding it helps assess fire risk.

The specific way in which a fire is started, such as using an open flame, electrical spark, or chemical reaction. Identifying the ignition method helps fire investigators determine whether a fire was accidental or intentional.