1. Fire Behavior Flashcards
How has the goal of the fire service evolved over its existence?
In the early days the goal was to extinguish all fires before they burned down the entire village. We have progressed to keeping the fire to the block of origin, then the building of origin, and now to the room of origin.
Claims for definitive evidence of use and control of fire by modern humans range from ____ to ____ years ago. Only in the past ____ or so years, have formal, scientific studies been undertaken to gain an understanding of fire suppression and prevention.
- 1.7 million to 200,000
* 100
In ____, in response to the ____ report written by the National Commission on Fire Prevention and Control titled ____, the US Congress passed US Public Law ____, which created ____, ____, and ____. This Law is also known as the ____.
- 1974
- 1973
- America Burning
- 93-498
- The National Fire Protection Association (NFPA)
- National Fire Academy (NFA)
- NIST
- Federal Fire Prevention and Control Act
The Federal Fire Prevention and Control Act gave NIST the mission of ____
performing and supporting research on all aspects of fire, with the aim of providing scientific and technical knowledge applicable to the prevention and control of fires. The act required NIST to conduct research on the dynamics of flame ignition, flame spread, and flame extinguishment.
Between the late 1970’s and 2009, the annual number of structure fires in the United States decreased by ____. During the same period, the overall number of firefighter deaths due to traumatic injuries also declined. However, the rate of firefighter deaths due to traumatic injuries on the fireground increased from ____ to ____ per 100,000 fires. This was an increase of more than ____.
- more than 50%
- 1.8 to 3
- 60%
Change is best accepted in a ____ environment when leadership is ____.
- supportive
* leading by example
Ambient
Someone’s or somethings surroundings, especially as they pertain to local environment. For example, ambient air and ambient temperature.
Backdraft
A deflagration resulting from the sudden introduction of air into a confined space containing oxygen-deficient products of incomplete combustion (aka smoke explosion)
Blast pressure front
The expanding leading edge of an explosion reaction that separates a major difference in pressure between normal ambient pressure ahead of the front and potentially damaging high pressure at and behind the front.
Ceiling layer
A buoyant layer of hot gases and smoke produced by a fire in a compartment.
Conduction
Heat transfer to another body of within a body by direct contact
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 spread
The movement of fire from one place to another.
Flame
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.
Flashover
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 or the compartment or enclosed space.
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-controlled 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.
Gas
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.
Heat
A form or energy characterized by vibration of molecules and capable of initiating and supporting chemical changes of state.
Heat flux
The measure or the rate of heat transfer to a surface, expressed in kilowatts, kilojoules, or BTUs per second.
Heat release rate (HRR)
The rate at which heat energy is generated by burning.
Ignition
The process or initiating self sustained combustion
Kilowatt
A measurement of energy release rate.
Oxygen deficiency
Insufficiency of oxygen to support combustion (aka ventilation limited)
Plume
The column of hot gases, flames, and smoke rising above a fire.
Pyrolysis
A process in which material is decomposed, or broken down, into simpler molecular compounds by the effects of heat alone; pyrolysis often precedes combustion.
Radiation
Heat transfer by way of electromagnetic energy.
Rollover
The condition where unburned fuel (pyrolysate) from the originating 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. Rollover can occur without ignition of, or prior to, the ignition of other fuels separate of the origin (i.e. flameover)
Scientific method
The systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of a hypothesis.
Smoke
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 mass.
Smoldering
Combustion without flame, usually with incandescence and smoke.
Temperature
The degree of sensible heat of a body as measured by a thermometer or similar instrument.
Ventilation
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 firefighting operation of removing smoke and heat from the structure by opening windows and doors or making holes in the roof.
Ventilation-limited fire
A fire in which the heat release rate or growth is controlled by the amount of air available to the fire (a.k.a. ventilation controlled fire)
Venting
The escape of smoke and heat through openings in a building.
Fire dynamics
The study of how fire starts, spreads, and develops. ____ has the scientific measurements and calculations needed to explain fire behavior.
Fire behavior
the way fire reacts and behaves to its environments.
In todays structures, fire temperatures increase at a faster rate, causing ____
fires to reach flashover temperatures sooner.
One of the keys in todays fires is ____ rather than the temperature.
- heat release rate
- A single candle compared to 10 candles, both have the same temperatures, but 10 candles have 10x the heat release rate.
Heat is always transferred from ____ to ____.
The hotter object to the colder object.
What are the different types of heat transfer?
Conduction, convection, and radiation.
Convection
Heat transferred by circulation within a medium such as a gas or a liquid.
Fire creates pressure and pressure moves from ____ to ____.
high to low
- High pressure is in the fire room and is created by the fire
- Low pressure is any opening that is created at a distance away from the fire.
When a pressure gradient is created we have the making of ____
a flow path
In a flow path, high pressure combustible gases (e.g. smoke) are forced ____ and ____ is drawing in the lower pressure air from ____
- across the upper parts of a compartment
- the fire
- a low pressure opening
If we stop or control ____ , we reduce the temperature and slow the combustion process.
- the air from being drawn into the fire
If we slow the combustion process, fire reduces in size along with the amount of combustible gases being produced. ____ will worsen, but ____ improve with lower temperatures and less or equal combustible gases.
- Interior visibility
* the rest of the interior conditions
Pressure is at its highest point if the fuel/air mixture is allowed to ____
go above the LEL and gets closer to the ideal mixture.
Legacy fire development is related to ____
fuel limited fires
Modern fire development commonly relates to ____
ventilation limited fires
Backdrafts most commonly occur in ____
attic spaces, knee walls, or any other void space
Flow path
The space through which fire, heat, and smoke progress, moving from the high-pressure fire area toward lower pressure oxygen sources, such as door and window openings.
Although a buildings openings are unpredictable, ____ should recognize imminent failure to a window or door.
a solid size up
Interrupting the flow path involves tactics that are innovative and sometimes counterintuitive, but fire research shows that these methods can ____ within the structure, minimize the potential for ____, and greatly enhance ____
- reduce heat
- flashover
- the safety for firefighters
The time between tactical ventilation and flashover could be as little as ____, compared to ____ in a traditional fire.
- 2 minutes
* 8 minutes
Increasing ventilation by opening doors, clearing windows, or cutting the roof in a ventilation-limited structure fire may lead to ____
a rapid transition to flashover
Its important to understand that ____ are what cause fire spread.
the smoke and fire gases
The smoke is what we should be keeping our eyes on. Smoke ____, ____, ____, and ____ are essential components to understanding fire behavior.
- volume, velocity, density, and color
