Chapter 2: Enhanced Fire Behavior Flashcards
Firefighters’ ____ serves as a foundation for understanding the strategies, tactics, and specific task assignments required in fire fighting operations.
Knowledge of fire behavior
Developing expertise in the application of one’s knowledge of fire behavior requires____ and ____.
An understanding of the science of fire dynamics;
Practical fireground experience
An exothermic chemical reaction that is a SELF-SUSTAINING process of RAPID oxidation of fuel, that produces HEAT and LIGHT
Combustion
When some solid fuels, particularly those that are porous and can char, undergo oxidation at the surface of the fuel is known as:
Nonflaming or Smoldering Combustion
A simple model that explains non flaming or surface combustion (smoldering).
Fire Triangle
Fire Triangle (components) (explanation)
Heat, Fuel, and Oxygen are required for the chemical reaction to occur. If any one of these are removed ore reduced, the reaction stops.
Model used to explain flaming combustion
Fire Tetrahedron
Fire tetrahedron (components) (explanation)
Heat, Fuel, Oxygen, and Self-sustaining chemical reaction. Reaction stops if any of these components is removed or sufficiently reduced.
Stored energy that can be released in the future to perform work once released
Potential energy
Energy possessed by a moving object (energy in motion)
Kinetic energy
Kinetic energy associated with the movement of the atoms and molecules that comprise matter
Thermal energy (Heat energy)
Before ignition, fuel has ____. When that fuel burns, the chemical energy is converted to ____ in the form of ____ and light.
Potential energy
Kinetic energy
Thermal energy (heat)
A measurement of kinetic energy
Temperature
The movement of thermal energy from objects of higher temperature to those of lower temperature.
Heat
Capacity to perform work
Energy
Work occurs and energy is expended when:
A force is applied to an object over a distance or when a chemical, biological, or physical transformation is made in a substance.
Since ____ cannot be measured, we measure ____
Energy
The work it does
In the case of heat, work means ____
Increasing temperature (causing the kinetic energy within the molecules of a substance to increase)
Unit of measurement for heat energy
Metric: Joule- equal to 1N over 1M
Standard: British Thermal Units (BTUs)- increase 1 lb of water 1 degree F
It takes ____ to raise the temperature of 1 kg of water 1 degree C
4,186 Joules
1 BTU = ____ joules
1,100
____ is the energy component of the fire tetrahedron
Heat
Thermal or chemical decomposition of fuel (matter) because of heat that generally results in the lowered ignition temperature of the material.
(the chemical decomposition of a substance through the action of heat)
Pyrolysis
Process that changes a liquid into a gaseous state.
Vaporization (the rate depends on: 1. substance involved 2. Heat 3. pressure
The total amount of energy released when a specific amount of that fuel is oxidized (burned)
Heat of combustion; measured in BTU/lb; calories/gram; kilojoules/gram (kJ/g); or megajoules/kilogram (MJ/kg)
The energy released per unit of time as a given fuel burns. Dependent on type, quantity, and orientation of the fuel.
Heat release rate; measured in kilowatts (kW) or megawatts (MW)
The tendency of gases to stratify according to temperature.
Thermal layering; Heat stratification; Thermal balance
When sufficient oxygen is available, fire development is controlled by ____. The fire is considered to be ____.
The characteristics and configuration of the fuel;
Fuel controlled
When fire development is limited by a lack of oxygen, the fire is considered to be ____.
Ventilation controlled
It is important to know if a fire is ventilation controlled or fuel controlled because
It determines how the fire will change when ventilation is increased.
Fuel controlled- increased ventilation will reduce temps and slow or prevent its progression to flashover.
Vent controlled- increased ventilation will increase the rate of heat release and may result in extreme fire behavior.
Flames begin to move intermittently through the hot gas layer
Rollover (ceiling temps approach 1,100 degrees)
How much heat is available for transfer to human skin
Heat flux
In the incipient and early growth stages of many compartment fires, heat transfer is largely dependent on
Convection
____ determines whether or not a fire within a compartment will progress to flashover
The availability of both fuel and oxygen
A fire may enter the decay stage due to ____ or ____.
Consumption of available fuel;
Limited oxygen supply (much greater concern to firefighters)
Most compartment fires that grow beyond the incipient stage become ______ controlled
Ventilation
____ are often the most readily available fuel source in a compartment fire.
The contents of a structure
A fire in a _____ will develop more slowly than one in a ____ due to the greater volume of air and structural material that must be heated.
Large compartment;
small compartment
A ____ may mask the extent of fire development by ____.
High ceiling;
Allowing a large volume of hot smoke and other fire gases to accumulate at upper levels.
The actual and potential ventilation of a structure based on structural openings, construction type, and building ventilation systems.
Existing ventilation
Fires that are ____ tend to produce a greater volume of smoke that those that are ____.
Ventilation controlled;
Fuel controlled
The burning of ____ and many ____ as well as ____ conditions will result in increased optical density of the smoke
Hydrocarbons; synthetic fuels; under-ventilated
Buoyancy, aka _____, is related to the temp of the smoke- The higher the temp, the ______ the buoyancy.
Physical density;
greater
A Sudden rise in the hot gas layer could indicate _____, while gradual lowering could indicate ____. Sudden lowering could indicate ____. Or _____ could lower the gas layer
Some type of ventilation has occurred;
Deteriorating conditions and increased potential for flashover;
Deteriorating conditions caused by flashover in an adjacent compartment;
Inappropriate or excessive application of water
If firefighters can see flames in the hot gas layer, it may indicate ____ (pockets of flame seen intermittently in the smoke) and ____.
Ghosting;
Impending flashover
When flashover occurs, it is ____
The sudden transition from the growth stage to the full developed stage in a compartment
The most effective way for firefighters to manage the risk of flashover, is by _____ and ____.
Maintaining an awareness of developing fire conditions;
Controlling the fire environment through effective fire control and ventilation tactics
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