Chapter 1 Flashcards
What is Fire Dynamics
The study of how fire starts, spreads, and develops.
Fire Dynamics has the..
Scientific measurements and calculations needed to explain fire behavior
Fire behavior is
Exactly what it sounds like: it is the way that fire reacts and behaves to its environment
In todays structures, fire ___ ___ at a faster rate, causing fires to reach ___ ___ sooner
Temperatures increase
Flashover temperatures
Increasingly common in fires, flashover occurs…
Before the fire department has aririved
One of the keys in todays fires..
Is the HRR rather than the temperature
A single candle vs 10 candles..
The have the same flame temps but 10x the HHR
A single candle has a HRR of..
80 watts
10 candles have a HRR of..
800 watts
Heat transfer, the mechanism of heat movement, is critical to understand because..
Heat is always transferred from the hotter object to the colder object
What are the different types of heat transfer?
Conduction
Convection
Radiation
Conduction is..
Heat transferred to the fires immediate surrounding area
Convection is..
Is heat transferred by means of moving gases or liquids
Radiation is..
Is heat transferred by electromagnetic waves; the closer you get, the hotter it feels
Heat can be transferred by all 3 mechanisms to the..
Ceiling, walls, and floors of the fire compartment
Fires create pressure, and pressure moves from..
High to low
The high pressure is the ___ ___ and is being created by the fire
Fire room
The low pressure is any ___ that is created a ___ ___ from the fire
Opening
Distance away
When the pressure gradient is created we have the making of a..
Flow path
If we stop or control the air from being drawn into the fire, we ___ the ___ and ___ the combustion process
Reduce
Temperatures
Slow
In slowing the combustion process, fire ___ in size along with the amount of ___ ___ being produced
Reduces
Combustible gases
The flammable range of combustible gases can be compared to the action of…
Combustion within an automobile engine
UEL is the
Rich
LEL is the
Lean
Fire cannot burn if its above the ___ or below the ___ because the mixture would either be too rich or too lean
UEL
LEL
Legacy fire development is related to…
Fuel limited fires
The legacy fire isn’t limited by a lack of..
Oxygen
Once all the fuel is burning, the fire is at its ___ ___ stage
Fully developed
As the fuel burns down, the legacy fire begins to ___, but it still has enough air to mix with ___ and complete its combustion
Decay
Gases
Modern fire development commonly relates to..
Ventilation limited fires
As the fire starts to run out of air it starts to ___ and temperatures ___
Decay
Decrease
___ is a dangerous transition between the growth stage and fully developed stage.
Flashover
Flashover is ___ and will cause serious injury or even kill FF’s if the precursors go unrecognized on the fireground
Predictable
Depending on the compartment size and the amount of pressure that builds prior to flashover, there could be a ___ ___ seen with the flashover.
Pressure wave
The dated definition of backdraft from basic ff textbook describe backdraft as and event that occurred at temperatures greater than___ and characterized by smoke stained windows, yellow grey smoke
1600*F
When ___ fires become ventilation limited, the temperatures decrease significantly
Modern
(Updated) a deflagration resulting from sudden introduction of air into a confined space containing oxygen deficient products of incomplete combustion
Backdraft
NFPA 921 (2011 version)
The backdrafts that most commonly occur in ___ spaces, ___ walls, or any other ___ space found on many documented fires are the cause of many ff injuries across the country
Attic
Knee
Void
For every action there is an equal and opposite reaction
Newtons 3rd law of motion
It is common to see a time delay from the initial ___ created by FF’s until ___ occurs
Opening
Flashover
If a small opening is made water should be applied to the ___ and into the ___ as quickly as possible
Smoke
Compartment
The ___ ___ is the space through which fire, heat, and smoke progress, moving from the ___-pressure fire area toward the ___ pressure oxygen sources
Flow path
High
Low
Controlling the ___ openings is critical
Ventilation
Recognizing ___ ___ as it changes and reacts to our tactics is possibly one of the most ___ skills for ff’s
Fire behavior
Underutilized
The time between tactical ventilation and flashover could be as little as ___ minutes, compared to ___ minutes in a traditional fire
2
8
Based on the buildings configuration, there may be several ___ ___ within a structure
Flow Paths
Anyone in the ___ ___-between the fire and its direction of travel-is in danger
Exhaust path
Who said “its not the first fire that kills FF’s, its the second”?
Dan Madrzykowski
UL research engineer
It’s important to understand that the ___ and ___ ___ are what cause fire spread
Smoke
Fire gases
The ___ is what we should be keeping our eyes on
Smoke
