Ch. 4 - Fire Dynamics (Test 4) Flashcards
Even though there are fewer fires today than there were in the late 1970’s, there are more firefighters dying as a result of traumatic fireground injuries. ______
(+67%)
(2014-2017)
Average of 295,975 fires per year ________________.
(58% decrease)
(2014-2017)
Average of 2,728 civilian deaths ________________
(53% decrease)
Despite there being countless examples of fire being mystified, stylized or humanized but the truth is:
______________________________
Fire is insentient
Devoid of all intent and/or emotion
_________ - A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities. (NFPA 921)
Fire
___________ - A self-sustaining chemical process of oxidation that occurs at a rate fast enough to produce heat and light. (i.e. a glow of a flame) – NFPA 921
Combustion
For generations, firefighters were taught that for fire to exist, only three (4) essential items needed to be present. Those elements are/were:
__________
__________
__________
Fuel
Oxidizing Agent
Heat (Activating energy)
For fire to exist, fuel, oxidizer, AND heat must interact in a such a way so as to for a _________________.
Sustained chemical reaction
The reaction we understand to be fire, is actually a _______________ reliant upon countless variables.
Complex chemical process
In the most general of terms, fuel is ______________.
Consumable matter
Matter exists in one of three physical states:
_________
_________
_________
Solid
Liquid
Gas
It’s ___________ (and density) can be altered by changes in:
-__________
and/or
-__________
-physical state
- temperature
- pressure
What happens to a substance when it changes its physical state? Does its molecular structure change? ____, only the distance between molecules changes
No
Density can be defined as:
A measure of the ___________ of a substance.
Compactness
(Density)
It affects matter’s ability to ________________ heat.
Absorb, transfer, and release
Solid fuels do not burn. They release flammable gases through _________, which is the chemical decomposition of solids through the action of heat.
Pyrolysis
Pyrolysis is ___________ by nature.
Endothermic
A few characteristics that affect solid fuels ability to generate ignitable gases.
- ______________
- ______________
- ______________ to heat source
- ______________
- ______________ of fuel
- ______________
- ______________
- Density
- Surface area to mass ratio
- Physical position/orientation
- Size and shape
- Continuity
- Ignition temperature
- Level of Exposure
Liquid fuels do not burn either. They release ignitable ashes through the process of ____________, which is the process of changing liquid matter into gaseous matter through variances in ___________________.
- vaporization
- temperature and/or pressure
A few characteristics that effect solid fuels ability to generate ignitable gases:
- ____________
- ____________
- ____________
- ____________
- ____________
- ____________
- Volatility
- Vapor Pressure
- Boiling Point
- Specific Gravity
- Solubility
- Fire Point
___________ - The ease with which a substance passes into a gaseous state at a given temperature and pressure.
Volatility
Volatility is determined by:
- ___________
- ___________
- ___________
- Flash point
- Exposed surface area
- Pressure
____________ - The lowest temperature at which a fuel will give off sufficient flammable vapors to ignite momentarily when provided with an external ignition source.
Flash point
Atmospheric pressure at sea level is: _____.
Atmospheric pressure in Salt Lake City is approx. _____.
- 7 psi
12. 5 psi