Ch. 5 - Fire Behavior Flashcards
Chemical reaction that gives off heat
exothermic
Chemical reaction that absorbs heat
endothermic
Conditions needed for fire
oxygen-fuel-heat
Pyrolysis
process that liberates flammable vapors from a fuel source
Conduction
process of transferring heat between two solids
Convection
transfer of heat by the flow of gas or liquid from hotter areas to cooler areas
Radiation
transfer of heat through the emission of energy
Class A Fire
ordinary solid combustible materials
Class B Fire
flammable or combustible liquids
Combustible material
a material that can combust when heated
Flammable material
a material that will combust immediately on exposure to heat
Class C Fire
energized electrical equipment
Class D Fire
combustible metals
Class K Fire
cooking oils and fat
HRR
Heat release rate; rate at which heat energy is generated
Thermal layering
process by which hot gases rise to the top
Neutral Plane
boundary between hot and cool gases
Rollover
spontaneous ignition of hot gases in the upper levels of a room; also known as flameover
Flashover
when all exposed surfaces have ignited
What is the critical temperature when flashover can occur?
1000F
Backdraft
occurs when oxygen is introduced to a ventilation-limited fire
Stages of Fire Development
- Incipient Stage
- Growth Stage
- Fully Developed
- Decay Stage
Volitility
amount of liquid that vaporizes
Flammable range
range in concentration between upper and lower flammable limits
lower explosive limit
minimum amount of gaseous fuel that must be present for the mixture to be flammable
BLEVE
boiling liquid/expanding vapor explosion
turbulent smoke flow
“boiling” smoke caused by absorbing radiant heat
Black fire
extremely hot and dense smoke
laminar smoke flow
smooth or streamlined flow
Minimum temperature at which a fuel will ignite when heated
ignition temperature
As electricity flows through a wire what relationship is there between the resistance of the wire and the heat produced?
Greater resistance = more heat
What is vapor density?
measures the weight of a gas fuel compared to air
what is the vapor density of gasoline?
varies widely
What occurs when a mixture of flammable gas and oxygen in a void or other confined area come in contact with an ignition source?
smoke explosion
What occurs when liquid fuel in a pressurized container is heated to fuel’s boiling point?
BLEVE - Boiling Liquid Expanding Vapor Explosion