Chapter 5: Fire Behavior Flashcards
Class A fires involve:
Ordinary combustible materials
Class B fires involve:
Flammable or combustible liquids
Class C fires involve:
Energized electrical equipment
Class D fires involve:
Combustible metals
Class K fires involve:
Combustible cooking oils and fats
What is a BLEVE?
A type of explosion that occurs when volatile liquid in a tank is heated
What does BLEVE stand for?
Boiling Liquid/Expanding Vapor Explosion
A smoke explosion occurs when:
A mixture of flammable gases and oxygen is present, usually in a void or other space, comes in contact with an ignition source
What are the four elements necessary for a self sustaining fire?
The fire tetrahedron
Oxygen
Fuel
Heat
Chemical chain reaction
What danger is suggested when you observe smoke puffing in and out of a structure?
Backdraft
Combustion
Rapid chemical process of oxidation that produces light and heat
4 ways of heat transfer
Conduction
Convection
Radiation
Direct flame impingement
4 stages of fire development
- Incipient stage
- Growth stage
- Fully developed stage
- Decay stage
Fire point (flame point)
The lowest temperature at which a liquid produces enough vapor to sustain a continuous fire
Oxidation
Process in which oxygen combines chemically with another substance to create a new compound
EX) rust
Wind conditions as low as ___ mph can create wind-driven fire conditions
10
Vapor density
Refers to the weight of a vapor or gas compared to the weight of an equal volume of air
The vapor density of air is assigned the value of:
A gas with a lower vapor density will:
A gas with a high vapor density will:
1
Rise
Fall
Most common method of extinguishing a fire
Cool the burning material
What does LEL stand for?
Also called LFL
Lower Explosive Limit
Lower Flammable Limit
What does UEL stand for?
Also called UFL
Upper Explosive Limit
Upper Flammable Limit
How can class B fires be extinguished?
Shuttting off the supply of fuel
Using foam to exclude the oxygen
Exothermic
Chemical reaction that produces heat
EX) fire
Endothermic
Chemical reaction that absorbs heat
EX) ice cubes melting
Pyrolysis
Process in which materials are decomposed, or broken down, into simple compounds by heat alone
Produces a flammable vapor
What state must a fuel be in for combustion to take place?
Vapor only
Rollover
A condition where flames move through or across unturned gasses
Usually occurs at ceiling level
Warning sign of flashover
Flashover
Occurs when all contents of a room with fire gets superheated and begin to release gases that ignite simultaneously
Flammability range and explosives limits are ____ terms
Interchangeable
Black fire
High-volume, high-velocity, turbulent, ultra-dense, black smoke
What is the approximate critical temperature for a flashover to occur?
1000° F
What is smoke-stained glass a warning sign of?
Backdraft
Introducing air into a ventilation-limited fire can result in:
Explosive fire growth
What are the 4 key attributes of smoke
Smoke volume, velocity, density, and color
When you open the door and
Smoke exits through the top half of the doorway:
Smoke rises and the opening clears out:
Smoke thins but remains at the doorway:
The fire is located
Same level
Above
Below
Thermal layering
Heat layers that occurs in a room from a fire
Turbulent smoke is an indication of:
A flashover
Flash point
The lowest temperature at which a liquid or solid produces a flammable vapor
