Fire Science Flashcards
Four products of combustion
Smoke, flame, heat, gas + irritants
Flashpoint
Minimum temperature for momentary, not sustained ignition
Ignition Temperature
Minimum temperature required for fuel to ignite and burn independent of ignition source
Firepoint
Minimum temperature required for liquid fuel to produce sufficient vapors to support combustion once fuels ignited. Firepoint must exceed a few degrees above the flashpoint
Boiling Point
Temperature required to boil liquid, and vapor pressure exceeds atmospheric pressure
Oxidation
A chemical process that occurs when a substance combines with an oxidizer such as oxygen in the air (i.e. rust)
Pyrolysis
The chemical decomposition of a solid material by heating. It often precedes combustion
Reducing Agent
The fuel that is being oxidized or burned during combustion
Vaporization
The physical process that changes liquid to gas
Vapor density
The weight of a given volume of pure vapor or gas compared to the equal volume of dry air
VD < 1 = lighter than air
VD > 1 = heavier than air
Specific gravity
The mass of a substance compared to the mass of an equal volume of water at a given temperature
SG < 1 = substance lighter than water
SG > 1 = substance heavier than water
Thermal layering
The outcome of combustion, in which gases form into layers (hottest gases to the ceiling and coldest to the floor)
Fire triangle
Heat, oxygen, fuel
Fire tetrahedron
Heat, fuel, oxygen, self-sustaining chemical chain reaction
Heat energy sources
Electrical, chemical, mechanical, nuclear
Phases of fire (textbook)
Ignition, growth, fully developed, decay
Phases of fire (curriculum)
Ignition, growth, flashover, fully developed, decay
Flameover/Rollover
A condition in which the unburned fire gases accumulate at top (ceiling) of compartment and ignite across ceiling
Backdraft
The explosive burning of heated gases that occurs when oxygen is introduced into a compartment that has a high concentration of flammable gases and a depleted supply of oxygen due to existing fire
Methods of Heat Transfer
Conduction, radiation, convection, direct-flame impingement
Conduction
Transfer of heat between solids through direct contact
Convection
Transfer of heat by circulation/movement of fluid (gas or liquid)
Radiation
Transmission of energy as an electromagnetic wave
Direct flame impingement
Combination of convection and radiation
Poisonous fire gases
Carbon Monoxide
Carbon Dioxide
Hydrogen Cyanide
Freezing and Boiling temps
Freezing= 32F ; 0C Boiling= 212F ; 100C
1 BTU=
252 Calories
Fire Extinguishment Theory
Remove any part of fire triangle or fire tetrahedron and fire goes out
Four Methods of Extinguishment
- Temperature reduction
- Fuel removal
- Oxygen exclusion
- Inhibiting chemical reaction