Chapter 6 Flashcards
Fire is a combustion process that can be self sustaining reaction. This chemical process is ___ in that two fo the products of fire are heat and light.
Exothermic
Oxygen is found in normal breathing air in the atmosphere at a volume of ___%. The rest of the air is mostly nitrogen, an inert chemical.
21%
Heat and light are released an energy form we refer to as a ___ or ___.
Flame or fire
A more complete explanation of the fire process involves the fire tetrahedron. This concept was developed in the early ___ by ___.
1950’s by Walter Haessler
The fire tetrahedron joins a fourth component, an ___.
Uninhibited chain reaction
Walter Haessler was interested in finding out why the chemical ___ was so effective as a fire extinguishing agent.
Ammonium phosphate
Fire tetrahedron… The fourth component deals with ___.
Free chain reactions
Fire tetrahedron… The fuel is considered a ___.
Reducing agent
Fire tetrahedron… In the fire process known as ___, the tetrahedron better describes the reaction taking place.
Flaming combustion
Five classes of fire.
Class A - Ordinary Combustibles
Class B - Flammable petroleum products
Class C - Electrically energized equipment
Class D - Combustible metals, end in IUM
Class K - Combustible cooking fuels such as veg oil or animal oils or fats.
Class ___; similar to class B fuels but involve very high temps and require wet chemicals to extinguish.
Class K
This is an ___ reaction, meaning it absorbs thermal energy from its surroundings.
Endothermic
Class A fires burning produce ___, ___, and ___.
Carbon dioxide
Carbon monoxide
Water
Plastics are considered to be hydrocarbon based. They produce heavy black smoke and high levels of ___, ___, ___, and ___.
Carbon monoxide
Carbon dioxide
Hydrogen cyanide
Hydrogen chloride
The most abundant gas produced at any fire is ___.
Carbon monoxide
Heat and gas carry CO in ___ throughout the structure.
Convection currents
CO poisoning is the cause of death in more than ___ of all fire fatalities.
50%
When fires involve natural and synthetic material that contain nitrogen, the materials release ___.
Hydrogen cyanide
___, a very potent irritant, is released from burning polyethylene.
Acrolein
___, a deadly gas released from polyvinyl chloride, is irritating to the eyes and upper respiratory tract.
Hydrogen chloride
The greater the supply of oxygen, the ___ gasses produced.
Fewer
4 phases of fire:
Incipient
Free-burning
Flashover
Smoldering decay
Fire growth depends on:
Type of fuel (combustible or flammable)
Physical property of the fuel (solid, liquid, vapor, or gas)
Surface to mass ratio (ex 4x4, wood shavings, or dust)
Arrangement of the fuel (tightly packed or spaces betwn)
Adequate ventilation (nat ventilation or airtight room)
Flame itself can produce a flame temp of ___ to ___, but the room temperature may not change significantly.
800°f to 1000°f
4 principle means of fire spread:
Convection
Radiation
Conduction
Direct flame impingement (sometimes considered a form of radiation)
The travel of ___ can be affected by air currents and ventilation systems.
Convection currents
Convection… Because of rapid smoke and fire spread, the greatest dangers exist on the ___, the ___ the fire, and the ___ of the building. The priority of search should be set in this order.
Fire floor
Floor immediately above
Top floor
MGM Grand Hotel Fire… Fire in the casino area burned at a rate of approx ___ - ___ feet per second.
15 - 19
___: Flames from the fire produce heat waves that move in a straight line form the fire.
Radiation
Radiant heat moves ___ from the fire, this heating everyone it can reach.
equally in all directions
Radiation… It is a ___ energy, thus can move through glass and water, that does not become thermal energy until it strikes an object and exited the molecules.
Electromagnetic energy
In the 1800’s, ___ defunded the law of heat and conduction as, the heat transfer in a. stationary medium(solids, liquids, and gases)
Joseph Fourier
There is no heat conduction through ___.
A perfect vacuum
Conduction… The rate of heat flow is directly proportional to temperature differences. The heat transfers from the point of heat ___ toward the colder areas.
Outward
The spread of fire through ___ is similar to that of radiant heat spread.
Direct flame impingement
Direct flame impingement is sometimes considered a form of ___.
Radiation
Heating process that contributes to flashover.
Thermal radiation feedback
Flashover… The combination of ___ and ___ are now bringing all things in the room to their ignition point.
radiant and convected heat
Flashover… ___ of fire across the ceiling is one of the first signs that flashover is imminent.
Rollover
___ feet into the room where flashover has occurred is commonly known as the point of no return.
5 feet
Flashover… The ___ in the room determines the fire temperature and the pressure generated by the expanding heat and gases of the self sustaining chemical process.
Fire load
The key to recognizing flashover is ___ and ___.
smoke movement and fire growth
Indicators of impending flashover:
Room size
Extreme, unbearable heat that drives you to the floor
Rollover
High ceilings can reach ___ feet, as typical in a warehouse, mask the signs of flashover due to the low heat at the floor level.
20 feet
When an oxygen starved fire in an enclosed compartment suddenly gets a fresh supply of air, it will ignite with explosive force. This is known as ___.
Backdraft
Backdraft… This phenomenon can occur from premature ___.
Horizontal ventilation
Indicators of backdraft:
Thick smoke pushing out opening under pressure
Heavy smoke appears with no visible fire
Dark yellowish-brown smoke seeping form tight building
Smoke is pushed out and drawn back in
Windows stained black and are hot
There is little or no visible flame
The building is tightly closed or contained
The use of insulation in ___ has severely limited natural airflow in modern buildings.
Thermal pane windows
The oxygen and CO mixture ignites at approximately ___.
1100°f
___ are common locations for backdraft.
Commercial occupancies
Smoke contains particles of ___, ___, and multiple ___.
Tar
Water
Gases
Dark black smoke is typical of ___ based fires, such as plastics and foams.
Hydrocarbon
___ smoke indicates and oxygen starved fire.
Dirty brown
Lighter smoke is more indicative of Class ___ fires.
A
___: A process by which the walls and furnishings in a compartment heat as heat is transferred within the compartment; this heat then feeds back and further heats the compartment.
Thermal radiation feedback
