Chap 6 Fire Dynamics Flashcards
A Chemical reaction that releases heat?
Fire does this by releasing heat, light, smoke, toxic gases and other products
Exothermic Reaction
Fire Triangle:
1st, 2nd and 3rd component
- Fuel
- Oxygen
- Heat
Oxygen is found in normal breathing air in the atmosphere at a volume of?
21%
Developed in 1950 by Walter Haessler, A chemical chain reaction unites fuel, oxygen, and heat in the fire triangle to create the fire tetrahedron
Fire tetrahedron
There are classes of fire? what are they?
5 classes
A,B,C,D,K
Ordinary combustible fires
Class A
What do class B fires involve?
Fuels comprising flammable petroleum products
Class c fires?
Electrically energized equipment. The fuel can be Class A B or D, electrical hazard deontes this category as Class C
What do Class D fires consist of?
Combustible metals such as sodium, titanium, magnesium and etc.
What must be avoid with class D fires?
Water
What do Class K fires involve?
Cooking fuels such as vegetable or animal oils and fats.
Process of converting the fatty acids in cooking oils or fats to soap or foam; the action caused by a Class K fire
Saponification
The extinguishing agent in Class K fires turn the burning substance to a non combustible soap. This process is an reaction, meaning it absorbs thermal energy from its surroundings.
Endothermic reaction.
Saponification
The cause of death in more than 50% of all fire fatalities.
Carbon Monoxide
When fires involve natural and synthetic materials that contain nitrogen, what is released?
Hydrogen Cyanide
This is released from burning polyethylene?
Acrolein
This deadly gas is released with Polyvinyl chloride (PVC) is burning.
Hydrogen Chloride.
A method of heat transfer by which there is direct contact between the object and the open flame. Sometimes considered a form of radiation.
Direct flame impingement.
Because of rapid smoke and fire spread, the greatest dangers exist on what three floors?
Fire floor, floor directly above, top floor
Process by which the walls and furnishings in a compartment heat as heat is transferred with the compartment; this heat then feeds back and further heats the compartment
Thermal radiation feedback
The point in the progression of the fire when all the combustibles in the room have ignited.
Flashover
The rolling of a flame under the ceiling as a fire progresses, first sign of a flashover.
Rollover
The key to recognizing flashover?
Smoke movement and fire growth.
Indicators of impending flashover include:
Room size
Extreme, unbearable heat build up that drives you to the floor
Rollover of fingerlike flames rolling out through the smoke
What is a back draft?
Oxygen starved fire in an enclosed compartment suddenly gets a fresh supply of air, it ignites back with an explosive force.
Indicators of Backdraft?
Thick smoke pushing our windows and other openings
Heavy smoke with no visible fire in well sealed spaces
Dark yellowish brown smoke seeping from tight buildings
smoke is pushed out and drawn back in
Windows are stained
What type of ventilation to help prevent backdraft?
Vertical Ventilation
More common on the east coast, in which a mercantile occupancy is on the first floor and living areas occupy the floors above.
Taxpayers
Artificial face or front to a building
Facade
The following are important aspects to consider in determining the stages of the fire growth:
Shape and Color of the flames
Density and color of the smoke
Pressure behind the smoke movement
The fire’s progress depends on what?
Fuel load
Combustibility of the fuel
Intensity of the heat produced
4 Phases of Fire Growth
Incipient
Growth
Fully Developed
Decay/Smoldering
Five feet into a room that has flashed is often referred to as?
“The point of no return”
