Fire Dynamics Flashcards
TB Fire Dynamics Chapter 1 - 4
What are the four parts of the Fire Tetrahedron?
Heat
Oxygen
Fuel
An uninhibited chemical chain reaction
If one part of the fire tetrahedron is missing can flaming combustion still take place?
No, all four are needed.
What state of matter burns?
Gasses
The conversion of solid into a gas is called?
Pyrolysis
The conversion of liquid into a gas is called?
Vaporization
T or F? Surface to Mass ratio affects the ease of ignition of liquid fuels?
False
Surface to Mass Ratio affects solid fuel.
Surface to Volume Ratio affects liquid fuels.
What color smoke indicates a wood structure is burning?
Brown
Oxygen in the air is normally?
20.8%
Fire can ignite and burn till what percentage of oxygen?
15 %, lower and it shall enter non-flaming mode.
Which fuels do not require oxygen in the air to burn
Chemical oxidizers
T or F? In oxygen rich environments, many materials that do not burn at all in normal environments will burn.
True.
What is the law of heat flow?
Heat always flows from a hot substance to a cold substance.
How does heat spread via conduction
direct contact of two objects or by an intervening heat-conducting medium.
How does heat spread via convection
By air or liquid.
Which is the most common way fire spreads through walls, up stairwells or elevator shafts
Convection
T or F? Forced convection is a critical factor in wind driven fires?
True
How does heat spread via Radiation?
Through the movement of heat waves until it reaches an object.
What are the four methods for extinguishment theory?
Heat Reduction
Fuel Removal
Oxygen Removal
Flame inhibition
Application of water is which of the extinguishment theory?
Heat Reduction
What are the three methods of fuel removal?
Stopping the flow of liquid or gaseous fuels
Removing solid fuel from the path of the fire.
Allow the fire to burn until the fuel is consumed.
Flooding an area with inert gas that displaces the oxygen is which part of extinguishment theory
Oxygen Removal
Extinguishment by Chemical Flame Inhibition is effective on what types of fuel?
gas and liquid fuels
Which Class is a Green Triangle
Class A: Common Combustibles
What Class is a Red Square
Class B: Flammable Liquids and Gases
What Class is a Blue Circle
Class C: Electrical
What Class is a Yellow Star
Class D: Combustible Materials
What Class is a Black Hexagon
Class K: Cooking oils and Fats
Flash Point is?
The lowest temperature of a liquid that gives off sufficient vapors to ignite but will not continue to burn.
T or F? Flammable Liquid is a liquid that has a flash point equal to or greater than 100 ‘ F
False.
Flammable Liquid is a liquid that has a flash point below 100’ F
Combustible Liquid has a flash point equal to or greater than 100’ F
What is a fire point?
The Lowest temperature at which a liquid will ignite and achieve sustained burning.
Will a gas with a vapor density greater than 1 sink or rise in a compartment?
Sink
Can a gaseous fuel concentration higher than the upper explosive limit ignite?
No
T or F? The Growth Stage is the earliest stage of a fire?
False, Incipient Stage
What is not a Characteristic of a Backdraft?
A)
B) Free Burning Fire
C)
D)
During the incipient stage, has the temperature in the room dramatically increased?
No, only slightly
What stage does rollover and flashover occur?
Growth Stage
What stage of the fire can be extinguished by a proper fire extinguisher?
Incipient Stage
When does a fully developed stage occur?
After a flashover
T or F? The fully developed stage can occur at the same time as the growth stage?
True, the fire is only fully developed within the compartment that has flashed over. Other compartments or rooms may be in the growth stage
At what point does a fire enter the decay stage?
When all the available fuel is consumed or when the oxygen concentration falls below 15 % and flaming combustion is diminished
What is the far more dangerous type of way a fire enters the decay stage: Fuel limited or Ventilation limited?
Ventilation limited. A Vent limited fire can rapidly restart if improperly introduced to oxygen.
The hottest gases tend to be where in thermal layering
At the top.
What are the two categories of thermal layering
Upper Layer and Lower Layer
The vertical distance from the floor of the enclosure to the thermal interface is called?
Interface height
The five characteristics of smoke to be sized up?
Volume
Velocity
Density
Color
Stratification
Of the two types of smoke flow, laminar or turbulent, which indicates some distance between you and the fire?
Laminar Smoke
T or F? Dense smoke can indicate the fire is a vent limited fire?
True
Black smoke indicates what?
Fuel-rich conditions and restricted air supply.
What does Grey smoke indicate?
That you are remote from the fire as it has lost its carbon.
What does White Smoke Indicate
1) Water is on fire and progress is being made on the fire.
2) Heat has continued to increase and there is insufficient oxygen even for smoldering.
A neutral plane that is at or near floor level may indicate?
The fire is on a floor below
A sudden rise in the interface height indicates?
Ventilation has occurred.
What is it when Unburned fire gases that have accumulated at the roof ignite and flames travel through the hot gas layer across the ceiling?
rollover
A Flashover is?
The simultaneous ignition of all the combustible materials in a compartment.
