Fire Behavior and Combustion Science Flashcards
7 cards from real Fire Safety practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fire Behavior and Combustion Science flashcards as text
What is the name of the phenomenon where fire spreads rapidly along the ceiling in a layer of unburned gases ahead of the flame front?
Answer: Rollover
Rollover (also called flameover) occurs when unburned gases at the ceiling ignite and flames roll across the top of the compartment ahead of the main fire.
Which factor does NOT directly affect the rate of heat release (RHR) of a burning fuel?
Answer: Color of the fuel
Color has no significant effect on rate of heat release; surface area, moisture content, and density all directly influence how quickly a fuel burns.
Pyrolysis is best described as:
Answer: The chemical decomposition of a solid fuel by heat into combustible vapors
Pyrolysis is a thermochemical decomposition process where solid fuels break down under heat, releasing combustible vapors that can then ignite.
In fire behavior, what is the 'upper flammable limit' (UFL)?
Answer: The concentration of fuel vapor above which the mixture is too rich to ignite
The UFL (upper flammable limit) is the highest fuel-vapor concentration in air above which there is insufficient oxygen to sustain combustion.
A fire investigator notes a low burn pattern and 'V' pattern on a wall. What does a narrow, sharply defined 'V' pattern typically indicate?
Answer: A fast, intense fire with a well-defined point of origin
A narrow, sharp 'V' pattern indicates a fast, intense fire with a localized point of origin, while a wide 'V' suggests slower fire development.
What effect does high humidity have on the ignition and spread of wildfires?
Answer: It raises the moisture content of fine fuels, making them harder to ignite
High relative humidity causes fine fuels to absorb atmospheric moisture, increasing their moisture content and making them more resistant to ignition and spread.
Which of the following best explains why a fire in a well-insulated, tightly sealed room reaches flashover faster than one in a drafty room?
Answer: Heat accumulates faster because less energy escapes through gaps or ventilation
In a tightly sealed, well-insulated compartment, heat energy cannot escape, so the upper gas layer and ceiling temperature rise more rapidly, accelerating flashover.