Fire Dynamics and Behavior Flashcards
7 cards from real CFPS 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 Dynamics and Behavior flashcards as text
In a fully developed (post-flashover) compartment fire, the fire is typically characterized as:
Answer: Ventilation-controlled with excess unburned fuel
Post-flashover fires are generally ventilation-controlled, meaning oxygen supply limits combustion and unburned gases may exit through openings and burn externally.
The 'equivalent fire resistance' method in structural fire protection is based on which fire concept?
Answer: Time-temperature curve comparison between a real fire and a standard fire
Equivalent fire resistance compares the thermal exposure of a real (parametric) fire with the standard ISO 834 or ASTM E119 time-temperature curve.
What term describes the minimum concentration of a gas or vapor in air below which a flame will not propagate from an ignition source?
Answer: Lower Flammable Limit (LFL)
The Lower Flammable Limit (LFL) is the minimum fuel concentration in air below which the mixture is too lean to sustain flame propagation.
Which parameter is used in Heskestad's flame height correlation to predict mean visible flame height?
Answer: Convective heat release rate and fire diameter
Heskestad's correlation uses the convective heat release rate (Q*) and fire source diameter to predict mean visible flame height above the base of the fire.
A 'thermally thick' solid is one where:
Answer: Heat does not penetrate significantly into the interior during the relevant exposure period
A thermally thick material behaves as if it has infinite depth because the thermal wave does not reach the back face during the exposure time of interest.
The 'neutral plane' in a fire-affected compartment refers to:
Answer: The elevation where pressure inside equals atmospheric pressure, separating inflow from outflow
The neutral plane is the elevation at which internal compartment pressure equals the external atmospheric pressure; smoke flows out above it and fresh air flows in below it.
What is the role of a 'thermal feedback' mechanism in sustaining flaming combustion on a solid fuel?
Answer: It returns heat from the flame to the fuel surface to maintain pyrolysis rates
Thermal feedback from the flame (via radiation and convection) continuously heats the fuel surface, maintaining pyrolysis and sustaining the combustion cycle.