FPE Fire Dynamics & Combustion Science Flashcards

Which SFPE Handbook equation is used to estimate the plume centerline temperature rise above ambient in a buoyant fire plume?

Answer: Heskestad plume correlation

The Heskestad plume correlation is the most widely used SFPE-referenced equation for predicting centerline temperatures and velocities in axisymmetric fire plumes.

In fire dynamics, the term 'heat release rate' (HRR) is most commonly expressed in which unit?

Answer: Watts (W) or kilowatts (kW)

HRR is expressed in watts or kilowatts and represents the thermal power output of a fire, the fundamental quantity driving fire engineering calculations.

What is the lower flammability limit (LFL) used to determine in fire and explosion protection design?

Answer: The minimum fuel-vapor concentration in air required to sustain combustion

The LFL is the minimum fuel-vapor concentration (% by volume) in air below which a flame cannot propagate, guiding ventilation and hazardous area classification.

Which compartment fire stage is characterized by oxygen-limited burning and potential backdraft conditions?

Answer: Fully developed stage

During the fully developed (steady-state) stage, fuel-rich burning consumes available oxygen, creating conditions that can lead to backdraft if fresh air suddenly enters.

The 'effective heat of combustion' of a material differs from its theoretical heat of combustion primarily because of:

Answer: Incomplete combustion and soot production

Incomplete combustion and the formation of carbon monoxide and soot reduce the actual energy released compared to the theoretical complete-combustion value.

Which parameter describes the ratio of actual mass of fuel burned to the theoretical maximum in fire dynamics?

Answer: Combustion efficiency

Combustion efficiency (χ) is the fraction of fuel energy actually released as heat, typically 0.7–0.9 for most ordinary combustibles.