What term describes movement of heat and smoke from higher pressure near the fire to lower pressure?

• A. Flow path
• B. Exhaust flow
• C. Chimney effect
• D. Thermal pressure gradient

Answer: (A)

Flow path describes the route that heat and smoke follow from the high-pressure zone near the fire to lower-pressure areas, moving through openings, cracks, doors, and voids. The fire heats the air and gases, creating a pressure difference so they push from where the pressure is higher toward where it’s lower. The path taken isn’t just vertical buoyancy; it’s the connected route shaped by the building’s openings and geometry. While chimney effect explains buoyant vertical movement and thermal pressure gradient explains the driving force, the flow path term best captures the actual movement through the structure along the available openings.