Duct Area is defined as

Duct Area is defined as

• A. The area of a cross-section of duct
• B. The area of a local hood opening
• C. The velocity pressure of the air
• D. The total pressure in the duct

Answer: (A)

Duct area is the cross-sectional area of the duct through which air flows. This area, often denoted A, is what you use with volumetric flow rate to find velocity (v = Q / A). For circular ducts, A = πr^2; for rectangular ducts, A = width × height. This geometric property determines how fast air moves for a given flow rate. It’s not the opening of a hood, nor a pressure value—velocity pressure (½ρv^2) and total pressure (static plus velocity) are separate concepts.

Duct area is the cross-sectional area of the duct through which air flows. This area, often denoted A, is what you use with volumetric flow rate to find velocity (v = Q / A). For circular ducts, A = πr^2; for rectangular ducts, A = width × height. This geometric property determines how fast air moves for a given flow rate. It’s not the opening of a hood, nor a pressure value—velocity pressure (½ρv^2) and total pressure (static plus velocity) are separate concepts.