ductdiameter
Duct diameter is the internal circular cross-section dimension of a duct, used to characterize the capacity of air-handling and exhaust systems. It is typically specified by the internal diameter in inches or millimeters and serves as a primary geometric parameter for design and performance assessment.
For a circular duct, the cross-sectional area is A = π d^2 / 4, where d is the diameter.
Designers select duct diameter to balance energy use, noise, and pressure drop. A too-small diameter raises
Non-circular ducts can be approximated by an equivalent diameter De, defined as De = 4A/P, where A
Diameter is specified alongside other factors such as duct material, insulation, and fittings. In practice, standards