Circular Ducts

Overview

Engineering reference data for Circular Ducts in HVAC systems.

Key Formulas

Sensible Heat

$Q = \dot{m} c_p \Delta T$

Heat causing temperature change.

Latent Heat

$Q = \dot{m} h_{fg} \Delta\omega$

Heat causing moisture change.

COP (Cooling)

$COP = Q_c / W$

Coefficient of performance.

Variables

Symbol	Description	Unit
$Q$	Heat transfer	W
$\dot{m}$	Mass flow rate	kg/s
$c_p$	Specific heat of air	J/(kg·K)
$\Delta T$	Temperature difference	K

Circular Duct Specifications

Metric Dimensions

The following table provides standard metric dimensions for circular ductwork used in air handling and ventilation systems.

Imperial Dimensions & Weights

This table shows galvanized steel duct dimensions, surface areas, and weights for different sheet metal gages in imperial units.

Key Properties

• Surface Area: The surface area per linear foot ($ft^2/ft$) is critical for calculating friction losses, insulation requirements, and material costs.
• Gage Thickness: Lower gage numbers indicate thicker sheet metal. For example, Gage 22 ($0.0299$ inches) is thicker than Gage 26 ($0.0179$ inches), providing greater structural strength and durability.
• Weight Variation: Weight increases with both duct diameter and decreasing gage number (increasing thickness).

Interactive Charts

References

• Original Source