Equivalent Diameter

Overview

Equivalent diameter is the diameter of a circular duct that gives the same pressure drop per unit length as a rectangular or non-circular duct for the same flow rate. For rectangular ducts, the hydraulic diameter $D_h = \frac{2ab}{a+b}$ is commonly used as an approximation.

Data Table

Notes

• Values are at standard conditions unless otherwise noted
• Always verify values for critical applications

References

• Original Source