Hydraulic Diameter Calculator — Formule
## Hydraulic Diameter
The hydraulic diameter allows non-circular conduits to be analysed using the same formulas developed for circular pipes.
### Formula
**D_h = 4 A / P**
where A is the cross-sectional flow area and P is the wetted perimeter. For a rectangular duct with sides a and b: D_h = 4ab / (2(a+b)) = 2ab / (a+b). For a circle, D_h equals the actual diameter.
The hydraulic diameter allows non-circular conduits to be analysed using the same formulas developed for circular pipes.
### Formula
**D_h = 4 A / P**
where A is the cross-sectional flow area and P is the wetted perimeter. For a rectangular duct with sides a and b: D_h = 4ab / (2(a+b)) = 2ab / (a+b). For a circle, D_h equals the actual diameter.
Exemple Résolu
A rectangular HVAC duct 400 mm wide and 300 mm tall.
- Area = 400 x 300 = 120,000 mm^2
- Perimeter = 2 x (400 + 300) = 1,400 mm
- D_h = 4 x 120,000 / 1,400 = 342.9 mm