Duct Pressure Loss Calculator

Pressure Loss Equation:

\[ \Delta P = f \times \frac{L}{D_h} \times \frac{\rho V^2}{2} \]

Friction Factor (f):

Length (L):

Hydraulic Diameter (Dh):

Density (ρ):

kg/m³

Velocity (V):

m/s

Pressure Loss (ΔP):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Duct Pressure Loss?

Duct pressure loss refers to the reduction in pressure that occurs as air or fluid flows through a duct system due to friction and other resistances. It is a critical parameter in HVAC system design and fluid dynamics engineering.

2. How Does the Calculator Work?

The calculator uses the pressure loss equation:

\[ \Delta P = f \times \frac{L}{D_h} \times \frac{\rho V^2}{2} \]

Where:

\( \Delta P \) — Pressure loss (Pa)
\( f \) — Friction factor (dimensionless)
\( L \) — Length of duct (m)
\( D_h \) — Hydraulic diameter (m)
\( \rho \) — Density of fluid (kg/m³)
\( V \) — Velocity of fluid (m/s)

Explanation: The equation calculates the pressure drop due to friction in a duct system, considering the fluid properties and duct geometry.

3. Importance of Pressure Loss Calculation

Details: Accurate pressure loss calculation is essential for proper HVAC system design, fan selection, energy efficiency optimization, and ensuring adequate airflow throughout the system.

4. Using the Calculator

Tips: Enter friction factor, duct length, hydraulic diameter, fluid density, and velocity. All values must be positive numbers with appropriate units.

5. Frequently Asked Questions (FAQ)

Q1: What is hydraulic diameter?
A: Hydraulic diameter is a measure of the effective cross-section of a duct, calculated as 4 times the cross-sectional area divided by the wetted perimeter.

Q2: How do I determine the friction factor?
A: The friction factor depends on Reynolds number and relative roughness. It can be found using Moody chart or Colebrook equation for turbulent flow.

Q3: What are typical pressure loss values?
A: Pressure loss varies widely but typically ranges from 0.5-5 Pa/m for low-velocity systems to higher values for high-velocity systems.

Q4: Does this account for fittings and bends?
A: This equation calculates only straight duct friction loss. Additional losses from fittings, bends, and other components must be calculated separately.

Q5: What units should I use?
A: Use consistent SI units: meters for length, kg/m³ for density, m/s for velocity, and the result will be in Pascals (Pa).