Air Friction Loss Calculator

Air Friction Loss Formula:

\[ \text{Loss} = \frac{f \cdot L \cdot \rho \cdot v^2}{2 \cdot D} \]

Friction Factor (f):

dimensionless

Length (L):

meters

Density (ρ):

kg/m³

Velocity (v):

m/s

Diameter (D):

meters

Friction Loss (Pa):

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1. What is an Air Friction Loss Calculator?

Definition: This calculator determines the pressure loss due to friction in air flow through pipes or ducts.

Purpose: It helps HVAC engineers, mechanical designers, and fluid dynamics professionals calculate energy losses in air distribution systems.

2. How Does the Calculator Work?

The calculator uses the Darcy-Weisbach equation:

\[ \text{Loss} = \frac{f \cdot L \cdot \rho \cdot v^2}{2 \cdot D} \]

Where:

\( \text{Loss} \) — Pressure loss (Pascals)
\( f \) — Darcy friction factor (dimensionless)
\( L \) — Length of pipe/duct (meters)
\( \rho \) — Air density (kg/m³)
\( v \) — Air velocity (m/s)
\( D \) — Hydraulic diameter (meters)

Explanation: The formula calculates the energy loss due to friction between the moving air and the pipe/duct walls.

3. Importance of Air Friction Loss Calculation

Details: Accurate calculation ensures proper fan sizing, energy efficiency, and system performance in HVAC and ventilation systems.

4. Using the Calculator

Tips: Enter the friction factor (typically 0.02-0.05 for turbulent flow), pipe length, air density (default 1.225 kg/m³ at sea level), air velocity, and hydraulic diameter. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the friction factor (f)?
A: For turbulent flow, use Moody chart or Colebrook equation based on Reynolds number and relative roughness.

Q2: What's typical air density at standard conditions?
A: 1.225 kg/m³ at 15°C and sea level, but decreases with altitude and increases with lower temperatures.

Q3: How does velocity affect friction loss?
A: Loss increases with the square of velocity - double the velocity quadruples the friction loss.

Q4: What is hydraulic diameter?
A: For circular pipes, it's the actual diameter. For non-circular ducts, use \( D_h = \frac{4 \times \text{Area}}{\text{Perimeter}} \).

Q5: Does this include minor losses from fittings?
A: No, this calculates only major (friction) losses. Minor losses must be calculated separately.