Air Pressure Drop Calculator

Pressure Drop Formula:

\[ \Delta P = f \times \left(\frac{L}{D}\right) \times \left(\frac{\rho \times V^2}{2}\right) \]

Friction Factor (f):

Length (L):

Diameter (D):

Air Density (ρ):

kg/m³

Velocity (V):

m/s

Pressure Drop (ΔP):

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1. What is an Air Pressure Drop Calculator?

Definition: This calculator estimates the pressure drop in air flow systems using the Darcy-Weisbach equation.

Purpose: It helps engineers and HVAC professionals determine pressure losses in ducts, pipes, and ventilation systems.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \Delta P = f \times \left(\frac{L}{D}\right) \times \left(\frac{\rho \times V^2}{2}\right) \]

Where:

\( \Delta P \) — Pressure drop (Pascals)
\( f \) — Friction factor (dimensionless)
\( L \) — Length of pipe/duct (meters)
\( D \) — Hydraulic diameter (meters)
\( \rho \) — Air density (kg/m³)
\( V \) — Air velocity (m/s)

Explanation: The equation calculates pressure loss due to friction in a straight section of duct or pipe.

3. Importance of Pressure Drop Calculation

Details: Accurate pressure drop calculations ensure proper fan selection, energy efficiency, and system performance in HVAC and pneumatic systems.

4. Using the Calculator

Tips: Enter the friction factor (default 0.02 for smooth ducts), length, diameter, air density (default 1.225 kg/m³ at sea level), and velocity. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical friction factor for air ducts?
A: For smooth metal ducts, 0.02-0.03 is common. For rough surfaces, it may be higher.

Q2: How does diameter affect pressure drop?
A: Pressure drop is inversely proportional to diameter - smaller ducts have significantly higher pressure drops.

Q3: What's the impact of velocity on pressure drop?
A: Pressure drop increases with the square of velocity, so doubling velocity quadruples the pressure drop.

Q4: When would I need to adjust air density?
A: At higher altitudes or different temperatures where air density changes from the standard 1.225 kg/m³.

Q5: Does this include fittings and bends?
A: No, this calculates straight-section losses only. Additional calculations are needed for fittings.