Air Pressure Drop in Pipe 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):

dimensionless

Pipe Length (L):

meters

Pipe Diameter (D):

meters

Air Density (ρ):

kg/m³

Air Velocity (V):

m/s

Pressure Drop (ΔP): Pa

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1. What is Air Pressure Drop in Pipe?

Definition: This calculator estimates the pressure loss of air flowing through a pipe due to friction and other factors.

Purpose: It helps engineers and HVAC professionals design efficient piping systems by predicting pressure losses.

2. How Does the Calculator Work?

The calculator uses the Darcy-Weisbach equation:

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

Where:

\( \Delta P \) — Pressure drop (Pascals)
\( f \) — Darcy friction factor (dimensionless)
\( L \) — Pipe length (meters)
\( D \) — Pipe diameter (meters)
\( \rho \) — Air density (kg/m³)
\( V \) — Air velocity (m/s)

Explanation: The equation calculates pressure loss due to friction between the moving air and pipe walls.

3. Importance of Pressure Drop Calculation

Details: Proper pressure drop estimation ensures adequate fan/pump sizing, energy efficiency, and system performance.

4. Using the Calculator

Tips: Enter the friction factor (default 0.02 for smooth pipes), pipe dimensions, air density (default 1.225 kg/m³ at sea level), and air velocity.

5. Frequently Asked Questions (FAQ)

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

Q2: What's a typical air velocity in ducts?
A: HVAC systems typically use 5-10 m/s for main ducts and 2-5 m/s for branch ducts.

Q3: When would I need to adjust air density?
A: At higher altitudes or different temperatures, use ρ = P/(RT) where P is pressure, R is gas constant, T is temperature.

Q4: Does this include fittings losses?
A: No, additional losses from elbows, valves etc. must be calculated separately and added.

Q5: What's an acceptable pressure drop?
A: Typically 1-2 Pa per meter of pipe, but depends on system requirements.