Pressure Drop Calculation Formula

Pressure Drop Formula:

\[ \Delta P = \frac{f \times L \times \rho \times V^2}{2 \times D \times 144} \]

Friction Factor (f):

dimensionless

Pipe Length (L):

feet

Fluid Density (ρ):

lb/ft³

Fluid Velocity (V):

ft/s

Pipe Diameter (D):

feet

Pressure Drop (ΔP): psi

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1. What is Pressure Drop Calculation?

Definition: This calculator estimates the pressure loss (ΔP) in a pipe or nozzle due to fluid flow using the Darcy-Weisbach equation.

Purpose: It helps engineers and technicians determine the pressure loss in piping systems for proper system design and pump sizing.

2. How Does the Calculator Work?

The calculator uses the Darcy-Weisbach equation:

\[ \Delta P = \frac{f \times L \times \rho \times V^2}{2 \times D \times 144} \]

Where:

\( \Delta P \) — Pressure drop (psi)
\( f \) — Darcy friction factor (dimensionless)
\( L \) — Pipe length (feet)
\( \rho \) — Fluid density (lb/ft³)
\( V \) — Fluid velocity (ft/s)
\( D \) — Pipe diameter (feet)

Explanation: The equation calculates pressure loss due to friction between the fluid and pipe walls, with the 144 factor converting lb/ft² to psi.

3. Importance of Pressure Drop Calculation

Details: Accurate pressure drop calculations ensure proper pump selection, system efficiency, and prevent flow-related issues in piping systems.

4. Using the Calculator

Tips: Enter all required parameters with consistent units. Friction factor depends on Reynolds number and pipe roughness - typical values range from 0.01 to 0.05.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the friction factor?
A: For turbulent flow, use Moody chart or Colebrook equation. For laminar flow, f = 64/Re.

Q2: What's a typical fluid velocity range?
A: For water systems, 2-8 ft/s is common. Higher velocities increase pressure drop and noise.

Q3: Does this include minor losses?
A: No, this calculates only major (friction) losses. Add minor losses from fittings separately.

Q4: What units should I use?
A: Consistent units are critical - feet for length/diameter, lb/ft³ for density, ft/s for velocity.

Q5: How does pipe diameter affect pressure drop?
A: Pressure drop is inversely proportional to diameter - smaller pipes have significantly higher ΔP.