Water Flow Pressure Calculator

Pressure Drop Formula:

\[ \Delta P = \frac{8 \times \mu \times L \times Q}{\pi \times r^4} \]

Dynamic Viscosity (μ):

Pa·s

Pipe Length (L):

meters

Flow Rate (Q):

m³/s

Pipe Radius (r):

meters

Pressure Drop (ΔP):

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1. What is a Water Flow Pressure Calculator?

Definition: This calculator estimates the pressure drop in a pipe due to viscous flow using the Hagen-Poiseuille equation.

Purpose: It helps engineers and plumbers determine the pressure loss in laminar flow conditions through cylindrical pipes.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \Delta P = \frac{8 \times \mu \times L \times Q}{\pi \times r^4} \]

Where:

\( \Delta P \) — Pressure drop (Pascals)
\( \mu \) — Dynamic viscosity (Pa·s)
\( L \) — Pipe length (meters)
\( Q \) — Volumetric flow rate (m³/s)
\( r \) — Pipe radius (meters)

Explanation: The formula shows that pressure drop is directly proportional to viscosity, pipe length, and flow rate, but inversely proportional to the fourth power of the pipe radius.

3. Importance of Pressure Drop Calculation

Details: Proper pressure drop estimation ensures adequate pump sizing, system efficiency, and prevents flow issues in piping systems.

4. Using the Calculator

Tips: Enter the fluid viscosity (default 0.001002 Pa·s for water at 20°C), pipe length, flow rate, and pipe radius. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the viscosity of water?
A: At 20°C, water has a viscosity of about 0.001002 Pa·s. This changes with temperature.

Q2: Does this work for turbulent flow?
A: No, this equation is only valid for laminar flow (Re < 2100). Different equations are needed for turbulent flow.

Q3: Why is radius to the fourth power?
A: This strong dependence shows how small changes in pipe diameter greatly affect pressure drop.

Q4: What units should I use?
A: Use consistent SI units: meters for length/radius, m³/s for flow rate, and Pa·s for viscosity.

Q5: How accurate is this calculation?
A: Very accurate for laminar flow in smooth, straight pipes. Real-world factors like bends or roughness may require adjustments.