Water Flow in Pipe Calculator

Hagen-Poiseuille Equation:

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

Pipe Radius:

meters

Pressure Difference:

Pascals

Fluid Viscosity:

Pa·s

Pipe Length:

meters

Flow Rate (m³/s):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a Water Flow in Pipe Calculator?

Definition: This calculator estimates the volumetric flow rate of water through a pipe using the Hagen-Poiseuille equation.

Purpose: It helps engineers, plumbers, and fluid system designers determine flow rates in laminar flow conditions.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

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

Where:

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

Explanation: The equation describes laminar flow through a cylindrical pipe, showing flow rate's strong dependence on pipe radius.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate estimation ensures proper pipe sizing, system efficiency, and meets design requirements for fluid transport systems.

4. Using the Calculator

Tips: Enter pipe radius (in meters), pressure difference (in Pascals), fluid viscosity (default 0.001002 Pa·s for water at 20°C), and pipe length. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What flow regime does this equation apply to?
A: The Hagen-Poiseuille equation applies only to laminar flow (Re < 2000).

Q2: Why is radius to the fourth power?
A: Flow rate is extremely sensitive to pipe diameter - doubling the radius increases flow 16 times.

Q3: What's the default viscosity value?
A: 0.001002 Pa·s is the dynamic viscosity of water at 20°C (68°F).

Q4: How do I convert to liters/second?
A: Multiply m³/s result by 1000 to get L/s.

Q5: Does this account for pipe roughness?
A: No, this equation assumes smooth pipes and Newtonian fluids.