1. What is the Water Flow Rate Calculator?

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

Purpose: It helps engineers and plumbers calculate laminar flow rates in pipes based on pressure differences and pipe characteristics.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

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 flow rate is directly proportional to the pressure difference and the fourth power of the radius, and inversely proportional to viscosity and pipe length.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate calculations ensure proper pipe sizing, efficient system design, and meet water supply requirements.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What are the limitations of this equation?
A: It only applies to laminar flow (Re < 2000) in straight, circular pipes with Newtonian fluids.

Q2: How does pipe radius affect flow rate?
A: Flow rate increases with the fourth power of radius - doubling radius increases flow 16 times!

Q3: What's the typical viscosity of water?
A: About 0.001002 Pa·s at 20°C, but decreases with temperature (0.000890 at 25°C).

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

Q5: What if my flow is turbulent?
A: Use the Darcy-Weisbach equation instead for turbulent flow calculations.