1. What is a Water Flow Rate Calculator Using Pressure?

Definition: This calculator estimates the volumetric flow rate of water through a pipe using the Hagen-Poiseuille equation, based on pipe dimensions, pressure difference, and water viscosity.

Purpose: It helps engineers, plumbers, and fluid dynamics researchers determine water flow rates in piping systems.

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 of water (Pa·s)
• \( L \) — Length of pipe (m)

Explanation: The equation describes laminar flow of an incompressible fluid through a long cylindrical pipe of constant cross section.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate calculations are essential for designing efficient piping systems, ensuring proper water supply, and calculating energy requirements.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What are typical water viscosity values?
A: At 20°C (68°F), water viscosity is about 0.001002 Pa·s. It decreases with increasing temperature.

Q2: Does this work for turbulent flow?
A: No, this equation is only valid for laminar flow (Re < 2000). For turbulent flow, use the Darcy-Weisbach equation.

Q3: How does pipe radius affect flow rate?
A: Flow rate is proportional to the fourth power of the radius, so small increases in radius dramatically increase flow.

Q4: What units should I use?
A: Use meters for length dimensions, Pascals for pressure, and Pa·s for viscosity to get flow rate in m³/s.

Q5: Can I use this for other fluids?
A: Yes, but you must use the correct viscosity value for your specific fluid at the operating temperature.