1. What is a Flow in Pipe Calculator?

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

Purpose: It helps engineers and technicians determine fluid flow rates in laminar flow conditions for pipe system design and analysis.

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 are essential for designing efficient piping systems, ensuring proper fluid delivery, and optimizing energy consumption.

4. Using the Calculator

Tips: Enter the pipe radius in meters, pressure difference in Pascals, dynamic viscosity (default 0.001002 Pa·s for water at 20°C), and pipe length in meters. 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 (not turbulent) flow in circular pipes.

Q2: What's a typical viscosity value for water?
A: Water at 20°C has a viscosity of about 0.001002 Pa·s (the default value in the calculator).

Q3: Why is radius to the fourth power so important?
A: The r⁴ term means small changes in pipe diameter have dramatic effects on flow rate (double the radius = 16× the flow).

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

Q5: Does this account for pipe roughness?
A: No, this equation assumes smooth pipes and Newtonian fluids. For rough pipes or turbulent flow, use the Darcy-Weisbach equation.