1. What is a Pressure to Flow Rate Calculator?

Definition: This calculator determines the volumetric flow rate of a fluid through a pipe based on pressure difference, pipe dimensions, and fluid viscosity.

Purpose: It helps engineers and technicians analyze fluid dynamics in piping systems using the Hagen-Poiseuille equation.

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 prediction is essential for designing efficient piping systems, selecting pumps, and ensuring proper fluid delivery in industrial processes.

4. Using the Calculator

Tips: Enter pipe radius in meters, pressure difference in Pascals, viscosity in Pa·s (default 0.001 for water at 20°C), and pipe length in meters (default 1). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the Hagen-Poiseuille equation used for?
A: It calculates laminar flow of Newtonian fluids in long, straight, circular pipes with constant cross-section.

Q2: What's a typical viscosity value for water?
A: Water at 20°C has viscosity of about 0.001 Pa·s, but this decreases with temperature.

Q3: Does this work for turbulent flow?
A: No, this equation is only valid for laminar flow (Re < 2100). For turbulent flow, use the Darcy-Weisbach equation.

Q4: Why is radius to the fourth power?
A: Flow rate is extremely sensitive to pipe diameter because of the velocity profile in laminar flow.

Q5: What units should I use?
A: Use consistent SI units: meters for length, Pascals for pressure, and Pa·s for viscosity.