1. What is a Flow Rate Calculator Based on Pressure?

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

Purpose: It helps engineers, physicists, and technicians determine fluid flow rates in laminar flow conditions.

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 estimation is crucial for designing piping systems, medical devices (like IV drips), and industrial fluid processes.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What are the limitations of this equation?
A: It only applies to laminar flow (Re < 2100), Newtonian fluids, and straight pipes with constant circular cross-sections.

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

Q3: How does radius affect flow rate?
A: Flow rate is proportional to r⁴, so doubling the radius increases flow rate by 16 times.

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

Q5: Can I use this for gases?
A: Only for very slow flows where compressibility effects are negligible.