1. What is Air Flow Rate from Pressure Calculation?

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

Purpose: It helps engineers and technicians design and analyze pneumatic systems, ventilation, and fluid transport 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 (Pa·s)
• \( L \) — Pipe length (m)

Explanation: The equation describes laminar flow of a Newtonian fluid in a cylindrical pipe. Flow rate increases with larger radius and pressure difference, but decreases with longer pipes and more viscous fluids.

3. Importance of Air Flow Rate Calculation

Details: Accurate flow rate calculations are essential for designing efficient systems, ensuring proper ventilation, and predicting system performance.

4. Using the Calculator

Tips: Enter pipe radius in meters, pressure difference in Pascals, dynamic viscosity (default 0.000018 Pa·s for air at 20°C), and pipe length in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical viscosity of air?
A: At 20°C, air has a dynamic viscosity of about 0.000018 Pa·s. This varies with temperature.

Q2: Does this work for any gas?
A: Yes, but you must use the correct viscosity value for your specific gas.

Q3: What are the limitations of this equation?
A: It only applies to laminar flow (Re < 2300) in long, straight pipes with constant circular cross-section.

Q4: How does pipe radius affect flow rate?
A: Flow rate is proportional to the fourth power of radius - doubling radius increases flow 16 times!

Q5: What if my flow is turbulent?
A: You would need to use the Darcy-Weisbach equation instead, which accounts for turbulence.