1. What is an Air Hose Flow Rate Calculator?

Definition: This calculator estimates the volumetric flow rate of air through a circular hose using the Hagen-Poiseuille equation for laminar flow conditions.

Purpose: It helps engineers, technicians, and HVAC professionals determine air flow rates in low-speed applications like pneumatic systems and ventilation.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

Where:

• \( Q \) — Volumetric flow rate (m³/s)
• \( r \) — Inner radius of the hose (m)
• \( \Delta P \) — Pressure difference between ends (Pa)
• \( \mu \) — Dynamic viscosity of air (Pa·s)
• \( L \) — Length of the hose (m)

Explanation: The flow rate is proportional to the fourth power of the radius and the pressure difference, and inversely proportional to viscosity and length.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate estimation ensures proper system design, adequate air supply for tools, and efficient energy usage in pneumatic systems.

4. Using the Calculator

Tips: Enter the hose radius (in meters), pressure difference (in Pascals), air viscosity (default 1.81×10⁻⁵ Pa·s for dry air at 20°C), and hose length (in meters). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What flow regime does this calculator apply to?
A: This calculator is for laminar flow only (Re < 2000). For turbulent flow, different equations apply.

Q2: What's the typical viscosity of air?
A: At 20°C, dry air has viscosity of about 1.81×10⁻⁵ Pa·s. This changes with temperature and humidity.

Q3: Why is radius to the fourth power so important?
A: The r⁴ relationship means small changes in hose diameter dramatically affect flow rate (doubling radius increases flow 16x).

Q4: How do I convert between different pressure units?
A: 1 psi ≈ 6895 Pa, 1 bar = 100,000 Pa, 1 atm ≈ 101,325 Pa.

Q5: What if my flow is turbulent?
A: For turbulent flow (Re > 4000), you would need to use the Darcy-Weisbach equation instead.