1. What is an Air Flow Rate Meter Calculator?

Definition: This calculator measures air flow rate in GPM (Gallons per Minute) equivalent based on velocity and cross-sectional area.

Purpose: It helps HVAC professionals, engineers, and technicians determine air flow rates in ducts and pipes for system design and analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (Gallons per Minute)
• \( V \) — Velocity (feet per second)
• \( A \) — Cross-sectional area (square feet)
• 448.83 — Conversion factor (ft³/s to GPM)

Explanation: The velocity is multiplied by the area to get volumetric flow in ft³/s, then converted to GPM.

3. Importance of Air Flow Rate Calculation

Details: Accurate flow rate measurement ensures proper system performance, energy efficiency, and comfort in HVAC applications.

4. Using the Calculator

Tips: Enter the air velocity in ft/s and the cross-sectional area in ft². All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why convert to GPM when measuring air?
A: GPM provides a standardized unit that's comparable to liquid flow rates in many systems.

Q2: How do I measure velocity (V)?
A: Use an anemometer or pitot tube to measure air velocity at the point of interest.

Q3: What's a typical velocity in HVAC ducts?
A: Typically 600-900 ft/min (10-15 ft/s) in main ducts, lower in branch ducts.

Q4: How do I calculate cross-sectional area?
A: For round ducts: A = π × (diameter/2)². For rectangular ducts: A = width × height.

Q5: Why the 448.83 conversion factor?
A: It converts cubic feet per second to gallons per minute (1 ft³/s = 448.83 GPM).