1. What is an Air Volume Flow Rate Calculator?

Definition: This calculator determines the air volume flow rate in gallons per minute (GPM) equivalent based on velocity and cross-sectional area.

Purpose: It helps HVAC professionals and engineers calculate air flow rates for system design and analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Air volume flow rate (GPM equivalent)
• \( V \) — Velocity of air (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 cubic feet per second, then converted to gallons per minute.

3. Importance of Air Flow Rate Calculation

Details: Proper air flow rate calculation ensures efficient HVAC system operation, proper ventilation, and energy efficiency.

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 use GPM equivalent for air flow?
A: GPM equivalent allows comparison between liquid and air flow rates in systems that handle both.

Q2: What's a typical air velocity in ducts?
A: Typically 600-900 ft/min (10-15 ft/s) for main ducts, 400-600 ft/min for branch ducts.

Q3: How do I measure duct cross-sectional area?
A: For round ducts: \( \pi \times r^2 \). For rectangular ducts: width × height.

Q4: Why the 448.83 conversion factor?
A: It converts cubic feet per second to gallons per minute (1 ft³/s = 448.83 GPM).

Q5: Can I use this for liquid flow calculations?
A: Yes, the same formula applies for liquid flow rates when using consistent units.