1. What is an Air Flow Volume Calculator?

Definition: This calculator estimates the air flow volume in Gallons per Minute (GPM) equivalent based on air velocity and duct cross-sectional area.

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Air flow volume (Gallons per Minute)
• \( V \) — Velocity (feet per second)
• \( A \) — Duct cross-sectional area (square feet)
• 448.83 — Conversion factor (ft³/s to GPM)

Explanation: The velocity is multiplied by duct area to get cubic feet per second, then converted to GPM.

3. Importance of Air Flow Calculation

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

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Why convert to GPM when measuring air flow?
A: GPM equivalent is useful for comparing air flow to liquid flow rates in combined systems.

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

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

Q4: What affects the conversion factor?
A: The factor 448.83 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, but omit the conversion factor (use Q = V × A × 60 for GPM from ft/s and ft²).