1. What is Air Volume Flow Rate?

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

Purpose: It helps HVAC engineers, mechanical designers, and technicians calculate air flow for ventilation systems, ducts, and piping.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Volumetric flow rate (GPM)
• \( V \) — Velocity of air (ft/s)
• \( A \) — Cross-sectional area (ft²)
• 448.83 — Conversion factor (ft³/s to GPM)

Explanation: The formula converts the product of velocity and area (which gives ft³/s) to gallons per minute.

3. Importance of Air Flow Calculation

Details: Proper air flow calculation ensures efficient system design, adequate ventilation, and proper equipment sizing.

4. Using the Calculator

Tips: Enter the air velocity in feet per second and the cross-sectional area in square feet. 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: What's a typical air velocity in ducts?
A: For HVAC systems, typical velocities range from 800-1200 ft/min (13.3-20 ft/s).

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

Q4: Can I use this for liquid flow?
A: Yes, but remove the 448.83 factor as liquid flow is already in GPM.

Q5: What affects the conversion factor?
A: The factor combines unit conversions (7.4805 gallons/ft³ × 60 s/min).