1. What is Volume Flow Rate of Air?

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

Purpose: It helps HVAC engineers, mechanical designers, and technicians calculate air flow rates for system design and analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Volume flow rate (gallons per minute, GPM)
• \( V \) — Velocity of air (feet per second, ft/s)
• \( A \) — Cross-sectional area (square feet, ft²)
• 448.83 — Conversion factor (ft³/s to GPM)

Explanation: The formula converts the volumetric flow rate from cubic feet per second to gallons per minute equivalent.

3. Importance of Volume Flow Rate Calculation

Details: Accurate flow rate calculations are essential for proper HVAC system design, duct sizing, and ensuring adequate ventilation.

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

Q2: What's a typical air velocity in HVAC systems?
A: Typically 500-1200 ft/min (8.33-20 ft/s) for main ducts, lower for branch ducts.

Q3: How do I measure cross-sectional area?
A: For round ducts: \( \pi \times r² \). For rectangular ducts: width × height.

Q4: Does this account for air density changes?
A: No, this assumes standard air conditions (0.075 lb/ft³ at 70°F and sea level).

Q5: Can I use this for liquid flow calculations?
A: Yes, but the conversion factor remains the same as it's purely volumetric.