1. What is an Air Flow Rate Calculator?

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

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

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 for air density adjustment

Explanation: The velocity is multiplied by the area to get the basic flow rate, then adjusted for standard air density conditions.

3. Importance of Air Flow Rate Calculation

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

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 is there a conversion factor of 448.83?
A: This factor adjusts for standard air density (0.075 lb/ft³) and converts cubic feet per second to gallons per minute.

Q2: What's a typical air velocity in HVAC systems?
A: Typically 500-1200 ft/min (8-20 ft/s) in ducts, but varies by application.

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

Q4: Can I use this for other gases?
A: No, this calculator is specifically calibrated for standard air density. Other gases require different conversion factors.

Q5: How accurate is this calculation?
A: It provides a good estimate for standard conditions. For precise calculations, consider temperature and pressure variations.