1. What is Air Flow Calculation in Pipe?

Definition: This calculator estimates the volumetric flow rate of air in a pipe, expressed in gallons per minute (GPM) equivalent.

Purpose: It helps engineers and HVAC professionals 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 of pipe (ft²)
• 448.83 — Conversion factor (ft³/s to GPM)

Explanation: The velocity is multiplied by the pipe's cross-sectional area to get flow in ft³/s, then converted to GPM.

3. Importance of Air Flow Calculation

Details: Proper air flow calculation ensures efficient system operation, proper ventilation, and energy optimization in HVAC systems.

4. Using the Calculator

Tips: Enter the air velocity in ft/s and the pipe's cross-sectional area in ft². All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why convert to GPM when measuring air flow?
A: GPM provides a familiar unit for comparison with liquid flow rates, though CFM is also commonly used for air.

Q2: How do I calculate pipe cross-sectional area?
A: For circular pipes: \( A = \pi \times (D/2)^2 \) where D is diameter in feet.

Q3: What's a typical air velocity in HVAC ducts?
A: Typically 800-1200 ft/min (13.3-20 ft/s) for main ducts, lower for branch ducts.

Q4: Does this account for pressure and temperature?
A: This is a simplified calculation. For precise work, consider using the ideal gas law for corrections.

Q5: Can I use this for liquid flow calculations?
A: Yes, but the conversion factor would be different (7.48052 for actual GPM calculation).