1. What is an Air Flow Through Pipe Calculator?

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

Purpose: It helps HVAC engineers, mechanical designers, 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 of pipe (ft²)
• \( 448.83 \) — Conversion factor for air density adjustment

Explanation: The formula converts air velocity and pipe area to an equivalent liquid flow rate for easier comparison with hydraulic systems.

3. Importance of Air Flow Calculation

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

4. Using the Calculator

Tips: Enter the air velocity in feet per second and the pipe's cross-sectional area in square feet. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the result in GPM when calculating air flow?
A: GPM (gallons per minute) provides a familiar unit for comparison with liquid flow rates in combined systems.

Q2: 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.

Q3: How do I calculate pipe cross-sectional area?
A: For round pipes: \( A = \pi \times (D/2)^2 \) where D is diameter in feet.

Q4: Does this account for pressure and temperature?
A: The conversion factor assumes standard conditions (68°F, 14.7 psi). For other conditions, additional corrections are needed.

Q5: When would I use this calculation?
A: When designing ventilation systems, sizing ducts, or troubleshooting airflow issues.