1. What is CFM to FPM Conversion?

CFM (cubic feet per minute) to FPM (feet per minute) conversion calculates the air velocity in a duct based on the airflow volume and duct cross-sectional area. This is essential for HVAC system design and analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( FPM \) — Feet per minute (air velocity)
• \( CFM \) — Cubic feet per minute (airflow volume)
• \( Duct\ Area \) — Cross-sectional area of the duct in square feet

Explanation: The formula converts volumetric airflow (CFM) to linear air velocity (FPM) by dividing the airflow by the duct cross-sectional area.

3. Importance of FPM Calculation

Details: Proper air velocity calculation is crucial for HVAC system efficiency, ensuring adequate air distribution, preventing noise issues, and maintaining proper system performance.

4. Using the Calculator

Tips: Enter CFM value in cubic feet per minute and duct area in square feet. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical FPM range for HVAC systems?
A: Residential systems typically operate at 600-900 FPM, while commercial systems may operate at 1000-2000 FPM depending on the application.

Q2: How do I calculate duct area for rectangular ducts?
A: For rectangular ducts, area = width × height (in feet). Convert inches to feet by dividing by 12.

Q3: How do I calculate duct area for round ducts?
A: For round ducts, area = π × (diameter/2)². Remember to use consistent units (feet for diameter).

Q4: Why is air velocity important in HVAC design?
A: Proper air velocity ensures efficient heat transfer, minimizes energy consumption, reduces noise, and prevents moisture issues in ducts.

Q5: What happens if air velocity is too high or too low?
A: Too high velocity causes noise and increased pressure drop. Too low velocity can lead to poor air distribution and potential moisture problems.