1. What is FPM Calculation?

FPM (Feet per Minute) calculation converts CFM (Cubic Feet per Minute) to linear velocity by dividing the airflow volume by the cross-sectional area. This is essential for understanding air velocity in ducts and ventilation systems.

2. How Does the Calculator Work?

The calculator uses the FPM formula:

Where:

• \( FPM \) — Feet per Minute (linear velocity)
• \( CFM \) — Cubic Feet per Minute (volumetric flow rate)
• \( Area \) — Cross-sectional Area (square feet)

Explanation: The formula calculates the linear velocity of air by dividing the volumetric flow rate by the area through which the air is moving.

3. Importance of FPM Calculation

Details: FPM calculation is crucial for HVAC system design, duct sizing, ventilation efficiency assessment, and ensuring proper air distribution in buildings and industrial settings.

4. Using the Calculator

Tips: Enter CFM in cubic feet per minute and 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 difference between CFM and FPM?
A: CFM measures volumetric airflow (volume per minute), while FPM measures linear velocity (distance per minute) of the air.

Q2: What are typical FPM values for HVAC systems?
A: Typical duct velocities range from 600-900 FPM for low-pressure systems and 1200-1800 FPM for high-pressure systems.

Q3: How does area affect FPM?
A: For a constant CFM, smaller areas result in higher FPM (faster air velocity), while larger areas result in lower FPM (slower air velocity).

Q4: When is FPM calculation important?
A: FPM is critical for proper duct design, avoiding noise issues, ensuring adequate ventilation, and maintaining system efficiency.

Q5: Can this calculator be used for circular ducts?
A: Yes, but you must first calculate the area using \( Area = \pi \times r^2 \) where r is the radius in feet.