1. What is the FPM to CFM Conversion?

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( CFM \) — Cubic feet per minute (ft³/min)
• \( FPM \) — Feet per minute (ft/min)
• \( A \) — Cross-sectional area (sq ft)

Explanation: The formula multiplies the air velocity by the duct area to determine the volumetric flow rate of air through the duct.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is crucial for proper HVAC system design, ensuring adequate air flow for ventilation, heating, and cooling requirements in buildings.

4. Using the Calculator

Tips: Enter FPM in feet per minute and cross-sectional area in square feet. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between FPM and CFM?
A: FPM measures air velocity (speed), while CFM measures volumetric flow rate (quantity of air moving through the duct).

Q2: How do I measure duct area for square ducts?
A: For square ducts, measure the width and height in feet, then multiply them to get the cross-sectional area in square feet.

Q3: What are typical FPM values for HVAC systems?
A: Typical values range from 600-1200 FPM for main ducts and 400-800 FPM for branch ducts, depending on the application.

Q4: Can this formula be used for rectangular ducts?
A: Yes, the same formula applies to rectangular ducts. Calculate the area by multiplying width by height.

Q5: Why is CFM important in HVAC design?
A: CFM determines the amount of air being delivered to spaces, affecting temperature control, ventilation effectiveness, and overall system performance.