1. What is CFM?

CFM (Cubic Feet Per Minute) is a measurement of airflow volume, indicating how many cubic feet of air pass by a stationary point in one minute. It's commonly used in HVAC, ventilation, and aerodynamics.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( V \) — Velocity in feet per minute (ft/min)
• \( A \) — Area in square feet (ft²)

Explanation: The calculation multiplies the velocity of air by the cross-sectional area through which it's flowing to determine the volumetric flow rate.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is essential for proper HVAC system design, ventilation requirements, industrial process control, and ensuring adequate air quality in enclosed spaces.

4. Using the Calculator

Tips: Enter velocity in ft/min and area in ft². Both values must be positive numbers. The calculator will compute the CFM (cubic feet per minute).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between CFM and ACFM?
A: CFM is cubic feet per minute at standard conditions, while ACFM (Actual Cubic Feet Per Minute) accounts for actual temperature and pressure conditions.

Q2: How do I measure velocity for CFM calculation?
A: Velocity is typically measured using an anemometer at various points across the duct or opening, then averaged.

Q3: What are typical CFM values for residential HVAC?
A: Residential systems typically range from 400-2000 CFM depending on the size of the home and system capacity.

Q4: Can I use this for circular ducts?
A: Yes, but you must calculate the area using πr² where r is the radius of the duct in feet.

Q5: How does CFM relate to air changes per hour?
A: Air changes per hour = (CFM × 60) / room volume (in cubic feet). This measures how many times the air in a space is completely replaced.