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CFM Equation:
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The CFM (Cubic Feet per Minute) equation calculates airflow volume by multiplying the cross-sectional area by the air velocity and dividing by 144 to convert square inches to square feet. It's essential for HVAC system design and ventilation calculations.
The calculator uses the CFM equation:
Where:
Explanation: The equation converts area from square inches to square feet and multiplies by velocity to determine the volume of air moving through a space per minute.
Details: Accurate CFM calculation is crucial for proper HVAC system design, ensuring adequate ventilation, maintaining indoor air quality, and optimizing energy efficiency in building systems.
Tips: Enter area in square inches and velocity in feet per minute. Both values must be positive numbers for accurate calculation.
Q1: Why divide by 144 in the CFM formula?
A: The division by 144 converts area from square inches to square feet, since 1 square foot equals 144 square inches, ensuring consistent units in the calculation.
Q2: What are typical CFM values for residential HVAC?
A: Typical residential systems range from 400-2000 CFM depending on the size of the home and specific ventilation requirements.
Q3: How is area measured for CFM calculations?
A: Area is measured as the cross-sectional area through which air is flowing, typically calculated as width × height for rectangular ducts or πr² for circular ducts.
Q4: What instruments measure air velocity?
A: Anemometers, pitot tubes, and hot-wire anemometers are commonly used to measure air velocity in HVAC applications.
Q5: Can CFM be converted to other airflow units?
A: Yes, CFM can be converted to cubic meters per second (m³/s) by multiplying by 0.0004719, or to liters per second (L/s) by multiplying by 0.4719.