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CFM Calculation Formula:
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The FPM to CFM conversion calculates the volumetric flow rate (cubic feet per minute) from the velocity (feet per minute) and cross-sectional area. This is essential in HVAC systems, ventilation design, and airflow measurements.
The calculator uses the simple formula:
Where:
Explanation: The formula converts linear velocity to volumetric flow by multiplying by the cross-sectional area through which the air is moving.
Details: Accurate CFM calculation is crucial for proper ventilation system design, ensuring adequate air exchange rates, maintaining indoor air quality, and optimizing energy efficiency in HVAC systems.
Tips: Enter FPM (velocity in feet per minute) and Area (cross-sectional area in square feet). Both values must be positive numbers for accurate calculation.
Q1: What's the difference between FPM and CFM?
A: FPM measures velocity (how fast air is moving), while CFM measures volumetric flow (how much air is moving through a given area).
Q2: When would I need to convert FPM to CFM?
A: This conversion is essential when designing ventilation systems, calculating air changes per hour, or determining the capacity requirements for fans and blowers.
Q3: What are typical FPM values in ventilation systems?
A: Typical duct velocities range from 600-2000 FPM for supply air and 500-1500 FPM for return air, depending on the application and noise considerations.
Q4: How do I measure the area for CFM calculation?
A: Measure the cross-sectional area of the duct or opening. For rectangular ducts: width × height. For circular ducts: π × (radius)².
Q5: Can this formula be used for liquids as well?
A: Yes, the same principle applies to any fluid flow calculation where you need to convert velocity to volumetric flow rate.