How do you calculate the flow rate of air in CFM (Cubic Feet per Minute)?

How do you calculate the flow rate of air in CFM (Cubic Feet per Minute)?

• A. CFM = Area + Velocity
• B. CFM = Area × Speed
• C. CFM = Area × Velocity
• D. CFM = Area / Velocity

Answer: (C)

To calculate the flow rate of air in cubic feet per minute (CFM), the correct formula is CFM = Area × Velocity. In this context, "Area" refers to the cross-sectional area through which the air is flowing, typically measured in square feet. "Velocity" indicates how fast the air is moving through that area, usually expressed in feet per minute. When you multiply the area by the velocity, you effectively determine the volume of air passing through that area over a specified period—hence the result is in cubic feet per minute. This assessment of air flow is critical in HVAC applications to ensure the proper ventilation and efficiency of heating and cooling systems. This relationship is fundamental because it highlights how both the size of the duct and the speed of the air combine to dictate the overall flow rate, which is essential for system design and performance calculations.

To calculate the flow rate of air in cubic feet per minute (CFM), the correct formula is CFM = Area × Velocity. In this context, "Area" refers to the cross-sectional area through which the air is flowing, typically measured in square feet. "Velocity" indicates how fast the air is moving through that area, usually expressed in feet per minute.

When you multiply the area by the velocity, you effectively determine the volume of air passing through that area over a specified period—hence the result is in cubic feet per minute. This assessment of air flow is critical in HVAC applications to ensure the proper ventilation and efficiency of heating and cooling systems.

This relationship is fundamental because it highlights how both the size of the duct and the speed of the air combine to dictate the overall flow rate, which is essential for system design and performance calculations.