If the air velocity in a duct is 500 fpm and the duct dimensions are 10" x 20", what is the calculated CFM?

To find the airflow in Cubic Feet per Minute (CFM) given the air velocity and duct dimensions, you can use the formula:

[ CFM = \text{Area} \times \text{Velocity} ]

First, you need to calculate the cross-sectional area of the duct. The duct dimensions given are 10 inches by 20 inches. Convert these dimensions from inches to feet:

• 10 inches = 10/12 feet = 0.833 feet

• 20 inches = 20/12 feet = 1.667 feet

Now, calculate the area:

[ \text{Area} = \text{Width} \times \text{Height} = 0.833 , \text{ft} \times 1.667 , \text{ft} ]

Calculating that gives:

[ \text{Area} = 1.388 , \text{ft}^2 ]

Next, use the air velocity which is given as 500 feet per minute (fpm) to calculate the CFM:

[ CFM = \text{Area} \times \text{Velocity} = 1.388 , \text{ft}^2 \