How is CFM calculated for air moving through a duct measuring 16" x 22" at a velocity of 1011 FPM?

To determine the cubic feet per minute (CFM) of air moving through a duct, you calculate the cross-sectional area of the duct and then multiply that area by the velocity of the air flowing through it.

In this case, the dimensions of the duct are 16 inches by 22 inches. To find the area in square feet, you first convert inches to feet:

• The width is 16 inches, which is 16 ÷ 12 = 1.3333 feet.

• The height is 22 inches, which is 22 ÷ 12 = 1.8333 feet.

Next, you calculate the area:

Area = Width x Height = 1.3333 feet x 1.8333 feet = approximately 2.4444 square feet.

Now, you multiply this area by the velocity of air, which is given as 1011 feet per minute (FPM):

CFM = Area (sq. ft.) x Velocity (FPM) = 2.4444 sq. ft. x 1011 FPM.

This formula shows how the CFM value directly relates to both the area and the air velocity.

The correct choice, which states to multiply the area in square