What is the velocity of 1400 CFM of air in feet per minute in a duct measuring 12" x 30"?

To find the velocity of air in a duct, you can use the formula:

[ \text{Velocity (FPM)} = \frac{\text{CFM} \times 144}{\text{Area (sq. in.)}} ]

First, we need to calculate the area of the duct in square inches. The duct dimensions are 12 inches and 30 inches, so:

[ \text{Area} = \text{Width} \times \text{Height} = 12 , \text{in} \times 30 , \text{in} = 360 , \text{sq. in.} ]

Next, convert the airflow from cubic feet per minute (CFM) to cubic inches per minute. Since there are 1,728 cubic inches in a cubic foot (12 inches x 12 inches x 12 inches):

[ 1400 , \text{CFM} = 1400 \times 1728 , \text{cubic inches per minute} ]

Now, we can substitute the values into the velocity formula:

1. CFM is already given as 1400.

2. The area we calculated is 360 square inches.