What is the velocity in a 25" x 8" duct section with a flow of 1450 cfm?

What is the velocity in a 25" x 8" duct section with a flow of 1450 cfm?

• A. 850 fpm
• B. 950 fpm
• C. 1050 fpm
• D. 1150 fpm

Answer: (C)

To determine the velocity of air in a duct, you can use the formula: \[ \text{Velocity} = \frac{\text{Flow Rate (CFM)}}{\text{Area (sq ft)}} \] First, you need to calculate the area of the duct section. The given dimensions of the duct are 25 inches by 8 inches. To convert these dimensions into feet, you need to divide by 12: - Height: \( \frac{25 \text{ inches}}{12} = 2.0833 \text{ feet} \) - Width: \( \frac{8 \text{ inches}}{12} = 0.6667 \text{ feet} \) Next, you can calculate the area of the duct in square feet: \[ \text{Area} = \text{Height} \times \text{Width} = 2.0833 \text{ ft} \times 0.6667 \text{ ft} \approx 1.3889 \text{ sq ft} \] Now that we have the area, we can substitute this and the flow rate into the velocity formula. Given the flow rate is 1450 CFM

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

[

\text{Velocity} = \frac{\text{Flow Rate (CFM)}}{\text{Area (sq ft)}}

]

First, you need to calculate the area of the duct section. The given dimensions of the duct are 25 inches by 8 inches. To convert these dimensions into feet, you need to divide by 12:

• Height: ( \frac{25 \text{ inches}}{12} = 2.0833 \text{ feet} )

• Width: ( \frac{8 \text{ inches}}{12} = 0.6667 \text{ feet} )

Next, you can calculate the area of the duct in square feet:

[

\text{Area} = \text{Height} \times \text{Width} = 2.0833 \text{ ft} \times 0.6667 \text{ ft} \approx 1.3889 \text{ sq ft}

]

Now that we have the area, we can substitute this and the flow rate into the velocity formula. Given the flow rate is 1450 CFM