Using the formula for CFM, if a duct measures 40 inches by 22 inches and the air velocity is 1,500 fpm, what is the CFM?

Using the formula for CFM, if a duct measures 40 inches by 22 inches and the air velocity is 1,500 fpm, what is the CFM?

• A. 8,000 CFM
• B. 9,167 CFM
• C. 10,500 CFM
• D. 11,000 CFM

Answer: (B)

To determine the CFM (Cubic Feet per Minute) in this scenario, you can use the formula: \[ \text{CFM} = \text{Area (sq ft)} \times \text{Velocity (fpm)} \] First, you need to calculate the area of the duct in square feet. The duct dimensions are given in inches, so you should first convert these dimensions to feet: - Width: 40 inches = \( \frac{40}{12} = \frac{10}{3} \) feet - Height: 22 inches = \( \frac{22}{12} = \frac{11}{6} \) feet Now, you can calculate the area: \[ \text{Area} = \text{Width} \times \text{Height} = \left( \frac{10}{3} \right) \times \left( \frac{11}{6} \right) = \frac{110}{18} \text{ sq ft} = \frac{55}{9} \text{ sq ft} \approx 6.11 \text{ sq ft} \] With the area calculated, you can now use the velocity provided, which

To determine the CFM (Cubic Feet per Minute) in this scenario, you can use the formula:

[ \text{CFM} = \text{Area (sq ft)} \times \text{Velocity (fpm)} ]

First, you need to calculate the area of the duct in square feet. The duct dimensions are given in inches, so you should first convert these dimensions to feet:

• Width: 40 inches = ( \frac{40}{12} = \frac{10}{3} ) feet

• Height: 22 inches = ( \frac{22}{12} = \frac{11}{6} ) feet

Now, you can calculate the area:

[

\text{Area} = \text{Width} \times \text{Height} = \left( \frac{10}{3} \right) \times \left( \frac{11}{6} \right) = \frac{110}{18} \text{ sq ft} = \frac{55}{9} \text{ sq ft} \approx 6.11 \text{ sq ft}

]

With the area calculated, you can now use the velocity provided, which