The formula to calculate Impeller Width (W) is:

\[ W = \frac{550 \cdot Q}{\phi \cdot N \cdot D^2} \]

Where:

• \(W\) is the width of the impeller (in.).
• \(Q\) is the airflow (cfm).
• \(N\) is the speed of the impeller (rpm).
• \(D\) is the diameter of the impeller (in.).
• \(\phi\) is the flow coefficient (0.01 to 0.80).