Duct Velocity Calculator

Formula

To calculate the duct velocity:

\[ V = \frac{\text{CFM}}{A} \]

Where:

\(V\) is the Duct Velocity (FPM)
\(CFM\) is the Volumetric Flow Rate (cubic feet per minute)
\(A\) is the Cross-sectional Area (square feet)

What is Duct Velocity?

A duct velocity is defined as the linear speed at which air is moving through the opening of a duct or air vent. This is the average linear speed of the air since normal airflow is not constant across an entire area.

Example Calculation 1

Let's assume the following values:

Flow Rate (\(CFM\)) = 500 cubic feet per minute
Cross-sectional Area (\(A\)) = 2 square feet

Using the formula:

\[ V = \frac{500}{2} = 250 \, \text{FPM} \]

The Duct Velocity is 250 FPM.

Example Calculation 2

Let's assume the following values:

Flow Rate (\(CFM\)) = 800 cubic feet per minute
Cross-sectional Area (\(A\)) = 4 square feet

Using the formula:

\[ V = \frac{800}{4} = 200 \, \text{FPM} \]

The Duct Velocity is 200 FPM.