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How to properly design an industrial ducting network - Duct velocities

Feb 14

How to properly design an industrial ducting network - Duct velocities

Your top priority is to make sure your system works efficiently at the lowest price, no matter whether you're installing or remodeling an existing ducting system. Because ducting systems can be very expensive to install and maintain, it is important that you only buy what you require. Columbus Airduct cleaning can assist you in making accurate calculations using your dust velocity.

Determining dust Velocity

The type of material to be transported inside the duct determines the velocity. The diameter and volume of the duct determine the airflow, which is measured as cubic feet per minute (cfm). In order to prevent particles from dropping from the airstream or settling inside the duct, the minimum design velocity must be met. An unusually high velocity, on the other hand, can cause rapid abrasion in the duct and be a waste of energy.

The following equation shows the relationship between Q, duct velocity (v), airflow (Q), and the diameter of the duct within a particular section of a system of ducting:

Q = A * v, where A = p * d2 / 4 or,


Q = (p * d2 / 4) * v

This equation allows you to calculate the Airflow (Q) needed for a given velocity (v), and duct dimension (d). The 9-inch diameter (0.75 ft. ) duct would require 4000 feet per second (fpm) of duct velocity. This would determine the required amount of airflow.

Q = (p * (0.75 ft.)2 / 4) * (4000 ft./min) = 562.5 cfm

This equation will determine the velocity of a system given an airflow (Q) through the section of the duct having a diameter (d).

v = (4 * Q) / (p * d2)

For example, 600 cfm fan will result in air speed of 6 inches. A duct of approximately 0.5 feet in diameter would be:

v = (4 * 600) / (p * (0.5)2) = 3056 fpm

This equation will help you determine the required duct diameter (d), to provide a velocity for a fan providing a particular airflow (Q).

d = (4 * Q) / (p * v)

For example, the duct size required for 4000fpm velocity in an airflow system of 1000cfm would be:

d = (4 * 1000) / (p * 4000) = 0.564 feet or 6.77 inches

For the 4000 fpm velocity to be achieved, you need to round down to a 6-inch diameter standard duct size.

By accurately calculating dust velocity, you can not only save money but also ensure that your system is operating at its maximum capacity. This will help you to avoid the frustration and expense of running an inefficient or inefficient system.


Columbus Airduct Cleaning

Columbus, OH

(740) 291 0950