Imagine you have a regular light switch and a dimmer switch for a light bulb. A regular switch only has “on” and “off,” while a dimmer lets you control how bright the light is. A VFD is like a dimmer switch for a fan motor – it lets you control the fan’s speed. Changing the fan’s speed with a VFD also changes the motor’s horsepower (its ability to do work) and torque (its turning power). Let’s break it down for centrifugal fans (the most common type).
Fan Knowledge
Bearings are crucial for industrial centrifugal fans, supporting the fan shaft and minimizing friction. Proper bearing selection ensures efficiency, longevity, and reliability in high-performance ventilation systems.
The Role of Bearings in Centrifugal Fans
Bearings hold the shaft in place as a fan rotates. In overhung applications, they are placed in close proximity to the wheel, placed together on the drive side of the fan housing, supporting the wheel mounted on the end of the shaft. In center-hung applications, one bearing is placed on the drive side and the other is placed on the inlet side of the fan as the wheel rotates on the shaft between the bearings.
New for 2025 is a regular feature on basic fan knowledge from Chet White, our Sales and Marketing Manager. This month we look at the various types of impellers for centrifugal fans.
Radial
Centrifugal impellers come in various styles, each with unique characteristics and applications. The radial bladed paddle wheel, the oldest style, features radial blades extending outward from the hub like wheel spokes. As the paddles rotate, they expel air and materials through the outlet. While the least efficient, this design excels at handling debris and abrasive materials. Its lack of a leading edge prevents damage, and the radial profile minimizes buildup, reducing vibration and extending the life of general-purpose fans.