More about Fans

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Fans move gas or particulate from one place to another. They can serve as exhaust fans to purge a certain gas from an area, or they can carry a gas (such as cool air) into an existing system. In some cases, they are simply used to send a gas to another location inside an operation. The process of using fans to remove a lighter particulate from another heavier substance is called winnowing.

In filtration and cleaning systems, fans help remove dust from the air or from a surface by forcing it through an air filter. In furnaces and similar firing applications, they may feed air to fuel the operation. Cooling and ventilation fans can be used to regulate the atmospheric conditions for human comfort or to keep mechanical systems and storage areas at a certain temperature. For the most part, fans work on automatic controls, driven by internal/external sensors or timers. Some fans, such as home ceiling and room fans, are manually controlled, but most industrial blowers run automatically.

Fans operate by three different methods, and are classified as either axial, centrifugal or tangential fans. An axial fan, with which we are perhaps most familiar, sends air directly across its axis. A typical household electric fan is a perfect example of an axial fan. Its blades draw and propel air parallel to their central shaft. Centrifugal fans send air and gas in a direction perpendicular to their intake. A centrifugal fan operates within a casing so that the air is forced down a single shaft in one direction. Good examples include engine driven blowers and pump fans. Tangential fans also expel air perpendicular to the central shaft, but they also draw it in perpendicularly. In other words, it is the edge of the fan which pulls in the air; its operation resembles that of a roller, collecting material along one edge and propelling it in another direction. Normally, tangential fan exhausts are 90 or 180 degrees from the intake. These fans are used in certain cooling and flow control applications.

Industries that use fans include food processing, manufacturing, molding and heavy industry. They have obvious applications in clean rooms (filtration) and chemical processing, and are essential to air pollution control systems. In addition to providing heat regulation for most machines and electronics, they have an integral role in drying and heat shrinking operations. Their uses vary widely, but virtually every industry requires some type of fan.