Page 106 - Root Cause Failure Analysis

FANS, BLOWERS, AND FLUIDIZERS

Technically, fans and blowers are separate types of devices that have a similar func-
tion. However, the terms often are used interchangeably to mean any device that
delivers a quantity of air or gas at a desired pressure. Differences between these two
devices are their rotating elements and discharge-pressure capabilities. Fluidizers are
identical to single-stage, screw-type compressors or blowers.

CENTRIFUGAL FANS
Centrifugal fans are one of the most common machines used in industry. They utilize
a rotating element with blades, vanes, or propellers to extract or deliver a specific vol-
ume of air or gas. The rotating element is mounted on a rotating shaft that must pro-
vide the energy required to overcome inertia, friction, and other factors that restrict or
resist air or gas flow in the application. These generally are low-pressure machines
designed to overcome friction and either suction or discharge-system pressure.

Configuration

Centrifugal fans can be. classified by the type of rotating element or wheel that is used
to move the air or gas. The major classifications are propeller and axial. Axial fans can
be further differentiated by blade configuration.

Propeller
This type of fan consists of a propeller, or paddle-wheel, mounted on a rotating shaft
within a ring, panel, or cage. The most widely used propeller fans perform light- or
medium-duty functions, such as in ventilation units where air can be moved in any
direction. These fans commonly are used in wall mountings to inject air into or

97