The main parts of an industrial fan have specific names that are useful when you are selecting equipment, reading drawings or ordering spare parts. While details vary between axial and centrifugal designs, most ventilation fans used in industrial plants and mines share a similar set of core components.
The heart of any fan is the impeller (also called the rotor or wheel). This is the rotating assembly of blades that imparts energy to the air. In axial fans the impeller looks like a propeller, while in centrifugal fans it resembles a wheel with blades arranged around the circumference. The impeller is mounted on a hub, which is the central boss that connects the blades to the shaft.
The impeller and hub are supported by the shaft, a steel bar that transfers torque from the motor to the impeller. The shaft runs in bearings, which can be ball or roller bearings housed in bearing pedestals or pillow blocks. These bearings carry the radial and axial loads and keep the rotor aligned. On belt-driven fans there are usually two bearing housings mounted on an external pedestal; on smaller direct-drive fans, bearings may be inside the motor.
Surrounding the impeller is the housing or casing. In centrifugal fans this is often called the scroll or volute; it has a spiral shape that collects air thrown from the impeller and directs it towards the outlet. In axial fans the housing may be a cylindrical casing, duct section or fan ring that guides air through the blades. At the inlet side, many fans have a shaped inlet cone or bellmouth to provide smooth, low-loss entry into the impeller.
On belt-driven units there is a drive system consisting of sheaves (pulleys), belts and often a guard. The motor drives the fan shaft via these belts, allowing speed adjustment by changing pulley sizes. In direct-drive fans, the motor is coupled directly to the shaft, either with a flexible coupling or with the impeller mounted on an extended motor shaft.
All of these components are supported on a base frame or fan pedestal. The base frame keeps the motor, bearings and housing in correct alignment and transfers loads to the building or foundation. Flexible connections between the fan and ductwork, as well as vibration isolators under the base, may be used to control vibration and noise.
Many industrial and mining fans also include accessories such as dampers, inlet boxes, outlet cones and silencers. Dampers regulate airflow by changing the opening area. Inlet boxes help distribute air evenly to the fan. Silencers on inlets and outlets are used to reduce noise. For critical fans, additional instrumentation such as vibration sensors, bearing temperature probes and differential pressure gauges may be installed.
In summary, the main parts of an industrial fan are the impeller and hub, shaft and bearings, housing or scroll with inlet and outlet sections, drive system (belts or coupling), electric motor, base frame and optional accessories like dampers and silencers. Knowing these component names makes it easier to specify, operate and maintain industrial and mining ventilation fans.
