Multiple Drive Arrangements of a Centrifugal Fan

Multiple Drive Arrangements of a Centrifugal Fan

Neel Rao Writes on Centrifugal Fan & Centrifugal blower technologies for Reitz India

When a centrifugal fan is to be installed for any industrial process, the airflow requirement has to be determined before considering different fan arrangements to accomplish the desired performance. Fans typically work better when they have optimal size that fits ideally in the designated area, placed in the right location to withstand the operational conditions and have proper drive method to modulate the speed. When considering

different centrifugal fan arrangements, the motor will have various placement settings with respect to the drive side of the fan. The fan can use different drive methods, depending on whether the motor is independent of the fan as in belt drive arrangement or motor connected directly to the fan axle or shaft as in direct drive configuration.

Here are some typical fan arrangements defined for single width single

inlet and double width double inlet centrifugal fans.

Arrangement 1 : SWSI (Single Width Single Inlet) • This is for belt or direct drive connection. The impeller is overhung on the motor shaft and two bearings mounted on pedestal base. • Alternative arrangement: Bearings mounted on independent pedestal, with or without inlet box.

Arrangement 2 : SWSI (Single Width Single Inlet) • This type of arrangement is similar to the above except that the impeller is directly overhung to the shaft with bearings and a coupling mounted on bracket supported by fan housing or casing.

Arrangement 3 : SWSI (Single Width Single Inlet) & DWDI (Double Width Double Inlet)

• This is for belt or direct drive. Impeller is mounted on shaft between bearings supported by the fan casing.

• Alternative: Bearings mounted on independent pedestal with inlet box.

Arrangement 4 : SWSI (Single Width Single Inlet) • It is direct drive arrangement where the fan wheel is connected direct to the motor shaft. No requirement for pulleys, belt drives or additional shaft bearings.

• Prime mover is mounted to the full length pedestal base.

• Because of close coupling of the motor, centrifugal fans in Arrangement 4 have a limitation of usage under high temperatures.

• To obtain optimal performance, it is common to add air volume control devices like dampers, vanes and VFDs.

Arrangement 7 : SWSI (Single Width Single Inlet) & DWDI (Double Width Double Inlet) • This is similar to Arrangement 3, except that it's motor base is attached to the drive side. • It is a direct drive arrangement through flexible coupling, but with a base for prime mover.

Arrangement 8 : SWSI (Single Width Single Inlet) • Directly connected to the fan shaft and bearing combination through coupling.

• Same as Arrangement 1, but with a base for prime mover.

• Since the motor is away from the shaft, the arrangement can be used for higher air stream temperatures.

Arrangement 9 : SWSI (Single Width Single Inlet) • For belt drive, similar as Arrangement 1, except that motor is mounted on the fan, either on the left or right side of the bearing pedestal, rather than on the floor. • Limitation on the airstream temperatures because of close proximity of motor to the fan scroll.

Arrangement 10 : SWSI (Single Width Single Inlet) • Same as Arrangement 9 for Single Width Single inlet, but with motor mounted inside bearing pedestal. • Since the motor is fitted under bearing pedestal, the motor gets moderate protection from outside weather conditions. However, the arrangement allows a restriction on motor frame size. • The proximity of motor to the fan scroll allows a limitation on airstream

temperatures. To avoid the effects of high operating temperatures on fan motor, an insulating panel can be used separating them.

About REITZINDIA Reitz India has set a benchmark to deliver high quality fans for heavy duty industries which can work at precise operating conditions like high temperatures and pressures. Reitz offer idealistic Centrifugal Fan and Centrifugal blower design that can be used in all large scale process industries like cement, iron & steel, power plants, fertilizers/ chemicals and more.

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