Centrifugal Fan Arrangements
Industry standards that define how the motor mounts to & drives the fan.
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Centrifugal Fan Arrangements
Centrifugal fan arrangements are standardized configurations that define how the motor is mounted and how it drives the fan. Based on Air Movement and Control Association (AMCA) standards, arrangements help specify key details like the drive method, bearing location, and overall layout, so performance and serviceability are clear from the start.
Most arrangements fall into two main categories: belt-drive and direct-drive. Within each category, there are several common options, and the right choice depends on your application requirements, operating conditions, and maintenance preferences.
AirPro Fan Arrangements Types
Belt-Drive
The motor shaft drives the fan shaft through sheaves/pulleys and v-belts. Belt-driven fans provide speed and flexibility because they enable the fan operating speed to differ from the motor synchronous speed. There is power transmission loss associated with belt-driven fans that should be considered when selecting the motor horsepower.
Arrangement 1 – The fan and motor mount separately to a unitary base.
Arrangement 3 – Involves a bearing on either side of the fan wheel, supported by separate pedestals or a support structure integrated with the fan housing.
Arrangement 9 – The motor mounts to the side of the fan pedestal with no unitary base required.
Direct-Drive
The fan operates at the synchronous speed of the motor, as the motor drives the fan directly, either with the fan wheel mounted on the motor shaft or with the fan shaft directly coupled to the motor shaft. Direct-driven fans experience negligible power transmission losses.
Arrangement 3 – Involves a bearing on either side of the fan wheel, supported by separate pedestals or a support structure integrated with the fan housing.
Arrangement 4 – A low-cost arrangement, the fan wheel mounts directly on the motor shaft.
Arrangement 4V / Top Mount – The wheel also mounts to the motor shaft, but in a vertical position.
Arrangement 7 – Involves a bearing on either side of the fan wheel and supported by the fan housing.
Arrangement 8 – The fan shaft couples directly to the motor shaft with a flexible coupling.
Additional Resources
Learn more about how to choose between belt-drive and direct-drive fans on our blog:
Industrial Fans: Belt-Drive or Direct-Drive?
