fan arrangements

Fan Arrangements

Centrifugal Fan Arrangements

Centrifugal fan arrangements are industry standards that define how the motor mounts to and drives the fan. Based on Air Movement and Control Association (AMCA) standards, these specifications provide the operating capabilities, drive configurations and placement of the bearings.

There are two main categories of fan arrangements: Belt-Drive and Direct-Drive. There are multiple belt drive and direct-drive options available. Selection, of course, will depend on your application.

To learn more about how to choose between belt-drive and direct-drive fans, check out our blog, Industrial Fans: Belt-Drive or Direct-Drive?

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 9 – The motor mounts to the side of the fan pedestal with no unitary base required.
  • Arrangement 2 Plug – The fan mounts to an enclosure with the wheel extending into the enclosure.
  • 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.

Learn More

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 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.
  • Arrangement 2 Plug – The fan mounts to an enclosure with the wheel extending into the enclosure.
  • 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.

Learn More