Arrangement 7 Fan Considerations
The Arrangement 7 fan is center-hung with the impeller mounted between two bearings and an integral inlet box to direct the air into the fan from above or from the side. This fan arrangement is optimal for use when your application requires large fan impellers and/or when you want to go the extra mile for increased fan life.
This arrangement is a higher priced option than some of its counterparts, such as a direct drive arrangement 8. While the larger fan base and additional bearing mount add to the fan’s cost of construction, the longer fan life may reduce your overall expenses.
How the Center-Hung Fan Extends Fan Life
It’s all about the bearings. The Arrangement 7 center-hung fan helps extend fan life by protecting the bearings. Because the wheel is larger, having the bearings on both sides helps balance the load of the fan. If the bearings were all on the same side, the load would be cantilevered, supported only on that side. That would cause strain and continuous wear on the bearings, which means they would fail faster. With a center-hung load, the bearings last longer, extending fan life.
Horsepower and Motor Drive
Because the Arrangement 7 fan can use either a belt drive or a direct drive motor configuration, it is worth mentioning here. We often specify direct-drive fans in larger applications with higher horsepower motors. But speed variations and other wear-and-tear considerations may suggest going with a belt drive in some instances. If you’re on the fence, it’s probably a great time to contact an application engineer to ensure that you select the optimal combination of motor drive and fan arrangement for your application.
Hear it from the Application Engineer
Senior Application Engineer Chet White provides an overview demo in this 35-second video.
To see more on fan arrangements and motor drives, take a look at these additional posts, videos, and pages:
- Getting into Gear: Motor Speed for Belt Drive Fans
- Industrial Fans: Direct Drive or Belt Drive?
- Centrifugal Fans & Blowers / Fan Arrangements