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Industrial Fan Inlet Box

A fan inlet box is necessary for industrial application where space is tight and access to the centrifugal fan or blower is constrained. An industrial inlet box allows for a more efficient 90-degree turn close to the inlet to pull the air from any direction. Otherwise, if you simply allow the ductwork to take a 90-degree turn into the fan inlet, you would see greater entry losses.

We all know that a 90-degree turn is not optimal for fan efficiency. But sometimes you can’t avoid it. There are a number of reasons why you would need to use an inlet box to accommodate a 90-degree turn, including facility size and layout, other equipment and machinery, need for access, and positioning of existing ductwork.

How the Fan Inlet Box Works

Attached to the fan inlet flange, the inlet box includes a mounting plate and support leg. The fan and ductwork should have their own support systems that don’t rely upon the inlet box support leg. Additional optional features of the inbox include bolted cleanout doors and drains.

Choose the most direct route for the air to enter the 90-degree turn into the box. You may also use an inlet box that contains a diverter to evenly distribute the air as it goes into the fan. This minimizes the impact of the quick turn on the performance of the fan. While the fan inlet box can rotate in any direction, some angles may require additional design engineering to steer clear of the fan support structure or other fan accessories.

Impact of the Fan Inlet Box on overall Performance

It’s important to consider the application and need for an inlet box in conjunction with the overall fan design. That’s because although the inlet box is more efficient, there will still be pressure loss due to the quick turn of the air. So you will need to specify or design the fan for the expected inlet pressure with the box, not without.

AirPro application engineers can help you determine all of the above to specify or design the right fan and the right positioning of the necessary fan inlet box. Contact us to start that conversation.

Other Useful Information/Resources

Senior Application Engineer Chet White recently shared how to determine the need for an Inlet Box in your industrial fan application via AirPro’s YouTube Channel. You can watch the 1½ minute video here.