At AirPro, one of the most common questions we get from customers is: How can I reduce static pressure in my system?
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AirPro Fan & Blower’s P Series radial pressure blower wheels—A, B, C, and D—feature a distinct impeller design optimized for specific performance needs.
Continue reading →Fan inlet boxes help manage airflow into the fan, reduce turbulence, and can support transitions or directional changes in ductwork. Why use an inlet box on a fan?
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Imagine you have a regular light switch and a dimmer switch for a light bulb. A regular switch only has “on” and “off,” while a dimmer lets you control how bright the light is. A VFD is like a dimmer switch for a fan motor – it lets you control the fan’s speed. Changing the fan’s speed with a VFD also changes the motor’s horsepower (its ability to do work) and torque (its turning power). Let’s break it down for centrifugal fans (the most common type).
An evasé (eee-va-say) is a critical component in industrial fan systems that significantly enhances performance and efficiency. Installed on the fan outlet, it helps improve airflow by providing a natural path for the gas to expand. The evasé connects to the fan outlet at the smaller flange side and gradually expands outward. While the outer edge of the evasé expands at a consistent rate, the inner edge expands more significantly, resulting in a much larger flange at the opposite end.
Bearings are crucial for industrial centrifugal fans, supporting the fan shaft and minimizing friction. Proper bearing selection ensures efficiency, longevity, and reliability in high-performance ventilation systems.
The Role of Bearings in Centrifugal Fans
Bearings hold the shaft in place as a fan rotates. In overhung applications, they are placed in close proximity to the wheel, placed together on the drive side of the fan housing, supporting the wheel mounted on the end of the shaft. In center-hung applications, one bearing is placed on the drive side and the other is placed on the inlet side of the fan as the wheel rotates on the shaft between the bearings.
Impeller Types for Centrifugal Fans
New for 2025 is a regular feature on basic fan knowledge from Chet White, our Sales and Marketing Manager. This month we look at the various types of impellers for centrifugal fans.
At AirPro, we take pride in designing and manufacturing custom fans tailored to our customers’ specific needs. The fan pictured in the video is still in production: but this gives us an opportunity to highlight some of the specialized features we integrate into our custom fan designs. AirPro designed this particular fan for an API 673 application.
Fan Wheels: The Basics
One of the coolest things about building fans is understanding industrial fan applications. At AirPro, we build all types of fan wheels depending on customer needs. So why one fan type over another? It all has to do with application.
Most of the fans we build are driven by electric motors, and this requires the fan wheel and/or shaft to connect with the motor shaft in some way. There are two broad classifications we use to describe this connection – 1) belt drive and 2) direct drive.
The Centrifugal Fan Basics
The most basic answer to the question, “What does a centrifugal fan do?”, is that it moves gas (air), drawing it into the inlet, turning it 90 degrees, and blowing it through the outlet to exit the fan. It moves a higher static pressure than an axial fan, which moves air and gas straight, in one direction. Without air movement inside buildings – whether a room (like in Chet’s example in the video), a house, or an industrial manufacturing facility – things would get dicey. If you were to be trapped in a small room with no ventilation, only breathing in your own exhaled air, you could only survive for so long. Imagine what would happen in a manufacturing facility where there are many other gases and particles at play! If that is all the information on centrifugal fans you were looking for, feel free to stop reading now. For a little more on how they work, carry on.
Why and How to Vary Speed in an Industrial Centrifugal Fan
A variable-speed fan is just what it sounds like. In this case, we’re talking about an industrial centrifugal fan that is capable of operating at more than one speed. That means it can run above or below the constant motor speed specified. There are several reasons why you would need a variable-speed fan, several ways to do it, and a few things to be careful to avoid when operating at varied speeds.
Use a Damper to Add Resistance and Reduce Airflow
If you want to reduce a fan’s air volume and horsepower without adjusting speed, then you can use a damper to add system resistance. The damper can be installed on either the inlet or outlet side of the fan, and you can determine the best location based on your specific application and your fan performance curve. More often than not, we’ll recommend placing the damper at the outlet as the most cost-effective way to simply add resistance.