Choosing the Right Motor Speed for Your Industrial Fan

How do you determine the right motor speed for your industrial centrifugal fan? You’ll need to consider your fan’s drive arrangement and one more factor that frequently gets missed: frequency of the motor’s input power.

Motor RPM for Direct-Driven Fans

Let’s consider direct-drive fans first. With the fan wheel mounted to the motor shaft or the fan shaft directly coupled to the motor shaft, the motor speed should match the fan’s operating speed. For example, a 3600 RPM motor at 60 Hz should be selected for fans operating at or within tolerance of 3600 RPM.

Motor RPM for Belt-Driven Fans

When you are using a belt drive fan, the challenge is to pick a motor speed relatively close to the fan’s operating speed. While belt drives do not require the motor speed to match the fan’s operating speed, the motor speed should be within certain ranges of the fan speed and even horsepower. Also, you want to pick the slowest motor speed possible to extend the life of the motor. Our application and design engineers use guidelines in selecting the motor RPM, and we are happy to share them with you here.


There is another factor to consider: measured in hertz (Hz) in the United States, frequency of power input is typically 60Hz, calling for synchronous motor speeds of 3600 RPM, 1800 RPM, 1200 RPM, 900 RPM. You need to check the voltage and frequency combination in the country where your fan will be installed. We often see 50Hz frequencies outside the US, calling for synchronous motor speeds of 3000 RPM, 1500 RPM, 1000 RPM, and so on. This is especially important to keep in mind when sizing a direct-drive fan.

Hear it from the Application Engineer

Senior Application Engineer Chet White explains what we need to know about how to determine the correct motor size for your belt-driven or direct-driven fan application in this 2-minute video.

When you’re ready to start your project, reach out and connect with one of our application engineers to discuss the details of your specification.

Related Content on Industrial Fan Applications

There are many factors to consider in every industrial fan application. We’ve seen it all. Here are two more articles that might be of interest as you think about your application:

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