Specifying, Testing and Adjusting for Fan Balance Quality Grades

Balance quality grades are among the more than 20,000 standards published by the International Standards Organization (ISO). These standards serve as generally accepted specifications for products, services, and systems, to ensure quality, safety, and efficiency.

Balance quality grades specify the acceptable amount of imbalance on each side of the fan wheel. We test and adjust for the specification through a two-plane dynamic balance process.

There are three different fan balance quality grades that buyers can specify: G6.3, G2.5, and G1.0. Most fan manufacturers will hold to is a G6.3, which is the least stringent of the three different ISO standards.

Maximum Imbalance to Meet Fan Balance Quality Grades

In the fan dynamic balancing process, we test the wheel on the shaft as a stand-alone component, before it goes into the complete fan assembly. In this case, we balance at approximately one sixth of the fan’s maximum operating speed, calculating the maximum imbalance allowed based on the specified fan. That tells us what the maximum imbalance is on each side of this wheel as measured in grams based on the size of the fan wheel.

The maximum imbalance calculated will satisfy the least stringent fan balance quality grade of 6.3. To calculate the allowed imbalance for the stricter grade of G2.5 and the most stringent grade of G1.0, we use a simple ratio. We would divide 2.5 by 6.3 or 1 by 6.3 respectively, then multiply the result by the maximum grams of imbalance calculated above.

Hear it from an Application Engineer

Senior Application Engineer Chet White demonstrates the dynamic fan balancing process to meet specified fan balance quality grades 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 specifications.

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