Two-Plane Dynamic Balancing: How to Balance an Industrial Fan

Before we dive into HOW to balance an industrial fan, we should start with WHY. The answer is that the better we balance the wheel in a two-plane balance setup in the shop, the better it’s going to be when we put it into the complete fan assembly, run it up to full speed and trim balance it. And of course, ultimately, fan balance is essential to fan performance, safety, and maintenance.

What is Two-Plane Dynamic Balancing?

Two-plane dynamic balancing is the answer for how to balance an industrial fan. The two-plane balance system includes a fan wheel secured to a shaft suspended between two supports, bearings, an amplitude reader port on each side of the wheel, and an optical tachometer to identify the phases where the impact is greatest. Once you have the measurements, you know where and by how much to adjust the weight to balance the fan wheel.

How to Balance an Industrial Fan: Measuring Amplitude

The first component in balancing an industrial fan is to measure the imbalance based on the amplitude of vibration. To do this, we use two amplitude reader ports, one snapped onto the back of each plane on either side of the fan wheel. As the wheel spins, the ports pick up the vibrations as indicators of imbalance.

How to Balance an Industrial Fan: Measuring Phase

The second component in balancing an industrial fan is to identify the phase or phases where the imbalance is most significant. We do this by placing a tachometer (tach reader) where it can read along the fan shaft using a laser, with a tach strip marking the “zero degree spot” on the 360-degree plane, and picking up the tach each time it crosses the corresponding zero degree spot on the outer rim of the fan wheel.

How to Balance an Industrial Fan: Determining Adjustments

With the amplitude reader ports, tachometer, and tach strip installed, we are ready to begin. We always take three initial runs. The first run happens with no weight applied to either side of the wheel. On the second run, we attach a weight to the “zero degree spot” on the left plane, and on the third run, the same weight moves over to the “zero degree spot on the right plane. The balancing equipment now uses the information gained from these three initial runs to let us know where and how much the imbalance is. Thus, we know where to make adjustments to restore balance by either welding weight on (or grinding weight away 180 degrees across). And that’s how to balance an industrial fan in the shop in advance of assembly and field balancing.

Hear it from an Application Engineer

Senior Application Engineer Chet White demonstrates how to balance an industrial fan using two-plane dynamic balancing in this 3-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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