Industrial Fan Noise Reduction

Industrial fans used in process manufacturing and Packers fans at Lambeau Field are in the same ballpark in terms of the noise level. They can both be loud enough to require mitigation. For Packers’ fans, that might be as simple as earplugs – we love a good loud crowd! But for industrial fans, it means taking fan noise reduction measures to stay below the specified level.

How Loud Are Industrial Fans?

Industrial fans are rotating industrial machinery, so they will naturally be pretty loud. The general specification in most manufacturing settings is that noise levels should fall below 85 decibels at five feet away for an eight-hour shift.

It’s possible for industrial fans to stay at or below that level without additional measures. But it can be or seem significantly louder, depending on the size, speed, type of fan, and the perception of the listener (which depends in part on the surrounding – we’ll cover that in our next video/post). And with every increase of three decibels, the safe exposure time is cut in half. That means you need fan noise reduction measures to maintain a comfortable and safe working environment.

For those of you wondering how loud Packers fans are, we can approximate. A blog post about Decibel Levels at Football Games on the AccuQuest Hearing Centers website, states, “on average, the sound levels at football stadiums range between 80 and 90 decibels.” But Packers fans are well above average. Another article titled The Top 25 Loudest Stadiums on Supertailgate.com lists Lambeau Field at #22. The current record holder for noise level is the Kansas City Chiefs’ Arrowhead Stadium with a recorded noise level of 142.2 decibels.

How to Achieve Industrial Fan Noise Reduction

There are several places we look to keep the noise level below the recommended 85 decibels at five feet in most manufacturing settings. These include:

  • Closing the inlet and/or outlet
  • Addressing radiant noise
  • Blocking motor noise.

Closing the Fan Inlet and/or Outlet

The inlet and outlet are the first places to look for fan noise reduction opportunities. Typically, an industrial fan is either ducted at the inlet, the outlet, or both. If you have an open outlet or an open inlet, you can reduce the noise level by putting a silencer on it. Though rare, we’ve even seen a silencer between the fan and the ductwork. The fan silencer works very much like a car muffler, extending the opening to muffle the sound.

Addressing Radiant Noise

Once you’ve ducted and/or silenced your inlet and outlet, the next thing to do is reduce radiant noise. Radiant noise is the sound that penetrates the housing surrounding the fan. There are two ways to achieve radiant fan noise reduction: sound insulation, and the thickness of the housing. If you only need a small amount of noise reduction, you may be able to get what you need by increasing the thickness of the housing that surrounds the fan wheel. If you need a substantial amount of noise reduction, the option is a sound insulation jacket.

Blocking Fan Motor Noise

Another noise source to consider is the motor. Typically motors operate below the standard 85 decibels at 5 feet. But what if your particular application requires an even lower decibel level? If you’ve already addressed the inlet, outlet, and radiant noise and it’s still too high, you’ll need to reduce motor noise by building a sound enclosure that houses the entire fan.

Recap: Industrial Fan Noise Reduction

Industrial fans are loud thanks to their moving parts, often requiring fan noise reduction measures for the safety and comfort of your workplace. First, make sure the inlet and outlet are ducted and/or use a silencer. If that doesn’t get you all the way there, increase the housing material thickness and/or add sound insulation. If that still isn’t enough, consider adding an enclosure around the entire unit to reduce additional noise from the motor. If you’re at a Green Bay Packers game, let it roar.

Hear it from an Application Engineer

Senior Application Engineer Chet White demonstrates industrial fan noise reduction in this five-minute video.

When you need to specify a centrifugal fan or blower for your industrial process application, or if you need centrifugal fan or blower maintenance, repair, or retrofit, reach out and connect with one of our application engineers to discuss the details of your project.

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For more information on centrifugal fans  noise reduction, check out these additional pages:

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