Fan Noise Diagnosis

Fan Noise Diagnosis

A large chemical company received noise nuisance complaints from nearby residents.  So they asked a large well-known noise consultant company to carry out a sound survey to identify the cause of the nuisance.  The acoustic consultant company carried out a very large and expensive noise survey.  They stated that the noise problem was caused by two large extract fans located in the yard outside the factory.

The chemical company then asked a different noise consultant company to design a solution to suppress the sound from the two large fans.  When they received the drawings and report specifying the fan noise solution, the chemical company found that it would be very difficult and costly to fit.  The reason was that the duct from one fan is wrapped around the casing of the second fan, preventing access to install the noise solution.  The chemical company said they would need to remove the entire fan and its ducting to be able to fit the solution.  They decided this would be too difficult, time consuming and expensive, so they asked us if we could provide a solution that was easier to install and lower cost.

We carried out diagnostic noise tests near the complainants’ houses.  This showed that the cause of the noise nuisance was a loud whine sound.  This whine was clearly audible at the complainants’ houses and it was the most noticeable sound from the factory, by far.  It was obvious that this whine sound was the cause of the nuisance.  We went onto the chemical company’s site with a specialist noise analyser.  The whine did not appear on our sound analyser close to the two large fans that the other noise company had stated were the cause of the noise problem.  So our diagnostic tests proved that these large fans were not the source of the noise nuisance.

There are many fans, chillers, pumps, AHUs and other equipment outside in the chemical company’s yard, some at ground level and some at high level.  This made it very difficult to identify the cause of the annoying whine that was causing the noise nuisance.  However, we eventually tracked the source down to a small laboratory fume extract fan.  The fan is at ground level but is attached to a long exhaust duct that terminates above the factory roof (shown in the photo).  Most of the noise affecting local residents is transmitted from the top of the exhaust duct. 

Fan Noise Solution

Our approach to noise control is to assess a range of noise reduction options with the aim of finding the lowest cost solution that achieves the necessary fan noise reduction at minimum cost.  For this laboratory fan, the lowest cost option was to fit a high performance silencer in the exhaust duct.  We selected a type and size of silencer that provided a very high noise reduction in the whine sound – 24 dB sound reduction.

Large Cost Saving

The silencer cost just £290.  This compares with around £6000 for the design, manufacture and installation of the solution that the other noise company had offered for the two large fans.  So our solution cost about £5700 less than the solution provided by the other noise reduction company.  In addition, our diagnostic noise survey cost considerably less than the survey carried out by the other noise company, and which failed to identify which fan was causing the noise nuisance.

Had the chemical company installed the proposed noise solution on the two large fans despite the difficulty in gaining access for installation, this would not have reduced the whine that was causing the noise nuisance.  So residents would have noticed no difference in the factory noise whatsoever.  The chemical company would have spent £6000 for no benefit to residents!

How to get our help with fan noise diagnostics and solutions

We have a long track record of accurately identifying the source of noise nuisance problems.  We have successfully and quickly identified the cause of noise nuisance in numerous factories using our specialist noise analyser and expertise gained from over 35 years’ experience.  In this time we have accurately identified noise sources for all types of equipment and fans found in manufacturing industry.  We have also provided many customers with fan noise solutions that achieved much higher sound reduction than noise control products from other companies, and at considerably lower cost – often saving our customers thousands of pounds in the process. 

To find out how we can help you accurately identify a fan or other equipment that is causing noise nuisance and / or to obtain a high performance, low cost solution that could save you thousands of pounds, ring us on the ‘phone number below or contact us

You can see more details of the benefits of our high performance, low cost solutions for factory machines on industrial noise nuisance.

For industrial fans, there are case studies and more details of our high performance solutions on fan noise solution.