Industrial Noise
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Industrial fan noise reduction: low frequency – tones – hums…

Award Winning Industrial Fan Noise Control – stealth and efficiency…

Self-financing fan silencing – without silencers…
Innovative fan noise reduction techniques that have saved £millions in capital and in reduced running costs…

industrial fan noise reduction without attenuators, silencers, acoustic enclosures or reduced fan efficiency

Self-financing fan silencing makes use of innovative aerodynamic noise reduction techniques instead of silencers. Installed in a multitude of fans and blowers across the planet, from 6cm diameter to 4MW behemoths, this technology has and is saving £millions in capital and reduced running costs. Retro-fitted in hours, our alternative to mufflers provides stealth and efficiency to reduce energy consumption and carbon footprint compared with attenuators.

Take advantage of our free email evaluation service to determine if you can retro-fit our technology to your fans (see how Quiet Fan Technology works). We provide instant diagnoses based on smartphone data (Remote Control of Fan Noise) followed by the solution anywhere in the world, so we can help wherever you are based.

Contact us for more information or call +447785265660

INVC Technology – best practice for fan noise attenuation, environmental impact and costs

winner of the rushlight award for innovation in environmental noise control for our fan noise reduction technologyThe annual UK industrial fan power consumption is estimated at well over 30TW-hours. If best practice was applied to fans that require silencing, this could reduce UK CO2 emissions by around 2 million tons per annum. We received the Rushlight Noise Abatement Award for applying our innovative fan noise reduction technology to a project at the Tata Scunthorpe steel-works. As well as eliminating a long-running environmental noise problem, Tata also reduced their capital costs (>£800,000) and running costs (c £200k per annum) compared with silencers.

Leave off the silencer and cut your fan silencing project costs by 50% – 80%
The Tata Steel project is just one example that highlights the benefits of our innovative approach to fan noise control across a wide range of applications. A second opinion from us typically reduces noise control project costs by 50% – 80% – and can even lead to the counter-intuitive result of noise reduction measures that are self-financing. Or you could save time by contacting us for a second opinion first….

Quiet Fan Technology (QFt) – industrial fan noise reduction without silencers

Contact us for more information or call +447785265660

The latest version of our award winning fan noise control technology reduces tonal noise at source at a fraction of the cost of traditional techniques such as silencers and enclosures. It achieves this noise reduction without the increased power consumption associated with conventional silencers, lasts the lifetime of the fan without maintenance and can be retro-fitted with little down-time. Applications include: extract fans, ID fans, chillers, air conditioning plant, process and ventilation fans, HVAC systems, power stations, cement and steel works and most fans where there are low frequency noise issues…

How does the industrial fan noise attenuating technology work?

We have taken a similar approach to that of the way that Formula 1 teams invest in the design of aerodynamic aids to control the airflow round their cars. As fan noise is the sum of the turbulence generated pressure fluctuations in the air shed by the blades, we have developed a range of aerodynamic inserts that are fitted inside the fan casing to smooth the flow. This reduces the pressure fluctuations – and hence the noise – at source without introducing the back-pressure often associated with silencers. This not only reduces the noise travelling down the intake and exhaust ductwork, but also that passing through the fan casing which may not only eliminate the need for silencers, but also the need for acoustic enclosures.

HVAC – Chiller – Condenser – Cooling Tower Noise Reduction

We have also developed innovative new techniques to control the noise from HVAC and chiller / condenser systems without compromising efficiency. These typically provide around 10dB of additional attenuation compared with conventional noise reduction packages and silencers – and at a fraction of the cost. Download HVAC / chiller / condenser / air conditioning noise attenuation case studies below.

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Award Winning Tata OG Fan Noise Reduction – £1,000,000 cost savings
The three 4 megawatt steel works fans generated a low frequency hum (c162Hz) over a wide area. As the fan speeds vary, sophisticated resonator silencers were ruled-out and conventional attenuators would have imposed a heavy penalty in terms of cost and reduced fan efficiency.

A second opinion saves a £million…
silencer-free industrial fan noise reduction on large steel-works gas stack fansTata approached us for a second opinion as to potential alternatives. Our solution was to develop novel fan casing modifications, avoiding the need to modify either the existing ductwork or the stacks to fit silencers – thereby minimising downtime. These modifications have eliminated the noise at source for the lifetime of the fans. Significantly, the new fan modifications require no maintenance and do not affect the efficiency of the fan. Moreover, the willingness of Tata to invest in new and innovative technology has reaped very substantial rewards compared with conventional silencing:-

  • 94% reduction in noise (12dB)
  • capital cost savings of over £800,000
  • substantial environmental benefits (carbon emissions)
  • c £200,000 saved each year on running costs (power and carbon)

“INVC’s modifications have brought about a huge reduction in fan noise, improving the environmental conditions across a wide area around the Plant. They’ve also saved us a large amount of money by negating the requirement for major capital expenditure, so it’s been a remarkably successful project.” – Grahame Wallace, Tata.

Applications include large centrifugal fans used in steel mills, cement works, power stations, brick works, kilns….

Record Breaking Formula One Fan Noise Control
Red Bull extract fan system silencing without a silencerFitting silencers to this fan extract system seemed a long winded process to a company used to the pace of change in Formula One. Red Bull looked for an alternative and found it in our aerodynamic noise control technology. The aerodynamic inserts were designed, manufactured and installed inside the fan casing within a pit-stop window of a few hours to dramatic effect. The 218Hz low frequency tone was reduced by a factor of around 1000 (30dB – a new record for the technique), completely eliminating the problem at source for the lifetime of the fan, without maintenance and without affecting fan efficiency.

“We felt that there had to be a better way to reduce the fan noise other than by compromising the system efficiency and creating additional long term maintenance” said Terry Brice of Red Bull Technology. “The INVC technique not only produced a fantastic result, but it’s also very satisfying as an elegant engineering solution”.

red bull before after

Combustion Fan Noise Reduction – problem solved overnight without silencers…
no silecners for this combustion fan noise reductionCombustion fan noise from a new waste heating system at a Palgrave Brown MDF site was the source of complaints from neighbours – and a potential noise abatement notice. The supplier and their consultants had tried conventional measures (additional silencing, reduced fan speed) over an extended period to no avail. On the point of admitting defeat, they were referred to us. Our solution (controlling the noise at source) was fitted in hours – next morning, it was hard to tell that the fan was running. The tonal ID fan noise was reduced by 22dB and the overall level by 9dB(A), quickly, permanently, at low cost and without affecting fan efficiency. The results have been so impressive that Alan Fillingham, the Director, recommended our approach throughout the group.palgrave-fan-before-after

Stacks of Low Cost Noise Control – emergency stack noise reduction
stack noise control retro-fit bespoke silencer insertsUnfortunately, the plant update to improve the efficiency of the exhaust fans in a large cement works created a serious noise problem that generated complaints from miles around. Conventional stack silencing would have resulted in an unacceptable delay in solving the problem, eye-watering costs and a prolonged shut-down. Our alternative solution was based on the design of a set of bespoke stack silencer elements tuned to suit the noise signature. These were pre-fabricated off site and then inserted into the stack through a small access door over a weekend. The result was a 19dB noise reduction over the critical frequency range with no effect on the fan and stack efficiency – and at a small fraction of the cost of conventional silencing.castle cement before after

Seriously Massive Axial Fan Noise Reduction – seriously little cost
axial fan noise reduction without silencersaxial fan noise control at source - no need to extend silencersLow frequency tonal noise from 8 architectural scale axial fans (several stories up and already fitted with 8m long silencers!) at a Tata steel-works had caused environmental noise problems over a number of years. All the possible conventional fan noise control solutions considered (largely additional silencers) would not only have cost a large fortune (and probably not been very effective), but would also have reduced efficiency and therefore increased the running costs. We diagnosed a system resonance which we addressed at source, reducing the tones by 20dB – and with no effect on fan efficiency.

Paint Plant Filter Extract Fan Noise Reduction – quiet painting
paint plant extract fan noise reduction without a silencer in sight....A pair of classic industrial extract fan filter systems used on an MDF paint plant generated a very irritating low frequency drone that was the subject of complaints both from operators inside the workshops and from local residents. Moreover, as the pair of fans were not quite synchronised, the sound also had a distinctive “beat” which made it even more annoying. As the fan noise was at a low frequency of 146Hz, conventional silencers would have been very large, very expensive, would have required relocation of the plant and supplementation with lagging and enclosures (and regular cleaning). We bypassed all these issues by reducing the noise at source (QFt), eliminating the fan tones (13dB reduction) and the “beat ” with no down-time outside normal maintenance requirements. This approach has a broad application for paint plant fans and other dust extract filtration systems as a more effective alternative to a silencer..

Quarry Suction Fan Noise Reduction – fan-tastic results, and no maintenance payments
quarry suction fan noise reduction at source instead of using an attenuatorA serious problem with conventional silencing for some fan applications is the need to shut-down to clean the silencers on a regular basis with the associated cost implications. In this instance, the tonal noise from this quarry suction fan working under very dirty conditions was reduced by 23dB using our unique Quiet Fan technology – a new record for the technique. No silencers, no enclosure, no lagging, little down-time and no maintenance – ever (despite the operating conditions). Plus, this all comes at a tiny fraction of the capital cost of conventional silencing and without the associated running cost penalty. This approach to fan noise reduction is particularly effective where the air is dirty as it avoids the need to clean silencers.

Scrap Fan Noise Reduction – both safety and environmental noise issues
fan silecning withoiut silencers or attenuators or lagging or acoustic enclosures...Three sets of chopper fans are used to pull-off scrap cans from the lines and to shred them for recycling. These generated  high levels of tonal noise causing both occupational and environmental noise problems. Instead of fitting conventional fan attenuators, acoustic enclosures and noise lagging at a potential cost of £30k or more, our Quiet Fan technology was fitted to the fans in a matter of hours to give an overall noise reduction of 22dB(A) at an installed cost of c £1000/line – a capital cost saving of 90% and with no effect on fan performance or efficiency.

Unlike fan silencers, the modifications are unaffected by the passage of scrap cans and will last the lifetime of the fans without maintenance – and at less than 1% of the previous noise level…

canfan be3fore after

Noise Control on Thermal Oxidiser Induced Draught Fans
forced draft thermal oxidiser fan noise reduced at source without noise enclosure, acoustics barriers or noise laggingSevere noise problems were encountered from a new regenerative thermal oxidiser plant on an industrial site. The suppliers suggested an earth berm noise barrier, large fan silencers and acoustic enclosures that would not only have cost 6 figure sums, but would also have been ineffective at low frequencies. We used accurate and precise diagnosis to isolate the key subjective sound features in addition to the broadband noise. We removed the tones; slowed one fan to remove the “beat” with the other unit; moved and changed the damper to improve flow and added small conventional attenuators to reduce broadband noise. These modifications eliminated all the noise character and reduced the overall noise by 15dB(A) at a few % of the costs associated with the traditional (and less effective)  noise control package.

draft fan
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Roof-Top HVAC – “chiller farm” air conditioning noise control at a 90% cost discount
roof mounted air conditioning unit chiller condenser unit noise control without attenuatorsThe cost of reducing the noise from air conditioning system chillers on the roof of a large multi-storey facility to meet the requirements of the Local Authority had been estimated at over £300,000. Fitting the proposed acoustic screens round the condensers would also have required considerable planning (closing streets and bringing-in cranes) and there was also the possibility that the noise control measures and silencers would reduce the cooling capacity of the HVAC system.

The communications company involved approached us in the hope that we could provide a better alternative. A very careful analysis of the noise sources and layout of the air conditioning plant plus some lateral thinking resulted in an elegant solution involving a combination of engineering control at source, novel local acoustic treatments and the clever use of geometry. The result was a set of modifications that were easy to implement in convenient stages and provided a reduction in the condenser axial fan noise of c 15dB(A) at a cost of c £40,000 – and with no effect on the normal operation or the overall efficiency of the system unlike conventional noise barriers and silencers.

Cooling Tower Fan Noise Reduction + improved efficiency
cooling tower fan noise controlCooling tower fan silencing by conventional means is often both very difficult and very costly as the problem is usually low frequency in nature. However, there are sometimes source control alternatives. For example, the dominant environmental noise problem from a food processing plant in the middle of a village was caused by noise from a pair of cooling towers – despite the silencers already fitted to the axial fan exhausts. We devised modifications that produced a substantial improvement in the efficiency of the cooling towers that, coupled with measures to reduce the noise from falling water, cut the overall noise level from the units by 15dB(A) and reduced running costs.

Cool Air Conditioning Plant Chiller Noise Control
HVAC chiller condenser noise dampingThe company running a server farm had spent £100,000 on noise control measures (acoustic barriers and silencers) for their HVAC plant to no avail – the complaints continued as the noise levels were virtually unchanged. We were invited by the Local Authority to provide both parties with a definitive statement as to what constituted “best practicable means”. Careful diagnosis allowed us to generate a set of best practice noise control measures that would eliminate the problem at a cost of c £30k.
acoustic barrier and silencers for chiller condensersThese measures included purpose designed silencing, geometry changes, improved acoustic screening and internal modifications to the main Air Handling Units. On the air conditioning condenser units, we by-passed the conventional solution of noise barriers and silencers as these are not only high cost control measures, but they can also reduce the efficiency of the chillers themselves. Our alternative was a set of low cost engineering noise control modifications that not only reduced the overall noise from the HVAC plant at source by 8dB(A), but also eliminated the tonal content (worth an additional 5dB(A) noise reduction with respect to environmental noise limits) – and with no effect at all on the chiller condenser performance or access.

The result was an overall noise reduction of 12dB(A) and the elimination of the tonal content of the noise from the condensers. If best practice had been used at the start, the company would have reduced the cost of the chiller plant noise control project by 70% and avoided several months of management hassle.

Plating Plant Cooling Tower Noise – acoustic un-screening…
cooling tower silencingA pair of new cooling towers had ignited complaints from residents across the road from the site. The company had been advised to fit the typical conventional acoustic package of silencers and a barrier along the edge of the site at a total cost of around £30k with an estimated reduction in noise to around 56dB(A) at the neighbours – still somewhat high for the area. Moreover, the acoustic barrier would have caused serious access problems.

Our solution was based on engineering source control, tackling the noise sources at source in rank order. The final noise reduction package for both cooling towers comprised intake and drive motor modifications, exhaust and pump silencers plus local acoustic screening. This achieved a noise level of <50dB(A) and at a cost of only £5k.

Download fan noise control information >


We have developed the technology to both diagnose industrial fan noise problems and to provide the solutions anywhere on the planet via the internet. Without a site visit. This saves time and money and gives the whole world access to our innovative noise and power saving noise control technology. We’ve completed a number of very successful long distance projects from our UK offices, including this oil refinery in the USA where their capital costs were reduced from c $1.25 million down to c $0.25 million…