Industrial Noise & Vibration Centre

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Case Studies

An elegant engineering solution to your noise or vibration problem may already be available. Search below the largest database of source control case studies in the world for alternatives to conventional, high-cost palliatives such as acoustic enclosures, silencers, barriers etc.

Showing 1 to 15 out of 92
  • damping
  • pump
  • noise control

Power Station 600hp Water Pump Noise Reduction

Power station water pump noise control

These water pumps generated 95 – 99 dB(A) and were the subject of a dispute with the suppliers re the agreed noise levels. Various acoustic barriers and partial enclosures were being considered – at high cost and with considerable access issues. Our detailed vibration analysis proved that the required noise reduction could be achieved simply via constrained layer damping plus laminated close shields. These provided a 12dB(A) noise reduction with no effect on access, operation or maintenance – and at a tiny fraction of the previously proposed costs.

This is an example of the efficacy of accurate diagnosis coupled with good engineering and knowledge of materials. More information is available on the Sound Damped Steel installer website here.

  • damping
  • noise control
  • machining

Alternator Casting Machining Noise Reduction

Alternator end shield casting machining noise control

Machining of alternator end castings produced 104 dB(A) at the operator, dominated by a “squeal” radiating from the casting. Overlapping hanging strips had been fitted round each machine in an attempt to reduce noise – but in every case they had been cut down at the operator location to improve access. Frequency analysis showed the dominant tones were excited by cutting forces with evidence of chatter-marks on some of the machined surfaces. We designed a low cost damper to reduce the casting vibration.

This reduced “squeal” tone by 32 dB and the overall noise level by 16 dB(A) at source, improved the quality of cut and reduced the machining cycle time to improve productivity.

  • gas
  • damping
  • noise control
  • oil

Power Station Gas Facility – high damping noise reduction

Gas pipeline acoustuic lagging noise control

Noise from a power station was uncomfortably close to their environmental noise planning conditions. Detailed diagnosis proved that the dominant contribution was high frequency noise (>500Hz) radiated by the Gas Reception Facility that also contributed to occupational noise exposure. Vibration measurements narrowed-down the source to the reducer, expander and associated valve section of the facility. Sound Damped Steel was brought in to fabricate our innovative, high performance acoustic lagging.

This has an outer skin constructed from highly damped laminated steel, making it very tolerant of installation practicalities. Moreover, options are available that eliminate the corrosion problems inherent in conventional lagging designs. The diagnostic process illustrates how costs can be kept to an absolute minimum by precisely ranking noise contributions from different components, even amidst complex arrays of pipework, valves and other sources. The effect of the treatment was to reduce the noise from this source by 16 -19dB(A), eliminating it as a contributor off-site. Occupational noise levels in the area were also reduced by an average of 8dB(A). More information is available on the Sound Damped Steel installer website here.

  • vibration isolation
  • hydraulic power pack
  • noise control

Hydraulic Billet Guillotine

The 96 dB(A)Leq recorded from a 250 ton Rhodes billet hydraulic guillotine was cut by 17dB(A) – without using an acoustic enclosure and hence without the associated access, maintenance and temperature issues. The noise was dominated by high levels of transmitted vibration from the motor-pump unit to the machine frame (and through rigid pipework to the remainder of the machine) and the transmission of impacts from the valve-bank.

The motor-pump unit was mounted on a rigid frame that was then isolated from the machine body and the valve bank isolated using rubber-cork composite. This reduced the noise level from 96 dB(A) down to 79 dB(A) at very little cost.

  • noise control
  • fan noise attenuation
  • environmental noise

Water Evaporator Mine Fans – 99.5% noise reduction

Axial mine water spray fan noise attenuation

Proposed £100k conventional attenuators for 10 axial mine water evaporation fans in Australia would have had zero effect! A few emails and <£20k gave 23dB noise reduction and improved efficiency.

The mining company had a series of 10 large axial fans that are used to evaporate water pumped from underground. However, these had caused complaints over a very wide area. The quote for £100k of mufflers would have provided zero attenuation as they would be fitted only to outlets (half the noise is from the intakes) and they have virtually no attenuation at the dominant 200Hz tone. Our emailed details for aerodynamic modifications reduced the tonal content by 23dB at a cost of <£2k/fan. Fan efficiency was also improved…

  • chiller fan
  • noise control
  • environmental noise

Roof-Top HVAC – “chiller farm” air conditioning noise control at a 90% cost discount

Rooftop chiller fan noise attenuation

The cost of reducing the noise from air conditioning system chillers on the roof of a large multi-storey data centre 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 the proposed noise control measures and silencers would have reduced the cooling capacity of the HVAC system. We had a better idea…

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.

More details of the best approach to reducing the noise from data centres, chillers and air conditioning plant >

  • noise control
  • environmental noise
  • cooling tower

Plating Plant Cooling Tower Noise – acoustic un-screening…

Cooling tower fan and pump noise reduction

The noise from a pair of new cooling towers had ignited complaints from residents across the road from the site. A typical acoustic consultant was drafted-in who recommended the industry default silencers and a noise barrier without carrying out any diagnosis. Not good practice, let alone best practice.

The predicted effect on the plant noise of fitting the typical conventional acoustic package of silencers and a barrier along the edge of the site was to reduce the noise level down to around 56dB(A) at the neighbours - still far too high for the area. Despite a total cooling tower noise attenuation package costing well over £40k, not only would the problem not have been solved but in addition, as the acoustic barrier would have caused serious transport access problems, the company had to look for alternatives.

Our solution was based on a very accurate diagnosis and ranking of the cooling tower fan, drive and pump noise sources to develop an engineering source control package. The final noise reduction measures for both cooling towers comprised:-

  • intake and drive motor modifications
  • exhaust and pump silencers
  • local acoustic screening

This package achieved a noise level of <50dB(A) at a cost of only £6k and without affecting normal site operation or cooling tower efficiency. Around 15% of the cost and more than 4 times the attenuation of the conventional noise reduction measures.

How to select the optimum cooling tower noise control measures >

  • environmental noise
  • noise control
  • fan noise attenuation
  • cooling tower

Cooling Tower Fan Noise Reduction + improved efficiency

Cooling tower fan noise attenuation at source

Cooling tower fan silencing by conventional means is often both very difficult and very costly as the problem is usually low frequency in nature so conventional silencers and noise barriers don’t work. Despite this fact, the cooling tower world is awash with placebo silencers and acoustic barriers that are just a waste of money. Alternatively…

… quite often there are low-cost source control alternatives. For example, the dominant environmental noise problem from a food processing plant in the middle of a village was caused by cooling tower noise from a pair of units – despite the large silencers already fitted to the axial fan exhausts. We devised engineering modifications that produced a substantial improvement in the efficiency of the cooling towers that, coupled with measures to reduce the noise from falling water, not only cut the overall noise level from the units by 15dB(A), but also substantially reduced running costs.

Details of how best to silence cooling towers >

  • chiller fan
  • environmental noise
  • server farm
  • data center
  • fan noise attenuation

Cool Air Conditioning Plant Chiller Noise Control

Axial chiller condenser fan noise reduction

Chiller noise control costs were cut by 80% using new technology. The company running a server farm had spent £100,000 on noise control measures (acoustic barriers and silencers) for their HVAC and AHU 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” and to sort the problem.

Careful diagnosis allowed us to generate a best practice noise control package that would eliminate the problem at a cost of c £30k.

These 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 hum (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 and a sacking…

More information on the optimum way to reduce noise from server farm, chiller, AHU and data center fans >

  • noise control
  • fan noise attenuation
  • environmental noise

Paint Plant Spray Booth Extract Fan Noise Reduction

Paint shop spray booth extract fan noise attenuation

Paint spray booth extract fan noise control poses a problem for conventional silencing in that, even with effective filtration, the silencer will clog and lose attenuation. Moreover, paint fans often generate a low-frequency hum that passes through mufflers with little attenuation. This case study illustrates a low-cost alternative approach to spray booth extract noise reduction that lasts the lifetime of the fan without loss of performance.

A pair of classic industrial paint spray booth 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. At these low frequencies, conventional silencers would not only have been ineffective, but would have quickly clogged.

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 spray booth extract 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 fan noise at source (Quiet Fan technology), eliminating the tones (13dB reduction) and the “beat ” with no down-time outside normal maintenance requirements. This approach has a broad application for paint plant, spray booth fans and other dust extract filtration systems as a more effective alternative to silencers…

  • environmental noise
  • fan noise attenuation

Dirty Air Quarry Fan Noise Reduction – no cleaning costs

Quarry fan noise reduction - no clogging

A serious problem with conventional silencing for fan applications like this where the air is very dirty is the need to shut-down to clean the silencers on a regular basis with the associated cost implications. Our noise attenuating technology is immune to clogging, so no cleaning needed - ever…

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.

  • environmental noise
  • fan noise attenuation
  • axial fan noise

Massive Axial Fan Noise Reduction – at seriously little cost

Steelworks axial extract fan noise attenuation

Low 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. We diagnosed, we tweaked – and the problem was solved…

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.

  • environmental noise
  • fan noise attenuation
  • fans

Combustion Fan Noise Reduction – problem solved overnight

Combustion fan noise attenuation

Despite considerable time and money being spent with the supplier and acoustic consultant installing silencers and reducing fan speed, a noise abatement notice was due because of numerous complaints about combustion fan noise. We resolved the problem overnight via Barry welding in 22dB of attenuation during a normal shutdown.

Combustion fan noise from a new waste heating system at a Palgrave Brown MDF site had caused numerous complaints from neighbours with a noise abatement notice in the offing. 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. The next morning, it was hard to tell that the fan was running as the tonal ID fan noise was reduced by 22dB and the overall level by 9dB(A), quickly, permanently and without affecting fan efficiency. The results were so impressive that the director, Alan Fillingham, recommended that our approach should be used throughout the group.

  • environmental noise
  • fan noise attenuation
  • fans

Noise Control on Thermal Oxidiser Induced Draught Fans

Thermal oxidiser fan and stack noise reduction at source

Severe 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 a 6 figure sum, but would have been a complete waste of money as they would not have worked.

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.

  • environmental noise
  • fan noise attenuation

Record Breaking Formula 1 Fan Noise Control

Red Bull extract fan noise attenuation

Fitting conventional silencers to this fan extract system seemed a long-winded and crude process to Red Bull who were used to the pace of change and the engineering innovation found in Formula One. Our approach was a perfect fit for their engineering ethos – 1000x less noise installed within a pit-stop of a few hours.

Red Bull found an alternative to traditional attenuators in our aerodynamic noise control technology. The aerodynamic inserts were designed, manufactured and installed inside the fan casing within a pit-stop window of just a few hours to dramatic effect. The problem 218Hz low-frequency tone was reduced by a factor of around 1000 (30dB – a new world record for the technique), completely eliminating the problem at the 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”.

Showing 1 to 15 out of 92