Award Winning Fan Noise Control Technology - self-financing noise reduction...
Innovative fan noise reduction techniques that have saved £millions
Fan noise is by far the most common cause of environmental noise problems and is also a common occupational noise issue. The UK currently wastes £millions per annum on fan noise reduction techniques that are not best practice. Additional £millions are wasted on the increased running costs often associated with conventional noise control methods such as fan silencers.
INVC Technology - best practice for fan noise attenuation, environmental impact and costs
The annual UK fan power consumption is estimated at well over 30TW-hours. If best practice was in use on those 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 our innovative fan noise reduction technology applied to a project at the Corus Scunthorpe steel-works site. Whilst the award was in recognition of the environmental benefits, Corus also benefited from reduced capital costs (>£800,000) and reduced running costs (c £200k per annum) compared with using silencers as well as from the elimination of a long running environmental noise problem.
Get a second opinion and cut your fan noise control project costs by 50% - 80%
The Corus project is just the latest example highlighting the benefits of our innovative approach to fan noise control across a wide range of applications. Getting 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 actually self-financing. Or you could save time by contacting us for a second opinion first....
Quiet Fan Technology (QFt) - fan noise reduction without silencers
This is the latest version of our award winning fan noise control technology that reduces tonal noise at source at a fraction of the cost of traditional techniques such as silencers and enclosures. Moreover, 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... Download our fan noise reduction technical note > [460kB pdf]
HVAC - Chiller - Cooling Tower Noise Reduction
We have also developed innovative new techniques to control the noise from HVAC and chiller systems without compromising efficiency. These typically provide around 10dB of additional attenuation compared with conventional noise reduction packages - and at a fraction of the cost. HVAC / Chiller noise control case studies >
FAN NOISE CONTROL CASE STUDIES
Award Winning Corus OG Fan Noise Reduction - £1,000,000 cost savings
The three 4 megawatt fans generated a low frequency hum (c162Hz) over a wide area. As the fan speeds vary, sophisticated resonator silencers were ruled-out and conventional silencers would have imposed a heavy penalty in terms of cost and reduced fan efficiency.
A second opinion saves a million... 
Corus 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 - 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 Corus 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, Corus.
Applications include large centrifugal fans used in steel mills, cement works, power stations, brick works, kilns....
Combustion Fan Noise Reduction - problem solved overnight without silencers... 
Combustion 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.
Stacks of Low Cost Noise Control - emergency stack noise reduction 
Unfortunately, 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.
Seriously Massive Axial Fan Noise Reduction - seriously little cost 
 Low frequency tonal noise from 8 architectural scale axial fans (several stories up and already fitted with 8m long silencers!) at a Corus steel-works had caused environmental noise problems over a number of years. All the possible conventional fan noise control solutions considered 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 
A pair of classic 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. Quarry Suction Fan Noise Reduction - fan-tastic results, and no maintenance payments
A 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.
Pick-and-Place Suction Fan Noise Reduction - a packet quieter...
This suction fan used in a newly designed, automated pick-and-place system for food packets on a production line generated high levels of noise. Conventional fan silencing would not only have posed a hygiene problem (attenuators make use of porous acoustic absorbent materials), but would also have required acoustic enclosure. We re-designed the fan mounting system (interestingly, the fan itself was designed for model aircraft engines) and modified the geometry slightly. This reduced the fan noise at source by 8dB(A) without affecting the efficiency.
HVAC - CHILLER - COOLING TOWER NOISE CONTROL
Roof-Top Air Conditioning Plant - "chiller farm" noise control at a 90% cost discount 
The 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 would also have required considerable planning (closing streets and bringing-in cranes) and there was also the possibility that the noise control measures 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 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 HVAC air conditioning system.
Cooling Tower Fan Noise Reduction + improved efficiency
Cooling tower noise control 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
The conventional techniques used to reduce chiller noise on air conditioning units involve erecting barriers and fitting silencers. These are not only high cost noise 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 this HVAC chiller 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 chiller performance or access.
Eurostar HVAC Fan Noise Control - no space, no spare capacity, no problem... 
The noise produced by the Eurostar Nightstock HVAC module (of which 140 had been built) was unacceptable both in terms of overall noise levels and tonal noise at the blade pass frequency of the fan and harmonics. Introducing conventional noise control techniques to reduce the tonal content (by the manufacturer) had been unsuccessful.
Maintaining the fan performance was critical and space within the air conditioning system was severely limited. Moreover, a retro-fit solution had to be developed very rapidly.
An HVAC module was tested in the workshop for both noise and performance. The optimum solution involved a combination of Quiet Fan technology coupled with a new 7 bladed impeller design. These modifications could not only be retro fitted quickly and at low cost, but they also fitted entirely within the existing HVAC unit i.e. no space implications. The whole project was completed within just a few days.
As the fan noise reduction modifications reduced the noise at source, they simultaneously treated the intake, exhaust and break-out noise through the fan casing. Conventional techniques would not only have required separate treatments for each of these 3 transmission paths, but would also have had a substantial impact on the HVAC system performance. In addition, the source control modifications will last the lifetime of the unit without maintenance or cleaning and with no degradation in acoustic or aerodynamic performance. Despite the remarkably high acoustic performance with a 24dB reduction in tonal content and an overall noise reduction of 8dB(A), the flow was only reduced by a very acceptable 4.7%. This engineering approach is widely applicable to other HVAC plant where it can be used to reduce costs and improve system efficiency.
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noise control audit - digital noise assessment - noise competency training - noise training - product noise control - fan noise control - VWF (Vibration White Finger) - Hand-Arm Vibration (HAV) assessment - HAV competency training - HAV database (HAV-Base) - Whole Body Vibration (WBV) measurement - environmental noise control - noise nuisance - environmental noise monitoring - production line testing (noise and vibration) - noise nuisance / annoyance recorders - frequency analyser and noise analyser software
Industrial Noise & Vibration Centre
889 Plymouth Road, Slough Berks SL1 4LP
Tel: 01753 698800 Fax: 01753 567 988
email:consult@invc.co.uk
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