Noise Control Best Practice noise Fan Noise Control Best Practicable Means (BPM) Industrial Noise and Vibration Centre http://www.invc.co.uk/noise/noise-control/fan-noise-reduction/
Industrial Noise and Vibration Centre Award winning noise control technology for fans 800k capital and 250k / p.a. running cost savings for Corus Best Practicable Means (BPM) Best Available Technology (BAT, BATNEEC) In many cases, (including centrifugal fans, chiller / HVAC plant, large stacks, burners / combustion) BPM / BAT often cannot be claimed without reference to our technology. BPM / BAT Evaluation Often used as the arbiter of what constitutes BPM / BAT including court cases Buy Quiet Policy De-facto UK standard noise purchasing policy Presentations and Training Noise training providers for English, Scottish, Irish Environment Agencies and local authorities
Noise Complaints from Industrial Premises Source: National Physical Laboratory
Environmental Fan Noise Control is... not just about the overall level Effective noise control must be based on an accurate diagnosis that relates noise features to subjective impact, not on just on assumptions about overall db(a). Although db(a) may also be an additional planning / specification requirement, this is often a completely separate issue. Noise control should not be implemented at the expense of fan system efficiency. Conventional silencing will often have a significant detrimental effect on fan performance, increasing power consumption (running costs) and the carbon footprint. All the options must be considered, not just the conventional high cost conventional palliatives of barriers, enclosures and silencers. These techniques should only be used where it can be proved that there is no engineering alternative.
BS4142 Fails at Low Frequencies... BS 4142 does not work well for noise containing low frequencies. 5dB(A) correction for noise with tones Tonal noise at 5dB(A) below non-tonal noise should be equally disturbing Inside rooms, the T.L. of windows shapes the spectrum, reducing mid and high frequency components - almost un-'a' weighting the sound. BS 4142 is supposed to assess the likelihood of complaints from people in the building. It should not be used where background noise levels are very low (<30dB(A))
Noise Control Best Practice noise Fan Noise Control Diagnosis Industrial Noise and Vibration Centre http://www.invc.co.uk/noise/noise-control/fan-noise-reduction/
Cooling Tower Source ID cooling towers 1 / 2 at 2m grinder 5m bedroom window open/shut
Cooling Towers: Detail Only 71.3Hz blade pass of fans in tower 1 matches bedroom spectrum - grinder and tower 2 are eliminated as sources
Restaurant Fans and Chiller Bedroom and room below chiller Chiller tone at 48.5Hz + harmonics previous recommendations would not have worked, must isolate from roof
Noise Control Best Practice noise Noise Control Techniques Industrial Noise and Vibration Centre: www.invc.co.uk
Fan Noise Control Options Techniques by priority and cost effectiveness. Control at source engineering modifications efficiency lowest fan noise coincides with maximum efficiency vibration isolation and vibration damping Only if the above are not practical should you consider Silencing Enclosures Lagging Barriers Building modifications Conventionally, these high cost techniques have been the only measures that are considered.
Innovative Noise Control Technology These are some of the innovations we use as part of current best practice in environmental noise control. Award winning Quiet Fan technology (QFt) typically 10% - 20% of the cost, no effect on fan efficiency Chiller / HVAC noise control <20% of the cost, free cooling unaffected, higher efficiency Fan / combustion stacks Retro-fit, low cost, fast Burner / combustion noise Unique source control technology typically <5% of the cost Acoustic Camouflage Psychological electronic silencing
Placebo Silencers + Acoustic Camouflage
Centrifugal Fan Installation NOISY high pressure low pressure QUIET
Fan: Outlet dampers
Axial Fan Installations NOISY QUIETER
Axial Fan Installations >2-3 duct diameters NOISY QUIETER
Efficiency: Fan Speed v Noise Variable speed drives Two speed motors (day and night) Proportional control systems speed reduction noise reduction db 10% 2 20% 5 30% 8 40% 11 50% 15
Splitter Silencer Mineral Wool Perforated Steel
Cooling Tower Silencer Little attenuation due to material build-up
Fan Outlet Silencer Cowl steel / plywood acoustic absorbent A simple, cheap absorbent lined cowl can give a 10-20dB(A) noise reduction in fan inlet /outlet noise
Noise Control Best Practice noise Reactive and Other Silencing Industrial Noise and Vibration Centre: www.invc.co.uk
Drying Oven Problem 95dB(A) from gas burners at low firing 82Hz "boom" dominant Enclosure large oven - 8m x 4m x 3m @ c 30,000 with serious hygiene and maintenance problems INVC BPM organ pipe resonance excited due to weak mixture at low firing standard weld fume extract motor controlled valves fitted to each inlet 21dB off boom; 8dB(A) overall reduction; 100 each for 12 burners
Extract Fan System Duct Resonances 30dB tonal noise reduction Improved efficiency
Damped Dry Chiller Total 8dB(A) noise reduction under chiller (damping + absorbent)
Fan: Steel and Elastomeric Spring Isolators
Axial Vent Fans 8 off axial vent fans with 8m long silencers several stories up 112Hz blade pass problem tone reduced by 20dB by fitting invertors to change speed slightly to avoid resonant condition.
Yoghurt-Based Noise Control - Boiler Burner 16dB tonal noise reduction
Noise Control Best Practice noise Quiet Fan technology Industrial Noise and Vibration Centre: www.invc.co.uk
OG Centrifugal Fans: Corus 12dB noise reduction > 1 million cost saving > 800k capital + c 250k p.a. on power 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. for the most significant development in noise control technology
OG Centrifugal Fans: Corus Conventional solutions not suitable: varying fan speed x3 4 megawatt fans (c3.5m high) - loss in efficiency due to silencers unacceptable Source Control 173Hz tone reduced by 12dB saving of 0.6-1.2 megawatts power consumption (carbon footprint) > 250,000 capital cost saving plus 5 figure savings on annual running costs
Fan Silencing without silencers
Fan Noise Control Options Techniques by priority and cost effectiveness. Control at source engineering modifications efficiency lowest fan noise coincides with maximum efficiency vibration isolation and vibration damping Only if the above are not practical should you consider Silencing Enclosures Lagging Barriers Building modifications Conventionally, these high cost techniques have been the only measures that are considered.
Remote Control of Noise video sound photos @ email - internet @ Specialised analysis BPM BAT Costs database experience
Remote Control of Noise Romanian power station Laundry fan Ship unloading Roof-top fans Garage A/C plant Punch press
Remote Control of Noise BP Refinery: $1.25m conventional silencers: $0.25m via engineering no impact on efficiency, no site visit
Noise Control Best Practice noise Fan Noise Control Best Practicable Means (BPM) Industrial Noise and Vibration Centre: www.invc.co.uk