COMPRESSED AIR
QUIET COMPRESSORS – THE KEY TO REDUCING FACTORY NOISE EMISSIONS
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n this article Andy Pulley, team leader & product specialist with Atlas Copco Compressors examines the historic issues of noise emissions in factories related to air compressor operation and its effect on workers and productivity. He explains how today’s need for compliance with health and safety noise level regulations has influenced the development of innovative technology to produce a new generation of quiet compressors. It is a matter of record that around 1 in 10 UK adults suffer from tinnitus and 1 in 6 are affected by other hearing loss. Overall, some 15 per cent of the population has suffered hearing loss as a result of sudden exposure to loud noise or long- term exposure to machinery noise emissions within an industrial environment. Probably the most extreme example of this problem was last century’s cotton mill workers deafened to the point that they were unable to communicate vocally even in close proximity to each other.
Working in a noisy environment long term can cause irritation, muffled hearing and increases the risk of developing tinnitus − vibration pressure waves are transformed into sound by tiny hairs in the ear that are flattened by excessive noise
and result in the continuous ringing sensation. Noise can also make it harder for workers to hear alarms and warnings, presenting a safety hazard. In the most severe cases the outcome is irreversible hearing loss affecting workers’ communication, concentration and performance, which in turn impacts on productivity. Since hearing loss is an issue, employers need take all the necessary actions to prevent this. All machines generate sound and vibration, so do compressors. The average noise level for an air compressor is 85 dBA. This is higher than a phone’s ringtone, which is 70 dBA, but lower than most headphones that can go up to 110 dBA. As set by the UK Control of Noise at Work Regulations 2005, employers are obliged to assess the risk to workers’ health and provide them with information and training if the noise level is 80 decibels and above. Employers must provide hearing protection and hearing protection zones when daily or weekly average exposure is up to 85 decibels. Even taking into account any reduction in exposure provided by hearing protection, there an upper limit value of 87 decibels above which workers must not be exposed.
28 OCTOBER 2020 | FACTORY&HANDLINGSOLUTIONS
WHAT CAUSES AIR COMPRESSOR NOISE? All machines generate sound and vibration and, until recent times, such has been the case with workplace compressors. A compressor’s perceived noise level can be influenced by a number of factors, the most obvious of which is proximity - the closer the compressor was sited to the workforce, the greater the disturbance and discomfort level.
It is for this reason it has been common practice to isolate compressor equipment into separate and, more often, outdoor locations remote from the point of use. This action may have successfully mitigated vibration and noise issues but at the same time it will have incurred significant cost and productivity penalties resulting from pressure drops in the air network as a consequence. The mechanical properties of different types of compressors plays a major part in noise creation, especially with reciprocating units operating with more moving parts that generate vibration. However, the physical properties of the room in which the compressor is installed can contribute significantly too.
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