Noise levels in a pharmaceutical manufacturing area were 95-100dB(A), dominated by the product air transport fan system. Whilst a traditional high-cost hygienic absorption system could be used to reduce the average area noise level by 5-10dB(A), it would still leave hot-spots of up to 95dB(A) near the air transport fans. As strict hygiene requirements ruled out conventional silencers, novel aerodynamic inserts were fitted inside the fan casings to reduce the tonal noise from these units by close to 20dB with no hygiene or performance implications over the life of the fans.
With the local fan noise eliminated, it was possible to reduce operator noise exposures to well below 85dB(A), reducing the hearing damage risk by around 95%, allowing PPE to be made advisory.
