A-weighted noise levels from high-speed presses operating in the production area of a health care company manufacturing metered dose aerosols were generally over 85 dB. Most of the operators' exposure was due to direct radiation from the nearest presses, but reflected noise also built up as reverberant sound energy.
As part of their overall noise control programme, the company decided to install a network of absorbers suspended from the roof of the building. The absorbers had to be as low as possible for maximum acoustic effect but could not interfere with the fire alarm, power and sprinkler systems already placed in the ceiling.
Approximately 1400 absorbers were suspended from the eaves. Each unit was 900 mm long x 600 mm wide x 50 mm thick with a perforated steel case and plastic wrapping to prevent oil getting into the absorbent material.
About £30 000 (1995)
After installation, the reverberation time of the press shop fell and overall there was a noise reduction of 4 dB.
Photographs courtesy of 3M Neotechnic Limited. Equipment supplied and installed by Ash Peace Limited.