Mechanical equipment at a juice processing plant produced excessive sound levels at work stations along the production line. The dominant noise source is a bottle filling station where an impact air tool tightens bottle caps and the bottles rattle on the line guide pan. Another significant noise source in the room is an air compressor that powers the facility.
The following chart shows a noise survey session record along with an expanded view of a shorter segment. The capper impact tool noise appears as four short bursts, followed by a pause while bottles are positioned. The compressor duty cycle lasts about four minutes as shown by the solid line. Overall noise level is 80 to 83 dB, with highest values when the compressor and capper are both on at the same time.
The capper air tool was treated using an exhaust baffle lined with glass fiber batt held in place by a wire mesh screen. The underside of the bottle guide pan was faced with multiple layers of rubber backed sheet metal flashing to act as a vibration absorber. The air compressor was fitted with an enclosure consisting of a plywood box lined with glass fiber batt insulation.
The overall reduction in noise level exposure at the bottle line operator workstation due to the combination of treatments described above was about 12 dB. This substantial improvement not only provided relief for workers, but also reduced exterior noise emissions from the building to neighbors.