Getting Noise Under Control

Employee safety is an important factor for a Western Michigan automobile parts recycling facility, which is why a wall of insulating curtain was specified to enclose the noisy grinder. The new enclosure has resulted in a 20 percent noise reduction, creating a more comfortable and productive work environment for employees.

At the recycling facility, plastic bumpers were being grinded inside a standalone, 836-m2(9000-sf) structure called the ‘grind house.’ Noise was an immediate issue and needed to be addressed; the heavy-duty grinder was running virtually non-stop five days a week. A facility employee would continually load the grinder during each eight-hour shift while other employees nearby stripped the bumpers. Grinder noise was greatly amplified by the expansiveness and 5.5-m (18-ft) tall ceilings of the room. To initially protect against grinder noise—which was recorded at 120 decibels (dB)—employees wore both earplugs and earmuffs. Although the ear protection was considered safe, verbal communication between employees inside the facility was virtually impossible during operation.

The company’s initial plan for noise reduction was to build a permanent wall around the grinder. Before starting the project, however, other options for keeping noise to a manageable level were explored.

In the end, a flexible, reconfigurable fabric wall system was specified rather than a permanent wall to enclose the grinder.

Hanging like a curtain, fabric walls can be configured to fit various interior spaces, and be installed faster than permanent walls. Each insulated wall panel was constructed of durable, fire-retardant industrial fabric surrounding multiple layers of recyclable, anti-microbial polyester batting. Individual 1.5-m (5-ft) wide fabric panels of varying lengths were interconnected with fabric connectors to form each continuous wall.

Employees of the automobile parts recycling company installed the sound-dampening assembly around the grinder, which sits against a back wall in one corner of the facility. Two of the fabric curtains run the length of the grinder from front to back. They are attached to a concrete wall at the back of the grinder with screws and polyester nailing flaps. At the front-end of the grinder, connectors secure the front of the enclosure to the two sides. The front wall also has an opening where bumpers are fed into the machine. The connectors tightly seal the cut-out that serves as the grinder opening.

At the top of each wall, the fabric curtain walls are attached to angle iron previously built above all three sides of the grinder. The curtain’s weight holds the bottom in place on all sides. Inside the enclosure, a 254-mm (10-in.) diameter metal conduit routes the plastic chips from the side of the grinder to a hopper located outside the building.

Although new to the installation of fabric walls, three grind house employees installed the flexible enclosure in a little more than three days. To check the grinder for maintenance, employees simply pull back a part of the wall where it is attached with fabric connectors to gain access.

With the fabric walls in place, the grinder is completely enclosed. Subsequent tests showed the sound level inside the grind house dropped from 120 dB to 96 dB, representing a 20 percent reduction in noise.

With grinder noise under control, employees working in the facility only need to wear earplugs and can more easily communicate with each other. Above all, the insulated fabric wall system creates a safer environment for employees.

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