Despite efforts to mitigate audible dangers – assembly and machine tool operations, process equipment like compressors and blowers, material handling equipment, and power tools like saws and grinders – OSHA estimates that more than 30 million workers in industrial settings are exposed to hazardous levels of noise each year in the U.S.
In addition to long-term damage, OSHA warns that excessive noise can cause physical and psychological stress, reduce productivity, interfere with communication and concentration, and contribute to workplace accidents and injuries.
Less than 90 decibels
Due to the dangers of extreme sound levels, OSHA requires employers to limit employee noise exposure to 90 dB or less on an eight-hour time-weighted average basis. Employers are required to take action to reduce employee exposure to levels below that threshold.
Typical noise control methods
There are alternatives to personal protection in loud industrial environments, like redesigning or replacing loud equipment with new, quieter models. This option is not always possible due to the cost or availability of quieter equipment. Some noisy machines can be modified with isolation pads or vibration dampeners to reduce or vanquish excessive sound. Encasing machines in sound-absorbing enclosures or materials is another option.
Yet another possibility is to implement noise-reduction barriers. Typically, these barriers are rigid, insulated walls or partitions that are strategically placed to block the path of transmitted sound waves, and absorb and scatter them, reducing the perceived sound that reaches the affected employees. These benefits can be realized after the downtime of construction.
A flexible way to control facility noise
Another option that is similar to rigid, permanent walls is sound-attenuating curtain walls. Curtain walls can be configured to fit virtually any interior space and require significantly less time to set up than it takes to build permanent walls. Individual fabric panels of virtually any length are interconnected with Velcro to form each continuous wall.
Curtain walls also can be easily re-configured to adapt to changing production demands and floor layouts. It’s easy to add to or enlarge an initial curtain wall installation. If source sound levels increase for any reason, it is very simple to add a second layer of flexible sound curtain to an existing one, or even to augment an existing rigid wall (a fairly common application).
How curtain walls turn the sound down
Acoustic curtain walls normally consist of two layers of a woven, coated fabric surrounding one or more layers of various insulating materials. These materials might include fiber batting (polymer or glass), open cell foam, or densified “loaded” vinyl or other flexible polymer sheet material.
Each component plays an important role in reducing sound levels encroaching on the curtain surface. The mass loaded vinyl sheet in a sound curtain is more effective in reducing lower frequency noise than the other components (low frequency sound is best absorbed or deflected with high-density solid materials). Fiber batting is effective in reducing sound at mid to higher range frequencies.
The interior core of a typical sound curtain will consist of a layer of sound-dampening, loaded vinyl and a layer of antimicrobial polyester batting as an additional sound buffer that also serves to fill out and maintain the body of the panel. This core is captured between two outer layers of 18-ounce flame-retardant vinyl, available in a number of colors for aesthetics.
Typically, the loaded vinyl side of the core is positioned facing the offending noise source, between the source and the desired ambient sound area. In a completed installation, the wall acts to trap the sound in a specific area and limit the migration of the sound to the ambient employee areas.
A new approach
Flexible acoustic curtain walls offer a relatively new approach to providing employee safety and comfort when it comes to noise levels in a commercial or industrial facility. These fabric curtains can be effectively used for noise source insulation, as well as for noise path insulation. Noisy machines can be wrapped in flexible sound curtains, like a “blanket.” They can also be attached to a close quarters support frame around the equipment.
Larger sound enclosures can be formed using these curtains, including complete rooms or separating walls. In a typical application of this sort, a metal mounting angle is installed across or along a run of the roof supporting bar joists (welded, clamped or bolted), and the insulated curtain is simply screwed to this angle along its top edge using self-drilling screws. The curtains are normally made of five-foot wide panels and have vertical Velcro® attachment hems to join multiple panels creating a full width curtain.
Low maintenance, all-purpose
In addition to their noise reduction performance and simple construction/adaptation, flexible curtain walls offer additional advantages. These fabric-covered walls can be easily cleaned with simple detergent and water. Acoustic curtain walls not only mitigate noise transmission, they have been engineered to provide thermal insulation for the prevention of condensate or frost buildup.
Handling dangerous noise effectively
Constant loud noises in the workplace are a significant health hazard to employees. Dealing with high noise levels can be a difficult and expensive undertaking, but it is also necessary. Acoustic curtain walls represent a cost-effective and flexible alternative to classic methods used for noise abatement, and bring their own value in other ways to an industrial environment. From employee safety to employee comfort resulting in higher productivity, the benefits of keeping noise levels under control, especially with insulated curtains, are real and obvious.
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