Robotics Assembly / Welding Assembly

Curtain Walls Control Noise and Dust

Originally employed for partitioning space, fabric curtain walls can insulate workers from noise and improve the cost-effectiveness of exhaust fans.

March 1, 2013
Trans

Industrial fabric curtain walls are growing in popularity. In assembly plants, two of the fastest-growing applications are for lowering noise levels and controlling

Three Reasons Fabric Curtain Wall Projects Are Affordable

Less is more. The simplicity of these flexible, modular wall systems allows facility managers to create, define, or control space rapidly. Because industrial curtains are typically comprised of vinyl fabric, insulated batting and thread, they can be custom fit quickly and easily. These simple components can be installed with minimal interruption to daily operations, saving dollars related to the project.

More is less. Sizeable curtain wall projects can be completed at roughly 40 percent to 60 percent of traditional construction costs. Industrial curtain walls are installed from the roof structure down and not from the floor level up, so there is no limit on height. Also, industrial curtains don’t have to get thicker in profile to carry the vertical height of the project. This saves space and allows room for additional racking. It also eliminates the need to provide costly forklift protection at the base of the curtain—making curtain wall projects more affordable.

Reconfigurable. Curtain wall systems can easily be reconfigured if a facility’s process or product flow changes in the future. Changes can be made quickly, without the cost or mess of demolition. This provides cost savings on future projects.

dust. Industrial environments that use fabric curtain walls to provide these benefits are safer and more pleasant for employees.

Noise from industrial machinery or processes can be merely an annoyance, or it can pose a serious long-term safety threat to employees. The Occupational Safety and Health Administration (OSHA) estimates that more than 30 million workers are exposed to hazardous noise levels in the United States every year.

Assembly and machine tool operation, process equipment (such as pumps, compressors and blowers), material-handling equipment (like conveyors and fork trucks), and power tools (nutrunners, grinders and drills) are just a few common sources of industrial facility noise. The effect of human exposure to noise levels higher than 90 decibels is cumulative. Because long-term exposure can result in permanent hearing loss, reducing noise levels is important for employee well-being.

OSHA requires employers to limit employee exposure to 90 decibels or less of noise on an 8-hour time weighted average basis. If industrial facilities are found to be above the 90-decibel limit, employers are required to take action to ensure employee exposure levels are below this limit.

Traditional Methods of Noise Control

There are multiple ways to address noise control issues in an industrial environment. These include redesigning the problematic equipment or replacing it with newer, quieter models.

Unfortunately, these approaches aren’t always feasible, due to the cost or availability of quieter equipment. Noisy machines can sometimes be modified to reduce or eliminate noise-producing vibration—often by the addition of isolation pads or vibration dampeners. Machines may also be encased in sound-absorbing enclosures or materials.

If these approaches prove impractical or fail to produce the desired result, noise-reduction barriers can be placed between the offending equipment and affected employees. These rigid, insulated walls or partitions are strategically placed to block the path of transmitted sound waves, as well as absorb and scatter them, reducing the decibel level that actually reaches the employees.

The final line of defense against excessive noise involves personal hearing protection equipment, such as earplugs or noise-cancelling earmuffs. Although effective, this equipment has the obvious shortcoming of only being useful while actually worn and fitted properly. Additionally, in a facility where hearing protection is required, regular hearing testing of affected employees is mandated by OSHA.

Sound (-Dampening) Solution

Flexible acoustic curtain walls offer a relatively new approach to providing employee safety and comfort from excessive noise levels in industrial facilities. These fabric curtains can be effectively used for both noise source and noise path insulation.

The flexible sound curtains can be wrapped around the noisy machines 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.

The sound transmission coefficient (STC) of flexible curtain walls ranges from 15 decibels to more than 30 decibels. A curtain with a high STC deadens sound better than one with a lower STC.

Curtains also offer additional advantages over rigid walls. For example, flexible curtain walls can be configured to fit virtually any interior space, and they require less time to build than permanent walls.

Sound-insulating industrial 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), which reduces sound at mid- to higher-range frequencies; open cell foam, which offers noise reduction over a range of frequencies; or densified loaded vinyl or other flexible polymer sheet material, which reduces lower-frequency noise. Each component plays an important role in reducing sound levels impinging on the curtain surface.

Dust is a Quality and Safety Issue

Dust or particulates suspended in the air can be a nuisance, as well as a quality issue. Most importantly, however, it is a safety issue.

As a nuisance, particulates generated from welding, cutting, grinding or mixing can settle on surfaces far from the operation if containment equipment is not in place. Dust on neighboring equipment becomes a constant drain on cleaning and maintenance resources.

Dust can also spoil or degrade batches of critical materials. While this problem is most associated with chemical or food processing operations, it can potentially affect a wide range of manufacturing processes.

From a safety standpoint, there are many circumstances where a high-enough concentration of airborne dust-sized particulates in a closed space can become explosive or flammable. This can often occur with seemingly innocuous products, such as grain in a grain elevator. When grain dust becomes too highly concentrated in an air space, a spark can ignite and set off an explosive chain reaction.

Additionally, airborne dust can be a health hazard to employees. These hazards can range from skin, eye or bronchial irritation, to more serious issues for people with asthma. Particulates even have the potential to cause serious diseases like lung cancer. That is why extremely thorough dust control is a critical component in asbestos remediation.

Traditional Methods of Dust Control

Several methods are used to prevent particulates in one space from contaminating another. These include:

Local exhaust. A high-velocity airflow stream captures particles at the point they are generated and carries them away.

Exhaust with filtration. A high-velocity airflow stream captures particles and passes them through a filter medium, where they are removed. The air is recirculated.
Area exhaust. A high-volume exhaust fan draws air from the entire space to an outside vent or recirculates air through a filtration and separation device.

Barrier separation. A wall or partition is placed between the affected areas.

Each of the first three separation methods involves using an exhaust fan to move a volume of air containing dust particles through ducts. A local exhaust setup incorporates some type of hood that collects the air (with particulates) and funnels it into the exhaust ductwork. The area exhaust method includes multiple draw points through louvered openings in the ceiling or wall.

Either of these methods most likely would include some type of inline filtration or particle separator to remove particulates from the air stream. This is necessary prior to either recirculation of the air back into the space, or discharge of the air into the atmosphere.

Benefits of Curtain Walls

Curtain walls can significantly improve the effectiveness of traditional dust control methods. They can also provide savings in the initial cost of the equipment and direct operating costs. The key is to make the space to be exhausted as small as possible.

Reducing the volume of space to be exhausted means there’s less total air to move, meaning smaller fans can be used. Lower air velocity through filter media increases the effective particle separation of the filtration device. Additionally, lower air flow through the filter reduces the frequency required for change out or cleaning.

Regardless of the specific model, curtain walls are flexible, yet very durable, and can withstand contact from machinery or product. Unlike a hard permanent wall, curtain walls simply bend without breaking.

Curtain walls are also relatively easy to reconfigure, should a space need to be enlarged or reduced, or the shape of the space footprint changed. Curtain walls are easily installed or trimmed to fit around conduit, piping and ductwork, and they can be anchored to the floor to withstand pressure differentials across them.

Depending on the application, a curtain wall can be suspended from the ceiling or hung from a stand-alone framework. Curtain walls are available in stationary or sliding versions, the latter being suspended from a roller track. The walls can be fitted with strip curtains, personnel doors, or high-speed industrial doors for a full range of access to the designated space. 

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