Five Types of Industrial Silencers Used for Noise Control

Noise-induced hearing loss is a significant health concern for individuals working in the manufacturing industry. Over 40 million people in the United States currently experience some form of hearing loss. Among these individuals, nearly 10 million Americans experience hearing problems caused by exposure to noise. This condition is often caused by repeated exposure to loud noises, particularly those that exceed 85 decibels, which is common in manufacturing facilities. To mitigate the harmful effects that noisy machinery and loud manufacturing floors have on employees, many manufacturing facilities are turning to industrial silencers to reduce this risk and enhance acoustical attenuation. To better understand the different types of industrial silencers and how they work to reduce hazardous noise levels, we must first understand the basics of acoustic attenuation.

Understanding Acoustic Attenuation

Acoustic attenuation refers to the weakening of sound as it travels through various materials. Sound waves are distributed, and thereby diminished, in two main ways. The first way this happens is through absorption. Acoustic absorption utilizes porous materials to absorb sound waves, converting sound energy into heat energy that is then dispersed throughout the atmosphere. The second element of acoustic attenuation is scattering. Scattering redirects sound waves away from their original path and sometimes reflects the waves toward the original noise source. Acoustic attenuation combines these two methods to reduce both the volume and perception of noise effectively. The industrial silencer types listed below utilize a combination of scattering and absorption to attenuate sound in industrial settings.  

Industrial Silencers and Applications

Reactive Silencers

Similar to the silencers used in automobile exhaust systems, reactive silencers are also commonly referred to as mufflers. Like car mufflers, industrial reactive silencers are designed with multiple chambers and perforated tubes. These perforations redirect the sound waves and reflect them toward the source of the sound, effectively reducing the volume of the noise we hear. These silencers do not contain any acoustic insulation and primarily attenuate sound by scattering and reflecting sound waves. One main benefit of reactive silencers is that they are relatively easy to clean because they do not contain fibrous materials, and they create negligible pressure loss. These silencers are also typically relatively small, making them suitable for use with engines and exhaust systems. Reactive silencers are commonly used for fixed-speed machinery, such as generators and blowers. They are best suited for machinery that produces pure tones and noises with frequencies ranging from low to medium.

Absorptive Silencers

Unlike reactive silencers, absorptive silencers primarily attenuate sound by absorbing sound energy, rather than reflecting it. These silencers use fibrous and porous packing materials to absorb sound waves and dampen the sound volume. As the sound waves travel through the insulating materials, some of the sound energy is partially transformed into heat energy, which is then dispersed into the air. The thickness of the acoustical lining used in absorptive silencers varies and is designed to meet specific project requirements. The thickness of the lining is often dependent on the predominant frequency of the noise. Absorptive silencers are particularly effective for high noise frequencies between a range of 500 and 8,000 Hz. They can also be used for frequencies outside this range, though adjustments to the thickness of the absorptive lining are required to provide the desired level of attenuation.

Since absorptive silencers rely on acoustic absorption rather than reflection of sound waves, they require minimal airflow to attenuate sound properly. For this reason, absorptive silencers are commonly used in centrifugal compressors, industrial fans, and gas turbine inlets. Additionally, they can be used in gas turbine exhaust systems and fans. Absorptive silencers can be installed vertically or horizontally, which makes them very popular in power and process applications. Absorptive silencers are also commonly referred to as parallel silencer baffles or splitters and can be specifically designed to optimize pressure drop and meet all noise criteria for your project.

Steam Vent Silencers

Also known as gas silencers, steam vent silencers are designed to reduce the amount of noise created by gas or steam. Steam vent silencers work differently from absorptive and reactive silencers, as they do not attempt to reflect sound waves and may or may not use absorptive materials. Instead, vent silencers attenuate noise by diffusing the flow of pressurized gas or steam as it exits a pipeline. Pressurized air can have a very high flow and velocity as it leaves a pipe. This creates unsafe noise levels and could potentially lead to noise-induced hearing problems. Steam vent silencers reduce the elevated gas and steam pressure created by machinery and eventually diffuse the flow to the atmosphere. These silencers are typically used in oil and gas processing, chemical processing, and heat recovery steam generators or boilers. They are also common in high-pressure vents, safety relief valve outlets, steam vents, and system blowdowns.

Combination Silencers

Combination silencers incorporate elements from multiple types of industrial silencers to create a customized noise control solution. These industrial silencers may utilize both scattering and absorption to attenuate sound, reducing noise to an acceptable and safe level. These silencers are more effective than a frequency-shifting silencer, however, as they are tuned to target a specific tonal noise. This process targets problematic frequencies and can reduce tonal spikes, thereby reducing the overall noise created by the fan exhaust. Combination silencers are installed in the gas path of a fan and are often used in conjunction with an absorptive silencer to provide additional attenuation. These silencers are custom-designed by our skilled experts at SVI Industrial to ensure that your manufacturing facility complies with all noise regulations and operates at a noise level that is safe for your employees.

New: BAR Silencers

BAR silencers, developed by SVI BREMCO, are a modern evolution in industrial silencing technology, designed to address both aerodynamic and structural challenges in high-performance environments. While reactive silencers use internal chambers to reflect and cancel targeted sound frequencies, and absorptive silencers rely on acoustical materials to dissipate noise across a broad spectrum, BAR silencers integrate the benefits of both approaches. Their perforated bar matrix allows for multi-directional flow dispersion and effective low-frequency attenuation, without the flow channeling limitations of parallel baffle systems. They also serve as a high-performance alternative to traditional parallel baffle silencers, offering enhanced acoustic control, reduced turbulence, and superior structural integrity under thermal cycling and side loading, as validated through finite element and vortex shedding analysis.

 

Choosing the best industrial silencer for your manufacturing facility depends on several factors, as each silencer type is best suited for specific projects. You need to consider the desired application of the silencer and the mandated noise regulations in your area.  For further information on the different types of industrial silencers, contact SVI Industrial’s team of skilled professionals.
We look forward to helping you meet your industrial silencer needs.