To comply with noise ordinances and protect the health of workers, industrial silencers are used throughout industrial facilities. The goal of these industrial silencers is to reduce noise without adversely impacting equipment or processes.
This presents a number of design challenges. Industrial silencers must often be built or installed in relatively small and awkward spaces. As with any object that could be placed in a system with flow, they will, inevitably, modify the flow of fluids.
Changes in the flow of fluids, including changes in pressure, turbulence, and velocity can all have effects on equipment downstream and upstream of the silencer. Designing silencers with this equipment in mind is key.
Core Takeaways
- Industrial silencers can be installed in high-air volume and static pressure systems, including vacuum intakes and exhaust stacks.
- The use of industrial silencers will change airflow; good industrial silencer design involves minimizing disruptions to airflow, especially when such disruptions would have significant upstream or downstream effects on equipment.
- By analyzing flow conditions, and simulating the effect of a given silencer on flow, it is possible to accurately predict the effect of silencers on airflow.
Analyzing Air Flow
Main Silencer Dimensions
Industrial silencers are matched to fan inlet and outlet flanges; they must fit within the ventilation system, which means there is a hard limit on how large a given silencer can be. At the same time, a silencer must reduce the noise produced by a system by a set amount so there is a practical limit on how small an industrial silencer can be.
Given these limitations, engineers must focus on achieving noise reduction targets and minimizing the impact of the silencer on flow all while working within set dimensions. There are several ways this can be done, including:
- The use of smooth transitions to allow air to flow freely
- Careful attention to the cross-section, spacing baffles appropriately to allow for noise control all while allowing air to pass through relatively unimpeded
- The use of flow management features to guide air and minimize resistance
Our silencers typically offer noise reduction through three means: We offer absorptive silencers, reactive silencers, and dissipative silencers. Most industrial fan silencers use absorptive properties to meet industrial noise control targets, but reactive silencers can help reduce low-frequency noise.
Each type of silencer will use different methods of mitigating their effects on flow. All of these methods will have some impact on the overall dimensions of the silencer; as such, each individual silencer must be carefully custom engineered for the conditions in which it will be used.
Flow Conditions
Industrial silencers affect both upstream and downstream flow. The pressure, velocity, temperature, contaminants, and other features in the airstream must be considered during industrial silencer design. The goal of the engineers should be to meet specific noise attenuation requirements with minimal impact on the flow conditions of the airstream.
The Effects Of A Silencer On A Flow System
Whether a silencer aims to absorb, dissipate, or reflect sound waves, it will inevitably have some effect on airflow within a system. When care is not taken to mitigate these effects, a host of problems can occur.
The first problems occur upstream: Pressure loss reduces the effectiveness of fans in the system, leading to more wear and tear, lower energy efficiency, and loss of functionality. Turbulence can also occur, especially when air isn’t properly guided through the silencer and this can lead to serious problems for upstream equipment.
Fans that are working harder and additional turbulence can also both lead to noise pollution. When the goal of a silencer is to reduce loud noises, and that silencer increases the noise generated upstream in the system, there’s been a failure in design.
Negative downstream effects are also possible; pressure drop and turbulence can affect the performance of filters, heat exchangers, and other equipment. This can again lead to turbulence, wear and tear, and additional noise.
Other Considerations To Make When Designing Silencers
Flow considerations are among the most important when designing silencers, but there are several other things to keep in mind during the design process.
- Which surface finishes are appropriate? Corrosion resistance may be required in airstreams with moisture, salinity, chemicals, or other corrosive elements. Antimicrobial coatings may be appropriate in food processing and other sensitive industries. Surface finishes can also make a silencer smoother, improving airflow.
- Field access and servicing: All industrial silencers will require occasional maintenance; that maintenance becomes more important for silencers in dirty airstreams. Ensuring that silencers are easily accessible and, when necessary, removable, can be an important element of design
- Space and weight restrictions: As discussed, all silencers must meet stringent size and weight requirements in order to fit within the existing system without disrupting or damaging any of its components.
Conclusion
To provide noise control while minimizing their effect on flow, industrial silencers must be custom-designed for their environment; there is no one-size-fits-all solution.
The team at VAW Systems designs industrial silencers for intake and discharge systems; our silencers are compatible with virtually all axial and centrifugal fans. Our engineers take care to consider all elements of your system, including flow considerations when designing your silencer.
We also have a number of other silencers available that are designed for industrial use, including blow-off steam vent silencers. Contact us today; we’ll design an industrial silencer that’s custom-built for your system and noise reduction needs.