Industrial fans can make a tremendous amount of noise; without proper noise attenuation, the sound they produce can lead to noise ordinance violations and hearing damage.
Fan silencers are designed to provide the noise attenuation that industrial operations need, without having a noticeable effect on upstream or downstream airflow. In this article, we’ll provide a high-level overview of how fan silencers work, the different types of fan silencers, how to choose the right fan silencer, and more.
What Are Fan Silencers
Fan silencers use a number of different sound attenuation principles, like absorption and reflection to reduce the noise generated by fans. They may be installed at a fan’s inlet or outlet, preventing the noise generated by the fan from traveling through ductwork and vents.
How Fan Silencers Work
There are various fan silencer types such as rectangular and elbow baffle and circular-pod configurations. Each fan silencer must be designed for the specific circumstances it’s being employed in: Connectors must match the fan, noise reduction levels must meet the goals of the facility, and the size, shape and materials of construction must be suitable for the infrastructure in which the silencer is being installed.
In addition to the above concerns, fan silencers must also have a minimal impact on the airstream; they’re carefully engineered to meet all of these stringent requirements. This includes an evaluation of both the silencer pressure loss and system effect interactions between the silencer and the fan, duct system, or both.
Sizing Industrial Fan Silencers
To properly size an industrial fan silencer, engineers must consider airflow; the goal is to provide adequate noise attenuation without creating pressure drop. Additionally, the physical parameters of the space where the silencer is being installed must be considered.
Like many highly engineered products, bigger (or smaller) is not necessarily better when it comes to fan silencers; several formulas are employed to ensure that your silencer is perfectly sized for the needs of the system in which it is being installed.
Passive Vs. Active Fan Silencers
At VAW, we offer passive fan silencers for commercial and industrial settings. Broadly speaking, there are two different types of fan silencers: Passive and active.
Passive Fan Silencers
Passive fan silencers are often the preferred solution for business owners, as they do not require an additional power source; they passively reduce sound through clever engineering.
These silencers are constructed with sound-absorbing materials; fiberglass, foam, and different types of acoustic insulation may be incorporated. They’re also frequently fitted with protective films and anti-corrosive coatings, depending on the airstream. They’re often designed to take sound through a type of maze, reflecting, absorbing, and dissipating noise.
VAW provides all types of passive silencers.
Active Fan Silencers
Active fan silencers employ a clever trick; they use microphones to pick up the sound produced by a fan, a control unit to process that sound, and a speaker to emit sounds that cancel out the original sound waves.
Unfortunately, these silencers are prone to the many problems you might expect from technology that relies on electronics; In addition to airflow limitations, active systems need to be repaired more frequently, they need a steady, reliable power source, and they are prone to malfunctioning.
VAW does not currently supply active silencers.
Types Of Fan Silencers
Fan silencers come in a variety of different types; listing all of them here would be next to impossible, as each type is suited for different fans and air handling units. The goal of reducing noise remains the same, however, and each silencer is designed to accomplish this goal within various parameters (like maximum allowable pressure drop).
Circular Silencers
Circular silencers are silencers designed for circular ducts. We offer both circular inlet and circular discharge silencers; they’re compatible with virtually all axial and centrifugal fans. We use a variety of different casing materials, including galvanized steel, stainless steel, and aluminum.
Rectangular Silencers
Rectangular silencers are silencers designed for rectangular ducts. Like our circular silencers, we offer rectangular inlet and discharge silencers that are compatible with axial and centrifugal fans. The casing options are the same as with our circular silencers; the only real difference is the shape.
Straight-Through Silencers
Straight-through silencers or in-line silencers are designed to be installed in a straight section of ductwork; for this reason, they sometimes fall under the broader category of “duct silencer”. They’re available in rectangular and circular form and often feature perforated metal linings along with sound-absorbing materials.
Reactive Silencers
Reactive silencers are used in applications where airflow contains contaminants like dust, oil, or ash that would clog absorptive baffles, degrading their performance. Reactive silencers direct sound waves through chambers that partially reflect sound waves; these partially reflected waves meet new sound waves, interfering with them and canceling them out. They’re particularly good at eliminating low-frequency noises.
Removable Baffles
Baffles are panels or segments of sound-absorbing material found within fan silencers; removable baffles are quite simply baffles that can be easily accessed and removed. These, too, are used for dirty airstreams, where cleaning the baffle may be important to avoid the degradation of its sound attenuating qualities.
Resonator Silencers
Resonator silencers use cavities that are tuned to a specific frequency; when sound waves of that frequency enter, the resonator cavity vibrates in a way that cancels out those sound waves. They’re used less frequently as fan silencers because fans generate broadband noise and they’re tuned to eliminate specific frequencies. They can, however, be used as duct silencers in some contexts.
Parts Of A Fan Silencer
As we’ve explored, fan silencers come with a variety of different components; baffles, protective shells, inner tubes for air to pass through, insulations, inlets, outlets, flanged connections, transition sections, and more. The exact parts of your fan silencer will depend on its construction; some might feature resonators, while others might have reactive chambers.
Why You Should Use A Fan Silencer
Fan silencers provide a number of essential benefits to businesses. Without a fan silencer, you may violate both occupational and property noise ordinances. Excessive self-generated noise can lead to by-law violations, but it can also lead to damage to the hearing of team members and visitors.
How To Choose The Right Fan Silencer
You should not attempt to choose a fan silencer yourself; these are carefully engineered products, and there’s no one-size-fits-all solution, especially for airstreams used in industrial processes.
We can help you pick the right fan silencer for your needs; to do so, we’ll need information from you, including:
- Acoustic requirements
- Max allowed pressure loss
- Operational flow and temperature
- Airstream composition (clean, dirt, grease, particulate, etc.)
- Size, space and weight restrictions
- Field access and installation constraints
- Exterior finish and/or interior surface protection
- And more
Understanding these factors can help us design the right industrial fan silencer for your needs. We highly recommend using our proprietary software, FANSIL, to get a better understanding of the information we’ll need and the types of fan silencers we may recommend for your business.
The Installation Process
To design your silencer, we’ve taken into account environmental, field access, and installation constraints, as well as the size of the system in which we’re installing the silencer. For these reasons, installation is typically fairly straightforward; where needed, we may be able to help you install the fan silencer. Installation should be performed with care; while the process is straightforward, errors can lead to your silencer losing some of its efficacy.
Safety Precautions
A properly designed fan silencer should not pose any safety risks during operation; it should have minimal effect on air pressure, and your fans should continue to function without any issues.
The most important thing to remember is that proper installation is key; without it, you could end up damaging your fan or downstream equipment. Another point that may seem obvious but is worth repeating: Be sure to turn the fan off during the installation process and to carefully test everything before resuming regular operations.
Conclusion
Industrial fan silencers are an essential part of many commercial and industrial processes; without them, fans can generate excessive noise that can damage hearing and violate noise ordinances.
Here at VAW Systems, we manufacture a variety of industrial silencers, including industrial fan silencers. We’ve even developed a best-in-class silencer selection software, FANSIL, that can help you ascertain which materials and silencer styles are best for achieving your noise reduction goals.
Interested in noise reduction technology for your business? Get in touch with us today for fan and vent silencers; our custom-engineered solutions can help you reduce noise without long-term disruptions to your business operations.