Vent Silencers: Features and Usage

Fortunately, the era of intrusive heavy industry is coming to an end, thanks to targeted technological efforts aimed at reducing environmental impact.

Unfortunately, compressors, electromechanical pumps, and air distribution systems invariably generate a certain amount of noise, which is linked both to the intrinsic vibrations of the motor, which can be easily reduced with damping systems and suspensions, and to the actual airflow. In some cases, this noise can be quite bothersome, especially when it comes to sudden variations and continuous emissions from openings with diameters conducive to resonance.

Therefore, it is essential to equip all systems with silencers, noise suppressors for vents, compensation chambers, and enclosures to progressively reduce the disturbance caused by industrial activity to the surrounding environment until it almost disappears.
There are inherent limits to current technology, but our company has been working since its inception to minimize these limits and improve performance and noise reduction for every new project.

What Are Vent Silencers?

Gas exiting from a vent produces noise associated with various factors, ranging from the size of the outlet hole to the flow rate and pressure. This noise can vary from high-pitched whistles for high-pressure releases from narrow pipes to deep gurgles for wider openings and lower pressures.

While local disturbance is often considered the main issue for those working near the facility, the presence of noise projected externally cannot be overlooked. This noise can be perceived at great distances, depending on the type of environment in which the system is installed. Factors such as variable moisture sources like fields, ponds, and swamps, as well as proximity to residential areas, play a role.

If local noise reduction measures are not implemented for industrial plants, it can lead to issues where the noise, though considered under control within the factory premises, is still perceived at a considerable distance, resulting in management problems.

Vent silencers are devices installed on high-pressure steam outlets and are designed to absorb much of the remaining vibrational energy. This is achieved by utilizing honeycomb structures, grids, materials of varying densities, or the creation of complex expulsion paths similar to the mufflers in motor vehicles.

There are various types of acoustic dampers for high-pressure gas flow, depending on their installation point and the degree of pressure involved. Production facilities are required by law to be equipped with these systems and to strictly adhere to the limits imposed by regulations, under the risk of penalties, shutdowns, and the obligation to follow specified guidelines.

PSP-Type Vent Silencers

These noise reduction systems are equipped with a single expansion chamber and an absorption system. They can reduce emitted noise by up to 75 dBa.

They require minimal maintenance since they are passive devices made from low-corrosion risk materials, capable of withstanding steam stress for an extended period without intervention.

In vent silencers, the gas expands through a system consisting of one or more large concentric metal cylinders with perforated walls. These holes are designed to prevent whistling or mechanical resonance. The holes in each cylinder are not aligned with each other.

This ensures that the air never follows a direct path from one hole to another, instead impacting a surface covered with sound-absorbing material, which prevents noise propagation by dissipating it within its structure. This construction is protected by a perforated sheet and ensures long-term continuous operation.

SVR-Type Baffle Vent Silencers

This solution can be employed both within suction process ducts and in discharge pipelines. It is constructed from a set of baffle separators and has a standard configuration normalized to 100 mm H2O pressure and 130°C emission temperature.

These silencers exhibit extremely high noise reduction efficiency. During the design phase, the silencer’s size is determined based on resonance and reflection considerations related to the duct section it must be connected to, as well as the desired noise reduction in dBa.

Sizing parameters, translated into pressure drop, length, and section, depend on performance factors and can be adjusted within relatively flexible limits to adapt to the installation type, achieving excellent noise reduction results.

These types of silencers operate with direct passage absorption and have a significant advantage over PSP types: they present a very low pressure drop, meaning that the inlet and outlet pressures are closely comparable, eliminating the need for pressurization through electromechanical pumps or changes in diameter to recover airflow performance.

Cabins and Soundproofing

When discussing silencers, it’s worth mentioning soundproof cabins, which are rooms designed to house machinery and can also contain other noise reduction systems to achieve a significant base attenuation, reaching up to 50 dBa, making them an excellent starting point for reducing external noise emissions.

Cabins are usually made of metal and feature passive sound-absorbing materials resistant to corrosion, oxidation, and vegetative attack, allowing for reduced machinery noise and, in many cases, improved performance of direct passage silencers.

It is not advisable to use cabins for final vents, as they could create a dense atmosphere inside, with risks of condensation and other issues. However, in some applications, exceptions can be made to address otherwise unsolvable problems.

From Request to Design

Our engineers handle all phases of design and manufacturing, starting with acoustic elements to identify the optimal configuration for the required performance while offering the greatest convenience and flexibility for a product that will accompany your operations throughout its useful life, adapting to evolving systems and processes.

Subsequently, we proceed with mechanical design, focusing on structural analysis based on dimensions and construction materials, oriented towards its future positioning within your facility.

We give utmost consideration to the critical factor of fluid dynamics, as altering lift, i.e., when the silencer becomes a load on the system, can lead to issues with the reliability of your results and the device’s lifespan.

Supporting elements such as flanges, fins, outlets, diffusers with their respective dampers, and the selection of construction materials, ranging from stainless steel to carbon steel to meet the corrosion resistance required by your processes, are also taken into account.

Upon request, components with a high nickel density can be used, and we always guarantee the use of non-putrescible soundproofing materials such as glass wool or minerals with complete non-combustibility to ensure years of safe continuous operation without the slightest maintenance requirement until the final disposal of the device.