Vent Silencers

In process, petro-chemical and electricity power generation plants there are typically numerous safety and control valves depending on the system configuration. The opening of these valves to vent steam, gas or vapour is accompanied by very high levels of noise. In order to protect employees from excessive plant noise and to comply with statutory regulations, installing vent silencers may reduce accidents arising from shock reactions, eliminate noise-induced hearing damage of personnel and prevent wider environmental noise issues.

Vent silencers are designed to reduce noise level of exhaust piping to the atmosphere for pressurized gaseous fluids, such as air, vapour, natural gas, nitrogen, oxygen, carbon dioxide, etc. They can be installed downstream any device acting as a link between a container of pressurized gaseous fluid and the atmosphere. The vent silencer can also provide high or low back pressure relief for the system ensuring proper operation.

Noise reduction can be attained using two principles: a reactive section to attenuate the low frequencies, providing broad band noise reduction; an absorptive section for high frequency noise mitigation. Vent silencers can be reactive, absorptive or combined type depending on applications and required attenuation, available up to 75 dB(A).

Typical performance characteristics and options include:

  • Flow up to 1500 t/hr
  • Fluid temperature -200°C > +550°C
  • Upstream pressure > 400 bars
  • Flanged or welded connections
  • Welded construction tailored to the fluids, pressure and temperatures
  • Flanged or welded tube connection
  • Design and Construction complies with ASME, Codap, CODETI, RCCM…
  • Horizontal or vertical position
  • Integrated supports, rain cover, protective mesh

We provide vent silencer acoustic solutions to a wide range of sectors and disciplines. Working with consulting engineers from design and specification through to contractors and clients for project implementation – we commonly deliver vent noise control solutions to the conversion of power and process sectors;

Combined Cycles

CHP Plants

Fossil Fuel Power Plants

Thermal Solar Plants

Waste to Energy

Nuclear Power Plants

Industrial Applications

Oil and Gas Applications

Gasification Process

Liquification Plants

Talk to us today

Please contact our team for advice relating to your new project.

Chetan Shah

+61 2 8781 0400
+61 404 822 976

Typical Applications

Vent silencers reduce the very high noise level created when high pressure gas or steam is expanded to atmosphere. This noise is produced by the rapid turbulence of the mixing gas jet and energy release of the compressed gas – back pressure relief for the system is another noise source operation which can be addressed. Most of the noise occurs at the expansion across the valve and is emitted at the stack opening. Typical applications for the noise reduction of high pressure gas flow:

  • Safety valve (PSV)
  • Relief valve (PRV)
  • Ejector
  • Start up valve
  • Snort-valve
  • Flash and Blow Down Tanks



Fluids under high pressures create lots of turbulence, noises and shock waves when they are released to the atmosphere.  IAC Acoustics range of vent silencers reduce noise that is generated by the expansion of gas or steam from elevated pressures to atmospheric pressure.  Comprised of a custom pressurised inlet diffuser that changes the noise spectrum from low frequency to a more easily attenuated high frequency range – this noise expands into a plenum and then passes through a tube module where the noise is absorbed by acoustic infill before being vented to atmosphere.

Please inquire today, we can propose a application specification for your installation – if no standard product meets your requirements we can propose a customised solution based on our extensive historical product and test data.


IAC Acoustics vent silencers can be tailored to suit a wide range of valve pressures and flow rates to provide attenuation of noise levels throughout the system flow range in order to meet the required noise reduction target. Noise level targets are typically at a specified distance from the silencer and are dependent on the;

  • Flow rate
  • Temperature
  • Pressure of the system


Due to the many variables and the complexity of vent silencer sizing, selection, and design, computer optimisation methods are employed. The size is generally dictated by velocity, required noise reduction, and allowable pressure drop.

Materials and Options

Silencer components are generally constructed from carbon steel. However, they may be constructed from other materials to meet specific design or application requirements such as high temperature, corrosive environment, or oxygen service. Material recommendations are dependent on the specified operating conditions.

For a corrosive environment, components or complete silencers can be constructed from Stainless Steel (usually 304 or 316). For oxygen service, Monel or a Monel/300 series steel combination is usually used together with special cleaning and degreasing procedures.

(Standard supply : Butt weld)
Connecting flanges

• Standard: WN flanges Class 150# as
per ASME B 16.5
• Options available for other classes
and alternatives (For example slip-on)

Standard supports are part of bottom plate

Other support can be supplied as options

Allows pipe movements due to thermal expansion, avoiding nozzle loads

• Standard radial movement is :
+/- 20 mm [3/4’’]
• Standard axial movement up to
50mm (2’’)
• Pipe sealing is maintained

• Prevents rain entering the silencer
• Bottom drain as standard




  • Flow rate, pressure, temperature
  • Saturated or superheated steam
  • Alternative gases



  • Control, start-up and blow down
  • Regular, intermittent or continuous



  • Pressure drop
  • Back pressure
  • Valve integrity factor
  • Process control & stabilisation



  • Up to 75dB (A)
  • Point of measure
  • Pipe noise interference
  • Rainhood impact

AGL - Torrens Power Station

AGL Torrens, located 18 km from Adelaide CBD on Torrens Island, is the largest power station in South Australia and the largest natural gas fired power station in Australia.

With a nameplate capacity total of 1,280 MW, the thermal power station burns natural gas in boilers to generate steam, which then drives the turbines to generate electricity. It produces enough power to meet the annual needs of approximately 470,000 average Australian homes.

We designed, manufactured and supplied 12 Vent Silencers for the Torrens Island site, as part of an upgrade project run by AGL.

“This was a very challenging but rewarding project for IAC Acoustics to deliver vent silencer solutions to AGL’s steam turbine power generation application. Located in the environmentally sensitive Port River estuary, controlling noise breakout from process activities was vital to both the surrounding wildlife and adjacent communities.  The installation and complexity of working with large silencers at height in a power generation facility was a challenge we thrived on, working with all partners and stakeholders to ensure the project was delivered on time and to budget. “

Jay Owen

Vent Silencer Solutions

IAC Acoustics extensive in-house engineering, manufacturing, and testing facilities ensure that both the mechanical and acoustic design is optimised for any application.  Our Vent Silencers have been developed so that they are completely customisable in order to suit a wide variety of installations.  With installations across a wide variety of sector applications, IAC Acoustics vent silencers are trusted globally to deliver installed acoustic performance with high quality product performance and durability.

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