Circular Silencers

Round Duct Silencers


  • Cylindrical pressure-tight casing
  • Streamlined acoustic core baffle
  • Acoustic media protected by galvanized perforated sheet metal
  • Spun head for reduced entrance pressure loss
  • Tapered tail optimally designed for velocity pressure regain and insertion loss
  • 3 in. (76 mm) slip flange on both ends


  • Fan Inlet and Discharge
  • Air Handling Units
  • Cooling Towers
  • Radiators
  • HVAC Duct Systems and Commercial, Institutional and Industrial Buildings


  • Elbow Dissipative
  • Straight Dissipative
  • Cross Talk
  • Reactive (No-Fill), Elbow and Straight
  • Axial Cone
  • Transitional
  • Custom


Silencers shall be fabricated from G90 galvanized steel. The casing shall have the following minimum thickness:

  • 22 ga. (0.85 mm) for Diameter (D) between 12 in. - 24 in. (305 - 610 mm)
  • 18 ga. (1.31 mm) for Diameter (D) greater than 24 in. (610 mm)

All silencers shall be airtight to a pressure differential of 10 in. Wg.

The acoustical absorption media shall be continuous strand fiberglass packed under compression and protected by a minimum 22 ga (0.85 mm) galvanized perforated steel. The absorptive core baffle shall be centered in the casing and shall have a spun head on the inlet end. The tapered tail of the core baffle shall be optimally designed for pressure drop and insertion loss.

Kinetics standard circular silencers are available in 10 different types and three standard lengths for a total choice of 30 different designs to cover most customer needs. Many non-standard variations are also available. Contact the factory for more information.

Round Sound Attenuator Selection Chart Circular Silencer Model Designation

Insertion Loss

Insertion loss data is provided for standard silencer construction. If special designs are required, such as plastic film or glass fiber cloth covering for the acoustic media, consult your local Kinetics representative or refer to our web-based silencer selection program.

Pressure Drop

The pressure drop across the silencer increases with the length of the silencer yeilding higher insertion loss. For silencers with a sound absorbing bullet, higher insertion losses are achieved by reducing the open area of silencer face area. This constricts the flow and increases the pressure drop.

Pressure drop data is presented for a silencer inserted in a duct when neither end is near a bend, elbow or transition.

Return Air Circular Silencers

Return Air Circular Duct Silencer
Model VCS-4-B2


  • Blank or drilled iron ring flanges, single or companion
  • Fiberglass cloth or tedlar film between acoustic media and perforated interior and bullet shells
  • Lifting lugs appropriate for horizontal or vertical orientation
  • Stainless steel type 304 or 316, aluminum construction
  • Mounting feet

System Noise Analysis

We offer a web-based silencer duct system and acoustical analysis program to engineers world-wide. Contact us to learn more.

*All Kinetics silencers are backed by independent testing in a NVLAP accredited laboratory in accorance with ASTM E477-06a and AMCA 1011-03.

Mechanical Systems

Vibration Isolation Seismic & Wind Noise Control