APPLICATION: Centrifugal/Axial compressors.

Noise is generated by high gas velocities associated with centrifugal and axial compressors, both because of turbulent flow and because of Von Karman vortices behind trailing edges. Noise problems are especially severe when a compressor operates in a surge condition, when hunting may cause flow reversal, and turbulance always increases.

The ACS compressor silencer is of the absorptive type, and is designed to attenuate noise created by high speed dynamic compressors handling gases at any pressures.

The Noise and Pulsation Control Ltd. compressor silencer typically provides attenuation of 15 to 45 dB, but attenuation figures can be supplied for each application, within specified allowable pressure drops.

Acoustic packing

Noise and Pulsation Control engineers select an acoustically absorbent material most suitable for the operating conditions. Acoustic packing is protected to prevent erosion into the gas stream.


The external casing is constructed of seamless pipe/pipe caps in smaller sizes, and continuously welded rolled plate/dished heads in larger sizes. The minimum thickness in carbon steel is 5mm. In pressure applications, silencers can be designed to pressure vessel codes such as BS5500 and ASME VIII. Construction can also be of stainless steel or other specified material.


Noise and Pulsation Control Ltd. model ACS silencers are guaranteed to meet, the customer's specified performance and integrity for a period of one and a half years after initial operation, or two and a half years after shipment.

Application data

For a specific recommendation on silencer, a customer should provide the following information:

  • Gas
  • Specific gravity and ratio of specific heats
  • Flow rate
  • Operating pressure
  • Operating temperature
  • Inlet connection size and type
  • Line connection size and type
  • Design pressure
  • Design temperature
  • Compressor type and speed
  • Number of impeller blades
  • Unsilenced sound pressure level at a specified distance
  • Required residual sound pressure level at a specified distance
  • Allowable pressure drop
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