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Circular Silencer

ALFA Circular Silencers are specially made for use in situations where it is necessary to reduce the noise in “air moving” applications such as axial fan, centrifugal fan and blower inlets and outlets, dust control equip¬ment, motor cooling fans, enclosure ventilation, diesel generator sets, compressors, pump house and other indus¬trial applications.

CONSTRUCTION

ALFA Circular Silencers are constructed from heavy gauge galvanised sheet metal casing with or without centre pod and internally filled with rockwool or fiberglass to provide high sound absorption. The standard construc¬tion of ALFA Circular Silencers remain it integrity up to a maximum pressure of 2000 Pa and continuous temperature exposure up to 260 degree C. Sound is attenuated by the acoustic infill in the silencer when the air passes through.
For special applications, such as high face velocity system or oily environment, a special acoustically transpar¬ent lamina can be inserted in between the perforated galvanized steel sheet and acoustic infill. Depend to the application; the lamina material can be glass tissue facing or polyester film.

TYPES & MODEL

They come in a range of sizes from 300mm diameter upwards and flange for direct attachment to axial or centrifugal fans.

There are 2 different models for the ALFA Circular Silencer:

  1. ACS – without centre pod Is a straight through circular silencers provide good acoustic performance with negligible pressure drop through the silencer.
  2. ACSP – with centre pod Is designed with a centre pod and provides higher attenuation with reasonable pressure drop.

Each model comes in 2 different lengths

  • 1D – 1 x diameter
  • 2D – 2 x diameter
DETERMINE CIRCULAR SILENCER WEIGHTDETERMINE PRESSURE DROPFINAL SELECTION
For ACS – without centre pod
Weight (kg) = 80 x Diameter x Length (in meter)

For ACSP – with centre pod
Weight (kg) = 120 x Diameter x Length (in meter)

To determine the ALFA Circular Silencers ACSP (with centre pod) pressure drop, there are 4 steps have to be considered

  1. Determine the airflow across the circular silencer (m3/s)
  2. Determine the circular silencer model, flange diameter and length
  3. Determine the “K” factor
  4. Pressure drop calculation in Pascal (Pa) = 0.6KV2
    where K “K” factor (refer to “K” factor table)
    V : Airflow (m3/s) / Cross-sectional area of the silencer
With our sound attenuator selection software, our acoustic engineer will be able to provide more precious silencer selection for particular noise control project requirement. The followings information is required for a professional acoustic calculation:

  • Noise source Sound Power Level in 1/1 Octave band (63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 80000Hz)
  • Flow rate through attenuator
  • Detail duct layout drawing
  • Maximum allowable pressure drop across attenuator
  • Resultant noise level design criteria