RECTANGULAR SILENCER

Construction

Body of the silencer:

  • Exterior casing in galvanized steel, stainless steel or other weldedmaterial.
  • Exterior casing in steel with minimum 0.8mm thickness with structural steel.
  • Additional reinforcements (frame, angle, etc)
  • Special paint finishes for certain environment condition.
  • Holes on flange for lifting and connection.

Baffles:

  • Choice of wool types (rockwool, fiberglas, etc)
  • Choice of wool thickness and density.
  • Polyester film, black matt finished, glass cloth, etc to protect the acoustic media from oil, water, fiber erosion, etc.
  • Hexagon profile for flow entry and taper end for flow discharge to limit turbulence and pressure drop.
  • Perforated galvanized steel, stainless steel or other material.
  • Baffles assemble with internal structure.

Connecting flanges:

  • Angle iron or TDC/TDF flanges to connect to the ventilation duct system.

Special assembly:

  • In case of concentrated smoke or accumulated dust, it is possible to opt for periodic cleaning or replacement of baffles.

 

 

Please use the form below to make an enquiry and we will get back to you as soon as possible. Alternatively you can use our full contact details.

RECTANGULAR SILENCER

RECTANGULAR SILENCER

Construction

Body of the silencer:

  • Exterior casing in galvanized steel, stainless steel or other weldedmaterial.
  • Exterior casing in steel with minimum 0.8mm thickness with structural steel.
  • Additional reinforcements (frame, angle, etc)
  • Special paint finishes for certain environment condition.
  • Holes on flange for lifting and connection.

Baffles:

  • Choice of wool types (rockwool, fiberglas, etc)
  • Choice of wool thickness and density.
  • Polyester film, black matt finished, glass cloth, etc to protect the acoustic media from oil, water, fiber erosion, etc.
  • Hexagon profile for flow entry and taper end for flow discharge to limit turbulence and pressure drop.
  • Perforated galvanized steel, stainless steel or other material.
  • Baffles assemble with internal structure.

Connecting flanges:

  • Angle iron or TDC/TDF flanges to connect to the ventilation duct system.

Special assembly:

  • In case of concentrated smoke or accumulated dust, it is possible to opt for periodic cleaning or replacement of baffles.
Installation in an Air Duct System

The following illustration shown how to use our silencers in optimal conditions and obtain maximum effectiveness.

It is best to install the silencer close to the noise source to avoid breakout noise across the ducts. An incorrectly installed silencer can short circuit the noise travel path and reduce the acoustic performance.

We recommend that the rules of HVAC Systems Duct Design to be followed. Improper installation waste energy, increase pressure drop and create high re-generated noise.

Selecting a BEL Rectangular Silencer

Selecting a silencer depends mainly on the noise band frequencies to attenuate and the acceptable pressure drop. If you require higher attenuation, the acoustic media must be thicker and/or the silencer must be longer. Follow the sample calculation sheet for HVAC silencer selection as below. It will help you choose your optimal silencer wisely

Noise Calculation Procedure:

The simplest calculation for attenuators is for downduct noise. This is, as it’s name suggests, the level of noise transmitted down a duct system. The following summary gives the calculation procedure.

  1. Find the fan sound power level, SWL(fan). The values for all octave bands.
  2. Choose the worst duct run (normally the shortest), and calculate the attenuation A1 due to straight duct runs, bends or elbow.
  3. Define the air grille/diffuser area and installation condition (flanged or unflanged), and calculate the attenuation A2 due to reflection of low frequencies at the air outlet or inlet.
  4. The total sound power leaving the ductwork system (Sound Power Leaving, Lw(l)) is,

    SWL(l) = SWL(fan) + A1 + A2

  5. Calculate the reverberant sound pressure level, SPL(rev) by correcting for the total % of flow to the chosen room, A3 [10log(%/100)] and find the corrections for room volume(V), A4 [10log(4/0.16V)] and reverberation time(t), A5 [10log(t)]. Allow for the number of systems(n) serving the room, A6 [10logn)].

    SPL(rev) = SWL(l) + A3 + A4 + A5 + A6

    Remark : for noise calculation to outside building (open space), reverberant sound
    pressure level to be omitted.

  6. Calculate the direct sound pressure level SPL(dir) by correcting for the total % of flow to the nearest grille, A7 [10log(%/100)]. This is in general different to A3. Find A8, the correction from sound power to direct sound pressure level at a distancer [10log(1/4πr2)] and A9 the correction for directivity.

    SPL(dir) = SWL(l) – A7 – A8 – A9

  7. Combine the direct and reverberant levels to get the resultant sound pressure level SPL(tot). Use dB addition for combining the direct and reverberant levels.
  8. Compare the SPL(tot) in octave band (noise spectrum) with the design NC curve. The SPL(tot) noise spectrum must be lower or equal to design NC curve, it means that the attenuation required, A10 should be 0. If not, a silencer should be selected (attenuation selected, A11) to overcome the attenuation required to ensure that the insufficient dB, A12 is 0.
  9. Calculate the resultant sound pressure level with silencer (dBA) in octave band by adding the silencer attenuation, A11 and A-weighted factor. Combine the resultant sound pressure level with silencer in octave band to get the Overall Sound Pressure Level (dBA). Use dB addition for combining the octave band sound pressure level.
Technical Specifications

Comparing the performance of the BEL line of rectangular silencers based on the different parameters (length, splitter width, airway width) will help you make the best choice

[Type 200]
[Type 300]

 

 

Please use the form below to make an enquiry and we will get back to you as soon as possible. Alternatively you can use our full contact details.

No. 1, Jalan Bunga Raya 6A/2, Seksyen BS 4, Bukit Sentosa 1,
48300 Rawang, Selangor Darul Ehsan, Malaysia.

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