Circular Duct Attenuators - S / P Series

  Features

• These notes apply to both the open and pod type attenuators.

  Construction

• The units are rigidly constructed and consist of an outer cylindrical galvanised steel casing, lined internally with no hygroscopic and incombustible sound absorbent material.
• This material is retained by an inner perforated metal cylinder.
• An impervious lining of the acoustic infill can be provided to prevent the ingress of moisture or grease.
• There is a small performance penalty in high frequencies when an impervious lining is fitted.
• Refer to our Sales Engineers if more information is required.

Insertion Loss

• The values quoted in the table represent the difference between the sound power level (Lw) of a fan and attenuator combination and that of the fan alone.

Selection

• To ascertain the sound power level of a fan fitted with an attenuator, the insertion loss should be subtracted from the sound power level (Lw) rating of the fan across the octave band centre-frequency spectrum quoted in the fan characteristic data (obtainable on request).
• The fan sound power, Lw, ratings and attenuator insertion loss apply to in-duct operation and where an attenuator is connected between the fan and duct system.

Rectangular Attenuators

• Whilst circular attenuators provide a convenient form of attenuation when used with axial flow fans and have the added advantage of minimising noise break-out, it is often more economical to consider standard rectangular attenuators.
• Please refer to the pages G-6/10 for details of these.
• Purpose-designed attenuators can be supplied for particularly demanding applications requiring performances or construction beyond that provided by our standard product.

  Suggested Specification

• Attenuators shall be as designed and manufactured by Elta Fans and shall have the performances as scheduled.
• The casing and end flanges shall be constructed from high quality galvanised mild steel sheet.
• The end flanges shall be match drilled and tapped to suit the fan flanges and facilitate installation.
• Attenuator pods, where fitted, shall be adequately supported and be fitted with a nose cone on the inlet to minimise noise regeneration and pressure loss.

  Dimensions

  Performance

  Technical Data

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