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Baffle silencers may be housed in rectangular or cylindrical enclosures in which one or more acoustic absorbent baffles are mounted. Each baffle is constructed as a cassette containing the absorbent material, which converts noise energy into friction heat. Dependent upon the specification and noise attenuation differing types of absorbent materials are used. The amount of noise attenuation and the frequencies treated are a function of the baffle thickness, the spacing of the baffles and their length.
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Principle |
Baffle silencers may be housed in rectangular or cylindrical enclosures in which one or more acoustic absorbent baffles are mounted. Each baffle is constructed as a cassette containing the absorbent material, which converts noise energy into friction heat. Dependent upon the specification and noise attenuation differing types of absorbent materials are used. The amount of noise attenuation and the frequencies treated are a function of the baffle thickness, the spacing of the baffles and their length.
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Applications |
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Baffle silencers are used in a wide variety of applications heating- and air-conditioning ducting:
- Separator Cyclones
- Compressor Systems
- Boiler Vents
- Fans
- Electric Motors
- Compressor Systems
- Internal Combustion Engines
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Insertion Loss |
The attenuation of baffle silencers is given as the difference between the noise level before the fitting of the silencer(s) and the noise level after fitting of the silencer(s) ‚ the insertion loss. As a rule the attenuation relates the decibel attenuation to the octave band. Because of “short-circuit” effects in the absorbent material attenuations greater than 50 dB(A) are not practicable. When the specification requires attenuations in excess of 50 dB(A) a series of silencers is used where each unit in the train is acoustically isolated from its neighbour.
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Custom Design |
Q.E. International has developed an advanced computer program that embodies the results of laboratory and on-site measurements of baffle silencers. The program automatically interpolates between the differing performances and dimensions of the baffles. In production the baffle silencers are not restricted to standardised proportions. As a result the silencers can be fitted into the available space and the noise spectrum precisely adjusted to meet the required levels. Custom building ensures that oversized silencers are not fitted and that economical production is attained.
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Reduced Pressure Losses |
The pressure loss across the silencer depends, among other things, upon the velocity increase within the silencer and the dimensions of the baffles. Shaping the baffle inlet with a curved geometry reduces inlet pressure loss. For those applications requiring a very low-pressure drop special trapezoidal profiles are fitted to the downstream of the baffles. Vortices at the exit are thus eliminated.
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Material Selection |
For standard applications
In the standard form the baffles are fabricated in galvanised steel plate. Each baffle is packed with high-density acoustic absorbent mineral wool material protected by woven glass-fibre cloth and perforated galvanised steel sheet.
Custom-built units
Dependent upon the job specifications the silencers may be furnished to meet high temperatures, corrosive media or tight hygienic requirements. Custom building permits construction in selected materials. For example, steel plate with electrolytically bonded zinc coating or high chrome-nickel alloy plates with sound absorbent selected for the extreme conditions and having added protection from dust or moisture. Where high velocities are inevitable, chrome-nickel alloy wire gausses will be fitted to minimise erosion.
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Required Data |
- Medium
- Flow
- Temperature (at inlet and discharge side)
- Connection size inlet
- Connection size outlet
- Flange rating
- Required noise reduction or required noise guarantee at …. Meter
- Restricted materials
- Max. allowable Pressure drop |
