Summary of Jigao Air Conditioning Maintenance: Precautions for the Use and Installation of Silencers
Note:
(1) Silencers should preferably be installed on stable airflow pipelines close to the fan room. When silencers are directly arranged inside the fan room, the maintenance doors of the silencers and the ducts after the silencers must have good sound insulation capabilities. If the air velocity in the main duct is too high and the silencer is placed near the ventilator, it will inevitably increase the aerodynamic regenerative noise of the silencer. In this case, it is advisable to install silencers separately on branch ducts with lower airflow velocities.
(2) When selecting a silencer, factors such as the required sound attenuation of the system, the frequency characteristics of the noise source, the acoustic performance, and the air performance of the silencer should be considered. Choose between resistive, reactive, or combined resistive-reactive silencers accordingly.
(3) During soundproof design, resistive silencers like sound-absorbing elbows are generally preferred. Reactive silencers have strict usage conditions, complex structures, large sizes, and higher costs. They are mainly used for absorbing low-frequency noise within a certain range but have a narrow soundproofing range. The sound attenuation of chamber-type silencers is usually small. To achieve significant sound attenuation, multiple chamber-type silencers need to be connected in series, which would lead to considerable airflow resistance. Therefore, this type of silencer should be used sparingly.
(4) Micro-perforated plate silencers. Due to their low flow resistance, no filler material, and dust-free operation, they are suitable for use in high-temperature, high-speed ducts, ultra-clean workshops, or dust-proof workshop ventilation systems. The wind speed for micro-perforated plate silencers can be up to 15m/s while maintaining good soundproofing performance. In the frequency range of (125~8000)Hz, the sound attenuation is over 1OdB(A).
Beijing Jigao Air Conditioning Maintenance Center
August 10, 2011.