Low frequency noise of control structure transmission:
Structural sound transmission means that transformers, water pumps and central air conditioning hosts installed in the building transmit low-frequency vibration sound waves to each household through the basic structural girders and load-bearing beams of the residential building. In view of the performance of low-frequency noise caused by structural sound transmission, it is considered that the valve noise should be reduced at the source of noise.
A. The noise of the transformer comes from the transformer body and the cooling system. Therefore, the Shanghai ball valve pneumatic butterfly valve manufacturer believes that the noise reduction of the transformer needs to start from two aspects. On the one hand, the noise of the transformer body can be controlled by reducing the vibration of the iron core and reducing the noise emission capacity; Noise can also be attenuated in the transmission path through vibration reduction, sound insulation, sound absorption and other measures. On the other hand, control the noise of the cooling system to make it close to or lower than the noise level of the body, which can also effectively reduce the noise of the transformer.
B When the pump is running, the low-frequency vibration generated by the rotation of the pneumatic motor spreads along the building structure, which has a great impact on the upstairs/downstairs rooms. The noise in the room sometimes reaches more than 55dB, and the humming low-frequency noise makes people feel uncomfortable. Vibration transmission, up to 30 floors high. Therefore, it is necessary to design valve sound insulation technology for pumps and pipelines against low-frequency vibration, and adopt valve sound insulation treatment. From our practice, it is necessary to design multi-stage vibration isolation technology to isolate vibration transmission at different frequencies for such low-frequency vibration. So as to achieve the goal of valve noise reduction.
C. The sound transmission of the air conditioning host is partly air borne, which enters the room through doors and windows, and partly through the vibration of the wall. The low-frequency noise transmitted by the external unit of the air conditioner through the air can be separated by soundproof windows; For those that transmit sound through structures, the foundation of air conditioning equipment shall be equipped with vibration damping devices according to the specifications. The structural noise generated by the excitation force of the equipment shell shall be coated with macromolecule damping materials with large internal friction. The manufacturer of Shanghai Dongfeng pneumatic butterfly valve suggested that the vibration isolation and damping technology can effectively reduce the structural noise caused by the excitation force. The solid vibration has low transmission frequency, long transmission, slow attenuation and wide influence range.