Phenomenon: The podium of a high-rise apartment is a shop.  Stores are equipped with air conditioners and fan coil units of water-cooled integral air conditioners.  In order not to interfere with the apartment, the cooling tower is set on the top of the high-rise building, and the cooling water pipeline is connected through the shaft.  After being put into use, the room near the pipeline shaft has continuous noise interference.

Reason: After careful investigation, it is found that the noise is related to the water pump of the cooling tower.  Because there is noise when the pump is running, there is no noise when the pump stops.  Furthermore, it was found that the suction pipe of the water pipe sucked some air from the cooling tower and mixed it into the water.  Bubbles are formed in the pumping section of the water pump to generate vibration and noise.

Countermeasures: Install an exhaust valve in the outlet pipe section of the pump to eliminate bubbles in time.  In addition, attention should be paid to the noise of water pipe system in design.

Generally, the following measures are taken:

1. The water pump unit is provided with vibration damping foundation.
2. Vibration isolation hoses are installed on the suction pipe and outlet pipe of the water pump.
3. Pipe supports and hangers, and places where they pass through walls and floors shall be filled with cushion layers of sound insulation and vibration reduction materials.
4. Reduce the water flow velocity in the pipeline.
5. Reduce sudden change and turning of pipe diameter.

Phenomenon: Noise of cooling tower.  A three-story high-rise office building was built in a residential area, and a 50RT cooling tower was installed on the roof.  Affect nearby residents during the day and night.

Reason: The cooling tower has high noise, is close to the residential area, and has not been silenced.

Countermeasures: Cover the tower with another shell.  Polyurethane material is pasted inside.

At present, the outlet noise of domestic low-noise cooling towers and ultra-low-noise cooling towers can be basically controlled at about 60dB(A).  The general cooling tower can also be equipped with a very variable speed fan. When the cooling load is low at night, the fan can be adjusted to a low speed, and its noise can be reduced by 6~7dB.