[AC] 問﹕Noise Control by BS System有啲乜方法？

答﹕

Design 上，要睇ASHRAE Hanbook - Application Chapter 48 Table 1 要求既NC Level, 如果做唔到就要諗計。見下表，大概既Design NC 都係40咁上下。


至於NC同dBA有啲乜分別？NC係八個Frequency Sound Pressure Level (dB) 縱合出嚟既一個值。



之後再睇個Source大概會gen幾多Noise, equipment catalogue有得睇；如果係風喉或風咀出風的話，都會有個建議數，係睇ASHRAE Hanbook - Application Chapter 48 Table8, 9, 當然，風管內風速越高，或Louver出風越快，Noise越高。
此外，Duct System Design 要注意
- Elbow 同 Branch 之間最少留返 5 個Duct Diameter 距離；
- Duct transition angle no be greater than 15 degree;

設計一般要預返5NC buffer.

Silencer

Turning Vanes inside Duct

Acoustic Enclosure

Duct Lagging

Vibration Isolation Mounts or Hangers


Flexible Connector

Inertia Block & Vibration Isolators


Floating Slab




(Source: ASHRAE Handbook - Application; https://www.engineeringtoolbox.com/nc-noise-criterion-d_725.html)