| 摘要 |
PURPOSE:To improve the sound attenuation effect especially in low frequency range by a method wherein a silencer to be connected to a circulation duct through which air is fed into a clean room is made up of square duct members whose inner surfaces are provided with porous plates having an arc cross section. CONSTITUTION:A clean room is furnished with HEPA or ULPA filters installed on the ceiling, gratings on the floor and a circulation duct which connects an underfloor chamber under the gratings and an above-ceiling chamber above the filters. An air conditioner is connected to the circulation duct and a silencer is mounted in the middle of the circulation duct. Porous plates 12, made by sintering aluminum particles, etc., into a plate, for example, are attached to opposite inner side surfaces 11 of members 10 of a square duct. The porous plate 12 consists of arc-shaped parts 12a located on the upstream and downstream sides in the air flow direction and a straight part 12b, and a honeycomb material 14 is provided between the straight part 12b and the inner side surface 11. |
