Packless silencer

Abstract

A non-fibrous acoustic silencing duct member capable of attenuating noise associated with a gaseous medium passing through it. Perforated sidewalls define a gas flow passageway and include at least two opposing walls, each perforated with a number of small holes distributed over its surface. Exterior sidewalls are positioned on the outside of the perforated sidewalls and are spaced therefrom. Enclosed chambers are formed between the perforated and exterior sidewalls, which chambers are of selected depths. One or more screen layers extend along and adjacent to outer surfaces of the perforated sidewalls, these screen layers being located in the chambers. Each screen layer is covered with an array of very small holes that are substantially smaller than the holes in the adjacent perforated sidewall. Internal dividers extend between each perforated sidewall and its respective exterior sidewall in order to divide the space between the sidewalls. In a preferred embodiment, the perforated sidewalls are made of sheet steel and the screen liners are metal screens.