Patent ID: 7416050

Claim:
A gas expansion silencer comprising a tubular endpiece having an axial cylindrical passageway with an open end for connection to a supply of gas under pressure flowing subsonically and having an opposite end closed by a transverse end wall, and a low-pressure stage having one end communicating with said opposite end of the endpiece via a series of inlet holes formed in said transverse end wall for gas flow at sonic speed and having an opposite end with orifices for gas outlet at subsonic speed, the low-pressure stage being filled entirely with porous metal packing, the low-pressure stage comprising at least two cylindrical portions of different diameters connected axially end to end and communicating with one another, the smaller-diameter portion being connected to the above-mentioned endpiece and the larger-diameter portion including a cylindrical wall in which the gas outlet orifices are formed, the gas outlet orifices being distributed around the circumference of said cylindrical wall such that the gas flows radially toward the outlet orifices, said cylindrical portions being of axial and radial dimensions that are determined so that the end of the smaller-diameter portion which is connected to the end of the larger-diameter portion constitutes a screening obstruction arranged such that said gas outlet orifices cannot be seen directly from said gas inlet holes, thereby creating a bend effect on the flow of gas through the low pressure stage, preventing a direct flow path for gas between the inlet holes and the outlet orifices.