extend through centralized bores in their respective end plates 16 and 14 and are fixedly attached thereto by welding crimping rolling or any other suitable means it is to be noted that said entry pipe 20 and said discharge pipe 18 extend inwardly toward the longitudinal center of housing 12 for a distance equivalent to their respective diameters from their point of attachment with their respective end plates spaced apart from the inner end of the entry pipe 20 at a distance of one and one half times the diameter of said entry pipe and fixedly attached by welding riveting or other suitable means to the interior wails of housing 12 is an alcove or recovery chamber 22 comprising a planar front wall in which there is provided a rectangular aperture 23 having a cross sectional area two and one half times greater than that of entry pipe 20 facing said entry pipe a planar back wall a planar ceiling and a planar floor the side walls of said recovery chamber are provided by the interior surface of the circumferential wall of housing 12 which also serves to support said chamber centrally within said housing where it is fixedly attached by the previously stated means fig2 clearly depicts the space allowed above and below recovery chamber 22 to allow the unrestricted flow of.