Abstract: Diffuser apparatus comprises a frame including end portions interconnected by and integrated with an elongate intermediate portion. The intermediate portion is formed to produce a longitudinally extended trough, preferably of generally hemi-cylindrical configuration. The diffuser sleeve which mounts about and the length of the frame is longer than the frame and its excess length is used to provide reversibly bent extremities which produce a double layer of the sleeve thickness in areas thereof which overlie the frame end portions. The latter have circumferentially and longitudinally spaced ribs to which the double layered sleeve end portions are clamped to produce a positive and insured seal as between the sleeve and the frame at their end portions. One end portion of the frame has a through bore outwardly extended by an integral adapter to which a line connected to a source of fluid under pressure may be directly coupled.