A port assembly for use with a single piece cavitation chamber, typically a spherical chamber, is provided. The port assembly includes a port, a mounting ring, a retaining ring and a central member mounted within the mounting ring. The mounting ring and the retaining ring can be fabricated from a single piece of material, thus combining the functions of both rings into a single retaining coupler. The mounting ring includes a cone-shaped port in which the port diameter corresponding to the external surface is smaller than the port diameter corresponding to the internal surface. The central member is cone-shaped such that it fits within the mounting ring.