Whirlpool tub with automatic pre-flushing of the system

An automatically closing nozzle for introducing a water-and-air mixture into a tub having a tub wall, comprising:

• (a) a valve body including a prechamber;
• (b) a support ring connected to said valve body for retaining said valve body against the tub wall;
• (c) a retaining ring which is releasably connected to said support ring and which is axially displaceable relative to said support ring;
• spring means for resiliently urging said retaining ring toward said prechamber;
• (e) a nozzle body having a generally tubular mouth and a ball-shaped portion which is spherically curved about a center of curvature, said nozzle body having a bore therein communicating with said prechamber and an annular sealing element bounding an inner perimeter portion of said bore;
• said nozzle body being pivotably retained in said valve body by said retaining ring;
• and
• (f) an air supply line having a mouth which protrudes into said bore in said nozzle body, said air supply line being disposed externally of the tub;
• said mouth having an outer surface portion having a generally spherical surface against which said annular sealing element of said nozzle body is urged by said spring means;
• whereby seating of said annular sealing element of said nozzle body against said generally spherical surface of said mouth substantially closes fluid communication between said prechamber and said generally tubular mouth of said nozzle body.