Venturi tube for shower head

A Venturi tube device comprising:

• a Venturi tube comprising an axial forward channel, an axial rear channel including a circular recess, an intermediate constriction cone communicating with both the forward and rear channels, the constriction cone having a forward portion with a cross sectional area less than that of a rear portion thereof, a transverse hole having one end communicating with the forward channel and the other end being open, and a rear D-shaped flange with the circular recess;
• a hollow cylindrical fitting comprising an axial tunnel, a rear D-shaped recess having a diameter greater than that of the tunnel, an externally threaded extension with the D-shaped recess contained therein, a forward internally threaded extension having a diameter greater than that of the tunnel, a shoulder interconnecting the tunnel and the internally threaded extension, a plurality of annular ridges formed on an outer surface of the fitting between the externally threaded extension and the internally threaded extension, and a conic hole disposed between two adjacent ones of the ridges to have one end communicating with the tunnel and the other end being open wherein the Venturi tube is fastened in the fitting with the flange complimentarily anchored in the D-shaped recess to align the transverse hole with the conic hole and dispose the transverse hole in close proximity to the conic hole;
• a shroud comprising two opposite communicating holes through an outer surface, each communicating hole having a diameter greater than a lengthwise distance between two adjacent ones of the ridges, and a plurality of equally spaced front latches wherein the shroud is mounted on the ridges by securing the latches thereto so that one communicating hole is spaced apart and aligned with the conic hole with air being capable of flowing through one communicating hole, a space defined by two adjacent ones of the ridges, the conic hole, and the transverse hole;
• and
• a hollow, cylindrical flow guide member disposed in the circular recess and comprising a rear annular cavity and a plurality of equally spaced front openings communicating with the cavity.