Method and system for generating microbubble-contained liquid and microbubble generator to be assembled in the system

A microbubble-contained liquid generating system, comprising:

• a pressure tank receiving a liquid supplied from a liquid source;
• a circulation pipe equipped with a circulation pump which draws the liquid from the pressure tank and returns the drawn liquid to the pressure tank;
• a gas supply means located upstream of the circulation pump to supply a gas to the liquid flowing in the circulation pipe;
• a discharge pipe connected to the pressure tank;
• a pressure chamber provided in the discharge pipe and having an inner wall isolated from a side wall of the discharge pipe;
• and
• a restriction passage communicating with the pressure chamber, said restriction passage having a recess formed in a wall surface thereof.

A microbubble generator, comprising:

• a main pipe through which a gas-dissolved liquid supplied under pressure flows;
• an intermediate wall partitioning the main pipe and having openings formed in a central portion thereof;
• a small-diameter pipe continuous from a downstream wall surface of the intermediate wall to face to the openings;
• a flange provided at the downstream end of the small-diameter pipe to extend radially outward;
• and
• a disk disposed to close the downstream end of the small-diameter pipe,
• wherein the disk and flange in combination define a restriction passage, and a recess is formed in one or both of opposed surfaces of the disk and the flange.