Patent ID: 7494534

Claim:
A device for controlling a dissolved amount of gas comprising: a reduced pressure rise part in which a lower end of a pipe having an opening is immersed into fluid to be treated in a liquid tub, said reduced pressure rise part further includes: a pretreatment tank which is connected to an upper end of the pipe; a hole for extracting gas which is provided at a position exceeding a height of 10.33 m relative to a liquid level of the liquid tub; and a vacuum pump connected to the hole so that a reduced pressure space is generated in the pipe thereby suck the fluid to be treated to a level of 10 m or the like above the liquid level of the liquid tub; an injection supply part for injecting the fluid to be treated pressurized by a pressurizing pump through a nozzle for mixing a large amount of gas; an upper liquid foam generating part in which a pipe having an opening is immersed into treated fluid in a liquid tub for recovery said upper liquid foam generating part further includes: a tank incorporating a container which receives the fluid to be treated injected from the nozzle for generating liquid bubbles at a position of approximately 10.6-11.2 m above the liquid level of the liquid tub; and a hole which is provided at an upper part of the tank and is connected to the vacuum pump so that the inside of the tank is brought into a reduced pressure space; and a self weight recovery part in which the treated fluid goes down through the pipe by a self weight according to a water head difference, and thereby can be recovered from the liquid tub.