PURPOSE: To simply remove dissolved oxygen by setting the flow velocity of the water flowing down in a cylinder to a specific value at the time of the removal of dissolved oxygen using a bubbling method.
CONSTITUTION: Oxygen-containing pure water is sent to a dissolved oxygen reducing device 11 from a pipe 13 to reduce the concn. of dissolved oxygen in the pure water to 10-100ppb. Subsequently, the pure water is introduced into the upper part of a dissolved oxygen removing cylinder 12 by a pipe 14 to be allowed to flow toward the lower part of the cylinder 12. At that time, the average flow velocity of the pure water is set to 1.6-9.0cm/sec and inert gas is introduced into the cylinder from a gas introducing pipe 3 to subject the pure water to bubbling treatment to reduce the concn. of dissolved oxygen in the pure water to 10ppb or less. The ultrapure water from which dissolved oxygen is removed is sent to a next process from a lead-out pipe 4. The introduced inert gas rises as small gas bubbles within a cylindrical body 1 to be discharged from an exhaust pipe 5.
YAMAZAKI HIROSHI
YAMANE SUMIYO
