Device for injecting a gas into a liquid

Apparatus for injecting a gas into a quantity of liquid to provide the treated liquid with a given quality, comprising means for supplying gas to the liquid at a predetermined pressure and having at the place where the injection of the gas is to be effected a wall portion provided with a plurality of holes, a plurality of pipes mounted at one end in the holes of said wall portion and having substantially the remainder of their lengths surrounded by liquid with the other free ends thereof submerged in the quantity of liquid, each of said pipes being thin-walled with a small inside diameter, less than 2 mm, and having a length at least 20 times that of said diameter, the pressure of the gas supplied to said pipes forming at the free ends of said pipes bubbles of a given size, and the flexibility of said submerged pipes being such that the gas supplied therethrough to form the bubbles on the free ends of said pipes imparts to each such free submerged pipe end a slight movement causing the detachment of such bubble from said free pipe end, the gas pressure and the pipe flexibility causing the bubbles to form and be detached regularly and preventing spurious particles adhering to such free ends of the pipes, whereby said pipes regularly and evenly bring the gas into close contact with the treated liquid in the form of discrete gas units of given size.