It is an air gap that allows air to escape rather than building up in the pipe and creating an air hammer within the pipes (banging noise), and problems with drainage. (think about pouring out of a can that doesnt have the second hole punched in it.
Suction Therapy : Suction therapy is provided to assist in the removal of bronchial secretions that cannot be expectorated by the patient spontaneously. Suct...
Cupping therapy is a form of alternative medicine in which a local suction is created on the skin. Cupping has been characterized as pseudoscience.[1] There is no good evidence it has any benefit on health and there are some concerns it may be harmful.[2]