PIPE CONNECTION STRUCTURE AND VACUUM-TYPE SEWAGE COLLECTING APPARATUS INCORPORATING THE PIPE CONNECTION STRUCTURE

A pipe connection structure for a vacuum-type sewage collecting apparatus for collecting sewage discharged from a multiplicity of houses or facilities in an accumulating tank through a vacuum sewage pipe the inner pressure of which has been made to be a negative level is disclosed. The vacuum sewage pipe includes a plurality of upper stream pipes and lower stream pipes fastened to each other in the branch-like shape. The pipe connection structure connects the upper stream pipe to the lower stream pipe formed in a sawtooth-like shape by alternating a downward-slope portion; which is arranged to slope gently downwards toward said accumulating tank, and a lift portion fastened to the lowermost portion of the downward-slope portion and arranged to be a steep upward slope. The upper stream pipe is connected to the lower stream pipe in a range in which a horizontal plane; which is positioned in contact with an upper end portion of the lower stream pipe at the position in which the downward-slope portion changes to the lift portion, is higher than the center of the lower stream pipe and at a position in which an opening of the upper stream pipe opened in the lower stream pipe is positioned diagonally upper than the pipe center of the lower stream pipe in a plane perpendicular to the pipe central axis. At least a portion of the opening is higher than the horizontal plane, and the upper stream pipe extends from the lower stream pipe diagonally upwards. By this arrangement, upper and lower stream pipes can be connected to each other in such a manner that the level difference between the two pipes can be significantly reduced and the back flow of sewage from the lower stream pipe toward the upper stream pipe can be prevented.