Repetition is to ensure drainage at any time, even if one can't drain, the other can still work. This well has the functions of sinking ingot and filtering. For the drainage of high-rise residential buildings, the exhaust pipe and sewage pipe are double connected (H pipe is mostly used at present). In order to better ensure the balance of air pressure at the upper and lower ends of the drainage pipe, prevent the piston effect when a large amount of sewage is discharged, and effectively prevent the floor drain or toilet water seal of downstairs residents from being washed away by the positive air pressure generated by the piston effect, so as to achieve the effect of preventing odor from overflowing.
The manhole is set up for the maintenance and convenient installation of urban underground infrastructure such as power supply, water supply, drainage, sewage discharge, communication, cable TV, gas pipeline and street lamp line. Generally, it is located at pipeline intersections, bends, pipe diameters or slope changes, and one is set at regular intervals on straight pipe sections to facilitate regular inspection of ancillary structures.