Study On The PVC-U Drainage Pipe Riser In Seven Floors

Seven-floors PVC-U draining water test equipment were took the experimental study object. Main water tank in Seven floors discharged water to the PVC-U drainage system for simulating centralized flow in the most unfavorable situation of theory. The experiment used the pressure transmitting instrument to survey the instantaneous value and the maximum value of pressure change in drainage system, and used gauging glass to survey the water height change value around turning on water in water seal of U-trap. Study mainly conducted three following aspects:Firstly, PVC-U draining pipe internal pressure undulation research. The experiment showed that, the pressure in the drainage system was changed frequently, and approached irregular sine curve, which was one kind of fluctuation pressure. In some short time (for instance several seconds), this fluctuation pressure pulsated about the mean value. But, along with the draining time extented, the fluctuation pressure changed frequently, and the precise pulsation mean value was extracted difficultly in the draining process, only was estimated for some short time from the real pressure graph.Secondly, the thorough study proceeded for the loss water seal of U-trap in the PVC-U draining pipe under the static evaporation and dynamic draining, and attempted to carry on the microscopic theoretical analysis. The major factor of U-trap static evaporation were the temperature and the relative humidity, the winter evaporation loss was smaller than the summer. The major factor of U-trap dynamic draining were positive pressure splattering and negative pressure suction, they changed in turn, and the frequency was very quick. Water was discharged difficultly under positive pressure from upper limb of U-trap, which was input joint of draining appliance draining-pipe. But, the positive pressure could cause fierce undulation of U-trap water-pressure in the drainage system, water could flow from the U-trap lower limb. In one draining process, the innumerable pressure fluctuation caused the negative pressure, which caused suction, then water of U-trap flowed the draining branch pipe, it was the primary factor of the dynamic U-trap losed. Moreover, the water loses for the fluctuation pressure were much smaller than those for the pulsation mean value. The reason possibly had two: First, the negative pressure suction of the fluctuation pressure had not enough time to discharge the suction water from the draining branch pipe; Second, along with the time passed and the suction times of fluctuation pressure increased, the negative pressure value which the loses of U-trap needed would be larger and larger.Thirdly, the simulation test was carried on for the PVC-U drainage system under the different active status, and pressure and current data was recorded through instrument. The test explored the correlations among draining load, ventilation, gradient for household crossing tube, condition of water leakage for household crossing tube and air pressure fluctuation in draining riser pipe.