【Daily Question】Utilities - Water Supply and Drainage - 20200304

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Which of the following statements about the single-bucket rainwater drainage system is correct? (   )   A. The drainage capacity of the rainwater gutter is affected by the height at which it is installed (i.e., its vertical distance from the discharge pipe). B. The drainage capacity of a single-gutter rainwater system is greater than that of a multi-gutter system. C. During rainwater drainage, negative pressure exists at the beginning of the suspended pipe, while positive pressure exists at its end. D. During rainwater drainage, positive pressure exists in the upper part of the vertical pipe, and negative pressure exists in its lower part. Answer: B. Option A does not correspond to the actual situation. The drainage capacity of a rainwater inlet is influenced not only by the height at which the gutter is located, but also by factors such as the water depth in the gutter, pipe friction, and the local resistance of the rainwater inlet itself. C. The statements in options D are all contrary to the actual situation. According to the measured data, the beginning of the suspension pipe is under positive pressure, the end of the suspension pipe and the upper part of the vertical pipe are under negative pressure, while the lower part of the vertical pipe is under positive pressure. Option B corresponds to the actual situation observed in the experiment. For specific details, refer to Section 7.2 of \"Building Water Supply and Drainage Engineering\" (4th edition)