【Daily Question】Utilities - Water Supply and Drainage - 20200211

Thread Content

Which of the following statements regarding the design discharge flow rate for building drainage is incorrect? (  )   A. The design second flow rate for building drainage is the maximum instantaneous drainage flow rate inside the building. B. The formula for the design second flow rate of drainage in residential buildings as specified in the codes corresponds to the formula for their design second flow rate for water supply; that is, calculations are carried out using the probability method. C. The design second flow rate for drainage in laundry rooms is calculated using the percentage of simultaneous drainage method. D. The design second flow rate for building drainage is greater than the average second flow rate of the maximum drainage volume. Answer: B. The maximum drainage volume refers to the drainage volume during the hour with the highest daily drainage volume. The design second flow rate represents the maximum instantaneous drainage volume when sanitary fixtures operate under the most unfavorable conditions; therefore, options A and D are incorrect. Option C refers to the provisions of Article 4.4.6 of the current \"Code for Design of Building Water Supply and Drainage\". Laundries are buildings where sanitary appliances are used intensively and wastewater is discharged at the same time, so the formula for the percentage of simultaneous discharge should be used for calculations. In accordance with Articles 3.6.4 and 4.4.5 of the current Code for Design of Building Water Supply and Drainage, the formula for the design second flow rate of water supply in residential buildings uses a probabilistic correction method, while the formula for the design second flow rate of drainage uses an equivalent calculation method; these two methods are not corresponding to each other.