Thread Content
This post was last edited by hesonchang214 on 2019-10-20 at 17:18. A secondary pressure boosting pump in a residential building is connected directly to the outdoor water supply network. Given that the height from the inlet pipe to the most unfavorable point in the water distribution system is 40.00 m, the head loss in the piping system is 8.56 m H2O, and the head loss due to the water meter is 2.05 m H2O. The required outlet head at the most unfavorable point in the water distribution system is 20 kPa, while the pressure provided by the outdoor water supply network is 20 m H2O. Therefore, the minimum head that the pump needs to generate is ( ) kPa. A. 305.6 B. 326.1 C. 505.6 D. 526.1 Answer: B is the correct answer. According to Equation (2.4) in Section 2.3 of \"Building Water Supply and Drainage Engineering\" regarding the head calculation when a water pump is connected directly to the external network, the head of the water pump should be calculated as Hb=H1+H2+H3+H4-H0. In this problem, H1 = 40.00 m H2O, H2 = 8.56 m H2O, H3 = 2.05 m H2O, H4 = 2 m H2O, and H0 = 20 m H2O. As a result of the calculations, the minimum value of Hb is 32.61 m H2O, which corresponds to 326.1 kPa. Option A fails to include the head loss due to water flow, H4. Option C fails to include the discharge head H4, and does not subtract the pressure H0 provided by the external network ； Option D does not subtract the pressure H0 provided by the external network.