给水排水专业英语课件12资料.pptVIP

* * * * 系统压力 * * 应该安装12英寸或者更小的阀门以提供好的隔离效果而不影响大量用户的供水。通常这些阀门间距至少5000英尺。 * * * * * * 哈代-克罗斯平差法是最古老也是最知名的一种管网分析方法。概括介绍其程序如下： 。 * * * Unit 12Distribution System Configuration and Analysis  * Where possible, mains should be placed in areas along the public right of way which are not subject to paving or obstacles to provide for ease of installation, repair, and maintenance. Dual mains should be installed on each side of streets and heavily traveled highways which are wider than 75 ft. One pipe usually supplies the domestic and fire flow requirements for one side of the street, while the other main supplies only domestic requirements for the other side of the street. * Occasionally, pipes are sized to supply both fire and domestic flows for each side of the street if it is extremely wide or the street is divided by a barrier such as a waterway, railroad, or some other obstacle. * The primary advantage of the dual-main system is that the required length of pipe is reduced significantly, allowing for pressure loss in a service pipe to be as small as possible and to eliminate the necessity of cutting through pavement to repair such services. 双侧干管系统的主要优点在于，显著降低所需管段的长度，允许入户管道的压力损失尽可能小，消除了通过路面切割维修此类服务的必要性。 The branch and loop are the two basic configurations for most water distribution systems. For both systems, distribution system pressures and valving are important considerations. * Branch Systems The layout of the branch system is like that of a tree branch with smaller pipes branching off larger pipes through the area to be served. 枝状管网的平面布置像一个树枝一样从较粗管道分叉出较细管道贯穿服务地区。 This system or a derivative of it is normally used to supply rural areas where the demand is relatively low and long distances must be covered. 这个系统或者由其衍生的系统通常用于供给需求相对较低和必须覆盖距离很长的农村地区。 * Disadvantages of this configuration are the possibility of a large number of customers being without service should a main break occur because of the absence of an alternative main, and the possibility