Application of nodal pressure measurements in leak detection

• The concept of 'Leak Index’ abbreviated as LI for the first time in the current manuscript is defined.
• The following definition is introduced for the leak index: LIik=ΔHikΔHmaxk in which ΔHmaxk is the maximum head difference among the whole nodes or pipes of the network which most likely occur in the leaky node or pipe.
• The relative real leak index (LIi/jk)r is introduced, which is actually equal to the ratio of leak index in ii to jj when the real leak occurs in nodekk. It has the following formulation:LIi/jk=LIikLIjk.
• The relative simulated leak index (LIi/jk′)s is calculated for all the pipes of the network. When (LIi/jk)r=(LIi/jk′)s, then the leak is identified in pipe k′.
• In the proposed method, at least four nodal pressure measurements are required to detect the leak location in a network with a moderate size.

Leaks are inevitable phenomena that are present in all water distribution systems (WDSs). The locations of leaks are determined through various methods, such as physical inspection of pipes, acoustic listening devices, and hydraulic network equations. Leak can be located by measuring the nodal pressure in a pipe, which is more effective and less expensive than measuring the amount of discharged water. These locating techniques focus on the direct relationship between leak and pressure. This study aims to devise a new method for locating a single leak in an entire WDS pipe line. The exact location of the leak is identified by analyzing the differences in the pressure of the pipes. In the proposed model, the leak refers to the beginning and end nodes of the pipe. The minimum number of pressure measurements to form a relative leak index is two. However, in this case two nodal pressure measurements is too few and the number of pressure measurement should be increased. Therefore the next option for the number of measurements is three. Although the real leaky pipe is in the list, it cannot identify the actual leaky pipe from two pseudo leaky pipes. So, the number of pressure measurements is increased to four. In a network with a moderate size, in least four nodal pressure measurements are required to detect the leak location.