Leak Detection by Using the Impedance Method
Consideration is given in this paper to the numerical techniques of leakage detection in pipes utilizing transient state heads and discharges. Transient flow, considered herein, is produced by a rapid valve closure at the downstream end of the pipe. A mathematical model of transient flows is presented and resolved by the method of characteristics. The computed results describe the influence of the presence of leaks on the head and discharge timehistories. In the case of steady oscillatory flow, the impedance method and the harmonic analysis is used to develop the transfer function at the closed valve. The impedance diagram of a system with leak is analyzed and compared with the one of a system without leak. To determine the leak location, a numerical tool, based on the values of the normalized harmonic frequencies and represented by the ratio of those producing infinite or zero impedance values, is developed.
Keywordstransient flow method of characteristics impedance method transfer function leak detection
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