Acoustic sensing is a relatively well known method for detecting leaks, particularly in transport pipelines. This methodology is based on the rarefaction phenomenon which occurs around the leak spot as a result of a sudden rupture of the pipe wall. The physical forces involved in the phenomenon generate a pressure disturbance that propagates through the fluid, upstream and downstream the pipe. The key feature behind acoustic technology, when applied to LDS, is the system's capability to monitor pressure disturbances and accurately recognize and pinpoint characteristic "leak waveforms" superimposed on the background noise. This is usually achieved by a combination of mechanical, hardware and software filtering techniques. Although real applications have demonstrated the effectiveness of acoustic technology over a quite broad range of scenarios, it has experienced few innovations along the past years. The relative technological stagnation and the experience achieved in several LDS installations in Brazil, encouraged Aselco, a Brazilian company focused on LDS applications, to invest in developing new strategies around the classical acoustic concept. The R&D project started in early 2006 jointly with NETeF, Thermal and Fluids Engineering Centre, at University of Sao Paulo at Sao Carlos. A 1.2Km pipeline was built at NETeF's lab in order to simulate leaks under mono or multiphase flow conditions. Among the project goals was the development of a new generation of systems dedicated to leak detection encompassing more elaborated algorithms to identify leak acoustic signatures. The core R&D is still centered on the acoustic concept, but under a different approach such as DSP-Digital Signal Processing, pattern recognition through neural network analysis. Another line of development is toward multivariate systems, which bring together both acoustic and hydraulic modeling algorithms running on the same platform. The experimental data obtained, proposed system architecture and characteristics are hereby discussed. Also, the prospective aspects and application of the new technology are objects of analysis.
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