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AE Leak Detection Method The :escape of Liquid LhrougIn a small hole in a tank causes liquid turbulence at the hole, along with bubbling, dripping and various other noise-emitting mechanisms. These mechanisms produce acoustic waves which radiate from their point source, through the ambient fluid to the tank wall. Ultra-sensitive acoustic sensors, attached along the outside tank. wall, are capable of detecting or "hearing" the low-level acoustic disturbances emitted by the leak. The leak need not be large nor the driving hydrostatic pressure great for these acoustic disturbances to be sensed. The acoustic disturbance (signal) detected by the sensors is transmitted to a mobile test van, where it is amplified , filtered , digitized and recorded. The digitized signal is further processed by specially designed computer software to generate a real-time location for the acoustic-emission source or sources. Monitoring of these signals is done at a relatively high acoustic- frequency which rejects the lower-frequency local noises such as traffic, operating machinery, etc. , and enhances the acoustic signals generated by the leak. The acoustic-emission technology used as a basis for the Pelagos AE system was developed primarily for the detection of cracks and leaks in nuclear reactor systems, and is now used for a wide.variety of applications where it is important to detect the minute sounds associated with material failure and small leaks. t Testing Operations Actual testing is simple and is performed quickly without emptying and cleaning. Preparation for testing requires that the tank has product or water in it and has been stilled at least six hours prior to testing. Also, prior to testing, plant personnel are contacted to discuss tank dimensions, product inventory, vehicle access and testing schedule. A test scenario will generally include: 1. A briefing with plant personnel and review of drawings of tanks and their associated piping. This helps define optimum sensor spacing;