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