Tank leakage detection method
First Claim
1. A method of detecting a perforation in the wall of a tank containing a stored liquid, comprising:
- inserting acoustic sensing means into the tank at an insertion point;
hermetically sealing the insertion point to be substantially gas-tight,reducing the gas pressure in the tank to a level sufficient to produce a pressure difference across the wall of the tank causing fluid to enter the tank, through the perforation;
detecting the acoustic signal produced by bubbles of said fluid entering said tank from said perforation;
separating from said signal a component attributable to the volume pulsation of said bubbles; and
converting said acoustic signal using said separated component to provide a signal indicative of the existence of the perforation.
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Accused Products
Abstract
A method and apparatus for detecting perforations in an underground fuel storage tank, employs the creation of a partial vacuum in the tank and a pressure difference across the tank wall, to cause air to pass through the perforation, and a hydrophone to sense the acoustic waves produced by the formation of air bubbles in the fuel. The acoustic waves of the bubbles caused by the air passage are sensed by a hydrophone and processed to provide an electrical signal indicative of the presence of the perforation. A water level sensor is also used to detect the level of water beneath hydrocarbon fuel in the tank. The method and apparatus can also be used with above ground fuel storage tanks and other types of above and below ground storage tanks.
72 Citations
24 Claims
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1. A method of detecting a perforation in the wall of a tank containing a stored liquid, comprising:
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inserting acoustic sensing means into the tank at an insertion point; hermetically sealing the insertion point to be substantially gas-tight, reducing the gas pressure in the tank to a level sufficient to produce a pressure difference across the wall of the tank causing fluid to enter the tank, through the perforation; detecting the acoustic signal produced by bubbles of said fluid entering said tank from said perforation; separating from said signal a component attributable to the volume pulsation of said bubbles; and converting said acoustic signal using said separated component to provide a signal indicative of the existence of the perforation. - View Dependent Claims (2, 3, 4)
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- 5. A method of detecting a perforation in a tank containing a stored liquid comprising:
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6. inserting acoustic sensing means into said tank at an insertion location;
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sealing the insertion location so as to be substantially gas-tight; reducing the gas pressure within said tank to a level sufficient to cause a pressure difference between the interior and the exterior of the tank, the pressure difference forcing air to enter the tank through the perforation, the air forming bubbles in the stored liquid, the volume pulsation of said bubble formation producing acoustic wave energy as the bubbles rise from the perforation to the liquid surface; using said acoustic sensing means to acoustically sense the volume pulsation during the formation of said bubbles, convering the acoustic wave energy sensed to produce an electrical signal representative of the volume pulsation of said bubbles; and processing said electrical signal to provide a signal indicative of the existence of the perforation.
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12. Apparatus for detecting a perforation in the wall of a tank containing a stored liquid, the apparatus comprising:
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means for hermetically sealing to provide a gas-tight seal at an inlet point of said tank; means for reducing the gas pressure within said sealed tank sufficient to cause a pressure difference across the wall of the tank, the pressure difference being sufficient to force a fluid to pass into the tank through the perforation in the tank wall; acoustic sensing means for sensing the formation of bubbles of said fluid entering the stored liquid in the tank through the perforation, said acoustic sensing means sensing acoustic wave energy produced by the volume pulsation during the formation of bubbles as they rise from the perforation towards the liquid surface, and said acoustic sensing means also converting the acoustic wave energy into an electrical signal; means for separating the component of the signal attributable to the volume pulsation of said bubbles; and means for detecting and processing said component of the electrical signal to provide an indication of the existence of said performation. - View Dependent Claims (14, 16, 18, 20)
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Specification