Leak detection
First Claim
1. A method of measuring the leakage from a primary containment means which comprises the steps of:
- so arranging a vessel and an essentially fluidtight envelope as to provide primary and secondary containment means and a space of controlled volume between said containment means;
predicting the rate at which a substance released from the primary containment means will collect in said space in the absence of a leak in the primary containment means;
employing a high vacuum system to withdraw from said space the contained substance collected therein;
comparing the amount of the substance removed from said space with the amount of the substance predicted to have been collected in said space in the absence of a leak;
generating an advisory warning of a possible leak in the primary containment means if the amount actually removed exceeds to a determined extent the amount predicted to have been collected; and
employing a second low vacuum system to maintain in the space between the primary and secondary containment means a negative pressure which is of sufficient magnitude to keep the primary and secondary containment means in firm contact, thereby keeping the controlled volume space constant and making possible the accurate detection of very small leaks.
1 Assignment
0 Petitions
Accused Products
Abstract
Methods of and apparatus for detecting the leakage of fluids from containment vessels. The tank is surrounded by or lined with a generally fluidtight envelope, and a vacuum is applied to hold the envelope against the tank and thereby control and limit to a very small volume the space between the primary containment, be it the vessel or liner, and the envelope. Fluids escaping from the containment vessel collect in that space. Collected fluids are evacuated; and fluid withdrawal information is processed, providing an advisory if a leak occurs or continues and/or information on the magnitude of the leak. An indication of a possible leak can also be obtained by monitoring the pressure in the space between the containment vessel and the encapsulating envelope. A trend-bucking change in that pressure is also an indication of a possible leak. Other installations make use of a second system to detect and evaluate leaks into the installation from the surrounding environs.
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Citations
36 Claims
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1. A method of measuring the leakage from a primary containment means which comprises the steps of:
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so arranging a vessel and an essentially fluidtight envelope as to provide primary and secondary containment means and a space of controlled volume between said containment means; predicting the rate at which a substance released from the primary containment means will collect in said space in the absence of a leak in the primary containment means; employing a high vacuum system to withdraw from said space the contained substance collected therein; comparing the amount of the substance removed from said space with the amount of the substance predicted to have been collected in said space in the absence of a leak; generating an advisory warning of a possible leak in the primary containment means if the amount actually removed exceeds to a determined extent the amount predicted to have been collected; and employing a second low vacuum system to maintain in the space between the primary and secondary containment means a negative pressure which is of sufficient magnitude to keep the primary and secondary containment means in firm contact, thereby keeping the controlled volume space constant and making possible the accurate detection of very small leaks. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for detecting the leakage of fluid from a primary containment means into a space of controlled, essentially constant volume between the primary containment means and a secondary containment means, said system comprising:
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means for periodically evacuating from said space contained substance collected in that space; means for comparing the amount of contained substance actually evacuated from the space between the primary containment means and the secondary containment means with the amount of the contained substance that would be expected to collect in said space in the absence of a leak and providing an advisory warning of a possible leak if the amount of the contained substance actually evacuated from said space exceeds the amount of substance expected to collect in that space; and a vacuum means for independently maintaining in said space of controlled volume a negative pressure which is of sufficient magnitude to keep the primary and secondary containment means in contact and thereby keep the volume of said space essentially constant. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of measuring the leakage from a primary containment means which comprises the steps of:
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so arranging a vessel and an essentially fluidtight envelope as to provide primary and secondary containment means and a space of controlled volume between said containment means; predicting the rate at which a substance released from the primary containment means will collect in said space in the absence of a leak in the primary containment means; and generating an advisory warning of a possible leak in the primary containment means if the amount actually removed exceeds to a determined extent the amount predicted to have been collected; the amount of contained substance expected to collect in the controlled volume space between the primary and secondary containment means being predicted by;
calculating the rate at which contained substance would be expected to be released from the primary containment means to the space of controlled volume by permeation, storing the thus calculated trend information, and projecting from the stored trend information a time-related increase in the volume of the contained substance in the controlled volume space between the primary and secondary containment means attributable to the release of contained substance from the primary containment means to said controlled volume space by permeation.
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36. A system for detecting the leakage of fluid from an essentially rigid primary containment means into a space between the primary containment means and a flexible secondary containment means in which the primary containment means is encapsulated, said system comprising:
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means for maintaining a negative pressure in the space between the primary containment means and the secondary containment means at a level high enough to keep the primary and secondary containment means in contact and thereby accurately control the volume of the space therebetween; means for periodically evacuating from the space between the primary containment means and the secondary containment means contained substance collected in that space; and means for comparing the amount of contained substance actually evacuated from the space between the primary containment means and the secondary containment means with the amount of the contained substance that would be expected to collect in said space in the absence of a leak and providing an advisory warning of a possible leak if the amount of the contained substance actually evacuated from said space exceeds the amount of substance expected to collect in that space.
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Specification