Method of confirming the presence of a leak in a liquid storage tank
First Claim
1. A method of confirming the presence of a leak into a liquid storage tank which comprises the steps of;
- closing all entry and exit passage connections to the tank;
connecting a vacuum pump to the tank for drawing a partial vacuum therein;
sensing the vacuum pressure level within the tank and turning the pump off at a first predetermined vacuum pressure level;
turning the pump on at a second predetermined vacuum pressure level within the tank, said second predetermined vacuum pressure level being higher than said first predetermined vacuum pressure level; and
measuring the time periods of pump cycling on and off, off cycles of relatively unchanging duration serving as confirmation of the presence of a leak in the tank and off cycles of increasingly longer duration confirming the absence of a leak.
11 Assignments
0 Petitions
Accused Products
Abstract
Method of confirming the presence or absence of leaks in a liquid storage container, particularly in partially filled underground storage tanks, subjected to partial vacuum for the purpose of testing the tank for the presence of a leak in the area above the liquid using a hydrophone or microphone either positioned in or attached to the container to detect the sound produced by the ingress of fluid into the container as a result of the vacuum. The ingress of fluid is confirmed by recording and observing the vacuum pump on/off cycles, the on/off cycles for a leaking container being distinguishable from the on/off cycles for a non-leaking container.
74 Citations
24 Claims
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1. A method of confirming the presence of a leak into a liquid storage tank which comprises the steps of;
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closing all entry and exit passage connections to the tank; connecting a vacuum pump to the tank for drawing a partial vacuum therein; sensing the vacuum pressure level within the tank and turning the pump off at a first predetermined vacuum pressure level; turning the pump on at a second predetermined vacuum pressure level within the tank, said second predetermined vacuum pressure level being higher than said first predetermined vacuum pressure level; and measuring the time periods of pump cycling on and off, off cycles of relatively unchanging duration serving as confirmation of the presence of a leak in the tank and off cycles of increasingly longer duration confirming the absence of a leak. - View Dependent Claims (2, 3)
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- 4. The method of claim additionally comprising detecting the sound produced by the ingress of air through a leak in the tank with audible detection means positioned within the tank.
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8. A method of confirming the presence of a leak in an underground liquid storage tank having a body of water in the tank below the liquid contained therein which comprises the steps of;
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closing the entry and exit passages to the tank; connecting a vacuum pump to the tank for drawing a partial vacuum therein; sensing the vacuum pressure level within the tank and turning the vacuum pump off at a predetermined vacuum pressure level at which the entire tank, top to bottom, is negative with respect to ambient pressure; observing the tank for an increase in pressure from the predetermined vacuum pressure level; and in the event of an increase in the pressure from the predetermined vacuum pressure level, detecting any variation in the level of the water in the tank, wherein (1) an increase in the predetermined pressure without variation in water level indicates an ingress of air through a leak in the tank located above the level of the liquid stored in the tank and, if the bottom of the tank is below the level of the water table, above the water table and (2) an increase in the predetermined pressure with variation in water level indicates, when the bottom of the tank is below the level of the water table, an ingress of water through a leak in the tank that is located below the water table. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of confirming the presence of a leak in an underground liquid storage tank which comprises the steps of;
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connecting a vacuum pump to an underground storage tank to be tested for the presence of a leak; closing the tank at all connections other than the connection to the vacuum pump; operating the vacuum pump until a first predetermined vacuum pressure level is reached in the tank; measuring the time which elapses until the pressure in the tank rises to a second predetermined vacuum pressure level; comparing the measured times from successive cycles of operation of the vacuum pump, cycles of relatively unchanging duration indicating the likelihood of a leak in the tank and cycles of increasing duration indicating the absence of a leak; and when the comparison of successive cycles indicates the likelihood of a leak, monitoring the conditions inside the tank so as to detect any influx of fluid which may occur, thereby confirming the presence of a leak. - View Dependent Claims (15, 16, 17, 18)
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19. A method of confirming the presence of a leak in a liquid storage tank having a body of water in the tank below the liquid contained therein which comprises the steps of;
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closing the entry and exit passages to the tank; connecting a vacuum pump to the tank for drawing a partial vacuum therein; sensing the vacuum pressure level within the tank and turning the vacuum pump off at a predetermined vacuum pressure level; in the event of an increase in the predetermined vacuum pressure level, turning the vacuum pump on when the vacuum pressure level increases by a predetermined amount and then turning the vacuum pump off at the predetermined vacuum pressure level while measuring the time periods of pump cycling on and off, off cycles of relatively unchanging duration serving as confirmation of the presence of a leak in the tank and off cycles of increasingly longer duration confirming the absence of a leak; and detecting any variation in the level of the water in the tank, increase in the predetermined pressure without variation in the water level indicating an ingress of air through a leak in the tank and an increase in the predetermined pressure with variation in water level and indicating an ingress of water through a leak in the tank. - View Dependent Claims (20)
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21. A method of detecting a leak in a liquid storage tank comprising the steps of;
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connecting a vacuum pump to the tank for drawing a partial vacuum therein; closing all entry and exit passages to and from the tank other than the connection to the pump; operating the pump until a first predetermined vacuum pressure is reached in the tank; measuring the time which elapses until the pressure in the tank increases to a second predetermined vacuum pressure, turning the pump on at the second pressure, and operating the pump until the pressure once again reaches the first pressure; and comparing the rate of increase in pressure from first to second pressures during successive cycles of operation of the pump. - View Dependent Claims (22, 23, 24)
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Specification