Leak detector

• US 4,850,223 A
• Filed: 07/17/1987
• Issued: 07/25/1989
• Est. Priority Date: 07/17/1987
• Status: Expired due to Term

• Current Assignee: Tanknology NDE Corporation, Underground Storage Tank Testing Incorporated
• Original Assignee: Tanktech, Inc.
• Inventors: Guberud, Robert B., Carlin, John A., Mobeck, William L.
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Roskos, Joseph W.
• Application Number:
  US07/075,046
• Time in Patent Office: 739 Days
• Field of Search: 73/49.2 T, 73/305, 73/312, 73/313, 73/293, 73/292, 340/605
• US Class Current: 73/49.2
• CPC Class Codes: G01M 3/3245 using a level monitoring device G01M3/3272 takes precedence

Abstract

Apparatus for detecting leaks in fuel storage tanks. A float suspended in the tank liquid determines liquid levels and transmits the liquid level information via an infrared beam to a probe processor in the upper port of the tank. The probe processor stores a plurality of level indications for subsequent uploading to an external computer which analyzes the level information to generate leakage rate information.

Claims

1. A method of determining information including information indicating the leakage of liquid in storage tanks, said method comprising the steps of:

inserting self contained measuring apparatus into a tank whose leakage is to be measured,

operating said apparatus to obtain a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

storing the data collected during each reading in said apparatus,

subsequently connecting said apparatus to a computer,

transferring said stored data from said apparatus to said computer, and

operating said computer to process said data to determine the leakage rate of said tank.

2. The method of claim 1 wherein said tanks have fill pipes and wherein said method further comprises the steps of:

inserting said apparatus in said tank so that the entirety of said apparatus is below the top of the fill pipe of said tank, and

inserting a fill pipe cap on said fill pipe.

3. The method of claim 2 wherein said cap is a locking type cap.

4. The method of claim 1 in combination with the steps of:

operating said apparatus to sense the temperature at different strata within said tank,

recording data indicating the temperature sensed for each strata, and

transferring said temperature data together with said stored liquid level data to said computer for use by said computer in determining said tank leakage information.

5. The method of claim 4 in combination with the steps of:

operating said apparatus to sense barometric pressure information,

recording said pressure information in said apparatus, and

transferring said recorded barometric pressure information to said computer together with said temperature data and said stored liquid level data for use in determining said tank leakage information.

6. A method of determining information including information indicating the leakage of liquid in storage tanks, said method comprising the steps of:

inserting self contained measuring apparatus into a tank whose leakage is to be measured wherein said inserted apparatus comprises a vertically oriented hollow tube, a probe processor in the upper portion of said tube, and a float including a float processor suspended in said liquid in the lower portion of said tube,

operating said float processor to generate a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

transmitting said data for each reading from said float processor to said probe processor,

recording the transmitted data for each reading in said probe processor,

subsequently removing said apparatus from said tank,

connecting said probe processor to a computer,

transferring said stored data from said probe processor to said computer, and

operating said computer to process said data to determine the leakage rate of said tank.

7. The method of claim 6 wherein said step of transmitting includes the steps of:

encoding said generated data readings into an encoded optical signal,

transmitting said optical signal upwards within said tube,

receiving said optical signal by a photo detector, and

applying a signal representing said generated data from said detector to said probe processor.

8. The method of claim 7 in combination with the steps of:

operating said probe processor to sense the temperature at different strata within said tank,

recording data indicating the temperature sensed for each strata, and

transferring said temperature data together with said stored liquid level data to said computer for use by said computer in determining said tank leakage information.

9. The method of claim 8 in combination with the steps of:

operating said apparatus to sense barometric pressure information,

recording said pressure information in said apparatus, and

transferring said recorded barometric pressure information to said computer together with said temperature data and said stored liquid level data for use in determining said tank leakage information.

10. Self contained measuring apparatus adapted to be inserted into a tank whose leakage of stored liquid is to be measured, said apparatus comprising:

means for obtaining a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

means for storing said data collected during each reading in said apparatus,

means for subsequently connecting said apparatus to a computer, and

means for transferring said stored data from said apparatus to said computer,

said computer being operable to process said data to determine the leakage rate of said tank.

11. The apparatus of claim 10 in combination with:

means for sensing the temperature at different strata within said tank,

means for recording data indicating the temperature sensed for each strata, and

means for transferring said temperature data together with said stored fluid level data to said computer for use by said computer in determining said tank leakage information.

12. Self contained measuring apparatus adapted to be inserted into a tank whose leakage of stored liquid is to be measured wherein said inserted apparatus comprises a vertically oriented hollow tube, a probe processor in the upper portion of said tube, and a float including a float processor suspended in said liquid in the lower portion of said tube, said apparatus further comprising:

means for operating said float processor to generate a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

means for transmitting said data for each reading from said float processor to said probe processor,

means for recording the transmitted data for each reading in said probe processor, and

means for connecting said probe processor to a computer for the transfer of said stored data from said probe processor to said computer,

said computer being operable to process said data to determine the leakage rate of said tank.

13. The apparatus of claim 12 wherein said means for transmitting includes:

means for encoding said generated data readings into an encoded optical signal,

means for transmitting said optical signal upwards within said tube,

means for receiving said optical signal, and

means for applying a signal representing said generated data from said detector to said probe processor.

14. Apparatus for determining information including information indicating the leakage of liquid in a storage tank, said apparatus comprising:

a probe processor in the upper portion of said tank,

a float suspended in said liquid,

a first means on said float for determining the instantaneous level of said tank liquid,

a second means on said float for transmitting data to said probe processor representing said determined fluid level at successive times,

said probe processor being operable for recording said transmitted level data, and

means for transferring said recorded data from said probe processor to an external computer to determine said tank leakage rate from said transferred data.

15. The apparatus of claim 14 in combination with:

means for sensing the temperature within said tank at different strata within said tank,

said probe processor being operable for recording data indicating the temperature sensed for each strata, and

means for transferring said recorded temperature data along with said stored liquid level data to said computer for use in determining said tank leakage information.

16. The apparatus of claim 15 wherein said probe processor is operable for sensing and recording barometric pressure information, said apparatus further comprising means for transferring said recorded barometric pressure information to said computer together with said recorded temperature data and said stored liquid level data for use in determining said tank leakage information.

17. Apparatus for determining information including information indicating the leakage of liquid in a storage tank, said apparatus comprising:

a hollow probe tube suspended vertically in said tank with at least a lower portion of said probe tube being immersed in said liquid in said tank,

a probe processor and a receiver in the upper inner portion of said tube,

a float suspended below said probe processor in said liquid within said tube,

encoder means mounted on said float within said tube for determining the instantaneous level of said tank liquid,

a float processor mounted on said float within said tube and responsive to said determination by said encoder means for transmitting data to said receiver representing said liquid level at successive times,

said probe processor being operable for recording said transmitted level data, and

means for transferring said recorded data to an external computer to determine said tank leakage.

18. The apparatus of claim 17 wherein said float comprises:

centering means for positioning said float within the center of said tube and away from the inner surface of said tube while permitting said float to move vertically with low hysteresis in response to changes in tank fluid level.

19. The apparatus of claim 18 wherein said centering means comprises:

a first vertically oriented member affixed to the bottom of said float,

a plurality of vertically oriented wheels affixed by spring loading means to said member and radially spaced from each other about the vertical axis of said member, each of said wheels bearing under control of said spring loading means against the inner surface of said tube to center the lower portion of said float within said tube,

a second vertically oriented member affixed to the top portion of said float,

a plurality of spring loaded vertically oriented wheels affixed by spring loading means to said second member and vertically spaced from each other about the vertical axis of said member, each of said wheels bearing under control of said spring loading means against the inner surface of said tube to center the upper portion of said float within said tube while maintaining contact between said friction wheel periphery and the inner surface of said tube.

20. The apparatus of claim 19 in combination with a first spring fixed to the lower portion of said first vertical member and a second spring positioned above said float to cushion said float against large magnitude downward and upward vertical shocks.

21. The apparatus of claim 19 wherein said encoder means comprises:

a data transducer,

a code wheel having radial slots for sequentially interrupting and enabling a high beam generated by said transducer as said code wheel rotates in response to changes in fluid level, and

means responsive to said interruption for generating output data indicating the direction and amount of rotation of said code wheel.

22. The apparatus of claim 21 in combination with:

an infrared beam generator,

means for applying output signals from said float processor to said infrared generator for generating a coded infrared beam containing said data that is transmitted to said receiver, and

means in said receiver for receiving and decoding said infrared beam to derive said transmitted data.

23. The apparatus of claim 19 in combination with:

means for operating said apparatus to sense the temperature at different strata within said tank,

means for recording data indicating the temperature sensed for each strata, and

means for transferring said temperature data with said stored liquid level data to said computer for use by said computer in determining said tank leakage information.

24. The apparatus of claim 23 in combination with:

apparatus for operating said apparatus to sense barometric pressure information,

means for recording said pressure information in said apparatus, and

means for transferring said recorded barometric pressure information to said computer together with said temperature data and said stored liquid level data for use in determining said tank leakage information.

25. A method of determining information including information indicating the leakage of liquid in storage tanks, said method comprising the steps of:

inserting self contained measuring apparatus into a tank whose leakage is to be measured,

operating said apparatus to obtain a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

transmitting information representing said data readings over an infrared beam from a lower portion to an upper portion of said apparatus,

storing the data transmitted over said infrared beam in said apparatus,

subsequently connecting said apparatus to a computer,

transferring said stored data from said apparatus to said computer, and

operating said computer to process said data to determine the leakage rate of said tank.

26. Self contained measuring apparatus adapted to be inserted into a tank whose leakage of stored liquid is to be measured, said apparatus comprising:

means for obtaining a plurality of data readings at different times indicating the instantaneous tank liquid level at the time of each reading,

means for transmitting information representing said date readings over an infrared beam from a lower to an upper portion of said apparatus,

means for storing said data transmitted over said infrared beam in said apparatus,

means for subsequently connecting said apparatus to a computer, and

means for transferring said stored data from said apparatus to said computer.