Secondary containment leak prevention and detection system and method

• US 7,051,576 B2
• Filed: 05/06/2003
• Issued: 05/30/2006
• Est. Priority Date: 09/10/2002
• Status: Expired due to Term

• Current Assignee: Veeder-Root Co (Vontier Corp.)
• Original Assignee: Gilbarco Incorporated (Vontier Corp.)
• Inventors: Reid, Kent D., Hutchinson, Ray J., Hart, Robert P., Lucas, Richard K., Dolson, Richard G., Halla, Donald D.
• Primary Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US10/430,890
• Publication Number:
  US 20050039518A1
• Time in Patent Office: 1,120 Days
• Field of Search: 73/405.R, 73/491, 73/495, 340/605
• US Class Current: 73/40.50R
• CPC Class Codes: B65D 88/76 for use underground manholes, inspection openings, covers therefor B65D90/105; special vessels for collecting or storing rain-water for use in the household E03B3/03; cesspools E03F11/00
• CPC Class Codes: B67D 7/3209 relating to spillage or leakage, e.g. spill containments, leak detection leak detectors for underground fuel dispensing systems G01M3/2892
• CPC Class Codes: B67D 7/66 of rotary type
• CPC Class Codes: B67D 7/78 Arrangements of storage tanks, reservoirs or pipe-lines

Abstract

A pump housing that contains a pump that draws fuel from an underground storage tank containing fuel to deliver to fuel dispensers in a service station environment. The pump is coupled to a double-walled fuel pipe that carries the fuel from the pump to the fuel dispensers. The double-walled fuel piping contains an inner annular space that carries the fuel and an outer annular space that captures any leaked fuel from the inner annular space. The outer annular space is maintained through the fuel piping from the pump to the fuel dispensers so that the outer annular space can be pressurized by a pump to determine if a leak exists in the outer annular space or so that fuel leaked from the inner annular space can be captured by a leak containment chamber in the pump housing.

Claims

1. A system for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising:

a pressure sensor that is coupled to the outer annular space to detect a vacuum level in the outer annular space;

a sensing unit controller that is coupled to said pressure sensor to determine the vacuum level in the outer annular space;

a submersible turbine pump that is fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank wherein said submersible turbine pump is also coupled to the outer annular space;

said submersible turbine pump creates a vacuum level in the outer annular space wherein said sensing unit controller determines the vacuum level in the outer annular space using said pressure sensor; and

a monitor that is electrically coupled to said submersible turbine pump wherein said submersible turbine pump creates a defined initial threshold vacuum level in the outer annular space after receiving a test initiation signal from said monitor;

said monitor is electrically coupled to said sensing unit controller to receive the vacuum level in the outer annular space;

said monitor determines if the vacuum level in the outer annular space has decayed to a threshold vacuum level from said defined initial threshold vacuum level; and

wherein said monitor activates said submersible turbine pump to attempt to lower the vacuum level in the outer annular space back down to said defined initial threshold vacuum level if the vacuum level in the outer annular space decays to said threshold vacuum level.

2. The system of claim 1, wherein said monitor determines if the vacuum level in the outer annular space lowers to said defined initial threshold vacuum level within a defined amount of time.

3. The system of claim 2, wherein said monitor generates a leak detection alarm if said monitor determines that the vacuum level in the outer annular space does not lower to said defined initial threshold vacuum level within said defined amount of time.

4. The system of claim 1, further comprising a vacuum control valve that is coupled inline to the outer annular space between said submersible turbine pump and said pressure sensor wherein said vacuum control valve is electrically coupled to and under control of said sensing unit controller.

5. The system of claim 4, wherein said sensing unit controller closes said vacuum control valve before monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping so that said submersible turbine pump is isolated from the outer annular space.

6. The system of claim 1, further comprising an isolation valve located in the outer annular space wherein closing said isolation valve isolates the outer annular space from the sensing unit controller to allow verification of a leak in the fuel piping without relieving the vacuum in the outer annular space.

7. The system of claim 1, further comprising a check valve located in the outer annular space between said submersible turbine pump and said sensing unit controller to prevent ingress from the outer annular space to said submersible turbine pump.

8. The system of claim 1, further comprising a differential pressure indicator that is coupled in the outer annular space between said submersible turbine pump and said sensing unit controller, and is communicatively coupled to said monitor, wherein said monitor determines if said submersible turbine pump is drawing a sufficient vacuum level in the outer annular space.

9. The system of claim 8, wherein said monitor generates an alarm if said differential pressure indicator indicates that said submersible turbine pump is not drawing a sufficient vacuum level in the outer annular space.

10. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor;

communicating the vacuum level in the outer annular space to a monitor; and

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping;

sending a test initiation signal to said submersible turbine pump before performing said step of creating a defined initial threshold vacuum level;

wherein said step of monitoring further comprises determining if the vacuum level in the outer annular space has decayed to a threshold vacuum level from said defined initial threshold vacuum level; and

wherein said step of monitoring further comprises activating said submersible turbine pump to attempt to lower the vacuum level in the outer annular space back down to said defined initial threshold vacuum level if the vacuum level in the outer annular space decays to said threshold vacuum level.

11. The method of claim 10, wherein said step of monitoring further comprises determining if the vacuum level in the outer annular space lowers to said defined initial threshold vacuum level within a defined amount of time.

12. The method of claim 11, wherein said step of monitoring further comprises generating a leak detection alarm if the vacuum level in the outer annular space does not lower to said defined initial threshold vacuum level within said defined amount of time.

13. The method of claim 12, further comprising communicating said leak detection alarm to a system comprised from the group consisting of a site controller and a remote system.

14. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor;

communicating the vacuum level in the outer annular space to a monitor;

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping; and

closing a vacuum control valve to isolate said submersible turbine pump from the outer annular space before performing said step of monitoring the vacuum level in the outer annular space.

15. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor;

communicating the vacuum level in the outer annular space to a monitor;

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping; and

verifying a leak in the outer annular space by closing an isolation valve coupled to the outer annular space that isolates the outer annular space from said submersible turbine pump.

16. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor;

communicating the vacuum level in the outer annular space to a monitor;

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping; and

preventing ingress from the outer annular space to said submersible turbine pump.

17. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor;

communicating the vacuum level in the outer annular space to a monitor;

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping; and

determining if said submersible turbine pump is drawing a sufficient vacuum level in the outer annular space.

18. The system of claim 17, further comprising generating an alarm if said submersible turbine pump is not drawing a sufficient vacuum level in the outer annular space.

19. A system for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising:

a pressure sensor that is coupled to the outer annular space to detect a vacuum level in the outer annular space;

a sensing unit controller that is coupled to said pressure sensor to detennine the vacuum level in the outer annular space;

a submersible turbine pump that is fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank wherein said submersible turbine pump is also coupled to the outer annular space;

said submersible turbine pump creates a vacuum level in the outer annular space wherein said sensing unit controller determines the vacuum level in the outer annular space using said pressure sensor; and

a monitor that is electrically coupled to said submersible turbine pump wherein said submersible turbine pump creates a defined initial threshold vacuum level in the outer annular space;

said monitor electrically coupled to said sensing unit controller to receive the vacuum level in the outer annular space;

wherein said monitor causes said submersible turbine pump to activate to attempt to lower the vacuum level in the outer annular space back down to said defined initial threshold vacuum level if the vacuum level in the outer annular space decays to a threshold vacuum level.

20. The system of claim 19, wherein said monitor determines if the vacuum level in the outer annular space lowers to said defined initial threshold vacuum level within a defined amount of time.

21. The system of claim 20, wherein said monitor generates a leak detection alarm if said monitor determines that the vacuum level in the outer annular space does not lower to said defined initial threshold vacuum level within said defined amount of time.

22. The system of claim 19, wherein said monitor determines if the vacuum level in the outer annular space has decayed to the threshold vacuum level from said defined initial threshold vacuum level.

23. The system of claim 19, further comprising a liquid detection sensor that is coupled to the outer annular space, wherein said liquid detection sensor is coupled to said sensing unit controller and wherein said liquid detection sensor detects if liquid is present in the outer annular space.

24. The system of claim 23, wherein said sensing unit controller communicates a liquid detection by said liquid detection sensor to said monitor.

25. The system of claim 24, wherein said monitor generates a leak detection alarm when said liquid detection is communicated from said sensing unit controller.

26. The system of claim 24, wherein said monitor disables said submersible turbine pump when said liquid detection is communicated from said sensing unit controller.

27. The system of claim 23, wherein said liquid detection sensor comprises a float.

28. The system of claim 19, further comprising a vacuum control valve that is coupled inline to the outer annular space between said submersible turbine pump and said pressure sensor wherein said vacuum control valve is electrically coupled to and under control of said sensing unit controller.

29. The system of claim 28, wherein said sensing unit controller closes said vacuum control valve before monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping so that said submersible turbine pump is isolated from the outer annular space.

30. The system of claim 19, further comprising an isolation valve located in the outer annular space wherein closing said isolation valve isolates the outer annular space from the sensing unit controller to allow verification of a leak in the fuel piping without relieving the vacuum in the outer annular space.

31. The system of claim 19, further comprising a check valve located in the outer annular space between said submersible turbine pump and said sensing unit controller to prevent ingress from the outer annular space to said submersible turbine pump.

32. The system of claim 19, wherein the electrical coupling between said monitor and said sensing unit controller uses intrinsically safe wiring.

33. The system of claim 25, wherein said monitor communicates said leak detection alarm to a system comprised from the group consisting of a site controller and a remote system.

34. The system of claim 19, further comprising a differential pressure indicator that is coupled in the outer annular space between said submersible turbine pump and said sensing unit controller, and is communicatively coupled to said monitor, wherein said monitor determines if said submersible turbine pump is drawing a sufficient vacuum level in the outer annular space.

35. A method for detecting a leak in a double-walled fuel piping having an outer annular space that carries fuel from an underground storage tank in a service station environment, comprising the steps of:

creating a defined initial threshold vacuum level in the outer annular space using a submersible turbine pump that is also fluidly coupled to the fuel in the underground storage tank to draw the fuel out of the underground storage tank;

sensing a vacuum level in the outer annular space using a pressure sensor; and

monitoring the vacuum level in the outer annular space to determine if a leak exists in the fuel piping;

wherein said step of monitoring further comprises determining if the vacuum level in the outer annular space has decayed to a threshold vacuum level from said defined initial threshold vacuum level; and

wherein said step of monitoring further comprises activating said submersible turbine pump to attempt to lower the vacuum level in the outer annular space back down to said defined initial threshold vacuum level if the vacuum level in the outer annular space decays to said threshold vacuum level.

36. The method of claim 35, further comprising sending a test signal to said submersible turbine pump before performing said step of creating a defined initial threshold vacuum level.

37. The method of claim 35, wherein said step of monitoring further comprises determining if the vacuum level in the outer annular space lowers to said defined initial threshold vacuum level within a defined amount of time.

38. The method of claim 37, wherein said step of monitoring further comprises generating a leak detection alarm if the vacuum level in the outer annular space does not lower to said defined initial threshold vacuum level within said defined amount of time.

39. The method of claim 35, further comprising the step of sensing whether fluid is present in the outer annular space using a liquid detection sensor.

40. The method of claim 39, further comprising generating a liquid leak detection alarm if said liquid detection sensor senses liquid in the outer annular space.

41. The method of claim 39, further comprising disabling said submersible turbine pump if said liquid detection sensor senses liquid in the outer annular space.

42. The method of claim 35, further comprising closing a vacuum control valve to isolate said submersible turbine pump from the outer annular space before performing said step of monitoring the vacuum level in the outer annular space.

43. The method of claim 35, further comprising verifying a leak in the outer annular space by closing an isolation valve in said vacuum tubing that isolates the outer annular space from said submersible turbine pump.

44. The method of claim 35, further comprising preventing ingress from the outer annular space to said submersible turbine pump.

45. The method of claim 38, further comprising communicating said leak detection alarm to a system comprised from the group consisting of a site controller and a remote system.

46. The method of claim 40, further comprising communicating said liquid leak detection alarm to a system comprised from the group consisting of a site controller and a remote system.

47. The method of claim 35, further comprising determining if said submersible turbine pump is drawing a sufficient vacuum level in the outer annular space.

48. The system of claim 47, further comprising generating an alarm if said submersible turbine pump is not drawing a sufficient vacuum level in the outer annular space.