Secondary containment leak prevention and detection system and method

• US 6,997,042 B2
• Filed: 11/06/2003
• Issued: 02/14/2006
• 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., Halla, Donald D., Dolson, Richard G.
• Primary Examiner(s): Larkin, Daniel S.
• Application Number:
  US10/703,156
• Publication Number:
  US 20040149017A1
• Time in Patent Office: 831 Days
• Field of Search: 73/405.R, 73/491, 73/492, 73/495
• 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: B65D 90/501 comprising hollow spaces within walls
• CPC Class Codes: B65D 90/503 under pressure or vacuum
• 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 7/68 submerged in storage tank or reservoir
• CPC Class Codes: B67D 7/78 Arrangements of storage tanks, reservoirs or pipe-lines
• CPC Class Codes: G01M 3/2892 for underground fuel dispensing systems G01M3/30 takes precedence
• CPC Class Codes: Y10T 137/0402 Cleaning, repairing, or assembling

Abstract

A pump housing contains a pump that draws fuel from an underground storage tank to deliver fuel to fuel dispensers in a service station environment. The pump is coupled to a double-walled riser pipe that carries the fuel from the underground storage tank to the pump. The double-walled fuel piping contains an inner space that carries the fuel and an outer annular space that captures any leaked fuel from the inner space. The outer annular space is coupled to a vacuum created by the pump to determine if a leak exists in the outer annular space. An alternate submersible turbine pump has a double-walled housing with a pressure sensor disposed in the interstitial space of the double-walled housing. A vacuum may be created therein to determine if leaks are present in the housing of the submersible turbine pump.

Claims

1. A system for detecting a leak, comprising:

a riser pipe formed from a length of double-walled piping, said riser pipe comprising;

an inner space adapted to draw fuel from a storage tank; and

an interstitial space between walls of the double-walled piping;

a pressure sensor coupled to the interstitial space to detect a vacuum level in the interstitial space; and

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

a submersible turbine pump coupled to said riser pipe to couple the submersible turbine pump to the storage tank, said submersible turbine pump fluidly coupled to the fuel in the storage tank to draw the fuel out of the storage tank through the inner space of the riser pipe

a vacuum-generating source coupled to the interstitial space;

said vacuum-generating source draws the vacuum level in in the interstitial space; and

said sensing unit controller determines the vacuum level in the interstitial space using said pressure sensor.

2. The system of claim 1, further comprising a control system that is electrically coupled to said vacuum-generating source wherein said vacuum-generating source draws a defined initial threshold vacuum level in the interstitial space after receiving a test initiation signal from said control system.

3. The system of claim 2, wherein said control system generates a leak detection alarm if said vacuum-generating source cannot draw said defined initial threshold vacuum level in the interstitial space.

4. The system of claim 2, wherein the control system is comprised of a system from the group consisting of a site controller, a tank monitor, or a remote system.

5. The system of claim 2, wherein said control system is electrically coupled to said sensing unit controller to receive the vacuum level in the interstitial space.

6. The system of claim 5, wherein said control system determines if the vacuum level in the interstitial space has decayed to a threshold vacuum level from said defined initial threshold vacuum level.

7. The system of claim 6, wherein said control system activates said vacuum-generating source to attempt to lower the vacuum level in the interstitial space back down to said defined initial threshold vacuum level if the vacuum level in the interstitial space decays to said threshold vacuum level.

8. The system of claim 5, wherein said control system determines if the vacuum level in the interstitial space lowers to said defined initial threshold vacuum level within a defined amount of time.

9. The system of claim 8, wherein said control system generates a leak detection alarm if said control system determines that the vacuum level in the interstitial space does not lower to said defined initial threshold vacuum level within said defined amount of time.

10. The system of claim 5, wherein said control system determines if a leak exists in the riser pipe by determining if the vacuum level in the interstitial space decays to a threshold vacuum level in a predetermined amount of time.

11. The system of claim 5, further comprising a liquid detection sensor that is coupled to the interstitial 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 interstitial space.

12. The system of claim 11 wherein said sensing unit controller communicates a liquid detection by said liquid detection sensor to said control system.

13. The system of claim 12, wherein said control system generates a leak detection alarm when said liquid detection is communicated from said sensing unit controller.

14. The system of claim 12, wherein said control system disables said vacuum-generating source when said liquid detection is communicated from said sensing unit controller.

15. The system of claim 11, wherein said liquid detection sensor comprises a float.

16. The system of claim 1, further comprising a vacuum control valve that is coupled inline to the interstitial space between said vacuum-generating source and said pressure sensor wherein said vacuum control valve is electrically coupled to and under control of said sensing unit controller.

17. The system of claim 16, wherein said sensing unit controller closes said vacuum control valve before monitoring the vacuum level in the interstitial space to determine if a leak exists in the fuel piping so that said vacuum-generating source is isolated from the interstitial space.

18. The system of claim 1, wherein said riser pipe is sealed.

19. The system of claim 1, further comprising vacuum tubing that is coupled to the interstitial space and the vacuum-generating source to couple the submersible turbine pump to the interstitial space.

20. The system of claim 19, wherein said vacuum tubing is connected to the interstitial space through a fitting.

21. The system of claim 19, wherein said vacuum tubing is connected to the interstitial space through an outer wall of the double-walled piping.

22. The system of claim 19, wherein said vacuum tubing is positioned within the vacuum-generating source.

23. The system of claim 19, further comprising a sump, said vacuum-generating source positioned within said sump.

24. The system of claim 23, wherein said vacuum tubing is positioned within said sump.

25. The system of claim 1, wherein said interstitial space is fluidly coupled to a second interstitial space, said second interstitial space surrounding the storage tank.

26. The system of claim 1, further comprising a check valve located in the interstitial space between said vacuum-generating source and said sensing unit controller to prevent ingress from the interstitial space to said vacuum-generating source.

27. The system of claim 1 wherein said interstitial space is fluidly connected to an interior portion of the vacuum-generating source.

28. The system of claim 27, wherein said riser pipe threads into said submersible turbine pump.

29. The system of claim 1, further comprising a sump, said submersible turbine pump and said riser pipe positioned within said sump.

30. The system of claim 1, wherein the submersible turbine pump acts as the vacuum-generating source to draw the vacuum level in the interstitial space.

31. The system of claim 30, further comprising a control system that is electrically coupled to said submersible turbine pump wherein said submersible turbine pump draws a defined initial threshold vacuum level in the interstitial space after receiving a test initiation signal from said control system.

32. The system of claim 31, wherein said control system generates a leak detection alarm if said submersible turbine pump cannot draw said defined initial threshold vacuum level in the interstitial space.

33. The system of claim 32, wherein said control system activates said submersible turbine pump to attempt to lower the vacuum level in the interstitial space back down to said defined initial threshold vacuum level if the vacuum level in the interstitial space decays to said threshold vacuum level.

34. The system of claim 33, wherein said control system determines if the vacuum level in the interstitial space lowers to said defined initial threshold vacuum level within a defined amount of time.

35. The system of claim 34, wherein said control system generates a leak detection alarm if said control system determines that the vacuum level in the interstitial space does not lower to said defined initial threshold vacuum level within said defined amount of time.

36. The system of claim 31, wherein said control system determines if a leak exists in the riser pipe by determining if the vacuum level in the interstitial space decays to a threshold vacuum level in a predetermined amount of time.

37. A method for detecting a leak in a double-walled riser pipe having an interstitial space, comprising:

creating a vacuum level in the interstitial space of the riser pipe coupling fuel in a storage tank to a submersible turbine pump that draws fuel out of the storage tank, using a vacuum-generating source

drawing the fuel out of the storage tank using the submersible turbine pump;

sensing a vacuum level in the interstitial space of the riser pipe using a pressure sensor; and

monitoring the vacuum level in the interstitial space of the riser pipe to determine if a leak exists in the riser pipe.

38. The method of claim 37, further comprising coupling the vacuum-generating source to the interstitial space using vacuum tubing.

39. The method of claim 38, wherein said step of coupling the vacuum-generating source to the interstitial space using vacuum tubing comprises coupling the vacuum tubing to the interstitial space through an outer wall of the riser pipe.

40. The method of claim 38, wherein said step of coupling the vacuum-generating source to the interstitial space using vacuum tubing comprises coupling the vacuum tubing to the interstitial space through a fitting associated with the riser pipe.

42. The method of claim 37, further comprising fluidly connecting the interstitial space of the riser pipe to an interstitial space of the storage tank.

43. The method of claim 37 further comprising fluidly connecting the interstitial space of the riser pipe to an interior portion of the vacuum-generating source.

44. The method of claim 37 further comprising crimping both ends of the riser pipe.

45. The method of claim 37 wherein the step of sensing the vacuum level in the interstitial space using a pressure sensor comprises sensing the vacuum level with a pressure sensor positioned in the interstitial space.

46. The method of claim 37, further comprising the step of sensing whether liquid is present in the interstitial space using a liquid detection sensor.

47. The method of claim 46, further comprising generating a liquid leak detection alarm if said liquid detection sensor senses liquid in the interstitial space.

48. The method of claim 46, further comprising disabling said submersible turbine pump if said liquid detection sensor senses liquid in the interstitial space.

49. The method of claim 37, further comprising closing a vacuum control valve to isolate said vacuum-generating source from the interstitial space before performing said step of monitoring the vacuum level in the interstitial space.

50. The method of claim 37, further comprising preventing ingress from the interstitial space to said vacuum-generating source.

51. The method of claim 37, further comprising determining if said vacuum-generating source is drawing a sufficient vacuum level in the interstitial space.

52. The method of claim 51, further comprising generating an alarm if said vacuum-generating source is not drawing a sufficient vacuum level in the interstitial space.

53. The method of claim 37, wherein the submersible turbine pump acts as the vacuum-generating source to draw the vacuum level in the interstitial space.

54. The method of claim 37, further comprising determining if said submersible turbine pump is drawing a sufficient vacuum level in the interstitial space.

55. The method of claim 54, further comprising generating an alarm if said submersible turbine pump is not drawing a sufficient vacuum level in the interstitial space.

56. The method of claim 54, further comprising activating said submersible turbine pump to attempt to lower the vacuum level in the interstitial space if the vacuum level in the interstitial space decays to a threshold vacuum level.

57. The method of claim 56, further comprising determining if the vacuum level in the interstitial space lowers to the threshold vacuum level within a defined amount of time.

58. The method of claim 57, further comprising generating a leak detection alarm if the vacuum level in the interstitial space does not lower to the threshold vacuum level within the defined amount of time.

41. The method of chum 38, further comprising verifying a leak in the interstitial space by closing an isolation valve in said vacuum tubing that isolates the interstitial space from said vacuum-generating source.

59. A method for detecting a leak in a double-walled riser pipe having an interstitial space, comprising:

creating a vacuum level in the interstitial space of the riser pipe coupling fuel in a storage tank to a submersible turbine pump that draws fuel out of the storage tunic, using the submersible turbine pump as a vacuum-generating source;

drawing die fuel out of the storage tank using the submersible turbine pump;

sensing a vacuum level in the interstitial space of the riser pipe using a pressure sensor; and

monitoring the vacuum level in the interstitial space of the riser pipe to determine if a leak exists in the riser pipe.

60. The method of claim 59, further comprising determining if a leak exists in the riser pipe by determining if the vacuum level in the interstitial space decays to a threshold vacuum level in a predetermined amount of time.