LINE LEAK DETECTOR

Abstract

A leak detector for detecting volumetric changes in a liquid volume includes a biased piston disposed in a housing and a liquid passage extending from the liquid volume to an expansible chamber defined by the housing and piston. The leak detector further includes a magnetostrictive sensor including a magnetostrictive waveguide, a magnet operably coupled to the piston and moveable therewith and pulsing and detection devices for detecting the position of the magnet along the magnetostrictive waveguide. A method of using the detector includes exposing the expansible chamber to liquid from the liquid volume and sensing the changes in the liquid volume magnetostrictively by causing relative movement between the waveguide and the magnet to obtain data representative of piston movement which is responsive to volumetric changes in the liquid volume.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

FIG. 1 is a diagrammatic illustration of an exemplary fuel dispensing system;

FIG. 2 is a perspective disassembled view of an embodiment of a line leak detector in accordance with the invention;

FIG. 3A is a cross-sectional view of the line leak detector shown in FIG. 2 after assembly;

FIG. 3B is another cross-sectional view of the line leak detector shown in FIG. 2 after assembly;

FIG. 4 is a cross-sectional view of an alternate embodiment of the line leak detector in accordance with the invention;

FIG. 5 is a cross-sectional view of an alternate embodiment of the line leak detector in accordance with the invention;

FIG. 6 is a cross-sectional view of an alternate embodiment of the line leak detector in accordance with the invention;

FIG. 7 is a cross-sectional view of an alternate embodiment of the line leak detector in accordance with the invention;

FIG. 8 is a cross-sectional view of an alternate embodiment of the line leak detector in accordance with the invention; and

FIGS. 9A-9C are a flowchart illustration of an exemplary leak detection system using embodiments of the leak detector of the invention.

Claims

1. An apparatus for detecting volumetric changes in a liquid volume comprising: a housing defining an interior bore therein;a piston disposed in the interior bore and movable along the interior bore, the interior bore and piston defining an expansible chamber;a biasing member for biasing the piston against movement within the interior bore;a liquid passage extending from the liquid volume to the expansible chamber; anda magnetostrictive sensor including a magnetostrictive waveguide, a magnet operably connected to the piston for movement therewith and in operative relation to said magnetostrictive waveguide, and pulsing and detection devices for detecting a position of the magnet along the magnetostrictive waveguide.

2. The apparatus of claim 1, wherein the biasing member is selected from the group consisting of a constant rate spring, a variable rate spring, a weight, an electromagnet, a permanent magnet, a fluid supply, and a sealed gas pocket.

3. The apparatus of claim 2, wherein the fluid supply is one of a pneumatic or hydraulic supply.

4. The apparatus of claim 1, wherein the biasing member imposes a fluid pressure in the liquid volume that varies with movement of the piston within the interior bore.

5. The apparatus of claim 1, wherein the biasing member imposes a fluid pressure in the liquid volume that remains relatively constant with movement of the piston within the interior bore.

6. The apparatus of claim 1, wherein the biasing member is disposed on a side of the piston opposite the expansible chamber.

7. The apparatus of claim 1, further comprising a vent port disposed on a side of the piston opposite the expansible chamber.

8. The apparatus of claim 1, wherein the piston further includes at least one seal along a periphery of the piston adapted to form a seal with the interior bore of the housing.

9. The apparatus of claim 1, further comprising: a hollow shaft positioned in the interior bore and extending between the proximal and distal end portions, the magnetostrictive waveguide positioned within the hollow shaft,wherein the piston includes a central passageway for receiving the hollow shaft therethrough and moving within the interior bore along the hollow shaft.

10. The apparatus of claim 9, wherein the piston further includes at least one seal along the central passageway adapted to form a seal with the hollow shaft.

11. The apparatus of claim 1, wherein the piston is configured as a buoyant float.

12. The apparatus of claim 1, wherein the magnetostrictive waveguide and the magnet are disposed on a side of the piston opposite the expansible chamber.

13. A dispensing system, comprising: a tank for holding a liquid;a dispensing unit for dispensing the liquid;a fluid conduit line providing fluid communication between the tank and the dispensing unit;a one-way valve disposed in the fluid conduit line, the portion of the fluid conduit line between the valve and the dispensing unit defining a liquid volume; anda leak detector in communication with the fluid conduit line and adapted to detect volumetric changes in the liquid volume, the leak detector comprising: a housing defining an interior bore therein;a piston disposed in the interior bore and movable along the interior bore, the interior bore and piston defining an expansible chamber;a biasing member for biasing the piston against movement within the interior bore;a liquid passage extending from the liquid volume to the expansible chamber; anda magnetostrictive sensor including a magnetostrictive waveguide, a magnet operably connected to the piston for movement therewith and in operative relation to said magnetostrictive waveguide, and pulsing and detection devices for detecting a position of the magnet along the magnetostrictive waveguide.

14. The dispensing system of claim 13, wherein the biasing member is selected from the group consisting of a constant rate spring, a variable rate spring, a weight, an electromagnet, a permanent magnet, a fluid supply, and a sealed gas pocket.

15. The dispensing system of claim 14, wherein the fluid supply is one of a pneumatic or hydraulic supply.

16. The dispensing system of claim 13, wherein fluid flow through the fluid conduit line is unimpeded by the leak detector.

17. The dispensing system of claim 13, further comprising a central control for analyzing the position data from the magnetostrictive sensor and determining whether a leak exists in the fluid conduit line.

18. A method of detecting changes in a liquid volume, comprising: exposing the liquid in the liquid volume to an expansible chamber apparatus comprising a housing having an interior bore and a piston movable along the interior bore in response to changes in the liquid volume; andsensing changes in the liquid volume magnetostrictively by causing relative movement of one of a magnetostrictive waveguide or a magnet operatively disposed proximate the magnetostrictive waveguide upon movement of the piston and obtaining data from the movement representative of piston movement responsive to volumetric changes in the liquid volume.

19. The method of claim 18, further comprising: biasing the movement of the piston against volumetric changes in the liquid volume.

20. The method of claim 19, wherein biasing the movement of the piston is caused by a biasing member selected from the group consisting of a constant rate spring, a variable rate spring, a weight, an electromagnet, a permanent magnet, a fluid supply, and a sealed gas pocket.

21. The method of claim 19, wherein biasing the movement of the piston comprises imposing a fluid pressure in the liquid volume that varies with movement of the piston within the interior bore.

22. The method of claim 19, biasing the movement of the piston comprises imposing a fluid pressure in the liquid volume that remains relatively constant with movement of the piston within the interior bore.

23. The method of claim 118, further comprising: transporting liquid within a liquid delivery line having a cross-sectional flow area; andexposing liquid from the liquid delivery line to the expansible chamber without restricting the cross-sectional flow area of the liquid delivery line.