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An apparatus for detecting a leak in a conduit line includes a housing in fluid communication with the line, a valve including a valve seat and a valve element movable relative to the seat between opened and closed positions, a bypass line around the valve, a flow detector coupled to the bypass line

An apparatus for detecting a leak in a conduit line includes a housing in fluid communication with the line, a valve including a valve seat and a valve element movable relative to the seat between opened and closed positions, a bypass line around the valve, a flow detector coupled to the bypass line for detecting fluid flow therethrough, and a first mechanism configured to urge the valve element toward the closed position. The apparatus may further include a second mechanism separate from the first mechanism for maintaining the valve element in the closed position until a threshold pressure drop is reached. The first mechanism may operate on the principle of buoyancy and the second mechanism may operate on the principle of magnetism.

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1. An apparatus for detecting a leak in a fluid conduit line, comprising: a housing configured to be in fluid communication with the fluid conduit line;a valve including a valve seat coupled to the housing and a valve element movable relative to the valve seat between an opened position wherein flui

1. An apparatus for detecting a leak in a fluid conduit line, comprising: a housing configured to be in fluid communication with the fluid conduit line;a valve including a valve seat coupled to the housing and a valve element movable relative to the valve seat between an opened position wherein fluid is permitted to flow through the valve, and a closed position wherein fluid is prevented from flowing through the valve, the valve having a longitudinal axis;a bypass line having a first end in fluid communication with a first side of the valve and a second end in fluid communication with a second side of the valve, the second end of the bypass line extending generally parallel to the longitudinal axis of the valve;a fluid flow detector operatively coupled to the bypass line and configured to detect the flow of fluid therethrough; anda first mechanism configured to provide a net positive buoyant force on the valve element when the valve element and first mechanism are immersed in the fluid flowing through the fluid conduit line, the net positive buoyant force configured to urge the valve element toward the closed position. 2. The apparatus of claim 1, wherein the first mechanism includes a fluid float. 3. The apparatus of claim 1, wherein the net positive buoyant force is between approximately 0.0625 lbf and approximately 0.5 lbf. 4. The apparatus of claim 1, further comprising: a sensor coupled to one of the housing and the valve element configured to detect when the valve element is in the closed position. 5. The apparatus of claim 1, wherein the fluid flow detector includes a thermal flow detector. 6. The apparatus of claim 1, further comprising: a second mechanism separate from the first mechanism and configured to maintain the valve element in the closed position until a threshold pressure drop across the valve element is reached. 7. The apparatus of claim 6, wherein the threshold pressure drop for causing the valve element to move away from the closed position is between approximately one-half (0.5) psi and approximately four (4) psi. 8. The apparatus of claim 6, wherein the second mechanism includes a magnet. 9. The apparatus of claim 8, wherein the second mechanism includes a first magnetic member coupled to the valve element and a second magnetic member coupled to the housing, the first and second magnetic members being in proximity to each other when the valve element is in the closed position. 10. The apparatus of claim 9, wherein each of the first and second magnetic members may be selected from the group consisting of a permanent magnet, an electromagnet, and a paramagnetic material. 11. The apparatus of claim 9, wherein the first magnetic member includes a portion of the valve element formed of a paramagnetic material, and the second magnetic member includes a permanent magnet. 12. An apparatus for detecting a leak in a fluid conduit line, comprising: a housing having an inlet, an outlet, and an interior cavity;a valve disposed at least in part in the interior cavity between the inlet and outlet, the valve including a valve seat coupled to the housing and a valve element movable relative to the valve seat between an opened position wherein fluid is permitted to flow through the valve, and a closed position wherein fluid is prevented from flowing through the valve, the valve having a longitudinal axis;a bypass line having a first end in fluid communication with a first side of the valve and a second end in fluid communication with a second side of the valve, the second end of the bypass line extending generally parallel to the longitudinal axis of the valve;a fluid flow detector operatively coupled to the bypass line and configured to detect the flow of fluid therethrough;a first mechanism configured to urge the valve element toward the closed position; anda second mechanism separate from the first mechanism and configured to maintain the valve element in the closed position until a threshold pressure drop across the valve element is reached. 13. The apparatus of claim 12, wherein the first mechanism includes a fluid float configured to provide a net positive buoyant force on the valve element when the valve element and float are immersed in the fluid flowing through the fluid conduit line. 14. The apparatus of claim 12, wherein the second mechanism includes a magnet. 15. The apparatus of claim 12, wherein the first mechanism is the primary force-providing mechanism when the valve element is in the opened position and the second mechanism is the primary force-providing mechanism when the valve element is in the closed position. 16. The apparatus of claim 12, wherein the first mechanism provides a substantially constant force for urging the valve element toward the closed position. 17. The apparatus of claim 16, wherein the force provided by the first mechanism is between approximately 0.0625 lbf and approximately 0.5 lbf. 18. The apparatus of claim 12, wherein the second mechanism provides a variable force on the valve element. 19. The apparatus of claim 18, wherein the second mechanism provides a force on the valve element when in the closed position having a magnitude, the magnitude of the force decreasing as the valve element moves toward the opened position. 20. The apparatus of claim 18, wherein the force provided by the second mechanism is substantially zero when the valve element is in the opened position. 21. An apparatus for detecting a leak in a fluid conduit line, comprising: a housing having an inlet, an outlet, and an interior cavity;a valve disposed at least in part in the interior cavity between the inlet and outlet, the valve including a valve seat operatively coupled to the housing and a valve element movable relative to the valve seat between an opened position wherein fluid is permitted to flow through the valve, and a closed position wherein fluid is prevented from flowing through the valve, the valve having a longitudinal axis;a bypass line having a first end in fluid communication with a first side of the valve and a second end in fluid communication with a second side of the valve, the second end of the bypass line extending generally parallel to the longitudinal axis of the valve;a fluid flow detector operatively coupled with the bypass line and configured to detect the flow of fluid therethrough;a first mechanism including a fluid float coupled to the valve element and configured to urge the valve element toward the closed position, the first mechanism configured to apply a substantially constant force to the valve element having a first magnitude; anda second mechanism including a magnet, the second mechanism configured to maintain the valve element in the closed position until a threshold pressure drop across the valve element is reached, the second mechanism configured to apply a force on the valve element at least when the valve element is adjacent the closed position, the force from the second mechanism having a second magnitude that is greater than the first magnitude of the force from the first mechanism. 22. 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; anda leak detector in fluid communication with the fluid conduit line and configured to detect a leak therein, the leak detector comprising: a housing having an inlet, an outlet, and an interior cavity;a valve disposed at least in part in the interior cavity between the inlet and outlet, the valve including a valve seat operatively coupled to the housing and a valve element movable relative to the valve seat between an opened position wherein liquid is permitted to flow through the valve, and a closed position wherein liquid is prevented from flowing through the valve, the valve having a longitudinal axis;a bypass line having a first end in fluid communication with a first side of the valve and a second end in fluid communication with a second side of the valve, the second end of the bypass line extending generally parallel to the longitudinal axis of the valve;a fluid flow detector operatively coupled with the bypass line and configured to detect the flow of liquid therethrough;a first mechanism coupled to the valve element and configured to urge the valve element toward the closed position; anda second mechanism separate from the first mechanism and configured to maintain the valve element in the closed position until a threshold pressure drop across the valve element is reached. 23. The dispensing system of claim 22, wherein the first mechanism includes a fluid float configured to provide a net positive buoyant force on the valve element when the valve element and float are immersed in the liquid flowing through the fluid conduit line. 24. The dispensing system of claim 22, wherein the second mechanism includes a magnet. 25. The dispensing system of claim 24, wherein the second mechanism includes a first magnetic member coupled to the valve element and a second magnetic member coupled to the housing, the first and second magnetic members being in proximity to each other when the valve element is in the closed position.