Method and apparatus for storage tank leak detection having temperature compensation

A leak detection system for an underground storage tank having a hydrocarbon product stored therein, comprising:

• an elongated manometer tube having first and second ends, an inlet adjacent the first end, and a substantially hollow core for supporting a liquid means having a temperature coefficient lower than the temperature coefficient of the hydrocarbon product by at least one order of magnitude;
• means for supporting the manometer tube in a substantially vertical manner in the underground storage tank such that the second end of the tube is located adjacent the base of the storage tank;
• a limp bladder connected to the tube adjacent the second end thereof for supporting a first portion of the liquid means in static equilibrium with respect to a second portion of the liquid means supported in the manometer tube, wherein the large disparity between the temperature coefficients of the liquid means and the hydrocarbon product insures that temperature-induced volumetric changes in the hydrocarbon product do not vary the level of the liquid means in the tube;
• a float supported by the liquid means within the manometer tube and including a corner cube reflector;
• and
• an interferometer supported adjacent the first end of the manometer tube for generating a signal for use in detecting movement of the float within the tube to thereby indicate a leak into or out of the storage tank.

A method for detecting a leak in a storage tank having a fluid product stored therein, comprising the steps of:

• connecting a bladder to an end of a tube having an inlet and a substantially hollow core;
• filling the tube and the bladder with a medium having a temperature coefficient substantially lower than the temperature coefficient of the product;
• supporting the tube and the bladder in the storage tank such that a first portion of the medium is supported in the bladder in static equilibrium with respect to a second portion of the medium supported in the tube, wherein the large disparity between the temperature coefficients of the medium and the product insures that temperature-induced volumetric changes in the product do not vary the level of the medium in the tube;
• and
• sensing variations in the level of the medium in the tube to thereby detect a leak in the storage tank.

A method for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the fluid product stored in the storage tank, comprising the steps of:

• connecting a bladder to an end of a pressure tube having an inlet and a substantially hollow core;
• filling the pressure tube and the bladder with a liquid having a temperature coefficient substantially lower than the temperature coefficient of the fluid product;
• and
• supporting the pressure tube and the bladder in a substantially vertical manner in a storage tank such that a first portion of the liquid is supported in the bladder in static equilibrium with respect to a second portion of the liquid supported in the tube, wherein the large disparity between the temperature coefficients of the liquid and the fluid product insures that temperature-induced volumetric changes in the fluid product do not vary the level of the liquid in the pressure tube.

A leak detection system for a storage tank having a fluid product stored therein, comprising:

• an elongated tube having first and second ends, an inlet adjacent to the first end, and a substantially hollow core for supporting a medium having a temperature coefficient substantially lower than the temperature coefficient of the fluid product;
• means for supporting the elongated tube in a substantially vertical manner in the storage tank such that the second end of the tube is located adjacent the base of the storage tank;
• a bladder connected to the tube adjacent the second end thereof for supporting a first portion of the medium in static equilibrium with respect to a second portion of the medium supported in the tube, wherein the large disparity between the temperature coefficients of the medium and the fluid product insures that temperature-induced volumetric changes in the fluid product do not vary the level of the medium in the tube;
• means for sensing variation in the level of the medium in the tube to thereby detect leakage into and from the storage tank;
• and
• a bladder connected to the inlet of the elongated tube for sealing and protecting the medium from contamination by the fluid product.

A leak detection system for an underground storage tank having a hydrocarbon product stored therein, comprising:

• an elongated manometer tube having first and second ends, an inlet adjacent the first end, and substantially hollow core for supporting a liquid means having a temperature coefficient lower than the temperature coefficient of the hydrocarbon product by at least one order of magnitude;
• means for supporting the manometer tube in a substantially vertical manner in the underground storage tank such that the second end of the tube is located adjacent the base of the storage tank;
• a limp bladder connected to the tube adjacent the second end thereof for supporting a first portion of the liquid means in static equilibrium with respect to a second portion of the liquid means supported in the manometer tube, wherein the large disparity between the temperature coefficients of the liquid means and the hydrocarbon product insures that temperature-induced volumetric changes in the hydrocarbon product do not vary the level of the liquid means in the tube;
• a float supported by the liquid means within the manometer tube and including a corner cube reflector;
• an interferometer supported adjacent the first end of the manometer tube for generating a signal for use in detecting movement of the float within the tube to thereby indicate a leak into or out of the storage tank;
• and
• a bladder connected to the inlet of the manometer tube for sealing and protecting the liquid means from contamination by the hydrocarbon product.

Apparatus for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the fluid product stored in the storage tank, comprising:

• an elongated tube having first and second ends, an inlet adjacent the first end, and a substantially hollow core for supporting a medium having a temperature coefficient substantially lower than the temperature coefficient of the fluid product;
• a first bladder connected to the tube adjacent the second end thereof for supporting a first portion of the medium in static equilibrium with respect to a second portion of the medium supported in the tube, wherein the large disparity between the temperature coefficients of the medium and the fluid product insures that temperaure-induced volumetric changes in the fluid product do not vary the level of the medium in the tube when the tube is supported in the storage tank;
• and
• a second bladder connected to the inlet of the tube for sealing and protecting the medium from contamination by the fluid product.