Volumetric leak detection system for underground storage tanks and the like
First Claim
Patent Images
1. A method for detecting and measuring leaks in an underground container such as a tank and piping containing a liquid, comprising:
- measuring the pressure and temperature of the liquid over a predetermining time interval,simultaneously measuring the liquid level in the container and the temperature of the liquid therein over the same predetermined time interval,calculating from each said measuring step the leak rate of the liquid from said container, andcomparing the two calculated leak rates with each other.
7 Assignments
0 Petitions
Accused Products
Abstract
Method and apparatus for detecting leaks in underground tanks containing a liquid. The pressure and temperature of the liquid are measured over a predetermining time interval, while simultaneously measuring the liquid level in the tank and the temperature of the liquid therein. From each measuring step the leak rate of the liquid from the tank is calculated and the two calculated leak rates are compared with each other. The temperature at a series of different depths in the tank is measured. Other measurements are made and fed to a suitable computer which computes the leakage rate.
150 Citations
92 Claims
-
1. A method for detecting and measuring leaks in an underground container such as a tank and piping containing a liquid, comprising:
-
measuring the pressure and temperature of the liquid over a predetermining time interval, simultaneously measuring the liquid level in the container and the temperature of the liquid therein over the same predetermined time interval, calculating from each said measuring step the leak rate of the liquid from said container, and comparing the two calculated leak rates with each other. - View Dependent Claims (2, 3, 4)
-
-
5. Apparatus for detecting and measuring leaks in an underground container, such as a tank or piping containing a liquid, comprising:
-
pressure sensing means for measuring the pressure of the liquid over a predetermined time interval, first temperature sensing means for simultaneously measuring the temperature of said liquid over said time interval, second temperature sensing means for simultaneously sensing the ambient temperature over said time interval, and level sensing means for simultaneously measuring the level of the liquid in the container over said time interval. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
-
-
13. Apparatus for detecting and measuring leaks from an underground tank having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, conductor means attached to the elements of said test instrumentation assembly, data acquisition means connected to said conductor means, digital computer means connected to and controlling said data acquisition unit and having timing means, a memory and an output, and recording means connected to said output, said instrumentation assembly including; first liquid level measuring means for measuring the level of liquid in said tank and for sending an analog signal thereof to said data acquisition means, first temperature sensing means attached to said first liquid level measuring means for monitoring its temperature thereof and for transmitting to said computer the value thereof, second liquid level measuring means contained in an evaporation level monitoring tube containing tank liquid, for measuring continuously the liquid level in the monitoring tube, at a height slightly above the liquid level in said tank, and for sending an analog signal thereof to said computer, second temperature sensing means attached to said second liquid level measuring means for monitoring its temperature and transmitting to said computer the value thereof, third temperature sensing means for measuring the ambient air temperature adjacent to said tank and transmitting the value thereof to said computer, and a plurality of temperature sensor and probe means for measuring the temperatures in the tank liquid at a plurality of locations, and for sending those temperatures to said computer, said computer having means for computing the tank leakage from the information provided by the elements recited above. - View Dependent Claims (14, 15, 16, 17, 18)
-
-
19. Apparatus for detecting and measuring leaks from an underground tank having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, conductor means attached to the elements of said test instrumentation assembly, data acquisition means connected to said conductor means, digital computer means connected to and controlling said data acquisition unit and having timing means, a memory and an output, and recording means connected to said output, said instrumentation assembly including; first liquid level measuring means for measuring the level of liquid in said tank and for sending an analog signal thereof to said data acquisition means, first temperature sensing means attached to said first liquid level measuring means for monitoring its temperature thereof and for transmitting to said computer the value thereof, second liquid level measuring means contained in an evaporation level monitoring tube containing tank liquid, for measuring the liquid level in the monitoring tube, at a height slightly above the liquid level in said tank, second temperature sensing means for measuring the ambient air temperature adjacent to said tank and transmitting the value thereof to said computer, and a plurality of temperature sensors and a plurality of probe means for measuring the temperatures in the tank liquid at a plurality of locations, and for sending those temperatures to said computer, said computer having means for computing the tank leakage from the information provided by the elements recited above.
-
-
20. Apparatus for detecting and measuring leaks from an underground tank having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, conductor means attached to the elements of said test instrumentation assembly, and digital monitoring means for manual recovery of the data obtained by said assembly, said instrumentation assembly including; first liquid level measuring means for measuring the liquid level of liquid in said tank and for sending an analog signal thereof to said digital monitoring means, first temperature sensing means attached to said first liquid level measuring means for monitoring its temperature thereof and for transmitting to said digital monitoring means the value thereof, second liquid level measuring means contained in an evaporation level monitoring tube for containing tank liquid, for measuring continuously the liquid level in the monitoring tube, at a height slightly above the liquid level in said tank, and for sending an analog thereof to said digital monitoring means, second temperature sensing means attached to said second liquid level measuring means for monitoring its temperature and transmitting to said digital monitoring means the value thereof, third temperature sensing means for measuring the ambient air temperature adjacent to said tank and transmitting the value thereof to said digital monitoring means, and a plurality of temperature sensors and a plurality of probe means for measuring the temperatures in the tank liquid at a plurality of locations, and for sending those temperatures to said digital monitoring means. - View Dependent Claims (21, 22, 23, 24)
-
-
25. Apparatus for detecting and measuring leaks from underground tanks having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, conductor means attached to the elements of said test instrumentation assembly, data acquisition means connected to said conductor means, digital computer means connected to and controlling said data acquisition unit and having timing means, a memory, and an output, and recording means connected to said output, said instrumentation assembly including; first liquid level measuring means for measuring the level of liquid in said tank and for sending an analog signal thereof to said data acquisition means, first temperature sensing means attached to said first liquid level measuring means for monitoring its temperature and for transmitting to said computer the value thereof, second light level measuring means contained in an evaporation level monitoring tube containing tank liquid, for measuring continuously the liquid level in the monitoring tube, at a height slightly above the liquid level in said tank, and for sending an analog signal thereof to said computer, second temperature sensing means attached to said second liquid level measuring means for monitoring its temperature and transmitting to said computer the value thereof, first pressure measuring means for measuring continuously the pressure of the liquid and for sending an analog signal thereof to said computer, third temperature sensing means attached to said pressure measuring means for measuring its temperature and transmitting to said computer the value thereof, second pressure measuring means for measuring atmospheric pressure adjacent said tank and for sending an analog signal thereof to said computer, fourth temperature sensing means for measuring the ambient air temperature adjacent to said tank and transmitting the value thereof to said computer, and a plurality of temperature sensor and probe means for measuring the temperatures in the tank liquid at a plurality of locations, and for sending those temperatures to said computer, said computer having means for computing the tank leakage from the information provided by the elements recited above. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
-
-
33. Apparatus for detecting and measuring leaks from underground tanks having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, a multiconductor electronic cable assembly with cables connected to the elements of said test instrumentation assembly, a computer-controlled data acquisition unit connected to said cable assembly, a digital computer connected to and controlling said data acquisition unit and having timing means, a memory, and an output, and recording means connected to said output, the elements of said instrumentation assembly including first linear variable displacement transducer and float means for measuring the level of liquid in said tank by vertical float movement, for converting the float movement to an electrical output voltage proportional to that movement and for sending said voltage through said cable assembly via said data acquisition unit to said computer, first temperature sensing means attached to said first linear variable displacement transducer and float means for monitoring the temperature thereof and for transmitting it through said cable assembly, evaporation level measurement means having an evaporation level monitoring tube, and second linear variable displacement transducer and float means for measuring continuously the liquid level in the monitoring tube, for converting the float movement thereof to an electrical output signal in volts, and for sending the voltage through the cable assembly via said data acquisition unit to said computer, second temperature sensing means attached to said second linear variable displacement transducer and float means for monitoring the temperature thereof and for transmitting it to said computer, and a plurality of temperature sensors and probe means for measuring the temperatures in the tank liquid at a plurality of vertically spaced locations, and for sending the temperatures to said computer, said computer having means for computing tank leakage from the information provided by the elements recited above. - View Dependent Claims (34, 35, 36, 37, 38)
-
-
39. Apparatus for detecting and measuring leaks from underground tanks having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test instrumentation assembly of test elements, a multiconductor electronic cable assembly connected to the elements of said test instrumentation assembly, a computer-controlled data acquisition unit connected to said cable assembly, a digital computer connected to and controlling said data acquisition unit and having timing means, a memory, and an output, recording means connected to said output, hydrometer means for measuring the specific gravity of the tank liquid, means for entering said specific gravity into said computer, and inclinometer means for measuring the inclination angle of the tank fill pipe, means for entering the value of that angle into said computer, the elements of said instrumentation assembly including first linear variable displacement transducer and float means for measuring the level of liquid in said tank by vertical float movement, for converting the float movement to an electrical output voltage proportional to that movement and for sending said voltage through said cable assembly via said data acquisition unit to said computer, first temperature sensing means attached to said first linear variable displacement transducer and float means for monitoring the temperature thereof and for transmitting it through said cable assembly, evaporation level measurement means having an evaporation level monitoring tube, and second linear variable displacement transducer and float means for measuring continuously the liquid level in the monitoring tube, for converting the float movement thereof to an electrical output signal in volts, and for sending the voltage through the cable assembly via said data acquisition unit to said computer, second temperature sensing means attached to said second linear variable displacement transducer and float means for monitoring the temperature thereof and for transmitting it to said computer, first pressure transducer and probe means for measuring continuously the pressure exerted in said liquid and the pressure difference between two locations in said liquid, for converting the sensed pressure to an electrical output signal in volts, proportional to the measured pressure and pressure difference, and for sending the resulting voltage via said cable to said computer, third temperature sensing means attached to said pressure transducer and probe means for measuring the temperature thereof and for sending that information to said computer, second pressure transducer means for measuring atmospheric pressure adjacent said tank, for converting the value thereof to voltage, and for sending that voltage to said computer, third temperature sensing means for measuring ambient air temperature adjacent to said tank and sending a value thereof to said computer, a plurality of temperature sensor and probe means for measuring the temperatures in the tank liquid at a plurality of locations, and for sending the temperatures to said computer, displacement calibrator means contained in a displacement calibrator tube for determining the proportion of volumetric displacement of said liquid into said fill pipe relative to that in said other pipes connected to said tank, means for measuring the ground water level just outside said tank, and means for locating the liquid level at a given height above said ground water level, said computer having means for computing tank leakage from the information provided by the elements recited above.
-
-
40. Apparatus for detecting and measuring leaks from underground tanks having a fill pipe at an upper end thereof and having other pipes connected thereto, and containing a liquid that extends up into said fill pipe, comprising:
-
a test pipe, a test instrumentation assembly of elements contained in said test pipe, a multiconductor electronic cable assembly with cables connected to the elements of said test instrumentation assembly, a computer-controlled data acquisition unit connected to said cable assembly, a digital computer connected to and controlling said data acquisition unit and having timing means, a memory, and an output, an integral plotter and a printer connected to said output, hydrometer means for measuring the specific gravity of the tank liquid and for passing the measured value to said data acquisition unit, and inclinometer means for measuring the inclination angle of the tank fill pipe and for passing the value of that angle to said data acquisition unit, said instrumentation assembly including; (a) first linear variable displacement transducer and float means connected to said cable assembly for measuring the level of liquid in said tank by vertical float movement, for converting the float movement to an electrical output voltage proportional to the vertical float movement, and for sending said voltage through said cable assembly to said data acquisition unit and said computer, wherein changes in liquid level are measured to an accuracy of at least 0.00001 inch, (b) first temperature sensing means attached to said first linear variable displacement transducer and float means and connected to said cable assembly, for monitoring the temperature thereof and for transmitting to said computer the value thereof, (c) an evaporation level monitoring tube adjacent to said fill pipe and above the liquid level in said tank, (d) second linear variable displacement transducer and float means for evaporation level measurement, contained in said evaporation level monitoring tube and connected to said cable assembly, for measuring continuously the liquid level in the monitoring tube, for converting the float movement thereof to an electrical output signal in volts and sending the voltage through the cable assembly to said data acquisition unit and said computer, wherein said evaporation liquid level changes are measured to an accuracy at least 0.00001 inch, (e) second temperature sensing means, attached to said second linear variable displacement transducer and float means and connected to said cable assembly, for monitoring the temperature thereof and for transmitting it via said cable assembly to said computer, (f) first pressure transducer and probe means connected to said cable assembly, for measuring continuously the pressure of the liquid, said pressure transducer and probe means having a sensing face located above the liquid and connected to a hollow pressure monitoring tube, the bottom end of which is placed at a fixed location in the liquid, said first pressure transducer and probe means measuring the pressure difference between said bottom end of said hollow tube and said sensing face, for converting the sensed pressure values to an electrical output signal in volts, proportional to said pressure values, and for sending the resulting voltage via said cable and said data acquisition unit to said computer, (g) third temperature sensing means attached to said pressure transducer and probe means and to said cable assembly for measuring the temperature thereof and for sending the temperature via said cable assembly to said computer, (h) second pressure transducer means attached to said cable assembly for measuring atmospheric pressure adjacent said tank, for converting the value thereof to voltage, and for sending that voltage to said computer via said cable assembly, both said first pressure transducer and probe means and said second pressure transducer measuring pressures to within 0.0001 p.s.i., (i) third temperature sensing means attached to said cable assembly, for measuring ambient air temperature adjacent to said tank and sending a value thereof to said computer, via said cable means, (j) a plurality of temperature sensors and a plurality of probe means connected to said cable assembly, for measuring the temperatures in the tank liquid at a plurality of locations for sending those temperatures to said computer, wherein all of said temperature sensing means and said temperature sensor and probe means measure to an accuracy of 0.001°
F., and(k) a displacement calibrator tube containing displacement calibrator means for determining the proportion of volumetric displacement of said liquid into said fill pipe relative to that in said other pipes connected to said tank, said computer having means for computing tank leakage from the information provided by the elements recited above.
-
-
41. A test instrumentation assembly of test elements, for detecting leaks from underground tanks having a fill pipe at an upper end thereof and and containing a liquid that extends up into said fill pipe, comprising
a test pipe comprising a cylinder open at both ends, for fitting in said fill pipe and containing each of the following elements: -
first linear variable displacement transducer and float means for measuring the level of liquid in said tank by vertical float movement and for converting the float movement to an electrical output voltage proportional to that movement, first temperature sensing means attached to said first linear variable displacement transducer and float means for monitoring the temperature thereof and for producing an electrical output voltage proportional thereto, evaporation level measurement means contained in an evaporation level monitoring tube, second linear variable displacement transducer and float means for measuring continuously the liquid level in the monitoring tube and for converting the float movement thereof to an electrical output voltage, second temperature sensing means attached to said second linear variable displacement transducer and float means for monitoring the temperature thereof and for producing an electrical output voltage therefrom, and a plurality of temperature sensors and a plurality of probe means extending down through the lower end of said test pipe for measuring the temperatures in the tank liquid at a plurality of vertically spaced locations, and for producing an electrical output voltage therefrom. - View Dependent Claims (43, 44, 45)
-
-
42. The apparatus of claim 42 having first pressure transducer and probe means for measuring continuously the pressure exerted in said liquid and for converting the sensed pressure to an electrical output signal voltage, proportional to the measured pressure and pressure difference,
third temperature sensing means attached to said pressure transducer and probe means for measuring the temperature thereof and for producing an electrical voltage therefrom, second pressure transducer means for measuring atmospheric pressure adjacent said tank and for converting the value thereof to voltage, and fourth temperature sensing means for measuring ambient air temperature adjacent to said tank and producing an electrical output voltage therefrom.
-
46. Apparatus for use in detecting leaks from underground tanks having a fill pipe at an upper end thereof and containing a liquid that extends up into said fill pipe, comprising:
-
a cylindrical test pipe open at an upper end and at a lower end and fitting in said fill pipe, a test instrumentation assembly of elements contained in said test pipe and comprising (a) first linear variable displacement transducer and float means for measuring the level of liquid in said tank to an accuracy of at least 0.1 inch, by vertical float movement and for converting the float movement to an electrical output voltage proportional to the vertical float movement, (b) first temperature sensing means attached to said first linear variable displacement transducer and float means for monitoring the temperature thereof and for converting that temperature to an electrical output voltage, (c) an evaporation level monitoring tube adjacent to said fill pipe and above the liquid level in said tank, (d) second linear variable displacement transducer and float means for evaporation level measurement, contained in said evaporation level monitoring tube for measuring continuously the liquid level in the monitoring tube to an accuracy at least 0.1 inch, and for converting the float movement thereof to an electrical output signal in volts, (e) second temperature sensing means, attached to said second linear variable displacement transducer and float means for monitoring the temperature thereof and for converting the temperature to electrical output voltage, and (f) a plurality of temperature, sensors and a plurality of probe means for measuring the temperatures in the tank liquid at a plurality of vertically spaced locations and for converting those temperatures to voltage outputs, all of said temperature sensing means and said temperature sensors and probe means measuring to an accuracy of 0.005°
F. - View Dependent Claims (47, 48, 49, 50, 51, 52)
-
-
53. A method for obtaining the rate of leakage from an underground tank having a known liquid therein at a predetermined starting level, comprising:
-
calculating a reference volume of the tank from the dimensions of the tank, measuring the average temperature of the liquid in the tank, obtaining a temperature correction factor from said average temperature and the temperature coefficient of expansion of said liquid, measuring the linear displacement of the liquid level with respect to time, over a predetermined time interval, and calculating the tank leakage rate from said reference volume, said linear displacement, said time interval, and said temperature factor. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
-
-
65. A method for obtaining the rate of leakage from an underground tank having a known liquid therein at a predetermined starting level, comprising:
-
calculating a reference volume of the tank from the dimensions of the tank, measuring the average temperature of the liquid in the tank, obtaining a temperature correction factor from said average temperature and the temperature coefficient of expansion of said liquid, measuring the pressure change of the tank liquid at a fixed location in the tank over a predetermined time interval, and calculating the tank leakage rate from said reference volume, said pressure change, said time interval, and said temperature factor. - View Dependent Claims (66, 67, 68, 69, 70, 71, 72, 73, 74, 75)
-
-
76. A method for obtaining the rate of leakage from an underground tank having a known liquid therein at a predetermined starting level, comprising:
-
calculating a reference volume of the tank and from the dimensions of the tank, measuring the average temperature of the liquid in the tank, obtaining a temperature correction factor from said average temperature and the temperature coefficient of expansion of said liquid, measuring the linear displacement of the liquid level with time over a predetermined time interval, measuring the pressure change of the tank liquid at a fixed location in the tank over said predetermined time interval, and calculating the tank leakage rate from said reference volume, said linear displacement, said pressure change, said time interval, and said temperature factor. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 85, 86)
-
-
87. A method for obtaining the rate of leakage from an underground tank having piping and a known liquid therein at a predetermined starting level, employing a digital computer having a timer, a memory, and an output, comprising:
-
computing with said computer a reference volume of the tank from the dimensions of the tank, measuring by an array of thermistors the temperatures of the liquid in the tank at a series of vertical strata of known dimensions, obtaining a temperature correction factor from said array temperatures and the temperature coefficient of expansion of said liquid, measuring the linear displacement of the liquid level with time over a predetermined time interval by an LVDT (linear variable displacement transducer), measuring the temperature of said LVDT, measuring the pressure change of the tank liquid at a fixed location in the tank over said time interval by a first pressure transducer above the liquid level in said tank and a probe connected to said transducer and extending into said tank, measuring the atmospheric pressure above said first pressure transducer by a second pressure transducer, measuring the temperatures of said first and second transducers, and computing the tank leakage from said reference volume, said time interval, and said temperature factor, and the measurements obtained by said measuring steps. - View Dependent Claims (88, 89, 90, 91, 92)
-
Specification