초록 ▼

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 s

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.

대표청구항 ▼

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

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.