Method and apparatus for measuring the change in volume with change in temperature of liquid in tanks

• US 4,811,601 A
• Filed: 10/11/1983
• Issued: 03/14/1989
• Est. Priority Date: 10/11/1983
• Status: Expired due to Term

• Current Assignee: Peter J. Tolan
• Original Assignee: Peter J. Tolan
• Inventors: Tolan, Peter J.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Application Number:
  US06/540,799
• Time in Patent Office: 1,981 Days
• Field of Search: 374/55, 374/56, 374/4, 374/201, 374/115, 374/116, 73/290 R, 73/290 B, 73/291, 73/313, 73/290 Y, 73/149, 73/295
• US Class Current: 73/290.00B
• CPC Class Codes: G01F 23/0038 using buoyant probes with floats G01F23/30 - G01F23/76
• CPC Class Codes: G01F 23/80 Arrangements for signal processing
• CPC Class Codes: G01M 3/3236 by monitoring the interior space of the containers
• CPC Class Codes: G01M 3/3245 using a level monitoring device G01M3/3272 takes precedence

Abstract

The rate of leaking from a liquid storage tank may be accurately determined by measuring the change in volume of the tank over a period of time, and during said same period (or during a period immediately before or after said measuring period, or both,) measuring the change in length of a probe which extends from the bottom of the tank to the top, and calculating, from the change in length of said probe, the change in volume of the liquid in the tank due to changes in temperature throughout the entire height of the tank. In one embodiment of the invention, the probe is a rod of material which has a high coefficient of thermal expansion and which is inert to the liquid being tested. Since each segment of the rod assume a length which is a function of the temperature at the level of that segment, the rod assumes a length which is a function of the integrated temperatures from the top of the bottom of the tank. Therefore changes in length of the rod are proportional to the total change in volume of the liquid due to temperature change. This change in volume may be applied algebraically to the total measured change in volume to obtain the change in volume due to leakage.

Claims

1. The method of measuring the change in volume with change in temperature of a quantity of liquid in a tank, comprising placing in said tank a length of material having a known temperature coefficient of expansion in relation to the temperature coefficient of expansion of the liquid in the tank, said length of material having a length and orientation such that it extends substantially from the bottom of the liquid to the top thereof, measuring the change of length of said length of material over a period of time, and computing the change in volume of the liquid in the tank from the change in length of said length of material.

2. A method as set out in claim 1 in which said length of material is a rod of solid material.

3. A method as set out in claim 1 in which said length of material is of a contained liquid-in place thereof liquid.

4. A method as set out in claim 3 in which said liquid has the same temperature coefficient of expansion as the liquid in the tank.

5. A method as set out in claim 4 in which said length of contained liquid material is of the same composition as the liquid in the tank.

6. A test probe assembly for measuring the change in volume with change in temperature of a liquid in a tank, comprising an elongated rod of material having a known temperature coefficient of expansion in relation to the temperature coefficient of expansion of the liquid in the tank, said rod having a length such that it can extend from the bottom of the tank into the fill tube thereof, an RF target mounted on the rod, and an RF radiating and sensing device mounted in fixed relation to the tank in position for measuring the change of position of said target.

7. A probe assembly for measuring the change in volume with change in temperature of the liquid in a tank, comprising a support plate, an elongated container depending from the support plate to receive a liquid to serve as a probe, said container having a neck portion at the upper end which has a cross-sectional area substantially less than that of the remainder of the container, an RF radiating and sensing device associated with the container so as to enable it to radiate into the top of the container, and a target capable of reflecting the RF radiation, said target having an overall specific gravity less than the liquid probe and having a surface capable of reflecting the RF radiation.

8. A probe assembly as set out in claim 7 in which said RF sensor is mounted on the support plate so as to extend downwardly into the open end of the container.

9. A test probe assembly for measuring the change of volume with the change of temperature of a liquid in a tank, comprising:

an elongated container having a closed bottom and an open top, said container having a portion at the upper end which has a cross-sectional area substantially less than that of the remainder of the container.

a test probe in the container, said test probe comprising a liquid in the container.

a target for RF energy floating on the top of the liquid in the container; and

an RF radiation and sensing device associated therewith to measure the change in level of the target.