JPH04504754A - Method and device for detecting liquid leaks - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method and device for detecting liquid leaks The present invention relates to liquid leak detectors, and more particularly to above ground vertically uniformly shaped storage tanks. The present invention relates to a method and apparatus for detecting leakage from a link.

Above ground liquid storage tanks, especially those containing liquids that unfortunately contaminate the surrounding ground but do not spill. A major problem with your tank is whether the tank is leaking or not. This means that it is possible to The diameter of this problem is approximately 2o (6m) In large tanks larger than It becomes all the more important because it only brings about fluctuations. In addition, in above-ground tanks, the temperature Changes in the outside world, such as water and wind, can affect the liquid level in the tank.

Until now, the best possible way to check for leaks in above-ground tanks has been to locate 6 feet into the tank. water head is installed, and changes in the liquid level in the sight glass outside the tank are detected using a visual detection method. The purpose was to measure the presence or absence of leakage. This method has a visual detection accuracy of 1 within the tank. The disadvantage is that the variation is limited to x16 inches (1.6 mm). This means that For a leak to be detectable, a tank 100 feet (30 m) in diameter requires a small There must be a leakage of at least 300 gallons (1135 dm’) and a diameter of 100 gallons (380 dm) leakage for a 50 ft (15 m) tank. There must be no leakage, and the temperature must be such that the liquid in the tank can expand. Variations are also significant in measurements, as are wind effects and sight glass meniscus resolution. have a new influence.

Another method being considered is to measure the pressure of the liquid at the bottom of the tank near the bottom of the tank. The solution is to install a force transducer. The liquid expands due to temperature changes. This method has no effect since the volume of the liquid may change, but the weight remains the same. It doesn't resonate. The problem with this method is that the heavy weight of the liquid in the tank cannot be measured. However, it requires a pressure transducer that can measure even the slightest variation in weight. be. Therefore, it is not affected by changes in external conditions, is relatively inexpensive, and is suitable for large-scale land use. It is desirable to have a detector that accurately detects even small leaks in the upper tank.

A liquid leak detector for a storage tank should be installed upright to the same level as the liquid level in the tank. The pipe can be connected to the tank so that liquid can be filled from the tank Contains standpipe. Cut off the liquid communication between the vertical pipe and the tank, and remove the liquid in the tank. Measures the pressure difference between the body and the liquid in the vertical pipe. Even if there is a large difference in this pressure difference, This indicates that there is a leak in the leak.

FIG. 1 is a schematic diagram of a liquid leak detector of the present invention.

Figures 2 to 5 show the results of tank leakage tests conducted using the detector of the present invention. It is a graph.

Referring first to FIG. A leak detector 10 is shown. The detector should not be placed upright on the ground near tank 12. There is a cylindrical standpipe 14. A tube is installed between the vertical pipe 14 and the tank 12 in close proximity to the bottom of each. A tubing or pipe 16 extends therethrough. The tubing or pipe 16 is A pressure changer that separates the pipe 14 and tank 12 so that the pressure difference can be measured. It is connected to the converter 18. Another tube or pipe 2o connects the standpipe 14 and the tank. and bypasses the pressure transducer 18. Second tube or pipe 2 0 has a valve 22. Opening the tank 12 above the liquid level 28 in the tank 12 A hose 24 is connected between the mouth 26 and the top of the vertical pipe 14. pressure transducer 18 is electrically connected to a signal processor 30 to process the signal from the pressure transducer 18. , the signal processor 30 is electrically connected to a recorder 32, such as a pen recorder, for receiving signals. The output of the signal processor 30 is recorded.

When operating the leak detector 10 to check for tank leaks, open the valve 22. and pour the liquid 28 until the liquid level in the vertical pipe is at the same height as the liquid level in the tank 12. The primary water flows from the tank 12 through the second tube or pipe 20 to the standpipe 14. Pressure transducer 18 is activated, which closes valve 22 and disconnects tank 12 and standpipe 14. Then, the pressure difference between the liquid in the tank 12 and the liquid in the vertical pipe 14 is measured. tank If there is a leak in tank 12, the liquid level 28 in tank 12 will fluctuate and be measured by pressure transducer 18. cause a change in the pressure that is determined. This changes the pressure difference exhibited by the pressure transducer 18. and the recorder 32 is instructed.

Some fluctuations in the liquid level 28 in the tank 12 due to slight leakage may cause Since the liquid level does not change, it is detected by the pressure transducer 18. This means that the liquid difference Using a liquid that reacts very sensitively to the pressure transducer 18, the liquid level 28 in the tank 12 and Water column (0,0O00361psi) with liquid level in vertical v14 (2,5X10P a) Measuring the head difference within a range of 0.001 inch (0,025 mm) enable. The pressure transducer 18 is intended to measure the pressure head of the liquid. Since it is not intended to measure the capacity, there may be problems in the tank 12 due to temperature changes. Alternatively, fluctuations in the liquid level in the vertical pipe 14 do not affect the output of the pressure transducer 18.

Also, the top of the vertical pipe 14 is connected to the tank 12 by the hose 24 above the liquid level 28. Since it is connected to the vertical pipe 14, the influence of the wind on the liquid level 28 in the tank 12 is also Since the pressure transducer 18 attempts to measure the pressure difference, which does not reach the liquid level inside the The effects cancel out and do not affect the output of pressure transducer 18.

2 to 5 show tests conducted in various tanks using the leak detector 10 of the present invention. Show the records taken. In the tests shown in Figures 2 and 3, the tanks used had a diameter of 50 feet (15 m), 35 feet (l1 m) high and approximately 60,000 g. It contained 2.27 x 102 m3 of water. Figure 2 takes 1 minute to complete the tank If 1 gallon (3.8 dm’) of water is removed from the tank and then returned to the tank The output of the recorder 32 is shown. As can be seen from Figure 2, this small amount of liquid in the tank Even small fluctuations were clearly recognized by the leak detector. Shows the output of the recorder when removing 1172 gallons (5,7 dm3) of water from .

This allows even slow leaks to be easily detected by leak detector 1o. I know that I can do it.

In the case of the test shown in Figure 4, the tank used was 30 feet (9 m) in diameter and high. The tank was 41 feet (12.5 m) long and was equipped with a Mobil Heat ingOil No. 2 was inserted to a depth of 3 inches (1 m) (approximately 16,0 00 gallons (61 m')), 5 gallons (61 m') during the 21/3 hour test period. 19 dm3> of oil was rapidly removed near the beginning of the (intermediate) test period; Another 5 gallons (19 dm3) were removed nearby. Removal of these two small amounts of oil can also be clearly seen in FIG. 4 by the two drops in the figure. Figure 5 is , a tank with a diameter of 75 feet (23 m) and a height of 40 feet (12 m) is M. obil Heating Oi! No. 2 to about 7 foot finch (2,3 Field trials contained up to approximately 257,705 gallons (975 m3) The results of the experiment are shown below. At the beginning of the test, 4 gallons (15 dm’) of oil was rapidly added to the tank. It was removed. This can be clearly seen from the overall drop in the line on the chart. Ru. The undulations in the chart are the result of cold and windy weather conditions. However However, these conditions adversely affect the ability to detect very small liquid leaks from tanks. It doesn't have any impact.

Thus, the present invention provides a leakage system that accurately detects small leaks in above-ground storage tanks. A method and apparatus for sensing is provided. The detector of the present invention detects external factors such as temperature, wind, etc. It is not adversely affected by changing conditions and is inexpensive to manufacture and install. be. The leak detector of the present invention is suitable for highly volatile gases such as gasoline, It can also be successfully used with heavy liquids. In addition, the detector can also be used for storage tank inventory management. It can be used as part of or in combination with a system.

Figure 5 international search report 1mannllaeal A+mlcaliM N & P mouth’/US 9010 0263 International Search Report

Claims (9)

[Claims] 1. An upright storage tank that is mounted on the ground and contains a liquid; the ground adjacent to the tank a leak detector for the storage tank comprising a vertical standpipe installed in the storage tank; Connect the bottom of the vertical pipe and the bottom of the storage tank, and tap until the liquid level is the same as the liquid level in the tank. means for filling liquid from the tank into the vertical pipe; a means for measuring a pressure difference in a liquid storage system. 2. The storage of claim 1, wherein the storage tank and the standpipe both have uniform vertical dimensions. system. 3. 3. The storage of claim 2, wherein the storage tank and standpipe are cylindrical along their entire vertical height. system. 4. It includes a first pipe that connects the bottom of the vertical pipe and the bottom of the storage tank and measures the pressure difference. 3. The storage system of claim 2, wherein said means for determining is within said first pipe. 5. The means for measuring a pressure difference comprises a pressure difference having an electrical output signal corresponding to the pressure difference. 5. The storage system of claim 4, which is a force transducer. 6. The means for connecting the standpipe to the storage tank connects the bottom of the standpipe and the bottom of the tank. and a second pipe bypassing the pressure transducer and a valve within the second pipe. 6. The storage system of claim 5. 7. A hole connected to the top of the vertical pipe and the storage tank above the liquid level in the storage tank. 8. The storage system of claim 7, including a base. 8. (a) Vertical standpipe: (b) Connect the standpipe to the storage tank at the bottom of the tank to connect the liquid in the tank. means for filling the standpipe with liquid to the same liquid level; (c) means for filling said standpipe with liquid at the bottom thereof; a first pipe connected and adapted to be connected to the tank at the bottom of the tank; (d) the pressure between the liquid in the tank and the liquid in the vertical pipe in the first pipe; a pressure transducer that measures a force difference and has an electrical output signal corresponding to the pressure difference; and ( e) Connected to the top of the vertical pipe and connected to the tank above the liquid level in the tank. In a liquid leak detector for a storage tank, the hose is The means for connecting the pipe to the tank is connected to the standpipe and bypasses the pressure transducer. , a leak detector which is a second pipe with a valve inside it. 9. Claim 8 further comprising a recorder connected to the pressure transducer to record the output of the pressure transducer. leak detector.