KR100760828B1 - Leak detection apparatus - Google Patents

Abstract

 A leak detection apparatus with improved reliability is disclosed. Leak detection apparatus according to the present invention is to detect the leakage by sensing the pressure of the test body, the standard pressure chamber selectively communicating with the test body; A buffer pressure chamber in communication with the test body to form the same pressure as the test body; A pressure sensor for detecting a pressure difference between the standard pressure chamber and the buffer pressure chamber; And a controller configured to calculate the pressure of the test body from the pressure difference detected by the pressure sensor and determine whether the test body leaks according to the calculated pressure of the test body.

Pressure differential, pressure sensor, tolerance, buffer pressure chamber, constant temperature, thermoelectric element, temperature sensor

Description

Leak Detection Device {LEAK DETECTION APPARATUS}

1 is an exploded perspective view of a leak detection apparatus according to an embodiment of the present invention;

Figure 2 is a plan view schematically showing an open state of the upper portion of the leak detection device shown in FIG.

3 is a cross-sectional view taken along line III-III of FIG. 1;

4 is a block diagram for explaining a control configuration of the leak detection apparatus shown in FIG. 1;

FIG. 5 is a cross-sectional view of the pressure sensor shown in FIG. 1 taken along VV. FIG.

<Description of the symbols for the main parts of the drawings>

10; Standard pressure chamber 12; housing

14; Separator 20; Buffer pressure chamber

30, 32; First and second connecting pipes 30a and 30b; 1st and 2nd branch pipe

31,33; First and second valves 40; Pressure sensor

50; Adiabatic chamber 52; Heat insulation

56; Insulation cover 58; Fastening member

60; Thermostat unit 62; Thermoelectric element

64; Temperature sensor 70; Control

The present invention relates to a leak detection device for detecting whether or not the leak of the test body, such as a liquefied natural gas (LNG) storage tank is required to maintain the airtight.

There are various types of non-destructive testing methods for testing the leakage of test bodies requiring airtightness such as foam leakage test, ammonia leak test, halogen leak test, helium leak test and ultrasonic leak test. However, large test specimens, such as LNG storage tanks of LNG carriers, must check the overall airtightness, and attempts to detect leaks through pressure changes in the test specimens are under way to confirm the leakage of such large test specimens.

The conventional leak detection apparatus which normally checks the pressure change of a test object and checks for leakage is equipped with the pressure sensor for measuring the pressure change of a test body. The pressure sensor measures the difference between the standard pressure formed in the standard pressure chamber and the internal pressure of the test specimen to calculate the leakage of the test specimen. Therefore, the pressure sensor includes a first sensor chamber in communication with the standard pressure chamber to form the same pressure as the standard pressure chamber, and a second sensor chamber in direct communication with the test body to form the same pressure as the interior of the test body, The first and second sensor chambers are partitioned by an elastic membrane.

Looking at the process of detecting the pressure difference by using a pressure sensor having the structure as described above, first to form a vacuum pressure on the test body. When the vacuum pressure is formed in the test body, the valve provided in the pipe connecting the test body, the pressure sensor and the standard pressure chamber is opened. Then, the pressure of the test body is transferred to the first sensor chamber via the standard pressure chamber. However, when the test body pressure is transmitted to the second sensor chamber, it is directly transmitted to the second sensor chamber without passing through any pressure chamber. Accordingly, a difference occurs between the time when the pressure of the test body is transmitted to the first sensor chamber and the time when the pressure of the test body is transmitted to the second sensor chamber, thereby causing an unintended pressure difference between the first sensor chamber and the second sensor chamber.

In addition, the leak detection test is completed, the valve is shut off and the test body is restored to atmospheric pressure. When the test body is restored to atmospheric pressure, the valve is opened again to restore the first and second sensor chambers of the pressure sensor to atmospheric pressure. Even in this case, a large pressure difference occurs between the first and second sensor chambers due to the difference in the delivery time of the test body pressure.

This pressure difference between the first and second sensor chambers inadvertently causes a case in which the pressure sensor exceeds the allowable value. If the pressure sensor exceeds the allowable value, the elastic membrane may be permanently deformed or broken, causing a large error in the information on the measured pressure or causing a failure of the pressure sensor.

The present invention has been made in view of the above point, and an object thereof is to provide a leak detection apparatus with improved reliability.

Another object of the present invention to provide a leak detection device that can detect whether more accurately leaks.

Leak detection apparatus according to the present invention for achieving the object as described above, for detecting the leakage by sensing the pressure of the test body, the standard pressure chamber selectively communicating with the test body; A buffer pressure chamber in communication with the test body to form the same pressure as the test body; A pressure sensor for detecting a pressure difference between the standard pressure chamber and the buffer pressure chamber; And a controller configured to calculate the pressure of the test body from the pressure difference detected by the pressure sensor and determine whether the test body leaks according to the calculated pressure of the test body.

Leak detection apparatus according to an embodiment of the present invention, the standard pressure chamber and the buffer pressure chamber in communication with, the first connecting pipe provided with a first valve; And the second connection pipe communicating with the first connection pipe and the test body and having a second valve, wherein the first connection pipe includes the standard pressure chamber based on a connection point with the second connection pipe. And a first branch pipe connected to the second branch pipe and a second branch pipe connected to the buffer pressure chamber, and the first valve is provided in the first branch pipe.

The standard pressure chamber and the buffer pressure chamber are formed by partitioning the inside of the hollow housing in which the outside and the airtightness are kept to be substantially the same volume by a separator, and the housing is disposed inside the insulated chamber that is insulated from the outside and is insulated. It includes a thermostat unit for maintaining a constant temperature of the chamber.

The constant temperature unit, the thermoelectric element provided in the heat insulating chamber; And a temperature sensor for measuring the temperature of the standard pressure chamber, wherein the controller controls the thermoelectric element according to the temperature measured from the temperature sensor. The heat insulation chamber, the hollow heat insulation body one side is open; An insulation cover for opening and closing one side of the insulation body; And a fastening member for fastening the heat insulation body and the heat insulation cover to maintain the airtightness of the heat insulation chamber.

On the other hand, the object as described above, the standard pressure chamber to selectively communicate with the test body; A pressure sensor having a first sensor chamber in communication with the standard pressure chamber and a second sensor chamber in communication with the test body, the pressure sensor detecting a pressure difference between the first sensor chamber and the second sensor chamber; A temperature sensor for measuring a temperature of the standard pressure chamber; A thermoelectric element for controlling the temperature of the standard pressure chamber; And a control unit for calculating the pressure of the test body from the pressure difference detected by the pressure sensor, determining whether the test body leaks according to the calculated pressure of the test body, and controlling the thermoelectric element according to the temperature measured by the temperature sensor. It can also be achieved by a leak detection device comprising a.

Hereinafter, a leak detection apparatus according to an embodiment of the present invention will be described in detail.

1 to 4, the leak detection apparatus according to an embodiment of the present invention, the standard pressure chamber 10, the buffer pressure chamber 20, the first and second connection pipes 30, 32, It includes a pressure sensor 40, the adiabatic chamber 50, the constant temperature unit 60 and the control unit 70.

The standard pressure chamber 10 communicates with the buffer pressure chamber 20 by the first connection pipe 30 as a space in which the standard pressure is formed.

The buffer pressure chamber 20 is a space in which the same pressure as the inside of the test body (not shown) is formed, and prevents the pressure transmitted from the test body to be rapidly transmitted to the pressure sensor 40.

As shown in FIG. 3, the standard pressure chamber 10 and the buffer pressure chamber 20 are formed by partitioning the inside of the hollow cylindrical housing 12 in which airtightness is maintained by a separator 14. In addition, the standard pressure chamber 10 and the buffer pressure chamber 20 preferably have substantially the same volume.

The first connection pipe 30 is connected to the second connection pipe 32 and the first branch pipe 30a and the second branch pipe 30b based on a connection point with the second connection pipe 32. Branch to. One end of the first branch pipe 30a is connected to the standard pressure chamber 10, and the other end is connected to one end of the second branch pipe 30b. The first branch pipe 30a is provided with a first valve 31 for selectively sealing the standard pressure chamber 10. The other end of the second branch pipe 30b is connected to the buffer pressure chamber 20. In this structure, when the first valve 31 is opened, the standard pressure chamber 10 and the buffer pressure chamber 20 communicate with each other, and when the first valve 31 is blocked, the standard pressure chamber 10 ) And the buffer pressure chamber 20 are blocked. That is, the standard pressure chamber 10 and the buffer pressure chamber 20 are selectively communicated by the first valve 31.

One end of the second connection pipe 32 is connected to the test body, and the other end thereof is connected to the first connection pipe 30. The second connection pipe 32 is provided with a second valve 33, and the test body and the first connection pipe 30 are selectively communicated by opening and closing the second valve 33.

As illustrated in FIG. 5, the pressure sensor 40 has a first sensor chamber 42 connected to the standard pressure chamber 10 and a second sensor chamber connected to the buffer pressure chamber 20. 44 is partitioned by the elastic membrane 46. When a pressure difference occurs between the first sensor chamber 42 and the second sensor chamber 44, the elastic membrane 46 is deformed and generates a different electrical signal according to the degree of deformation, thereby detecting the pressure difference. In addition, the pressure sensor 40 is connected in signal communication with the control unit 70. The pressure sensor 40 is already known in the art and a detailed description thereof will be omitted.

The insulating chamber 50 is a space for insulating the standard pressure chamber 10 and the buffer pressure chamber 20, and the housing 12 is seated. The heat insulating chamber 50 is formed by the heat insulating body 52, the heat insulating cover 56 and the fastening member 58.

The heat insulation body 52 is a hollow cylindrical one side is open, as shown in Figure 3, having a double structure of the outer wall 53 and the inner wall 54 is filled with a heat insulating material 55 therebetween.

The heat insulation cover 56 is coupled to the heat insulation body 52 to cover an open side of the heat insulation body 52.

The fastening member 58 is provided on the heat insulating body 52, and fastens the heat insulating body 52 and the heat insulating cover 56 to maintain airtightness. Fastening member 58 may be used in a variety of fastening means for coupling the lid with a conventional container.

The constant temperature unit 60 includes a thermoelectric element 62 and a temperature sensor 64.

The thermoelectric element is a device in which a plurality of P-type and N-type semiconductors are alternately arranged between two plates and each semiconductor is electrically connected in series, and one surface of the thermoelectric element is selectively heated according to the direction of current. And the other surface is an element to be cooled. The thermoelectric element 62 is already known and used in various industrial fields, and a detailed description thereof will be omitted. The thermoelectric element 62 is electrically connected to the controller 70.

The temperature sensor 64 is for measuring the temperature of the standard pressure chamber 10 and is installed to be inserted into the standard pressure chamber 10. The temperature sensor 64 is connected in signal communication with the control unit 70.

As described above, the controller 70 is electrically connected to the pressure sensor 40, the thermoelectric element 62, and the temperature sensor 64. The controller 70 transmits the differential pressure from the pressure sensor 40, and compares the differential pressure with the calculated pressure and the reference pressure for the temperature preset in the memory 80 to determine whether the test object is leaked or the amount of leakage. . The reference pressure for temperature is obtained from Boyle-Charles 'Law and van der Waals' equation of equations with a correction term. The controller 70 determines that the test object has leaked when the difference value between the actual pressure and the reference pressure of the test object exceeds the reference difference value stored in the memory 80.

In addition, the controller 70 compares the temperature measured by the temperature sensor 64 with the reference temperature stored in the memory 80 to turn on / off the thermoelectric element 62 and the direction of the current applied to the thermoelectric element 62. Adjust

Hereinafter, a leak detection method using a leak detection apparatus according to an exemplary embodiment of the present invention will be described.

1 to 5, first, a vacuum pressure is formed on the test body. When a vacuum pressure is formed in the test body, one end of the second connecting pipe 32 is connected to the test body, and then the first and second valves 31 and 33 are opened to open the standard pressure chamber 10 and the buffer pressure chamber ( 20) is in communication with the test body so that the pressure of the standard pressure chamber 10 and the buffer pressure chamber 20 is equal to the pressure of the test body. In this case, the buffer pressure chamber 20 may transmit the pressure of the test body to the first sensor chamber 42 and the second sensor chamber 44 at the same time, thereby preventing a sudden pressure difference. That is, the sudden pressure between the first and second sensor chambers 42 and 44 of the pressure sensor 40 in which the buffer pressure chamber 20 communicates with the standard pressure chamber 10 and the buffer pressure chamber 20, respectively. By suppressing the occurrence of the difference and preventing the elastic membrane 46 of the pressure sensor 40 from being damaged, the pressure can be measured more accurately and stably. In particular, since the buffer pressure chamber 20 and the standard pressure chamber 10 have substantially the same volume, it is possible to minimize the pressure difference generated in the pressure sensor 40.

After the pressure of the test body and the pressure of the standard pressure chamber 10 and the buffer pressure chamber 20 are equalized, the first valve 31 is cut off so that the standard pressure chamber 10 is constant regardless of the pressure of the test body. Try to have pressure. The test body is left in the state as described above. The standing time is approximately 48 hours, and during the standing time, the temperature of the test specimen is changed according to the change in the temperature of the atmosphere. As the temperature of the test specimen changes, the pressure of the test specimen changes according to Boyle-Charles' law. At this time, the control unit 70 receives the pressure difference from the pressure sensor 40 to calculate the pressure of the test object, and the reference stored in the memory 80 corresponding to the temperature of the test object when measuring the actual pressure and the actual pressure of the test specimen. The pressure is compared and it is determined that the test object is leaked when the difference value is equal to or greater than the reference difference value stored in the memory 80. And, if it is determined that the test body leaks, the control unit 70 can determine the leakage amount, that is, the degree of leakage by measuring the leakage pressure from the difference value between the actual pressure and the reference pressure of the test body.

On the other hand, the pressure in the standard pressure chamber 10 should be kept constant. Therefore, in order to maintain a constant pressure in the standard pressure chamber 10 according to Boyle-Charles' law, the temperature of the standard pressure chamber 10 should be constant. For this reason, the controller 70 receives the measured temperature from the temperature sensor 64 and compares the set temperature stored in the memory 80 with the set temperature stored in the memory 80. The direction is controlled to keep the temperature of the standard pressure chamber 10 constant. As such, by keeping the temperature of the standard pressure chamber 10 constant, it is possible to measure the pressure difference of the test body more accurately.

When the leak detection test is completed, the second valve 33 is shut off and the test body is opened to generate atmospheric pressure. When atmospheric pressure is formed in the test body, the first and second valves 31 and 33 are opened to open the standard pressure chamber 10, the buffer pressure chamber 20, and the first and second sensor chambers of the pressure sensor 40. Atmospheric pressure is formed at (42) (44). In this case, the buffer pressure chamber 20 delays the time for transferring the pressure of the test body to the second sensor chamber 44, so that the rapid pressure with the first sensor chamber 42 is delayed by the standard pressure chamber 10. The pressure difference can be reduced.

According to the present invention as described above, the buffer pressure chamber can suppress the sudden pressure difference generated in the pressure sensor, it is possible to prevent damage to the pressure sensor.

In addition, by using a thermoelectric element to maintain a constant temperature of the insulated chamber, the pressure of the standard pressure chamber can be kept constant, so that the information measured by the pressure sensor is more accurate.

As such, the pressure sensor can be prevented from being damaged and the pressure sensor can detect more accurate information, thereby improving the reliability of the leak detection device and more accurately determining the leakage and the amount of leakage.

While the invention has been shown and described in connection with preferred embodiments for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described. That is, those skilled in the art to which the present invention pertains will appreciate that many changes and modifications can be made to the present invention without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (9)

delete In the leak detection device for detecting the leakage of the test object by detecting the pressure, A standard pressure chamber in selective communication with the test body; A buffer pressure chamber in communication with the test body to form the same pressure as the test body; A pressure sensor for detecting a pressure difference between the standard pressure chamber and the buffer pressure chamber; And And a controller configured to calculate the pressure of the test body from the pressure difference detected by the pressure sensor and determine whether the test body leaks according to the calculated pressure of the test body. A first connection pipe communicating with the standard pressure chamber and the buffer pressure chamber, and provided with a first valve; And And a second connecting pipe communicating with the first connecting pipe and the test body and provided with a second valve. The first connection pipe, The first branch pipe is connected to the standard pressure chamber and the second branch pipe is connected to the buffer pressure chamber on the basis of the connection point with the second connection pipe, and the first valve is provided in the first branch pipe. Leak detection apparatus, characterized in that. The method of claim 2, The standard pressure chamber and the buffer pressure chamber is leak detection device, characterized in that the hollow housing inside and the airtight is maintained by the separation membrane formed. The method of claim 3, And the standard pressure chamber and the buffer pressure chamber have substantially the same volume. The method of claim 3, The housing is a leak detection device, characterized in that disposed in the interior of the insulated chamber insulated from the outside. The method of claim 5, Leakage detection device comprising a constant temperature unit for maintaining a constant temperature of the insulated chamber. The method of claim 6, The constant temperature unit, A thermoelectric element provided in the insulation chamber; And And a temperature sensor for measuring the temperature of the standard pressure chamber. The control unit is a leak detection device, characterized in that for controlling the thermoelectric element in accordance with the temperature measured from the temperature sensor. The method of claim 7, wherein the thermal insulation chamber, Hollow insulation body of which one side is open; An insulation cover for opening and closing one side of the insulation body; And And a fastening member for fastening the heat insulation body and the heat insulation cover to maintain the airtightness of the heat insulation chamber. In the leak detection device for detecting the leakage of the test object by detecting the pressure, A standard pressure chamber in selective communication with the test body; A pressure sensor having a first sensor chamber in communication with the standard pressure chamber and a second sensor chamber in communication with the test body, the pressure sensor detecting a pressure difference between the first sensor chamber and the second sensor chamber; A temperature sensor for measuring a temperature of the standard pressure chamber; A thermoelectric element for controlling the temperature of the standard pressure chamber; And A controller for calculating the pressure of the test object from the pressure difference detected by the pressure sensor, determining whether the test object leaks according to the calculated pressure of the test object, and controlling the thermoelectric element according to the temperature measured by the temperature sensor; Leak detection device comprising a.

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