JP6710152B2 - Method for detecting fluid leakage from piping structure, piping structure, and construction method - Google Patents

Description

The present invention relates to a method for detecting leakage of a fluid from a piping structure through which a fluid such as a refrigerant flows, a piping structure configured to detect the leakage of the fluid, and a method for constructing the piping structure.

It has been proposed to install a fluid sensor having a pair of electrodes near each of a plurality of joints of a refrigerant pipe and detect leakage of the refrigerant based on a change in impedance between the electrodes (Patent Document 1). According to Patent Document 1, it is possible to detect refrigerant leakage, including identification of where the refrigerant leaks from a plurality of joints installed in the vicinity of each fluid sensor.

JP, 2009-198154, A

In Patent Document 1, refrigerant leakage is detected based on a change in impedance between electrodes of a fluid sensor. However, not only the presence of the leaked refrigerant but also the presence of dew condensation or the like influences the impedance measurement value, and there is much noise, so that it is difficult to establish the leak detection based on the change in the impedance.
In addition, if a refrigerant leak occurs at a position distant from the fluid sensor, or if a small amount of refrigerant leaks near the fluid sensor (slow leak), the impedance change is small. Is difficult to detect.
Furthermore, if it is possible to prevent the refrigerant leaking from the pipe from leaking to the outside of the apparatus, Patent Document 1 does not take any measure to suppress the refrigerant leaking to the outside.

As described above, the present invention is capable of detecting leaks of fluid from a wider range of piping structure as well as specific locations such as joints and valves, including slow leaks, and the leaked fluid further leaks to the outside. An object of the present invention is to provide a fluid leakage detection method and a piping structure capable of suppressing the occurrence of the above.

The present invention is a method for detecting a leakage of a fluid from a piping structure in which a fluid is present, in which the outer periphery of the piping structure is covered by a conductive film which is insulated from the piping structure over a predetermined section of the piping structure. The part is pre-covered, the step of monitoring the electrical resistance between both ends of the conductive film corresponding to one end and the other end of the section, and the electrical resistance changed due to deformation or breakage of the conductive film , seen containing a step of detecting a fluid leak in the section on the basis that deviates from a predetermined threshold value, the threshold value is the electrical resistance value of the conductive film corresponding to the amount of deformation at break immediately before the conductive film It is set to .

Further, the present invention is a method for detecting leakage of a fluid from a piping structure in which fluid is present, wherein a piping structure is formed by a conductive film that is insulated from the piping structure over a predetermined section of the piping structure. The outer peripheral portion of the section is previously covered, one end of the conductive film corresponding to one end of the section is connected to the piping structure, the other end of the conductive film corresponding to the other section has a constant electrical resistance value. By connecting in series with a constant resistance that has a piping structure, a conductive film, and an electric circuit including a constant resistance are formed, the step of monitoring the voltage drop due to the constant resistance, and the deformation or breakage of the conductive film potential difference corresponding to the voltage drop changes due to the, viewed contains the steps of: detecting a fluid leak for the interval on the basis that deviates from the predetermined thresholds, the threshold in the fracture immediately prior to conducting film It is characterized in that it is set to a value of a voltage drop due to a constant resistance, which corresponds to the deformation amount .

In the fluid leakage detection method of the present invention, a plurality of sections are set in the piping structure, the outer peripheral portion of the piping structure is covered with a conductive film over each of the plurality of sections, and the fluid leakage occurs in each section. Is preferably detected.

In the method for detecting fluid leakage of the present invention, it is preferable that the outer peripheral portion of the piping structure and the conductive film are insulated by a non-conductive film interposed between the outer peripheral portion and the conductive film.

In the fluid leakage detection method of the present invention, the fluid is preferably a refrigerant.

Next, the present invention is a piping structure configured to be able to detect leakage of fluid from the inside, over a predetermined section in the piping structure, and the outer peripheral portion of the piping structure in an insulated state from the piping structure. The covering conductive film, the electric resistance measuring unit for measuring the electric resistance between the both ends of the conductive film corresponding to one end and the other end of the section, and that the electric resistance deviates from the predetermined threshold value. Based on this, a leakage detection unit for detecting fluid leakage in the section is provided, and at the time of fluid leakage, the electric resistance that changes due to deformation or breakage of the conductive film and deviates from the threshold value is measured by the electric resistance measurement unit. The threshold value is set to the value of the electric resistance of the conductive film corresponding to the deformation amount of the conductive film immediately before breaking .

Further, the present invention is a piping structure configured to be able to detect leakage of fluid from the inside, and covers the outer peripheral portion of the piping structure in a state of being insulated from the piping structure over a predetermined section of the piping structure. , A conductive film whose one end corresponding to one end of the section is connected to the piping structure, and which has a constant electric resistance value, is connected in series to the other end of the conductive film corresponding to the other end of the section, and has conductivity. Resistance in an electric circuit together with a flexible film and a piping structure, a potential difference measuring unit for measuring a potential difference corresponding to a voltage drop due to the constant resistance, and a fluid in a section based on the potential difference deviating from a predetermined threshold value. and a leakage detection unit for detecting the leakage, when the fluid leakage, due to the deformation or breakage of the conductive film varies, the potential difference that deviates from the threshold is measured by the potential difference measuring unit, the threshold value of the conductive film It is characterized in that it is set to a value of a voltage drop due to a constant resistance, which corresponds to the amount of deformation immediately before breakage .

In the piping structure of the present invention, a plurality of sections are set in the piping structure, the outer peripheral portion of the piping structure is covered with a conductive film over each of the plurality of sections, and the leak detection unit is a fluid for each section. It is preferable to detect leaks.

In the piping structure of the present invention, the outer peripheral portion of the piping structure and the conductive film are preferably insulated by a non-conductive film interposed between the outer peripheral portion and the conductive film.

In the piping structure of the present invention, the fluid is preferably a refrigerant.

Then, the present invention is a construction method for constructing a piping structure capable of detecting the leakage of fluid from the inside of the piping structure, over the entire length of a predetermined section including a joint of the piping structure, not to the conductive film. The conductive film is laminated, by using the film laminate in a state of being formed in an arc shape, by surrounding the pipe structure in an annular shape by the film laminate, by the non-conductive film to the pipe structure forming a step Ru provided a conductive film in a state of being insulated, respectively provided wire at both ends of the conductive film corresponding to the one and the other end of the section, an electrical circuit capable of measuring the electrical resistance between the two ends And the electrical resistance between both ends of the conductive film changes due to deformation or breakage of the conductive film and deviates from a predetermined threshold based on the fluid in the section. It is characterized in that it can detect leakage.

Further, the present invention is a construction method for constructing a piping structure capable of detecting leakage of fluid from the inside of the piping structure, wherein the conductive film is not covered over the entire length of a predetermined section including the joint of the piping structure. The conductive film is laminated, by using the film laminate in a state of being formed in an arc shape, by surrounding the pipe structure in an annular shape by the film laminate, by the non-conductive film to the pipe structure a step of Ru provided a conductive film in a state of being insulated, comprising the steps of connecting one end of the conductive film corresponding to one end of the section to the piping structure, the other end of the conductive film, a predetermined electric resistance value Connecting a constant resistance having in series, forming a piping structure, a conductive film, and an electric circuit including a constant resistance, the potential difference corresponding to the voltage drop due to the constant resistance, due to the deformation or breakage of the conductive film. It is characterized in that the fluid leakage in the section can be detected based on the fact that it has changed and deviated from a predetermined threshold value .

In the construction method of the present invention, prior to the step of covering the outer peripheral portion of the piping structure with the conductive film, a step of covering the outer peripheral portion with the non-conductive film is included .

In the construction method of the present invention, in the step of covering the outer peripheral portion of the piping structure with the conductive film, a film laminate which is formed in a size suitable for the length of the section and capable of surrounding the piping structure over the entire circumference is used. The film laminate includes a conductive film and a non-conductive film laminated on the conductive film to insulate the conductive film from the outer peripheral portion .

In the construction method of the present invention, the piping structure, to set the plurality of sections, for each section, it is preferable that the outer peripheral portion of the piping structure to implement the step of enclosing the full Irumu laminate.

In the fluid leakage detection method, the piping structure, and the construction method of the present invention, since the outer peripheral portion of the piping structure is covered with the conductive film over a predetermined section, the conductive film is deformed by the pressure of the leaked fluid. The fluid can be stored inside the conductive film. Even if it is a slow leak that continues to leak by a small amount, the fluid accumulates inside the conductive film and the conductive film deforms sufficiently, so the electrical resistance of the conductive film changes significantly compared to the initial value. To do. Even when the conductive film is broken due to the pressure of the leaked fluid, the electric resistance of the conductive film significantly changes. Then, the electric resistance of the conductive film deviates from the threshold value , and based on this, the leakage of the fluid generated in the section can be reliably detected. Further, the present invention, instead of using the electrical resistance of the conductive film, based on the change in the potential difference corresponding to the voltage drop due to a constant resistance connected in series with the conductive film, also a method of detecting the fluid leakage provide.
Furthermore, according to the present invention, since the leaked portion from the inside of the piping structure is covered with the conductive film, the leaked fluid is prevented from being immediately released to the atmosphere, and the fluid is leaked to the outside. Can be suppressed.

It is a figure which shows the piping structure which concerns on 1st Embodiment. (A) is a figure which shows typically the state in which the non-conductive film and the conductive film are deformed by the pressure of the leaked refrigerant to form a refrigerant pool. (B) is a diagram showing a state in which the conductive film is broken by the pressure of the refrigerant. It is a figure which shows the construction method using a film laminated body. It is a figure which shows the piping structure which concerns on 2nd Embodiment. (A) is a schematic diagram which shows an electric circuit when a refrigerant leak has not generate|occur|produced. (B) is a schematic diagram which shows an electric circuit when a refrigerant leak occurs.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
Hereinafter, detection of refrigerant leakage from the piping structure through which the refrigerant flows will be described, but the present invention can be used to detect leakage of any fluid, not limited to refrigerant. “Fluid” includes gas and liquid.

[First Embodiment]
A refrigerant leakage detection method and a piping structure according to the first embodiment of the present invention will be described.
The piping structure 10 shown in FIG. 1 constitutes a refrigerant circuit such as an air conditioner or a refrigerator, and the refrigerant exists inside the piping structure 10.
The pipe structure 10 includes a plurality of pipes 101 to 103, various valves 104 and 105, a joint (not shown) that connects these pipes and valves, and the like.

The piping structure 10 uses the conductive film 12 provided over each of the set one or more sections, and detects the leakage of the refrigerant based on the change in the electric resistance caused by the deformation or breakage of the conductive film 12. To do.
In FIG. 1, two sections P1 and P2 are shown as sections set in the piping structure 10, but in addition, whether the sections are linearly extended or bent over an appropriate range is shown. Regardless, the section for detecting refrigerant leakage can be set in the piping structure 10. It is possible to divide the piping structure 10 into a plurality of sections in the length direction and detect the refrigerant leakage for each section.

The piping structure 10 includes a non-conductive film 11 that covers the outer peripheral portion 10A of the piping structure 10 over the section P1, a conductive film 12 that covers the outer peripheral portion 10A from above the non-conductive film 11 over the section P1, and a conductive material. A resistance measuring unit 14 that measures an electric resistance between both ends of the film 12 (a resistance between terminals of the conductive film 12) and a leak detecting unit 15 that detects the leakage of the refrigerant using the measured electric resistance. ing.
Similarly for the section P2, the piping structure 10 also includes a non-conductive film 11, a conductive film 12, a resistance measurement unit 14, and a leak detection unit 15.
The leak detection unit 15 is configured to be able to detect both the refrigerant leak in the section P1 and the refrigerant leak in the section P2, but to detect the refrigerant leak in each of the sections P1 and P2, in each of the sections P1 and P2. It is also possible to prepare the leak detection unit 15.

The non-conductive film 11 is an insulator formed of a resin material, and surrounds the outer peripheral portion 10A over the entire section P1 and the entire circumference of the piping structure 10.
The conductive film 12 is a conductor formed of a metal material such as a copper alloy or an aluminum alloy, and surrounds the outer peripheral portion 10A in a state of being laminated on the non-conductive film 11.
By interposing the non-conductive film 11 between the outer peripheral portion 10A and the conductive film 12, the conductive film 12 is insulated from the piping structure 10 made of a metal material.

Although the leak detection method of the present embodiment is strong against disturbance, the conductive film 12 may be covered with a sheet, a member or the like in order to reduce the influence of the disturbance factor on the electric resistance of the conductive film 12.

The non-conductive film 11 and the conductive film 12 enclose components such as pipes and valves in each of the sections P1 and P2.
As shown in FIG. 2A, both the non-conductive film 11 and the conductive film 12 have appropriate rigidity that they are locally pushed up and deformed by the pressure of the refrigerant leaked from the inside of the piping structure 10. The material and thickness are selected.
The thickness of each of the non-conductive film 11 and the conductive film 12 is, for example, 0.01 to 0.3 mm.
As the conductive film 12, for example, a conductive material such as aluminum foil can be used, and the surface thereof may be insulating. An example of a product that can be used for the conductive film 12 is "AL-35FR" manufactured by 3M Co., which is an aluminum foil laminated with a polyester film coated with a conductive pressure-sensitive adhesive.
As the non-conductive film 11, for example, an insulating material such as a film made of a resin material such as PET (polyethylene terephthalate) resin can be used. Examples of products that can be used for the non-conductive film 11 are G2 (thickness 0.016 to 0.1 mm) or "Melinex" of "Teijin Tetoron Film" (Teijin and Tetoron are registered trademarks) which is a PET film of Teijin DuPont Films Limited. (Registered trademark) S (0.05 to 0.25 mm) can be mentioned.
A portion where the refrigerant leaks from the inside of the piping structure 10 is indicated by X. The point X corresponds to, for example, a connecting portion between pipes, a connecting portion between a valve and a pipe, a crack generated in a wall of the pipe, or the like.

Due to the pressure of the refrigerant, the non-conductive film 11 and the conductive film 12 are deformed so as to swell, so that a refrigerant pool 18 is formed between the outer peripheral portion 10A and the films 11 and 12.
At the location where the films 11 and 12 adjacent to the leak location X are not deformed, the laminated films 11 and 12 are along the outer peripheral portion 10A, so that the refrigerant reservoir 18 is almost sealed, and , It is difficult for the refrigerant to flow out to the surrounding area. If there is a gap between the films 11 and 12 and between the film 11 and the outer peripheral portion 10A, the refrigerant in the refrigerant reservoir 18 slightly flows out through the gap, but a larger amount of the refrigerant leaks from the leakage point X. By continuing, the refrigerant pool 18 becomes gradually larger.

Since the non-conductive film 11 and the conductive film 12 are laminated, the non-conductive film 11 and the conductive film 12 are less likely to be broken even by the pressure of the leaked refrigerant. However, when the refrigerant leaks a large amount and the pressure in the refrigerant reservoir 18 increases until the flexibility of the conductive film 12 or the non-conductive film 11 is exceeded, as shown in FIG. The non-conductive film 11 is broken. FIG. 2B shows an example in which only the conductive film 12 is broken.
When the refrigerant is ejected from the inside of the piping structure 10 with an excessive pressure, the non-conductive film 11 or the conductive film 12 may be instantly broken.

When the conductive film 12 is deformed or broken, the electric resistance of the conductive film 12 changes as compared with that before the deformation. A large amount of deformation of the conductive film 12 can be obtained by collecting the leaked refrigerant inside the conductive film 12. When the amount of deformation is large, the electric resistance changes significantly compared to when the conductive film 12 is not deformed. Further, even when the conductive film 12 is broken, the electric resistance is significantly changed as compared with the case where the conductive film 12 is not deformed or broken.

The conductive film 12 is provided with rigidity that is sufficiently deformed by the pressure of the leaked refrigerant, and is also flexible enough to hold the refrigerant pool 18 without easily breaking.
The non-conductive film 11 is provided with appropriate rigidity so as to be deformed without hindering the deformation of the conductive film 12.
Since the pressures of the refrigerants flowing through the plurality of sections of the piping structure 10 are different, the conductive film 12 and the non-conductive film 11 are provided for each of the sections P1 and P2 so as to match the pressure of the refrigerant in each of the sections P1 and P2. It is possible to set the rigidity of each.

The resistance measuring unit 14 measures the electric resistance between the both ends 121, 122 of the conductive film 12. One end 121 of the conductive film 12 corresponds to one end of the section P1 (or P2), and the other end 122 of the conductive film 12 corresponds to the other end of the section P1 (or P2).
The resistance measuring unit 14 is electrically connected to both ends 121 and 122 of the conductive film 12 by wirings 141 and 142. Although not shown, the resistance measuring unit 14 includes a DC power supply, a DC voltmeter, and a DC ammeter and a constant current circuit required according to the resistance measuring principle to be adopted.

The leak detection unit 15 monitors the electric resistance of the conductive film 12 for each of the sections P1 and P2, and detects the refrigerant leakage based on the fact that the electric resistance deviates from a predetermined reference value.
The “reference value” corresponds to the electric resistance of the conductive film 12 measured by the resistance measuring unit 14 when the refrigerant leakage does not occur in the state where the films 11 and 12 and the wiring are installed in the piping structure 10. To do.
The reference value is stored in the storage unit for each of the sections P1 and P2.
The leak detection unit 15 reads the reference value corresponding to the section (for example, P1) from the storage unit, and when the electric resistance measured by the resistance measuring unit 14 corresponding to the section deviates from the reference value, It is detected that the refrigerant is leaking in the section.

The leak detection unit 15 can determine that the measured value of the electric resistance deviates from the reference value, for example, when the measured value exceeds the predetermined threshold value.
Here, the electrical resistance of the conductive film 12 changes due to water, oil, dust, or the like adhering to the conductive film 12, or the temperature of the conductive film 12 changing due to a change in the refrigerant temperature or the atmospheric temperature. Even if it does, the threshold value used for the determination of the deviation from the reference value can be set so that the refrigerant leakage is not erroneously detected.
As the threshold value, a value larger than a value obtained by adding the amount of change, which is caused by disturbance factors such as adhesion of water or dust or temperature change, to the electric resistance of the conductive film 12 to the reference value, can be set.
Further, based on the tendency that the amount of change in the electric resistance with respect to the reference value increases as the conductive film 12 greatly expands due to the leaked refrigerant, it corresponds to the amount of deformation of the conductive film 12 in a sufficiently expanded state before breaking. The electric resistance can be set to the threshold value.

It is also possible to set a plurality of threshold values for the electric resistance of the conductive film 12.
From these thresholds, for example, different thresholds may be selected according to the rate of change of the measured value of electric resistance, and if the electric resistance exceeds the threshold, it may be determined that the electric resistance deviates from the reference value. it can.

The piping structure 10 having the configuration described above can be constructed by the following procedure.
First, one or more sections (here, two sections) are set in the piping structure 10 (section setting step). Then, the conductive film 12 is provided on the outer peripheral portion 10A of the piping structure 10 for each of the sections P1 and P2. Here, the piping structure 10 and the conductive film 12 can also be insulated by, for example, applying a non-conductive paint over the entire circumference of the outer peripheral portion 10A, but in the present embodiment, the conductivity is reduced. Prior to the construction of the film 12, the outer peripheral portion 10A is covered with the non-conductive film 11 to insulate the piping structure 10 from the conductive film 12 (non-conductive film construction step). Then, the conductive film 12 is piled up over substantially the entire area of the non-conductive film 11 (conductive film construction step).

When constructing the non-conductive film 11 and the conductive film 12, as shown in FIG. 3, a film laminate 13 which is integrated in advance in a state where the non-conductive film 11 and the conductive film 12 are laminated is used. You can also The film laminated body 13 is formed in a size that fits the length of the section to be constructed (here, P1) and that can surround the piping structure 10 over the entire circumference.
The film laminated body 13 is formed in an arc shape so as to follow the outer peripheral portion 10A of the piping structure 10, and is wound around a core (not shown). When the film laminated body 13 is attached to the outer peripheral portion 10A and the end portions 13A and 13B in the circumferential direction of the film laminated body 13 are joined with an adhesive tape or an adhesive, the outer peripheral portion 10A is surrounded by the annular film laminated body 13. It
By using the film laminate 13, the non-conductive film 11 and the conductive film 12 can be easily applied at once.
As shown in FIG. 3, if wirings 141 and 142 are provided in advance on both ends 121 and 122 in the length direction of the conductive film 12, wiring work becomes easy.

When the outer peripheral portion 10A of the piping structure 10 is covered with the non-conductive film 11 and the conductive film 12, the wirings 141 and 142 are connected to the resistance measuring unit 14. Thereby, a DC circuit including the conductive film 12, the wirings 141 and 142, and the resistance measuring unit 14 is formed (wiring step).
Then, the electric resistance between the both ends 121 and 122 of the conductive film 12 changes due to the deformation or breakage of the conductive film 12, and deviates from the predetermined reference value. It is possible to obtain the piping structure 10 configured to be able to detect leakage.
Since the electric resistance of the conductive film 12 can be measured by a simple DC circuit as compared with a circuit for measuring impedance, the measuring circuit can be constructed at low cost.

The non-conductive film construction step, the conductive film construction step, and the wiring step described above are performed for each of the sections P1 and P2.

The above-mentioned construction can be carried out at the time of factory shipment when the device or system (air conditioned, etc.) including the piping structure 10 is a new one, or at the time of on-site installation of such device or system. .. In addition, in the existing device or system, the films 11, 12 and the resistance measuring unit 14 can be retrofitted to the piping structure 10.
The construction timing for a new or existing device or system is the same for the piping structure 20 of the second embodiment.

Now, the refrigerant leakage detection method of this embodiment will be described.
In order to detect the leakage of the refrigerant from the sections P1 and P2 of the piping structure 10 covered with the conductive film 12 as described above, the resistance measuring unit 14 measures both ends 121 and 122 of the conductive film 12. The electric resistance between them is monitored by the leak detection unit 15.
Under the monitoring of the electric resistance of the conductive film 12, the leakage of the refrigerant from the inside of the piping structure 10 occurs and the following process is followed until the leakage of the refrigerant is detected by the leakage detection unit 15.

When a refrigerant leak occurs, as shown in FIG. 2A, the pressure of the leaked refrigerant deforms the non-conductive film 11 and the conductive film 12, and the refrigerant accumulates near the leakage point X, or As shown in FIG. 2(b), the conductive film 12 is broken by the pressure of the leaked refrigerant (deformation or breaking step S1).
Here, when a slow leak that slowly leaks by a small amount occurs at the leak location X, the electric resistance value of the conductive film 12 does not change greatly in a moment, but a certain time has elapsed since the leak occurred, When the conductive film 12 is sufficiently deformed to form the coolant reservoir 18, the deformation of the conductive film 12 causes the electric resistance of the conductive film 12 to remarkably change from the initial value. As a result, the value of the electric resistance measured by the resistance measuring unit 14 deviates from the reference value before deformation. Therefore, unless it breaks instantly, the leak detection unit 15 reliably detects the refrigerant leak before the conductive film 12 breaks by properly setting the threshold value used for determining the deviation from the reference value. It is possible (refrigerant leakage detection step S2).
Since the refrigerant leaked from the leak point X is accumulated inside the conductive film 12 and the non-conductive film 11, it is possible to prevent the refrigerant leaked from the inside of the piping structure 10 from being released to the atmosphere inside or outside the room. ..

When excessive pressure is applied to the non-conductive film 11 and the conductive film 12 due to the pressure of the refrigerant ejected from the leakage point X, the films 11 and 12 may be broken. Even in that case, since the electric resistance deviating from the reference value is measured immediately after the breakage, the refrigerant leakage can be reliably detected based on the electric resistance.

The leak detection unit 15 can identify the section in which the refrigerant has leaked, based on the change in the electrical resistance caused by the deformation or breakage of the conductive film 12 provided for each of the sections P1 and P2.
Therefore, for example, it is possible to change the operation mode of the air conditioner or the refrigerator so as not to use the section, or to shut off the valve, depending on the section in which the refrigerant leakage has occurred. Therefore, even if the films 11 and 12 are broken, it is possible to prevent a large amount of refrigerant from leaking to the atmosphere. When the section is specified, it is easy to repair the leakage point X and replace the part.

According to the refrigerant leakage detection method and the piping structure 20 of the present embodiment, the section P1, which is set based on the change in electric resistance due to the deformation or breakage of the conductive film 12 covering the outer peripheral portion 10A of the piping structure 10. It is possible to reliably detect the leakage of the refrigerant in P2 including the slow leakage, and it is possible to specify the section in which the leakage has occurred.
In addition to that, since the leaked portion X is covered with the conductive film 12 and the non-conductive film 11, it is possible to prevent the leaked refrigerant from further leaking to the outside. Therefore, the leakage of the refrigerant can be prevented from affecting the environment. Further, in that the leakage to the outside can be suppressed as much as possible, the present embodiment is also useful for detecting leakage of a refrigerant such as R32 or HFC having combustibility, while having a low GWP (Global Warming Potential). ..

[Second Embodiment]
Next, a refrigerant leakage detection method and a piping structure according to the second embodiment of the present invention will be described.
Hereinafter, matters different from the first embodiment will be mainly described.
The piping structure 20 shown in FIG. 4 also has a plurality of sections P1 and P2. It is preferable that each of the sections P1 and P2 include a leak-prone portion such as a connecting portion between the valve and the pipe.
The piping structure 20 includes a non-conductive film 11 and a conductive film 12 which cover the outer peripheral portion 10A of the piping structure 20 over each of the sections P1 and P2, a constant resistance 21 which is a resistance element having a predetermined electric resistance, and a constant resistance 21. A potential difference measuring unit 24 that measures a potential difference corresponding to a voltage drop due to the resistor 21 and a leak detection unit 25 that detects a refrigerant leak based on a change in the potential difference are provided.

In the second embodiment, one end 121 of the conductive film 12 is electrically connected to the piping structure 20 by soldering or brazing. The constant resistance 21 is connected in series with the conductive film 12 at the other end 122 of the conductive film 12. The constant resistance 21 is connected to a ground (GND) 23 by a wiring 22.
An electric circuit including the constant resistance 21, the conductive film 12, the DC power supply 26 connected to the piping structure 20, and the ground 23 is formed.

The constant resistance 21 is provided in each of the conductive film 12 corresponding to the section P1 and the conductive film 12 corresponding to the section P1. The constant resistance 21 corresponding to the section P1 and the constant resistance 21 corresponding to the section P2 are both connected to a common ground 23.
In the second embodiment, it is not necessary to wire the one end 121 of the conductive film 12, and the wire 22 is connected only to the other end 122, and the wire 22 is used as a housing as the ground 23 or prepared in advance. Wiring can be done easily because it can be connected to the existing ground line.

The potential difference measuring unit 24 measures the potential difference (voltage drop) across the constant resistance 21. The potential difference measuring unit 24 is provided in each of the constant resistance 21 in the section P1 and the constant resistance 21 in the section P2.
When the refrigerant leaks, the conductive film 12 is deformed or ruptured by the pressure of the refrigerant so as to swell, as in the case described in the first embodiment. Then, when the electric resistance of the conductive film 12 changes, the voltage drop due to the constant resistance 21 connected in series with the conductive film 12 also changes accordingly. In this embodiment, this voltage drop is used for leak detection.

The leak detection unit 25 detects the refrigerant leak based on the fact that the potential difference corresponding to the voltage drop of the constant resistance 21 measured by the potential difference measurement unit 24 deviates from a predetermined reference value.
A leak detection unit may be prepared for each of the sections P1 and P2 so that the refrigerant leakage is detected for each of the sections P1 and P2.

The construction of the piping structure 20 of the second embodiment is carried out in the same way as the construction of the piping structure 10 of the first embodiment up to the middle.
After the outer peripheral portion 10A of the piping structure 20 is covered with the non-conductive film 11 and the conductive film 12, the one end 121 of the conductive film 12 is connected to the outer peripheral portion 10A of the piping structure 20 using solder or solder. Further, the constant resistance 21 is connected to the other end 122 of the conductive film 12 by the wiring 22, and the wiring 22 is further connected to the ground 23. Then, a DC circuit including the conductive film 12, the constant resistance 21, the ground 23, and the power supply 26 is formed (wiring step).
Then, it is possible to obtain the piping structure 20 configured to be able to detect the leakage of the refrigerant.

In the second embodiment, in order to detect the leakage of the refrigerant from the sections P1 and P2 of the piping structure 20 covered with the conductive film 12, the leak detection unit detects the potential difference due to the constant resistance 21 measured by the potential difference measurement unit 24. 25 to monitor.
The second embodiment is different from the first embodiment only in that the measurement target is a potential difference corresponding to the voltage drop due to the constant resistance 21, and the method of detecting refrigerant leakage is the same as in the first embodiment. The following is a brief description.

When the refrigerant leaks from the leakage point X of the piping structure 20, the conductive film 12 is deformed or broken by the pressure of the refrigerant (deformation or breaking step S1). Even if it is a slow leak, when the conductive film 12 is sufficiently deformed with the passage of time (FIG. 5B), when the conductive film 12 is not deformed as shown in FIG. 5A. In comparison, the voltage drop due to the constant resistance 21 significantly changes. If the conductive film 12 and the non-conductive film 11 are broken and the conductive film 12 and the piping structure 20 are electrically connected to each other, the piping structure 20 is broken from the broken portion, as indicated by a chain double-dashed line in FIG. 5B. The electric current starts to flow. Then, the voltage drop due to the constant resistance 21 changes more significantly.
When the conductive film 12 is sufficiently deformed or broken, the value of the potential difference (voltage drop) measured by the potential difference measuring unit 24 deviates from the reference value before the deformation. Therefore, the leakage detection unit 25 can reliably detect the refrigerant leakage for each of the sections P1 and P2 based on the fact that the measured value of the voltage drop deviates from the stored reference value (refrigerant). Leakage detection step S2).
At this time, the refrigerant leaked from the leakage point X is accumulated inside the conductive film 12 and the non-conductive film 11, so that the refrigerant leaked from the inside of the piping structure 10 is prevented from being released to the outside atmosphere. it can.

Other than the above, the configurations described in the above embodiments can be selected or changed to other configurations without departing from the gist of the present invention.
When the insulating heat insulating material is provided on the outer peripheral portion 10A of the piping structure 10 (or 20), the conductive film 12 may be provided so as to cover the heat insulating material. In that case, since the conductive film 12 is insulated from the piping structure 10 (or 20) by the heat insulating material interposed between the outer peripheral portion 10A and the conductive film 12, the non-conductive film 11 is used, There is no need to apply insulating paint to the outer peripheral portion 10A.
In addition, the non-conductive film 11 and the conductive film 12 may be arranged on the inner peripheral side of the heat insulating material.

10, 20 Piping structure 10A Outer peripheral portion 11 Non-conductive film 12 Conductive film 13 Film laminated body 13A, 13B End portion 14 Resistance measurement unit (electrical resistance measurement unit)
15 Leakage detection unit 21 Constant resistance 22 Wiring 23 Ground 24 Potential difference measurement unit 25 Leakage detection unit 26 DC power supplies 101-103 Piping 104, 105 Valve 121 One end 122 Other end 141, 142 Wiring P1, P2 Section X Leakage location

Claims (3)

A construction method for configuring the piping structure to detect fluid leakage from the inside of the piping structure,
The film laminated body is obtained by laminating a non-conductive film on a conductive film over the entire length of a predetermined section including the joint of the piping structure, and using the film laminated body in a state of being formed in an arc shape. By surrounding the piping structure in an annular shape by, by providing a conductive film in a state insulated by the non-conductive film to the piping structure,
Wiring is provided at both ends of the conductive film corresponding to one end and the other end of the section, and a step of forming an electric circuit capable of measuring the electric resistance between the both ends,
The electrical resistance between the both ends of the conductive film changes due to deformation or breakage of the conductive film, and based on deviation from a predetermined threshold value, fluid leakage in the section is prevented. Configure to detect,
A construction method characterized by the above. A construction method for configuring the piping structure to detect fluid leakage from the inside of the piping structure,
The film laminated body is obtained by laminating a non-conductive film on a conductive film over the entire length of a predetermined section including the joint of the piping structure, and using the film laminated body in a state of being formed in an arc shape. By surrounding the piping structure in an annular shape by, by providing a conductive film in a state insulated by the non-conductive film to the piping structure,
Connecting one end of the conductive film corresponding to one end of the section to the piping structure,
At the other end of the conductive film, a constant resistance having a constant electric resistance value is connected in series, the piping structure, the conductive film, and a step of forming an electric circuit including the constant resistance,
A potential difference corresponding to a voltage drop due to the constant resistance changes due to deformation or breakage of the conductive film, and deviates from a predetermined threshold, based on which fluid leakage in the section can be detected. To do
A construction method characterized by the above. Setting a plurality of the sections in the piping structure,
Performing a step of surrounding the outer peripheral portion of the piping structure with the film laminate for each section,
The construction method according to claim 1 .

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