Leak detection line

Abstract

The present invention addresses the problem of providing a liquid leak detecting line capable of suppressing erroneous detection while suppressing a significant decrease in liquid leak detection performance.　In order to resolve the abovementioned problem, the present invention provides a liquid leak detecting line comprising a plurality of detecting lines each comprising a conductor and a braided body covering the conductor, wherein the plurality of detecting lines include a first detecting line and a second detecting line, the braided body is configured from an electrically insulating yarn, and an electrically conductive liquid is detected when the liquid electrically connects the conductor of the first detecting line and the conductor of the second detecting line through the braided bodies, and wherein the braided body of one or both of the first detecting line and the second detecting line comprises a first yarn and a second yarn intersecting the first yarn, and the second yarn is thinner than the first yarn.

Description

Cross-reference of related applications

[0001] This application claims priority under Japanese Patent Application No. 2023-202477, which is incorporated into the description of this application by reference. [Technical Field]

[0002] This invention relates to a leak detection wire. [Background technology]

[0003] Conventionally, leak detection wires, such as the one shown in Patent Document 1 below, have been used to detect leaks from pipes and other structures through which electrically conductive liquids, such as water, flow. These leak detection wires are known to comprise multiple detection wires, each comprising a conductor and a braided structure covering the conductors. The braided structure is made of electrically insulating threads, ensuring electrical insulation between conductors under normal conditions. When liquid leaks from a pipe or other structure, the liquid electrically connects the conductors of one detection wire to another through the braided structure, thereby detecting the leak. Furthermore, leak detection wires of this type are known to include an external braided structure that bundles the detection wires together.

[0004] This type of leak detection wire may be laid along piping, for example, and may even extend over areas where pipes are connected by flanges. Furthermore, leak detection wires are often installed in confined spaces. Therefore, highly flexible materials are often used for leak detection wires. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese National Law Publication No. 6-35294 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Leak detection wires have a problem where the conductors of two detection wires become electrically connected unintentionally, leading to a false detection of a leak even when no leak has occurred, and countermeasures are needed. One possible solution to this problem is to use detection wires in which the conductors are covered with a tightly woven braid. However, such measures can make it difficult for the conductors to electrically connect when the amount of leak is small, potentially significantly reducing leak detection accuracy. To date, no effective means to solve this problem has been provided. Therefore, the object of the present invention is to provide a leak detection wire that can suppress false detections while suppressing a significant decrease in leak detection accuracy. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: The device comprises multiple detection wires, each consisting of a conductor and a braided structure covering the conductor. The plurality of detection lines include a first detection line and a second detection line, The braided body is made of electrically insulating threads, and the leak detection wire detects the liquid by electrically connecting the conductor of the first detection wire and the conductor of the second detection wire through the braided body. The braided body of one or both of the first detection line and the second detection line is The present invention provides a leak detection wire comprising a first thread and a second thread intersecting the first thread, wherein the second thread is thinner than the first thread. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing a leak detection line in one embodiment. [Figure 2] Figure 2 is a schematic diagram showing the shape of the cross-section as seen by the line II-II in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing the shape of the cross-section as seen by the line III-III in Figure 1. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. As shown in Figure 1, the leak detection wire 100 of this embodiment includes a plurality of detection wires 10. The leak detection wire 100 of this embodiment is provided with a pair of first detection wires 10a and second detection wires 10b. Each of the first detection wire 10a and the second detection wire 10b of this embodiment comprises a conductor 11 and a braided body 12 covering the conductor 11. In this embodiment, the first detection wire 10a comprises a first conductor 11a which becomes the first conductor 11 in the leak detection wire 100 and a first braided body 12a covering the first conductor 11a, and the second detection wire 10b comprises a second conductor 11b which becomes the second conductor 11 in the leak detection wire 100 and a second braided body 12b covering the second conductor 11b.

[0010] The first conductor 11a and the second conductor 11b are each made of electrically conductive wire. The first braid 12a and the second braid 12b are each electrically insulating (for example, with a volume resistivity of 1 × 10 at 25°C). 8 It is composed of thread made of a material having a resistance of Ω·cm or more. The leak detection wire 100 of this embodiment is designed so that when an electrically conductive liquid leaks from a pipe or the like, the liquid reaches the first conductor 11a through the first braid 12a and the second conductor 11b through the second braid 12b, causing the first conductor 11a and the second conductor 11b to be electrically connected, and the electrical resistance between the two detection wires 10, which should normally have electrical insulation, to drop significantly, thereby detecting the presence of the liquid.

[0011] The liquid leakage detection line 100 of the present embodiment is not particularly limited in its use, but can be arranged, for example, along a pipe connected by a flange. Further, for example, it can be arranged in parallel or wound along a pipe with a small diameter and many bent portions, such as a pipe of a water-cooled large-capacity data server. The liquid leakage detection line 100 of the present embodiment, which may be arranged in a narrow space by being bent with a small radius of curvature (for example, a radius of curvature of 10 mm or less), has a small diameter, excellent flexibility, and excellent bending property.

[0012] In the liquid leakage detection line 100, the first detection line 10a and the second detection line 10b extend in the length direction DL of the liquid leakage detection line 100 while being in contact with each other, and are arranged so as to be parallel to each other in the length direction DL of the liquid leakage detection line 100. In the liquid leakage detection line 100 of the present embodiment, an external braided body 20 is provided to bundle and cover these detection lines 10 so that the contact state between the first detection line 10a and the second detection line 10b is maintained. The external braided body 20 has a cylindrical shape with a thickness that can enclose the first detection line 10a and the second detection line 10b, and is configured to extend in the length direction DL of the liquid leakage detection line 100.

[0013] The first detection line 10a and the second detection line 10b may be simply arranged side by side, or may be provided in the liquid leakage detection line 100 in a twisted state. When it is assumed that the liquid leakage detection line 100 is bent, if the first detection line 10a and the second detection line 10b are stacked in the bending direction, the contact state between the detection lines 10 is likely to be maintained in a good state. On the other hand, when the first detection line 10a and the second detection line 10b are arranged side by side at the bent portion, for example, when an edge portion of a pipe flange hits an intermediate point between the first detection line 10a and the second detection line 10b and a local stress is applied to the portion, the first detection line 10a and the second detection line 10b may be separated from each other, resulting in a decrease in the detectability of the liquid. Also, even when bending stress acts evenly on the two side-by-side detection lines 10, if the first braided body 12a and the second braided body 12b each spread horizontally and the cross-sectional shape is deformed into a horizontally long elliptical cylinder shape, the distance between the first conductor 11a and the second conductor 11b may be increased.

[0014] The first detection line 10a and the second detection line 10b can be prevented from being separated from each other in an unintended manner by being twisted together. The first detection line 10a and the second detection line 10b are more likely to maintain a contact state when twisted together at a short pitch. From such a perspective, the number of twists of the first detection line 10a and the second detection line 10b per unit length of the liquid leakage detection line 100 can be, for example, 15 turns / m or more. The number of twists of the first detection line 10a and the second detection line 10b may be 20 turns / m or more, or may be 25 turns / m or more. On the other hand, the first detection line 10a and the second detection line 10b are more advantageous in terms of causing the liquid leakage detection line 100 to exhibit good flexibility when twisted together at a long pitch. From such a perspective, the number of twists of the first detection line 10a and the second detection line 10b per unit length of the liquid leakage detection line 100 can be, for example, 90 turns / m or less. The number of twists of the first detection line 10a and the second detection line 10b may be 80 turns / m or less, or may be 70 turns / m or less.

[0015] The liquid leakage detection line 100 may include three or more detection lines 10 including a third detection line. And the liquid leakage detection line 100 may be configured to be able to detect liquid leakage not only by the electrical connection state between the first detection line 10a and the second detection line 10b, but also by the electrical connection state between the first detection line and the third detection line, the electrical connection state between the second detection line and the third detection line, and the like.

[0016] The leak detection wire 100 may include wires other than the detection wire 10. When measuring the electrical connection between the first detection wire 10a and the second detection wire 10b by applying a voltage between them at one end of the leak detection wire 100, the other end of the leak detection wire 100 will be open (insulated) from the first detection wire 10a and the second detection wire 10b. The wires other than the detection wire 10 may be, for example, electric wires that are electrically connected to the first detection wire 10a and the second detection wire 10b at the other end of the leak detection wire 100. In this case, if the conductor 11 (first conductor 11a) of one of the detection wires 10 (for example, the first detection wire 10a) is made of a conductor similar to that of a general electric wire (for example, copper wire, aluminum wire, etc.), and the conductor 11 (second conductor 11b) of the other detection wire 10 (for example, the second detection wire 10b) is made of a conductor (hereinafter referred to as "resistive conductor") made of a material with a higher electrical resistance value than that of a general electric wire conductor, such as an alloy wire, and the electric wire is connected to a detection wire equipped with a resistive conductor, the location of the leak can be easily identified when a leak is detected.

[0017] The aforementioned wire material may function as a tension member, or it may be an intervening material that fills the gap between the outer braid 20 and the detection wire 10. By covering the first detection wire 10a and the second detection wire 10b with the outer braid 20 along with such an intervening material, the tightening force of the outer braid 20 can be easily applied as a contact force between the first detection wire 10a and the second detection wire 10b, and it becomes possible to suppress the separation of the detection wires 10 (conductors 11) from each other, especially when the leak detection wire 100 is bent with a small radius of curvature (for example, a radius of curvature of 8 mm or less).

[0018] The first braided body 12a comprises a first thread (hereinafter also referred to as the "right-handed thread") that is wound around the first conductor 11a so as to rotate clockwise when the longitudinal direction DL of the leak detection wire 100 is the direction of travel, and a second thread (hereinafter also referred to as the "left-handed thread") that is wound around the first conductor 11a so as to rotate counterclockwise. In the first braided body 12a, the right-handed thread and the left-handed thread are woven together while switching their positions in the radial direction DD of the leak detection wire 100 toward the direction of travel. The second braided body 12b is the same, and is braided by a right-handed thread wound around the second conductor 11b while rotating clockwise toward the direction of travel and a left-handed thread wound around the second conductor 11b while rotating counterclockwise.

[0019] In each detection wire 10 of the first detection wire 10a and the second detection wire 10b included in the leak detection wire 100, the thickness of two threads is created at the point where the right-handed and left-handed twisted threads constituting the braided body 12 intersect. As shown in Figure 2, the calculated outer diameter, when expressed as radius (hereinafter also referred to as "theoretical radius (Ri)"), is the sum of the radius of the conductor 11 and the thickness of two threads, and when expressed as diameter (hereinafter also referred to as "theoretical diameter (Di)"), it is the sum of the diameter Dc of the conductor 11 and the thickness of four threads.

[0020] As described above, by making the threads constituting the braided body 12 thinner, the thickness of the detection wire 10 can be reduced, and the diameter of the leak detection wire 100 can also be reduced. In this regard, according to the facts discovered by the inventors by focusing on the structure of the leak detection wire, the braided body does not have a thickness of two threads at all points. For example, at the intermediate point between when one right-handed twisted thread crosses over a left-handed twisted thread and when it goes under the next left-handed twisted thread, the thickness of the braided body is that of one thread. That is, at this intermediate point, when the direction in which the detection wire 10 rotates around the conductor 10 is considered the circumferential direction, the right-handed twisted thread and the left-handed twisted thread are aligned side by side in the circumferential direction, so the thickness of the braided body in the radial direction of the detection wire 10 becomes that of one thread. For this reason, if all the threads constituting the braided body are made thinner, it becomes difficult to secure the distance between conductors. Furthermore, if the leak detection wire is bent with a small radius of curvature to follow the flange of a pipe, large gaps may open between adjacent threads in the braided structure. In such places, due to the difference in bending rigidity between the braided structure and the conductor, there is a risk that the conductor may protrude through the gap to the outside of the braided structure. Therefore, simply making the threads that make up the braided structure thinner not only makes it easier for the conductor to protrude, but also makes it easier for the protruding conductor to penetrate the braided structure of an adjacent detection wire from the outside and come into contact with the conductor of that detection wire. Consequently, simply making the threads thinner may not ensure sufficient insulation between conductors, potentially causing false detections. It is conceivable to form a tightly woven braided structure using thin threads to prevent exposure of the detection wire's conductor, but in that case, the time it takes for the liquid to reach the conductor through the braided structure will increase, which may reduce the responsiveness of leak detection.

[0021] In this embodiment, the above-mentioned problems are solved by making the right-handed and left-handed spindles different in thickness. Specifically, by making one of the right-handed and left-handed spindles thinner, the theoretical diameter of the detection line 10 (Di in Figure 2) can be reduced, and as shown in Figure 3, at the point where the right-handed and left-handed spindles are aligned horizontally in the circumferential direction, a distance is maintained between the conductors 11 equal to the thickness of the thicker thread (the first threads 121a and 121b). Therefore, in this embodiment, false detections by the leak detection line 100 can be suppressed.

[0022] In the leak detection wire 100 of this embodiment, the left-handed twister may be made of a thinner thread than the right-handed twister, or the right-handed twister may be made of a thinner thread than the left-handed twister. In the leak detection wire 100 of this embodiment, the braided body 12 may be made of threads of different diameters (thickness) in only one of the first braided body 12a and the second braided body 12b, or both may be braided bodies made of threads of different diameters. In this embodiment, in order to more reliably achieve the above effects, both the first braided body 12a and the second braided body 12b are braided bodies made of threads of different diameters. Also, as shown in Figure 1, in the first braided body 12a of this embodiment, a left-handed twister is used that is thinner than the right-handed twister. On the other hand, in the second braided body 12b, a right-handed twister is used that is thinner than the left-handed twister. In this embodiment, the two adjacent detection lines 10 make it easier for the first threads 121 to come into contact with each other, and make it easier to maintain a certain distance between the conductors 11.

[0023] Right-handed and left-handed yarns may be monofilament yarns, multifilament yarns, or spun yarns. It is preferable that right-handed and left-handed yarns are monofilament yarns or multifilament yarns. It is preferable that right-handed and left-handed yarns do not deform under force applied in the radial direction (thickness direction), and are either monofilament yarns or, in the case of multifilament yarns, twisted yarns may be preferred. Examples of monofilament yarns include: polyolefin resin monofilaments such as polyethylene resin monofilaments and polypropylene resin monofilaments; polyester resin monofilaments such as polyethylene terephthalate resin monofilaments, polybutylene terephthalate resin monofilaments, polylactic acid resin monofilaments, and polyethylene terephthalate resin monofilaments; polyamide resin monofilaments such as polyamide 6 resin monofilaments, polyamide 66 resin monofilaments, polyamide 610 resin monofilaments, semi-aromatic polyamide resin monofilaments, and fully aromatic polyamide resin monofilaments; polytetrafluoroethylene resin monofilaments, ethylene-tetrafluoroethylene copolymer resin monofilaments, and polytetrafluoroethylene. The monofilaments may include ethylene-perfluoroalkyl ether copolymer resin monofilaments, tetrafluoroethylene-hexafluoropropylene copolymer resin monofilaments, fluororesin monofilaments such as polyvinylidene fluoride resin monofilaments, super engineering plastic monofilaments such as polyethersulfone resin monofilaments, polysulfone resin monofilaments, polyphenylsulfone resin monofilaments, polyphenylene sulfide resin monofilaments, polyetherimide resin monofilaments, and polyphenylene ether resin monofilaments, as well as ethylene-vinyl acetate copolymer resin monofilaments, polyvinyl chloride resin monofilaments, polyurethane resin monofilaments, and thermoplastic elastomer monofilaments. The monofilament yarn may also be made of highly hydrophilic resins such as polyester resin monofilaments or polyamide resin monofilaments, as they offer excellent detection performance when the target of detection is water.Furthermore, the monofilament yarn may be a super engineering plastic monofilament in order to enhance the flame retardancy of the leak detection wire 100.

[0024] The material of the multifilament yarn may be the same as that of the monofilament yarn exemplified above. If the multifilament yarn is twisted, it may be a loosely twisted yarn with fewer than 500 twists (500T / m) per meter, a mediumly twisted yarn with 500 twists (500T / m) or more but less than 1000 twists (1000T / m), a highly twisted yarn with 1000 twists (1000T / m) or more but less than 2500 twists (2500T / m), or an extremely highly twisted yarn with 2500 twists (2500T / m) or more. The right-handed and left-handed twisted yarns may consist of one monofilament yarn and the other multifilament yarn. If one or both of the right-handed and left-handed twisted yarns are twisted, the twisted yarn may be an S-twist or a Z-twist. Right-handed and left-handed yarns may be S-twisted and Z-twisted, both S-twisted, or both Z-twisted.

[0025] The thickness of the first thread (right-handed spindle in the first detection line 10a, left-handed spindle in the second detection line 10b), which is the thicker of the two right-handed and left-handed spindles, and the second thread (left-handed spindle in the first detection line 10a, right-handed spindle in the second detection line 10b), which is the thinner of the two right-handed and left-handed spindles, can be appropriately changed depending on the location where the leak detection line 100 is used and the thickness of the first conductor 11a and the second conductor 11b. However, the thickness (diameter: D1) of the first thread 121 in this embodiment can be any of the ranges of 0.2 mm or more and 0.3 mm or less. The thickness (diameter: D1) of the first thread 121 in this embodiment may be 0.21 mm or more, or 0.22 mm or more. The thickness (diameter: D1) of the first thread 121 may be 0.29 mm or less, or 0.28 mm or less. In this embodiment, the thickness (diameter: D2) of the second thread 122 can be, for example, any value within the range of 0.05 mm or more and less than 0.2 mm. In this embodiment, the thickness (diameter: D2) of the second thread 122 may be 0.08 mm or more, or 0.10 mm or more. The thickness (diameter: D2) of the second thread 122 may be 0.18 mm or less, or 0.17 mm or less.

[0026] The thicknesses (D1, D2) of the first thread 121 and the second thread 122 can be measured using a digital micrometer, and the thickness can be calculated by taking the arithmetic mean of the values ​​measured with the digital micrometer at multiple randomly selected points (for example, 10 points) on a single thread.

[0027] The difference in thickness between the first thread 121 and the second thread 122 (ΔD = D1 - D2) can be, for example, 0.05 mm or more and 0.15 mm or less. The difference in thickness between the first thread 121 and the second thread 122 (ΔD) may be 0.06 mm or more, or 0.07 mm or more. The difference in thickness between the first thread 121 and the second thread 122 (ΔD) may be 0.14 mm or less, or 0.13 mm or less.

[0028] The ratio (D2 / D1) of the thickness of the second thread 122 to the thickness of the first thread 121 can be, for example, 0.30 or more and 0.80 or less. The ratio (D2 / D1) may also be 0.35 or more, or 0.40 or more. The ratio (D2 / D1) may also be 0.75 or less, or 0.70 or less.

[0029] The first braided structure 12a and the second braided structure 12b may each be composed of multiple right-handed spines and multiple left-handed spines. The material and thickness of the right-handed spines in the first braided structure 12a may be the same as or different from those in the second braided structure 12b. Similarly, the material and thickness of the left-handed spines in the first braided structure 12a may be the same as or different from those in the second braided structure 12b. The first braided structure 12a and the second braided structure 12b may have the same or different tissue structures.

[0030] The first braided structure 12a and the second braided structure 12b can be, for example, braided in such a way that right-handed and left-handed yarns form a plain weave, twill weave, satin weave, or other structure. In the satin weave structure, one of the right-handed and left-handed yarns crosses the other yarns skipping four or more threads, so while the yarns may be in close proximity where the detection line is straight, the gaps between the yarns tend to widen where the detection line is bent with a small radius of curvature, potentially allowing a large portion of the conductor to be exposed. In the plain weave structure of right-handed and left-handed yarns, one of the right-handed and left-handed yarns crosses the other yarn one thread at a time, making it difficult for adjacent right-handed yarns or adjacent left-handed yarns to be closely spaced. Furthermore, in a structure where right-handed and left-handed yarns are woven in a plain weave, the flexibility when bending the detection line is reduced compared to when knitted in a satin weave, but the gaps between the yarns do not widen easily even in places where the detection line is bent with a small radius of curvature. Among the knitted bodies knitted in the above structure, a knitted body in which right-handed and left-handed yarns are woven in a twill weave can be made to have a good balance between flexibility and the effect of suppressing the exposure of the conductor. In particular, a knitted body knitted with right-handed and left-handed yarns in a 2 / 2 twill weave is suitable as the first knitted body 12a and the second knitted body 12b of this embodiment.

[0031] In the first braided structure 12a and the second braided structure 12b, a smaller number of right-handed twisted threads (holdings) or left-handed twisted threads (holdings) that make up one stitch is preferable in order to suppress the formation of gaps between threads and prevent exposure of the conductor 11. Preferably, the holdings are 2 or less for each, and more preferably 1 for each.

[0032] The number of stitches (count) formed in the first braid 12a within a section that encircles the first conductor 11a, and the number of stitches (count) formed in the second braid 12b during a section that encircles the second conductor 11b, vary depending on the size of the first conductor 11a and the second conductor 11b, but are, for example, between 4 and 20. The count of stitches in the first braid 12a and the second braid 12b may be 16 or less, or 12 or less.

[0033] The rotation pitch of the right-handed or left-handed spinning threads on the first detection line 10a (the distance traveled while making one rotation around the first conductor 11a) can be, for example, 4 mm or more and 20 mm or less. Similarly, the rotation pitch of the right-handed or left-handed spinning threads on the second detection line 10b (the distance traveled while making one rotation around the second conductor) can be, for example, 4 mm or more and 20 mm or less. The rotation pitch may be 5 mm or more, 6 mm or more, or 7 mm or more. The rotation pitch may be 18 mm or less, 16 mm or less, or 14 mm or less.

[0034] The conductor diameters (Dc) of the first conductor 11a and the second conductor 11b may be the same or different, and may be, for example, 0.20 mm or more and 1.00 mm or less, respectively. The conductor diameters (Dc) of the first conductor 11a and the second conductor 11b may be 0.25 mm or more, or 0.30 mm or more. The conductor diameters (Dc) of the first conductor 11a and the second conductor 11b may be 0.80 mm or less, or 0.60 mm or less.

[0035] The first conductor 11a and the second conductor 11b may be single wires, but it is preferable that they be stranded wires. The first conductor 11a and the second conductor 11b may have, for example, a nominal cross-sectional area of ​​0.024 mm². 2 0.5mm or more 2 The following stranded wires may also be used. The nominal cross-sectional area of ​​the first conductor 11a and the second conductor 11b is 0.035 mm². 2 It may be greater than or equal to 0.05 mm 2 The above is also acceptable. The nominal cross-sectional area of ​​the first conductor 11a and the second conductor 11b is 0.3 mm². 2 The following may also be acceptable: 0.2 mm 2 Even if it is less than 0.15mm, it is still acceptable. 2 The following is also acceptable.

[0036] When the first conductor 11a and the second conductor 11b are stranded wires, they may be bundled stranded conductors or concentric stranded conductors. When the first conductor 11a and the second conductor 11b are stranded wires, the stranding pitch of the outermost strands in the radial direction is, for example, 3 mm or more and 50 mm or less. The stranding pitch may be 4 mm or more, or 5 mm or more. The stranding pitch may be 30 mm or less, 20 mm or less, or 15 mm or less.

[0037] The first conductor 11a and the second conductor 11b are preferably made of soft copper wire. The soft copper wire may be tin-plated soft copper wire, or it may be unplated.

[0038] In the braided structure 12, the thicker first thread 121 (right-handed twisted in the first detection line 10a) has higher rigidity than the thinner second thread 122 (left-handed twisted in the first detection line 10a), and the thicker thread has higher resistance to twisting in the direction that tightens (clockwise in the first detection line 10a). When the first conductor 11a and the second conductor 11b are stranded wires, by setting the twist direction of the outermost strands to be opposite to the twisting direction of the first thread 121 (counterclockwise in the first detection line 10a: S-twist), it is possible to suppress the unraveling of the twist and the strands from sticking out of the braided structure 12. On the other hand, in the braided structure 12, the thinner second thread 122 (left-handed twisted in the first detection line 10a) has better conformability to the surface of the conductor 11 than the thicker first thread 121 (right-handed twisted in the first detection line 10a). When the first conductor 11a and the second conductor 11b are made of stranded wire, by setting the twisting direction of the outermost strands to be opposite to the twisting direction of the second thread 122 (clockwise for the first detection wire 10a: Z-twist), it is expected that the tip of the broken strand will not protrude from the braided body 12 if a break occurs in the strand.

[0039] It is preferable that the first braid 12a and the second braid 12b cover the first conductor 11a and the second conductor 11b in such a way that the following inequality (1) is satisfied.

[0040] Length occupancy rate ≤ 45% ···(1) Length occupancy = {(Wn1 × Cn1 × D1) / P1 + (Wn2 × Cn2 × D2) / P2} × 100% Wn1 = number of threads of the first thread, Wn2 = number of threads of the second thread, Cn1 = number of beats of the first thread, Cn2 = number of beats of the second thread, D1 = diameter of the first thread (mm), D2 = diameter of the second thread (mm), P1 = circumferential pitch (mm) of the first thread (thick thread) in the length direction of the detection line, P2 = circumferential pitch (mm) of the second thread (thin thread) in the length direction of the detection line Regarding the circumferential pitch (P1) of the first thread 121 and the circumferential pitch (P2) of the second thread 122, taking the length direction of the first detection line 10a or the second detection line 10b as the traveling direction, the length (detection line length) advanced until the right-handed thread or the left-handed thread makes a predetermined number of turns (for example, 10 turns) around the conductor 11 can be measured, and the length can be obtained by dividing the length by the number of turns.

[0041] The length occupancy ratio obtained from the above formula may be 43% or less, may be 41% or less, may be 39% or less, may be 37% or less, or may be 35% or less. The length occupancy ratio may be, for example, 10% or more. The length occupancy ratio may be 12% or more, may be 15% or more, or may be 18% or more.

[0042] The first braided body 12a and the second braided body 12b are the exclusive area of the braided body 12 in the cross-section in the plane orthogonal to the length direction of the first detection line 10a and the second detection line 10b (π·(Di 2 -Dc 2 ) / 4), and the cross-sectional area occupancy ratio obtained as the area ratio of the thread is preferably 30% or more and 50% or less. The cross-sectional area occupancy ratio may be 32% or more, may be 33% or more, may be 34% or more, or may be 35% or more. The cross-sectional area occupancy ratio may be 48% or less, may be 46% or less, may be 44% or less, or may be 40% or less.

[0043] The cross-sectional area occupancy ratio is calculated and obtained by the following formula (2).

[0044] Cross-sectional area occupancy (%)={(ΣS1+ΣS2) / (Si-Sc)}×100 ΣS1: Cross-sectional area of ​​the first thread (thick thread) (π·D1 2 ( / 4) × Number of first threads (thick threads) in the detection line cross-section ΣS2: Cross-sectional area of ​​the second thread (thin thread) (π·D2) 2 ( / 4) × Number of second threads (thin threads) in the detection line cross-section Si: Theoretical cross-sectional area of ​​the detection line (= {(π × Di 2 ) / 4}) Di: Theoretical diameter of the detection wire (= conductor diameter + diameter of the first thread (thick thread) (D1) × 2 + diameter of the second thread (thin thread) (D2) × 2) Sc: Conductor cross-sectional area (= {(π × Dc 2 ) / 4}) Dc: Conductor diameter The outer braided body 20 covering the first detection line 10a and the second detection line 10b can be made of, for example, glass fiber yarn, basalt fiber yarn, aramid fiber yarn, polyester fiber yarn, or the like.

[0045] The leak detection line 100 of this embodiment can be used to detect not only water but also aqueous solutions and highly conductive organic solvents. The liquid to be detected is 1 × 10⁻⁶ at room temperature (e.g., 25°C). -3 A conductivity of 1 × 10⁻¹⁰ (μS / cm) or higher is preferred. The conductivity of the liquid to be detected at room temperature (e.g., 25°C) is 1 × 10⁻¹⁰. -2 It may be greater than (μS / cm), and 1 × 10 -1 The concentration may be greater than or equal to (μS / cm), or greater than or equal to 1 (μS / cm). Specific examples of liquids suitable for detection include, for example, water; acidic solutions such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid; alkaline aqueous solutions such as ammonia and sodium hydroxide; and hydrophilic organic solvents such as methyl alcohol, ethyl alcohol, acetone, propylene glycol, and ethylene glycol.

[0046] The leak detection wire 100 of this embodiment is useful for detecting leaks in equipment with significant space constraints, such as water-cooled data servers. However, its applications are not particularly limited and can be used for detecting leaks in pipes, fittings, valves, etc., in general equipment, as well as in detecting leaks in heat exchangers, tanks, etc. In other words, the disclosure of the leak detection wire 100 in this embodiment is limited, and the leak detection wire 100 of the present invention is not limited in any way to the above examples.

[0047] Furthermore, this specification includes the following disclosures regarding the invention of the leak detection wire. [1] The device comprises multiple detection wires, each consisting of a conductor and a braided structure covering the conductor. The plurality of detection lines include a first detection line and a second detection line, The aforementioned braided body is made of electrically insulating threads, and the leak detection wire detects the liquid by electrically connecting the conductor of the first detection wire and the conductor of the second detection wire through the braided body, The braided body of one or both of the first detection line and the second detection line is A leak detection wire comprising a first thread and a second thread that intersects the first thread, wherein the second thread is thinner than the first thread. [2] The first thread is a monofilament or multifilament thread with a diameter of 0.2 mm or more and 0.3 mm or less. The leak detection wire described in [1], wherein the second thread is a monofilament thread or multifilament thread having a diameter of 0.05 mm or more and less than 0.2 mm. [3] A leak detection line according to [2], wherein the number of first threads in the braided body is 1 and the number of second threads is 1. [4] Leak detection wires as described in any of the items [1] to [3], wherein one or both of the first detection wire and the second detection wire are leak detection wires as described in any of the items [1] to [3], wherein the conductor is covered with the braided material such that the following inequality (1) is satisfied.

[0048] Length occupancy rate ≤ 45% ···(1) Length occupancy = {(Wn1×Cn1×D1) / P1+(Wn2×Cn2×D2) / P2}×100% Wn1 = number of first threads, Wn2 = number of second threads, Cn1 = number of beats in the first thread, Cn2 = number of beats in the second thread, D1 = diameter of the first thread (mm), D2 = diameter of the second thread (mm) P1 = Circumference pitch of the first thread in the longitudinal direction of the detection line (mm), P2 = Circumference pitch of the second thread in the longitudinal direction of the detection line (mm) [Examples]

[0049] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. (Comparative Example 1 (Conventional Example)) As shown in Table 1, a leak detection wire of Comparative Example 1 (conventional example) was fabricated by braiding the first detection wire and the second detection wire together with basalt yarn, and then incorporating the braided outer structure made of basalt yarn.

[0050] The first detection line and the second detection line were designed to have the same structure.

[0051] Each conductor used a stranded wire (with a stranding pitch of 6 mm) made by twisting together seven strands of tin-plated soft copper wire, each with a thickness of 0.127 mm.

[0052] The conductor was braided with 0.25mm thick monofilament yarn.

[0053] The braided structure was constructed so that the right-handed and left-handed twisted threads each had a count of 1 and a count of 4, with a circumference pitch of 10 mm for each thread.

[0054] The leak detection wire in this comparative example 1 had a thickness (theoretical diameter) of 1.76 mm. The length occupancy rate and cross-sectional area occupancy rate were calculated using the following formulas and were found to be 20.0% (length occupancy rate) and 19.8% (cross-sectional area occupancy rate), respectively. • Length occupancy rate = {(Number of right-handed spines held: 1 × Number of right-handed spines twisted: 4 × Right-handed spine diameter: 0.25) / Pitch: 10 + (Number of left-handed spines held: 1 × Number of left-handed spines twisted: 4 × Left-handed spine diameter: 0.25) / Pitch: 10} × 100 (%) ·Cross-sectional area occupancy = {right-handed thread cross-sectional area (π · 0.25 2 / 4) × Number of right-handed spinning strokes 4 + Cross-sectional area of ​​left-handed spinning (π·0.25 2 / 4) × Number of left-handed spinning strands 4} / [Detection line theoretical cross-sectional area {π × (conductor diameter 0.76 + right-handed spinning diameter 0.25 × 2 + left-handed spinning diameter 0.25 × 2) 2 / 4}-Conductor cross-sectional area (π × Conductor diameter 0.76 2 / 4)] × 100 (%) (evaluation) The leak detection line of Comparative Example 1 was evaluated for its leak detection capability, flexibility, and ease of recovery after leak detection.

[0055] The specific evaluation method is as follows. The evaluation results are shown in Table 1. (Detectability) A leak detection wire was held approximately horizontally in the air, and water with a conductivity of 100.0 μS / cm was dripped from a position 1 cm directly above it, maintaining a roughly constant dripping interval. The water was dripped at a rate of 0.6 ml per minute. The number of drops until the resistance between the detection wires fell below 100 kΩ was measured. The test was performed with 10 leak detection wires, and the average number of drops was determined. (flexibility) Six leak detection wires were used as measurement samples. Each leak detection wire was bent 180° and straightened 100 times. After this bending and straightening, two detection wires were taken out and observed, and the number of places where the conductor protruded from the braided material was counted. The total number for all 12 detection wires was then calculated. (Recoverability) The detection performance was evaluated, and moisture was wiped off the leak detection wires where the resistance between the detection wires fell below 100kΩ. It was then checked whether the resistance value recovered after wiping off the moisture. A "○" rating was given if the resistance value recovered, and a "×" rating was given if it did not. (Comparative Examples 2-4) A leak detection wire was fabricated in the same manner as in Comparative Example 1, except that the thickness of the right-handed and left-handed spirals was reduced from 0.25 mm to 0.15 mm, and a braided body with the circumferential pitch shown in Table 1 was provided. The same evaluation as in Comparative Example 1 was performed. The evaluation results are shown in Table 1.

[0056] The results in Table 1 show that simply making the threads that make up the braided structure thinner makes it easier for the conductors to pop out, which can lead to false detections. (Comparative Examples 5-8) Except for reducing the thickness of the right-handed and left-handed twisted threads from 0.25 mm to 0.15 mm, increasing the number of twists in the right-handed and left-handed twisted threads from 4 to 8, and creating a braided body with a circular pitch as shown in Table 1, a leak detection wire was fabricated in the same manner as in Comparative Example 1, and the same evaluation as in Comparative Example 1 was performed. The evaluation results are shown in Table 1.

[0057] The results in Table 1 show that while thinner threads and increased bends can suppress conductor protrusion to some extent, simply doubling the bends is insufficient to adequately suppress conductor protrusion. (Comparative Examples 9-11) Except for reducing the thickness of the right-handed and left-handed twisted threads from 0.25 mm to 0.15 mm, increasing the number of twists in the right-handed and left-handed twisted threads from 4 to 12, and creating a braided body with a circular pitch as shown in Table 1, a leak detection wire was fabricated in the same manner as in Comparative Example 1, and the same evaluation as in Comparative Example 1 was performed. The evaluation results are shown in Table 1.

[0058] The results in Table 1 show that by tripling the number of dots compared to Comparative Examples 1-4, as in Comparative Examples 9-11, conductor protrusion can be suppressed even more effectively than in Comparative Examples 5-8, where the number of dots was doubled. Furthermore, the results in Table 1 also show that tripling the number of dots simultaneously significantly reduces detectability. (Examples 1-3) Except for reducing the thickness of only the left-handed twisted thread from 0.25 mm to 0.15 mm, and increasing the number of strands in both the right-handed and left-handed twisted threads from 4 to 12, a leak detection wire was fabricated in the same manner as in Comparative Example 1, and the same evaluation was performed as in Comparative Example 1. The evaluation results are shown in Table 2.

[0059] The results in Table 2 show that by making one of the threads thinner, although the detectability is slightly worse than in Comparative Example 1, the conductor protrusion is greatly improved, and it is possible to achieve both high detectability and suppression of false detections. (Examples 4-6, Comparative Examples 12-14) The leak detection wires were fabricated so that the first and second detection wires were simply placed side-by-side without being twisted together and housed in the external braided structure, and the same evaluation as before was performed. The results are shown in Table 3.

[0060] Table 3 shows that by varying the thickness of the threads, the same effect as shown in Table 2 can be observed even when the first and second detection lines are not twisted together.

[0061] Furthermore, the results in Tables 1-3 show that adjusting the length occupancy rate and cross-sectional area occupancy rate to predetermined values ​​is advantageous in significantly enhancing the effect.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] From the above, it can be seen that the present invention provides a leak detection line that can suppress false detections while suppressing a significant decrease in leak detection performance. [Explanation of Symbols]

[0066] 10: Detection lines (10a: First detection line, 10b: Second detection line) 11: Conductor (11a: First conductor, 11b: Second conductor), 12, braided body (12a: first braided body, 12b: second braided body), 121: First thread, 122: Second thread, 20: External braided body, 100: Leak detection line, DD: Radial direction (of the leak detection line), DL: Length direction (of the leak detection line)

Claims

1. The device comprises multiple detection wires, each consisting of a conductor and a braided structure covering the conductor. The plurality of detection lines include a first detection line and a second detection line, The aforementioned braided body is made of electrically insulating threads, and the leak detection wire detects the liquid by electrically connecting the conductor of the first detection wire and the conductor of the second detection wire through the braided body, The braided body of one or both of the first detection line and the second detection line is A leak detection wire comprising a first thread and a second thread that intersects the first thread, wherein the second thread is thinner than the first thread.

2. The first thread is a monofilament or multifilament thread with a diameter of 0.2 mm or more and 0.3 mm or less. The leak detection wire according to claim 1, wherein the second thread is a monofilament thread or multifilament thread having a diameter of 0.05 mm or more and less than 0.2 mm.

3. The leak detection wire according to claim 2, wherein the number of first threads in the braided body is 1 and the number of second threads is 1.

4. A leak detection wire according to any one of claims 1 to 3, wherein one or both of the first detection wire and the second detection wire are covered with the braided material such that the conductor satisfies the following inequality (1). Length occupancy rate ≤ 45% ... (1) Length occupancy rate = {(Wn1×Cn1×D1) / P1+(Wn2×Cn2×D2) / P2}×100% Wn1 = number of first threads, Wn2 = number of second threads, Cn1 = number of beats of the first thread, Cn2 = number of beats of the second thread, D1 = diameter of the first thread (mm), D2 = diameter of the second thread (mm) P1 = Circumference pitch of the first thread in the longitudinal direction of the detection line (mm), P2 = Circumference pitch of the second thread in the longitudinal direction of the detection line (mm)

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