JPH0571743U - Leak detection line - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a liquid leakage detection line that has no risk of malfunction and has a small temperature dependence. In a liquid leakage detection line in which a pair of electrode wires 3 and 3 are arranged substantially parallel to each other and an outer braid layer 4 and an outer braid layer 5 are sequentially covered on the outer periphery thereof, the electrode wire 3 is on a conductor 1. A thermoplastic polyester elastomer extruded and coated as the insulator 2, and the inner braid layer 4 includes a group of non-liquid-soluble and non-liquid-absorbent threads, and a group of liquid-soluble and liquid-absorbent threads. And the outer braid layer 5 is made of a liquid-soluble, liquid-absorbent and weather-resistant yarn.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a leak detection line that detects when a pipeline or a storage tank that transports liquid such as sulfuric acid or caustic soda is damaged.

[0002]

[Prior Art]

 The applicant of the present invention was able to detect a leak over a wide range by previously installing it in a pipeline or a storage tank that transports liquids such as sulfuric acid and caustic soda, and the leak detection time. We proposed a leak detection line with very little variation in the above (Actual Application No. 2-102880). This liquid leakage detection line consists of a pair of enameled wires coated with polyester resin as an insulator on the conductor as electrode lines and arranged in parallel with each other, and consists of a non-liquid-soluble, non-liquid-absorbing thread on the outer circumference. A group and alternating groups of liquid-soluble and absorbent yarns and an outer-braid layer of liquid-soluble, absorbent and weather-resistant yarn It consists of

In this leak detection line, when a leak of sulfuric acid or the like occurs, first the liquid-soluble and liquid-absorbent yarns of the outer braid layer absorb it, and then the liquid-soluble of the inner braid layer. The liquid-absorbent yarn further absorbs this, the non-liquid-soluble, non-liquid-absorbent yarn of the braid layer holds it, and the sulfuric acid that permeates through the braid layer dissolves the insulator, The pair of conductors of the electrode wire is short-circuited or close to a short-circuit. Therefore, the leakage can be detected by measuring the insulation resistance between the conductor and the one end of the leakage detection line. Even if normal water enters the leak detection line due to rainfall or the like, malfunction does not occur because the insulator layer does not dissolve.

[0004]

[Problems to be solved by the device]

 However, in the above-mentioned conventional liquid leakage detection wire, the insulator of the electrode wire is formed by so-called enamel coating by coating and baking polyester resin, so the pressure and pulling force applied to the electrode wire during the manufacturing process and laying work. Crazing or cracking may occur due to the stress generated in the insulator due to external force such as bending. Therefore, in order to prevent excessive external force from acting on the leak detection line during the manufacturing process and installation work, a high degree of caution was required for its management. However, its attention is limited, and there is a problem in that the leak detection line may malfunction if rainfall or other inevitable cracks penetrate. Further, the leak detection line of the enamel coating has a problem that the detection time of sulfuric acid or the like has a large temperature dependency, and particularly when the temperature is 15 ° C. or less, the detection time becomes drastically long.

The present invention has been made in view of the above problems of the conventional technology. The purpose of the present invention is to further improve the previously proposed liquid leakage detection line to prevent malfunction. It is to provide a leak detection line that has no temperature dependence and has little temperature dependence.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the liquid leakage detection line in the present invention is a liquid leakage detection line formed by arranging a pair of electrode wires substantially parallel to each other and coating an outer braid layer and an inner braid layer in order on the outer periphery thereof. , The electrode wire is formed by extrusion coating a polyester thermoplastic elastomer as an insulator on the conductor, and the inner braid layer is a group consisting of non-liquid-soluble and non-liquid-absorbing threads, and liquid-soluble and liquid-absorbing And the outer braid layer is made of a liquid-soluble, liquid-absorbent, weather-resistant yarn. Here, in the thermoplastic polyester-based elastomer (hereinafter referred to as polyester elastomer), the hard segment is made of polyester, and the soft segment is polyether-based or polyester-based. For the hard segment of polyester and the soft segment of polyether, "Hytrel" (trade name of Toray-Dupont Co., Ltd.), "Perprene-P" (trade name of Toyobo Co., Ltd.), "Lomod" (Product name of Akzo Co., Ltd.). Examples of those in which the hard segment is polyester and the soft segment is polyester include "Perprene-S" (trade name of Toyobo Co., Ltd.) and "ARINTEL-S" (trade name of Akzo).

[0007]

[Effect] In the liquid leakage detection wire having the above-mentioned structure, the polyester elastomer forming the insulator of the electrode wire has a particularly high mechanical strength, rubber elasticity, flex fatigue resistance, and crack propagation in a wide operating temperature range from low temperature to high temperature. Since it has excellent resistance, there is no risk of pinholes, crazing, etc. occurring due to external force such as pressure, tensile force, bending, etc. applied to the electrode wire in the manufacturing process or laying process or as one of the factors. Moreover, the temperature dependence of the detection time is low for the detection target liquid such as sulfuric acid. In addition, since the inner braid is configured by alternately arranging groups of non-liquid-soluble and non-liquid-absorbing yarns and groups of liquid-soluble and liquid-absorbing yarns, liquid leakage may cause liquid leakage. The group of soluble, liquid-absorbent threads dissolves quickly to ensure a path for leakage to the insulator, while the group of non-liquid-soluble, non-liquid-absorbent threads neither dissolves nor absorbs liquids. Leakage liquid that dissolves soluble and liquid-absorbent threads is prevented from diffusing to the surroundings and held until the insulator is dissolved, which reduces variations in liquid leakage detection time. In addition, the outer braid is liquid-soluble and absorbs liquid efficiently to guide the leak to the inside of the detection line, and since it has excellent weather resistance, it is suppressed from changing over time due to weather and the like, and the above predetermined operation is prevented. Hold constant.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a leak detection line of the present invention, and FIG. 2 is a structural diagram of a braid.

In FIG. 1, 1 is a conductor having a circular cross section, 2 is an insulator coated on the conductor 1, and an electrode wire 3 is formed from these, and a pair of electrode wires 3 and 3 are made substantially parallel. Arranged (may be twisted). Reference numeral 4 denotes an inner braid covering the outer circumferences of the pair of electrode wires 3 and 3, and 5 denotes an outer braid.

As the insulator 2, any of the above polyester elastomers is used. Then, as the non-liquid-soluble and non-liquid-absorbing thread which constitutes the inner braided body 4, for example, a monofilament-like thread made of fibers such as polyethylene and polypropylene is suitable. Further, as the liquid-soluble and liquid-absorbent yarn which is used in combination with the non-liquid-soluble and non-liquid-absorbent yarn, for example, a multifilament yarn made of fibers such as polyester and tetron is suitable. FIG. 2 shows a braid example of a group of non-liquid-soluble and non-liquid-absorbing yarns 4a and a group of liquid-soluble and liquid-absorbing yarns 4b. The group of yarns refers to one yarn or a plurality of yarns gathered into one yarn, which is fed from one supply reel when braiding. In the illustrated example, the left-handed yarn and the right-handed yarn are arranged alternately with two monofilament-shaped yarns 4a (white) and eight-strokes and two multi-filament-shaped yarns 4b (black) and two-held yarns. The inner braid 4 is shown as a total of 32 shots. The outer braid 5 has a mechanical protection function such as relieving the pressure applied to the insulator 2 of the electrode wire 3 via the inner braid 4 at the binding portion or the like. As the liquid-soluble, liquid-absorbent, and weather-resistant yarn forming the outer braid 5, a black multifilament yarn made of, for example, polyester fiber is preferable.

When a leak of sulfuric acid or caustic soda occurs, the liquid-absorbent and liquid-soluble outer braid layer 5 first absorbs it, and when this leak touches the inner braid layer 4, the leak liquid is multi-layered. The filament 4b is absorbed into the filament yarn 4b, and the multifilament yarn 4b is melted. However, since the monofilament-shaped thread 4a remains in the lattice shape, the leakage of the multifilament-shaped thread 4b dissolves the insulator 2 while being held by the lattice. The monofilament-shaped yarn 4a of the inner braid 4 described above is held. In particular, since the outer braid 5 has weather resistance due to black color, the outer braid 5 absorbs sunlight such as ultraviolet rays, and the inner braid 4 is particularly non-liquid-soluble and non-liquid-absorbing yarn. 4 A change over time is prevented. Further, at the liquid leakage site, the black outer braid 5 and the group of the liquid-soluble and liquid-absorbent yarns 4b of the inner braid 4 are dissolved, and the non-liquid-soluble and non-liquid-absorbent of the inner braid 4 is dissolved. Since only the group 4a of white threads remains, the white color of the non-liquid soluble / non-absorptive thread 4a remaining at the leakage point can be clearly seen in the black color of the outer braid 5 around the leakage point. It is easy to find the leak point.

Next, the results of measuring the leak detection performance with respect to sulfuric acid in the invention examples A and B and the comparative examples A and B described below will be described. The specific structures of the invention examples A and B and the comparative examples A and B are shown in Table 1. In particular, the difference between the present invention examples A and B and the comparative examples A and B is that in the present invention example A, Hytrel which is extrusion-coated to a thickness of 40 μm is used as the insulator, and in the present invention example B, the insulator is made of perprene. -S is used as an extruded coating having a thickness of 40 µm, whereas in Comparative Examples A and B, a terephthalic acid polyhydric alcohol varnish is applied and baked at a thickness of 45 µm (so-called enamel coating). Is the point. Further, in Examples A and B of the present invention and Comparative Example A, a group of non-liquid-soluble and non-liquid-absorbent threads and a group of liquid-soluble and liquid-absorbent threads are alternately arranged on the inner braid layer. In contrast to Comparative Example B, the inner braid layer is made of only liquid-soluble and liquid-absorbent yarns.

[0013]

[Table 1]

Regarding the invention examples A and B and the comparative examples A and B described above, as shown in FIG. 3, the detection sample 11 having a length of about 1 m is placed on the pad 12, and the conductors on the electrode wires at both ends are placed. It was exposed, and a 5 kilohm resistor 13 was connected to one end with a clip 14, and a leak detector 15 with a recorder 16 was connected to the other end with a clip 14. The liquid leakage detector 15 converts the current flowing by the voltage application into a DC voltage by a circuit resistance or a rectifier circuit inserted in the voltage application circuit, for example, an AC power supply that applies an AC voltage between the electrode wires, and a reference voltage value. In comparison with, the recorder 16 detects the occurrence of an abnormal current, and the recorder 16 records the change in the DC voltage. Then, the detection sample 11 is placed in a temperature-controlled room where the temperature can be set to a predetermined temperature, a buret 17 is installed in the upper middle of the room, and sulfuric acid with a concentration of 98% is dropped at a rate of 0.02 ml / sec. The time (minutes) required to reach was measured.

The results of Invention Examples A and B and Comparative Examples A and B are shown in Table 3 and FIG. In particular, in the low temperature range of 15 ° C. or lower, Comparative Examples A and B show a tendency for the detection time to increase sharply, but Invention Examples A and B do not increase so much in the low temperature range. In addition, Comparative Example B, which uses only liquid-soluble and liquid-absorbent yarns in the braid layer, has a large standard deviation, but even when compared at the same detection time, Examples A and B of the present invention show a standard deviation. It can be seen that the variation is small.

[0016]

[Table 2]

[0017]

[Effect of the device]

 The leak detection wire of the present invention is one in which the electrode wire is formed by extrusion coating a polyester elastomer on the conductor as an insulator, and this polyester elastomer has mechanical strength and rubber elasticity in a wide operating temperature range from low temperature to high temperature. Since it has excellent bending fatigue resistance and crack propagation resistance, there is no risk of pinholes, crazing, etc. due to external forces such as pressure applied to the electrode wire, tensile force, and bending during the manufacturing process and laying process. Therefore, there is no risk of malfunction due to rainfall or the like. In addition, since the detection time is less dependent on the temperature of the liquid to be detected, such as sulfuric acid, and it is an insulator, it is possible to detect liquid leakage in a short time even at low temperatures. Furthermore, the internal coating layer and the external coating layer with a specific structure provide less variation in the liquid leakage detection time and excellent weather resistance.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid leakage detection line of the present invention.

FIG. 2 is a structural diagram of a braided body.

FIG. 3 is a diagram showing a device for inspecting a leak detection line.

FIG. 4 is a graph showing the temperature dependence of the detection time on the leak detection line.

[Explanation of symbols]

 1 Conductor 2 Insulator (Polyester Elastomer) 3 Electrode Wire 4 Inner Braid Layer 4a Non-Liquid Soluble Non-Liquid Thread 4b Liquid Soluble and Absorbent Thread 5 External Braid Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadaaki Masui, 2-3-1, Iwata-cho, Higashi-Osaka City, Osaka Prefecture Tatsuta Electric Wire Co., Ltd. 2-3-1, Tatsuta Electric Cable Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A liquid leakage detection line comprising a pair of electrode wires arranged substantially parallel to each other and an outer braid layer and an outer braid layer being sequentially covered on the outer periphery of the electrode wire. Made by extrusion coating a thermoplastic elastomer
A group of inner braid layers composed of non-liquid-soluble, non-liquid-absorbent yarns,
A leak detection line, characterized in that groups of liquid-soluble and liquid-absorbent yarns are alternately arranged, and the outer braid layer is made of liquid-soluble, liquid-absorbent and weather-resistant yarns.