JPH0571742U - 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. A leak detection line in which a pair of electrode wires 3 and 3 are arranged substantially parallel to each other and a braid layer 4 is coated on the outer circumference thereof,
The electrode wire 3 is formed by extrusion-coating a polyester-based thermoplastic elastomer as the insulator 2 on the conductor 1, the braid layer 4 is a group of non-liquid-soluble, non-liquid-absorbing and weather-resistant yarns, and a liquid-soluble A group of liquid-absorbent and weather-resistant yarns is alternately arranged.

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 have proposed a leak detection line with extremely small variation (Actual application No. 2-102881). The liquid leakage detection line consists of a pair of enameled wires coated with a polyester resin as an insulator on the conductor and as electrode lines, arranged approximately parallel to each other, and is surrounded by a non-liquid-soluble, non-liquid-absorbing, weather-resistant wire. The braid layers are provided by alternately arranging groups of yarns and groups of liquid-soluble, liquid-absorbing and weather-resistant yarns.

In this liquid leak detection line, when liquid leak such as sulfuric acid occurs, the liquid-soluble and liquid-absorbent yarn of the braid layer absorbs the liquid, and the liquid-soluble and non-liquid-absorbent layer of the braid layer is absorbed. The yarn holds this, and sulfuric acid or the like that permeates through the braid layer dissolves the insulator, resulting in a short circuit or a state close to a short circuit between the pair of conductors of the electrode wire. 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, 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 in which a pair of electrode wires are arranged substantially parallel to each other and a braid layer is coated on the outer periphery of the electrode wire. A polyester-based thermoplastic elastomer as an insulator is extrusion coated on the braid, and the braid layer is a group of non-liquid-soluble, non-liquid-absorbing and weather-resistant yarns, and liquid-soluble, liquid-absorbing and weather-resistant yarns. And groups of are alternately arranged. Here, in the thermoplastic polyester elastomer (hereinafter referred to as polyester elastomer), the hard segment is made of polyester, and the soft segment is polyether or polyester. As 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.), Lo mod ”(trade name of Akzo). 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]

[Action]

 In the leak detection wire with the above configuration, the polyester elastomer that forms the insulator of the electrode wire is particularly excellent in mechanical strength, rubber elasticity, flex fatigue resistance, and crack propagation resistance in a wide operating temperature range from low temperature to high temperature. As a result, there is no risk of pinholes, crazing, etc. occurring due to external forces such as pressure, tensile force, and bending applied to the electrode wire during the manufacturing process and laying process. In addition, the temperature dependence of the detection time is low for the detection target liquid such as sulfuric acid. In addition, since the braid is composed of groups of non-liquid-soluble and non-liquid-absorbing yarns and groups of liquid-soluble and liquid-absorbing yarns, which are alternately arranged, liquid leakage may cause A group of liquid-soluble, liquid-absorbent threads dissolves quickly to ensure a path for leakage to the insulator, while a group of non-liquid-soluble, non-liquid-absorbent threads neither dissolves nor absorbs. , Leakage liquid that dissolves liquid-soluble and liquid-absorbent threads is prevented from diffusing to the surroundings, and is held until the insulator is dissolved, which reduces variations in the liquid leakage detection time. Further, since the braided body has excellent weather resistance, it is possible to suppress a change with time due to weather or the like, and to keep the above predetermined operation 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 is a braided body covering the outer circumference of the pair of electrode wires 3 and 3.

As the insulator 2, any of the above polyester elastomers is used. Then, as the non-liquid-soluble, non-liquid-absorbing and weather-resistant yarn forming the braided body 4, for example, monofilament-like yarn made of fibers such as polyethylene and polypropylene is suitable. Further, as the liquid-soluble and liquid-absorbent yarns that are used in combination with the non-liquid-soluble, non-liquid-absorbent and weather-resistant yarn, for example, a multifilament yarn made of fibers such as polyester and tetron is suitable. Is. FIG. 2 shows a braid example of a group of non-liquid-soluble, non-liquid-absorbing and weather-resistant yarns 4a and a group of liquid-soluble, liquid-absorbing and weather-resistant yarns 4b. The group of yarns means one yarn that is fed from one supply reel or a plurality of yarns that are gathered into one yarn when braiding. In the example shown in the figure, the left-handed yarn and the right-handed yarn are arranged alternately with two monofilament-shaped yarns 4a and 8 strokes and two multi-filament-shaped yarns 4b and 8 strokes in total, for a total of 32 braids. 4 is shown.

Upon contact with a leak liquid such as sulfuric acid or caustic soda, the leak liquid is absorbed in the multifilament yarn 4b, and the multifilament yarn 4b is melted. However, since the monofilament-shaped yarn 4a remains in the lattice shape, the leaked liquid that dissolves the multifilament-shaped yarn 4b dissolves the insulator 2 while being retained by the lattice. Furthermore, both the monofilament-shaped thread 4a and the multifilament-shaped thread 4b are black and have excellent weather resistance, and there is little change over time.

Next, the results of measuring the leak detection performance with respect to sulfuric acid in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2 described below will be described. Table 1 shows specific structures of Examples 1 and 2 of the present invention and Comparative Examples 1 and 2. In particular, the difference between the present invention examples 1 and 2 and the comparative examples 1 and 2 is that, in the present invention example 1, the one in which Hytrel is extrusion-coated to a thickness of 40 μm is used as the insulator, and in the present invention example 2, the insulator is made of perprene. -S is extruded and coated to a thickness of 40 μm, whereas in Comparative Examples 1 and 2, terephthalic acid polyhydric alcohol varnish is coated and baked to a thickness of 45 μm (so-called enamel coating). That is the point. In addition, in the invention examples 1 and 2 and the comparative example 1, the group consisting of the non-liquid-soluble, non-liquid-absorbing and weather-resistant yarn and the group of liquid-soluble, liquid-absorbing and weather-resistant yarn in the braid layer In contrast to Comparative Example 2, the braid layer is made of only liquid-soluble and liquid-absorbent yarns.

[0013]

[Table 1]

As to the invention examples 1 and 2 and the comparative examples 1 and 2 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 in 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 1 and 2 and Comparative Examples 1 and 2 are shown in Table 3 and FIG. In particular, in the low temperature range of 15 ° C. or lower, Comparative Examples 1 and 2 show a tendency for the detection time to increase sharply, but in Invention Examples 1 and 2, the detection time does not increase so much even in the low temperature range. Further, although the standard deviation showing variation is large in Comparative Example 2 in which only the liquid-soluble and liquid-absorbent yarns are used for the braid layer, the inventions of Examples 1 and 2 show a standard deviation even if they are compared at the same detection time. 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, due to the braided layer having a specific structure, there is little variation in the leak 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]

 DESCRIPTION OF SYMBOLS 1 conductor 2 insulator (polyester elastomer) 3 electrode wire 4 braid layer 4a non-liquid-soluble, non-liquid-absorbing and weather-resistant yarn 4b liquid-soluble, liquid-absorbing and weather-resistant yarn

 ─────────────────────────────────────────────────── ─── 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 a braid layer covering the outer circumference of the electrode wires, wherein the electrode wires are extruded and coated with a thermoplastic polyester elastomer as an insulator on a conductor. The braided layer comprises alternating groups of non-liquid-soluble, non-absorbent, weather-resistant yarns and groups of liquid-soluble, liquid-absorbent, weather-resistant yarns. Liquid leakage detection line.