JP2931613B2 - Water leak detection sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a water leakage detection sensor for protecting electronic computers and various electric equipment in buildings such as buildings and factories from leakage and damage caused by a conductive liquid. About.

SUMMARY OF THE INVENTION The present invention provides a full-surface insulating / full-surface detection type water leakage detection sensor which is highly sensitive but does not cause malfunction due to moisture absorption such as dew condensation or high humidity environmental conditions.

[Prior Art and its Problems] FIGS. 2 to 4 show a conventional leak detection sensor.
FIG. 2 shows an example in which the water leakage detection sensor (S-1F) of our company extrudes the parallel conductor plate 2 as a core material together with an insulating coating material 3 such as soft PVC, and forms a plurality of electrode exposed portions 10. This sensor (S-1F) has the advantage of excellent mechanical properties because it is a molded product, and has the advantage that the insulation between the electrodes is kept constant. On the contrary, the sensor (S-1F) has a structure in which the electrodes are partially exposed. There was a problem in the insulation with the equipment and the stability of the detection characteristics. Fig. 3 also shows our leak detection sensor (B-3P), which is an external electrode type and the electrode 101 is exposed outside, so it cannot be laid directly on a conductor. In this case, insulation treatment is performed. Need arises.

FIG. 4 shows a leak detection sensor (A) of another company according to Japanese Utility Model Publication No. Sho 62-45388, in which the braid density is 50 to 95% and the thickness is 0.3 to 0.6 mm by the insulating yarn (polyethylene) of the conductor 102. Two cores covered and insulated with a braid 103 are twisted together, and a protective braid 104 is further applied on top of this. The whole surface is detected and the whole surface is insulated. The layer is composed of a braid and the braid density is 50-95
%, It easily absorbs moisture under high-humidity environmental conditions or under dew condensation or the like, and is liable to cause false reports, and is inferior in recoverability after occurrence of water leakage.

[Means for Solving the Problems] In the present invention, as shown in FIG. 1, the parallel conductor plate 2 shown in FIG. Our company's water leak detection sensor (S-1F), which is extruded with the insulating coating material 3 such as soft PVC and has a plurality of electrode exposed portions 10, is used.
By covering the braid 1 with a braid density of 40 ± 20% using an insulating thread (PP, PET, PE, nylon, etc.) of up to 0.6 mmΦ, the mechanical properties of the conventional product and the insulation properties between the electrodes are maintained. In addition, the braided coating provides an overall insulating structure, and the braid absorbs water to form a full-surface detection structure, thereby providing stable detection characteristics. Further, since the braid density is as low as 20 to 40%, malfunctions due to high humidity environment conditions or moisture absorption such as dew condensation hardly occur, and excellent recoverability after water leakage occurs.

Also, the braided coating becomes a spacer between the attached surface and the sensor electrode due to the thickness of the braided yarn, compared to a structure in which the electrode is in direct contact with the sensor attached surface as in the conventional product (S-1F sensor). Therefore, the dew condensation resistance is significantly improved.

When the electrode or the electrode and its braided coating are treated with a surfactant, the detection sensitivity of the sensor can be improved. As a treatment method, the electrode is immersed in a surfactant aqueous solution, pulled up, dried naturally, and then covered with a braid. Alternatively, a method may be used in which the electrode is coated and then immersed in an aqueous surfactant solution and air-dried. The effect of improving the sensitivity by the surfactant is generally lost after the sensor is once connected to water leakage, and the sensitivity is generally reduced when the sensor is used repeatedly without any significant difference depending on the type of the surfactant. Exceptionally, when a fluorine-containing nonionic surfactant is used as a surfactant, it can be used with good sensitivity even if water leak detection is repeated several times.

[Comparison of Characteristics between Example and Conventional Product] Example 1 This example showing the effect of the coating was performed as follows.

The conventional leak detection sensor (S-1F) is replaced by Florad FC-
Immersed in an aqueous solution of 430 (our fluorinated surfactant), lifted up, lightly cut off excess liquid, air-dried immersion-treated product, as it is and a braided product (polypropylene yarn 0.2m
Detection sensitivity characteristics test and dew condensation resistance characteristics of sensors coated with three types of braids with braid densities of 20%, 40%, and 80%, respectively, using mΦ, and conventional product A (without surfactant treatment) Was done.

 The test results are shown in the table.

From the evaluation results (Table 1), S-1F
The sensor requires more than 6.3ml of water to detect water leakage, and is less sensitive than other sensors (3.47ml-6.00ml). Regarding the anti-condensation property, the conventional product of another company (A), S-1F +
Since the braid density of both PP braids with a density of 80% is high, the dew condensation lowers the interelectrode resistance in the false alarm occurrence area (500 KΩ or less).

Regarding the anti-condensation characteristics, those with a structure in which the electrode is in direct contact with the installation surface, such as the conventional product (S-1F sensor),
Water droplets formed by condensation tend to lower the insulation resistance between the electrodes.

On the other hand, the sensor (the present invention) having a structure in which a spacer effect is provided from the laying surface by a braided wire of 0.2 mmΦ (the present invention) is hardly affected by water droplets due to dew condensation, and exhibits significantly improved dew condensation resistance.

Reference Example 1 The effect of the surfactant treatment on the water leakage detection sensor was examined.
Our conventional leak detection sensor (S-1F) was immersed in aqueous solutions of various surfactants and pulled up to remove excess liquid and air-dried. With respect to this sensor, a detection sensitivity characteristic test and durability of a surfactant treatment to water were examined. Table 2 shows the results.

As a result, it was confirmed that only Florard FC-430 within the range was persistent in the effect of improving water leak detection sensitivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view and an end view of an embodiment of a water leak detection sensor according to the present invention, FIG. 2 is a plan view and an end view of a conventional water leak detection sensor, and FIG. FIG. 4 is a plan view and an end view of another conventional water leak detection sensor. [Description of Signs] 1,103: Insulated braid 2,101,102: Conductor to be an electrode 3: Insulating coating material 104: Protective braid 10: Electrode exposed portion

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-201042 (JP, A) JP-A-1-146138 (JP, A) Jiko 62-45388 (JP, Y2) (58) Survey Field (Int.Cl. ⁶ , DB name) G01M 3/16 H01B 7/32 G01N 27/07

Claims (2)

(57) [Claims] 1. A pair of parallel conductors are coated by extruding an insulating material by extrusion molding and exposing outer ends of the conductors at a plurality of locations to form electrodes. The outer circumference of the conductors has a wire diameter of 0.1 mm to 0.6 mm.
A water leakage detection sensor characterized in that the insulation yarn is braided so as to have a single layer of braid density of 20 to 40%. 2. The water leakage detection sensor according to claim 1, wherein the electrode or the electrode and its coating are treated with a fluorine-containing nonionic surfactant.