JPH03235031A - Water leak detector - Google Patents

Abstract

PURPOSE:To obtain a sensor with high sensitivity adapted not to drive erroneously even under the high humidities or by absorption of dew drops etc. by coating a pair of parallel conductors with an insulative material and exposing a plurality of points of an outer end of each conductor to form an electrode. CONSTITUTION:A pair of parallel conductor plates 2 are used as core members. The core members are extruded and molded together with an insulative coating material 3 of soft vinyl chloride or the like. At the same time, a plurality of exposing electrode parts 10 are formed. The obtained body is coated with a mesh 1 of the meshing density of 40+ or -20% using an insulative thread of the diameter of 0.1mm-0.6mmphi. Accordingly, while the mechanical properties and insulative properties between the electrodes are maintained, the totally-insulated structure can be obtained because of the coating mesh. Moreover, the water absorption properties of the mesh makes the sensor able to detect the water at every part of the sensor, thereby realizing stable detecting characteristics. Since the meshing density is as low as 40+ or -20%, the title sensor is hard to erroneously work under the high humidities or when it absorbs dew drops, and is superior in recovering after detecting the leakage of water.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a water leakage detection sensor for protecting electronic computers and various electrical equipment in buildings such as buildings and factories from damage caused by water leakage and conductive liquid in water. Regarding.

The present invention provides a fully insulated, fully-detecting water leakage sensor that is highly sensitive but does not malfunction under high-humidity environmental conditions or due to moisture absorption such as condensation.

[Prior art and its problems 1] A conventional water leak detection sensor is shown in Figs. 2 to 4. Fig. 2 shows a water leakage detection sensor (S-IF) of our company, which is extrusion-molded with a parallel conductor plate 2 as a core material together with an insulating coating material 3 such as soft PVC, and a plurality of exposed electrode parts 10 are formed. Since this sensor (S-IF) is a molded product, it has excellent mechanical properties and has the advantage of maintaining constant insulation between electrodes. There were problems with insulation with equipment and stability of detection characteristics. Figure 3 is also our water leak detection sensor (B-3D).
Since it is an external electrode method and the electrode 101 is exposed to the outside, it cannot be laid directly on the conductor, and in this case it is necessary to perform insulation treatment.

Figure 4 shows a water leak detection sensor (A) made by another company according to Utility Model Publication No. 62-45388, in which the conductor 102 is braided with insulating thread (polyethylene) at a braid density of 50 to 95%.
．． Two wire cores each covered and insulated with a braided material 103 are twisted together to a thickness of 3 to 0.6 mm, and a protective braided material 104 is further applied on top of this, resulting in a structure that can detect the entire surface and is fully insulated. However, since all the insulating layers are made of braided material and the braid density is high (50-95%), it is easy to absorb moisture under high humidity conditions or due to condensation, resulting in false alarms. The reversibility is poor.

[Means for Solving the Problems] In order to solve the problems of the conventional water leak detection sensor, the present invention, as shown in FIG. 1, uses the parallel conductor plate 2 shown in FIG. 2 as a core material. Our water leakage detection sensor (S-IF) is extruded together with an insulating coating material 3 such as soft PVC and has a plurality of electrode exposed parts 10 formed therein, and a wire diameter of 0.
Insulating thread (PP, PET) of 1 mm to 0.6 mmΦ
, PE, nylon, etc.) with a braid density of 40±20
By covering the braided material of 1%, the mechanical properties and insulation properties between the electrodes of the conventional product are maintained, and the braid coating provides a full-surface insulation structure, and the water absorption of the braid creates a full-surface detection structure, resulting in stable detection. characteristics are obtained. Also, the braid density is 40
Due to its low density of ±20%, malfunctions are unlikely to occur under high humidity conditions or due to moisture absorption such as condensation, and it has excellent recovery performance after water leakage occurs.

In addition, compared to a structure in which the electrode is in direct contact with the sensor mounting surface, such as the conventional product (A-IF sensor), the braided covering acts as a spacer between the mounting surface and the sensor electrode due to the thickness of the braided thread, reducing its effectiveness. Therefore, the anti-condensation properties are significantly improved.

[Comparison of characteristics between Example and conventional product] Example 1 It has been confirmed in another experiment that the sensitivity of the sensor can be improved by treating it with a surfactant.

(Reference example 1) This example, which shows the effectiveness of the coating, was conducted as follows.

The conventional water leak detection sensor (S-IF) is now available at Florado FC.
-430 (a soaked product made by soaking our yarn in a surfactant aqueous solution, pulling it up, lightly draining the excess liquid, and air drying it, as it is, and braided with it (polypropylene thread 0.
Using 2mmΦ, braid density is 20%, 40%, respectively.
Detection sensitivity characteristics tests and dew condensation resistance characteristics were conducted on a sensor coated with 80% triple-braid material) and a conventional product A from another company (not treated with a surfactant).

Evaluation results showing the test results in the table Table-1 *1: When the sensor is connected to one terminal of the sensor of our water leakage detector and tap water with a conductivity of 125 ps/am is dripped at a rate of 1 second, the electrode The amount of water dripped that resulted in a water resistance of 500Ω or less was measured.

*2 Oven at 20°C (30 minutes) to +60°C
A decrease in inter-electrode resistance due to dew condensation was measured 10 seconds after the detection sensor sample was moved to an oven at 95% RH.

From the evaluation results (Table 1), 5-IF regarding detection sensitivity characteristics
The sensor requires 6.3 ml or more of water to detect water leaks, and other sensors (3,47 ml to 6.00 ml)
) has inferior water leak detection sensitivity. Regarding anti-condensation properties,
Competitor's conventional product (A), S-IF + PP braid density 8
In the case of 0%, since the braid density is high, the interelectrode resistance decreases (500Ω or less) in the false alarm generation area due to dew condensation.

In addition, regarding dew condensation resistance, products with a structure in which the electrodes are in direct contact with the installation surface, such as conventional products (S-IF sensors),
Water droplets generated by condensation tend to reduce interelectrode insulation resistance.

On the other hand, a sensor (invention) having a structure in which a 0.2 mmΦ braided wire has a spacer effect from the installation surface is less susceptible to the effects of water droplets due to dew condensation, and exhibits significantly improved dew condensation resistance.

Reference Example 1 The influence of surfactant treatment on a water leak detection sensor was investigated. Our conventional water leak detection sensor (S-IF) was immersed in various surfactant aqueous solutions, pulled out, excess liquid removed, and air-dried. This sensor was tested for detection sensitivity characteristics and durability of surfactant treatment against water. The results are shown in Table-2.

As a result, within the tested range, only Florard FC-430 was found to have a sustained effect of improving water leakage detection sensitivity.

Table-2 *1: Sensor 5-IF, treated and untreated, are connected to the sensor terminal of our water leak detector WR-NA type, and the conductivity is 12.
5) When a drop of tap water of Is/cm was dropped at a rate of 1 second, the amount of water dropped that made the inter-electrode water resistance 50 Ω or less was measured.

*2: After immersing the 5-IF treated sensor in tap water (still water) for 5 seconds, wipe off the water on the surface with Kimwipe S-200, and check that the effect of the surfactant remains due to the surface tension of the sensor surface. I determined whether it was there. For samples in which the effect of the surfactant remained, the above water treatment was repeated.

[Brief explanation of drawings]

Fig. 1 is a plan view and an end view of an embodiment of a water leakage detection sensor according to the present invention, Fig. 2 is a plan view and an end view of a conventional water leakage detection sensor, and Fig. 3 is a plan view of a conventional external electrode type water leakage detection sensor. FIG. 4 is a plan view and an end view of another conventional water leakage detection sensor. [Explanation of symbols] 1.103... Insulating braided material 2, 101.102... Conductor 3 serving as an electrode... Insulating coating material 104... Protective braided material 10... Electrode exposed portion Fig. 2

Claims (1)

[Claims] (1) A pair of parallel conductors are covered with an insulating material, the outer ends of each conductor are exposed in multiple places to serve as electrodes, and an insulating thread with a wire diameter of 0.1 mm to 0.6 mmΦ is attached to the outside of the electrodes. A water leak detection sensor characterized by being coated with a braid at a braid density of 40±20%.