JPH048107A - Gas detector - Google Patents

Abstract

PURPOSE:To surely detect slow leakage of gas in a fine amount by heating a water holding member in a gas detecting room sealed with a substance which reacts on specific gas in specimen gas under the presence of the specimen gas and water. CONSTITUTION:A water holding member 17, consisting of synthetic zeolite, is heated to about 80 deg.C by a heating means 20 in a gas detecting room 11, and a steam pressure therein is set in the vicinity of 150Torr. When oxygen is present in the detecting room 11, balanced with the gas atmosphere in a gas sealed vessel main unit side in the outside of an opening part 91a through a gas permeation window material 12, electric resistance across electrodes 14, 15 is increased by advancing oxidation of a reaction substance 13, mixing iron dust with salt, held between the electrodes 14, 15. When no oxygen is present, the resistance is not changed even when the reaction substance 13 absorbs moisture. A change of the resistance is detected by connecting a discriminating circuit, not shown in the drawing, to lead wires 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas detection device that is preferably used, for example, in detecting gas leaks from power distribution SFs, gas-filled load switches, and the like.

[Conventional technology]

FIGS. 2 to 4 are diagrams illustrating a conventional gas detection device disclosed in, for example, Japanese Patent Publication No. 64-3304, which is used to detect gas leaks in gas-filled electrical equipment.

Figure 2 is a schematic diagram of a load switch filled with SF and gas.
In the figure, (1) is the sealed container of the switch, (2) is the movable contact that opens and closes the electric circuit, and (3) is the movable contact (
Fixed contact corresponding to 2), (4) is bushing (5)
The above contacts (2), (3) and external equipment (
A conductor (6) connects the movable contact (2) with a drive lever (7) attached to the outside of the container (1).
), (8) is the drive shaft operated by the drive lever (
7) A lock mechanism interposed between the drive shaft (6) and the switch to lock the switch; (9) monitors changes in the properties of the gas in the container (1), detects abnormalities in the gas properties, and locks the switch; (8
) is a gas monitoring device that simultaneously locks the container (1) and activates an alarm display device (10) attached to the outside of the container (1).

Next, this gas monitoring device (9) will be described in detail based on FIG. The switching member is further composed of a fixed contact (92) and a movable contact (93) that undergoes thermal deformation due to temperature rise.The movable contact (93) A reactive material (93a) that contains group V elements (phosphorus, antimony, etc.) and undergoes an exothermic reaction with oxygen, and a material (93a) that is coated on both sides and has many holes H that expand thermally with each other. The metal members (93b) and (93c) having different coefficients are formed as a thermally responsive element, and the metal member (93) on the fixed contact (92) side
The coefficient of thermal expansion of metal member 3c) is made smaller than that of the other metal member (93b), and each of the metal members (93b) and (93c) is configured as a bimetal. In addition, the above fixed contact (92)
and the movable contact (93) are connected to the locking mechanism (8) and the alarm display device (10) via a conductor (94) as shown in FIG.

Next, the operation of the gas monitoring device (9) having the above configuration will be explained. In other words, a switch that has been used for a long period of time deteriorates, and the sealed gas pressure, which was initially set at 0.058 Pa, drops to atmospheric pressure (0.0 ONPa), and after that, the gas pressure increases and decreases with changes in the outside temperature. , when the pressure decreases, air will flow into the container (1) from the deteriorated area. In such a case, if oxygen in the air is detected by the gas monitoring device (9)
) through each hole (91a) in the casing of the movable contact (
93) reactive substance (93g), this substance (93)
The group V element, which is a component of 3a), is oxidized and generates heat.Then, the bimetal sandwiching the reactive substance (93a) undergoes thermal deformation, bending the movable contact (93) toward the fixed contact (92), and forming the fixed contact. contact and establish continuity between the two. Thus,
At the same time that the lock mechanism (8) operates to stop the operation of the switch, the alarm display device ff (10) operates to notify the worker of the abnormality.

[Problem to be solved by the invention]

The conventional gas observation device has the above configuration and SF6
Because a synthetic zeolite adsorbent (not shown) is used to keep the moisture concentration in the gas atmosphere low, rapid gas leaks can be easily detected, but slow gas leaks cannot be detected. The problem was that it was slow.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a gas detection device that can detect even slow gas leaks due to minute gas leaks.

[Means to solve the problem]

The gas detection device according to the present invention is configured to include a moisture retaining material and a heating means for heating the moisture retaining material in a detection chamber.

[For production]

The moisture retaining material in this invention supplies water vapor into the detection chamber by being heated by the heating means at a predetermined time. When a specific gas is present in the test gas,
the gas and the reactant react in the presence of the water vapor,
Detects gas.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, (11) is a detection chamber formed by a detection container (91), and (12) is a gas consisting of a porous film of polytetrafluoroethylene resin (PTFE) provided in an opening (91a). It is a transparent window material. (13) is a reactant that reacts with oxygen in the presence of moisture, and in this example, a mixture containing iron and salt as main components (iron powder: salt water -
60-70:3-5:30-40) is used.

The reactant (13) is formed as a molded body or a green compact housed in a non-deformable container.

(14) and (15) are electrodes disposed at both ends of the reactant (13); (16) is an electrode (14) at one end;
(15), the other end of which is led out of the detection container (91), (17) is Na-X type synthetic zeolite (e.g. Zeolum F-9 manufactured by Toso), which has been preabsorbed with moisture. (18) is a container containing the moisture retaining material (17);
(19) is a wire mesh installed on the top of the container (18);
(20> is a heating means for heating the moisture retaining material (17). This heating means (20) has a temperature rise limit of 100
It consists of a heating element with a temperature of about ℃. (21) is heating means (20)
This is a conducting wire for supplying power to the

Note that this gas detection device corresponds to the gas monitoring device N (9) in the SF6 gas-filled load switch shown in Fig.
This device is suitable for detecting gas leaks in electrical equipment that has a small gas filling volume and a small gas filling pressure.

The operation will be explained below. When the moisture retaining material (17) made of synthetic zeolite is heated to about 80°C by the heating means (2o), the water vapor pressure in the detection chamber (11) increases to 150To.
It will be close to rr. This water concentration is sufficient to promote oxidation of the reactant (13) that reacts with oxygen.

When oxygen exists in the detection chamber (11) that is in equilibrium with the gas atmosphere on the gas-filled container main body side through the gas permeable window material (12), the oxidation reaction of the reactant (13) progresses, and the reactant (
Since the iron particles (not shown) constituting the electrode (13) are covered with an oxide film layer, the electrode (14),
Although the reactant (13) between (15) absorbs moisture, no oxygen film layer is formed on the iron particles, so the resistance does not increase. and,
When heating is stopped, a moisture retaining material made of synthetic zeolite (
17) re-adsorbs the water once released into the detection chamber (11) in order to naturally cool down and recover its moisture absorption ability. In this way, synthetic zeolite (17) that has absorbed moisture in advance
releases moisture into the detection chamber (11) only when it is heated by the heating means (2o), and at other times adsorbs the released moisture, so it can be heated repeatedly.

In this way, a determining circuit (not shown) determines whether the resistance between the electrodes (14) and (15) has increased, and when the resistance increases, the lock function can be activated. Note that the response after the SF or gas leak is detected is the same as the conventional response.

Therefore, according to the above embodiment, the configuration is such that the necessary moisture can be supplied to the oxygen detection chamber without adversely affecting the moisture concentration in the atmosphere on the side of the electrical equipment main body, so SF, gas leakage occurs very slowly. Even the presence of oxygen gas can be detected with high sensitivity. (SF6 gas purity is 30
% or more, it has been experimentally confirmed that the blocking performance does not deteriorate. Note that in the description of the above embodiment, the detection of oxygen when air is mixed in due to a gas leak from an electrical device filled with SF6 gas has been described as an example, but the present invention is not limited to this. In the case of the embodiment, the present invention can be applied to any application as long as the atmosphere is low in moisture and the phenomenon in which oxygen appears in this atmosphere is to be avoided.

In addition, although the above-mentioned reactant was mainly composed of iron powder and common salt, the composition ratio is not limited to that in the example, and other materials may be used. In short, any substance that reacts with the specific gas to be detected in the presence of moisture and changes physical properties such as electrical resistivity is sufficient, and the substance or composition can be changed as appropriate depending on the type of gas to be detected. I can do it. Further, although the reactant (13) is a molded body or a green compact, and the electrodes (14) and (15) are disposed at both ends thereof, other shapes or structures may be used.

Furthermore, changes such as changing the type of moisture retaining material (17) are also possible.

〔Effect of the invention〕

As described above, according to the present invention, the detection chamber is configured to include a moisture retaining material and a heating means for heating the moisture retaining material, so that even slow gas leaks due to minute gas leaks can be detected. This has the effect that a detection device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a gas detection device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a load switch filled with SF6 gas, and FIG. 3 is a sectional view of a main part of a conventional gas detection device. FIG. 4 is a block diagram showing the functions of the gas detection device shown in FIG. 3. In the figure, (11) is a detection chamber, (13) is a reaction material, (17) is a moisture retention material, and (20) is a heating means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] It includes a detection chamber that receives a test gas, and a reactant that reacts with a specific gas in the test gas in the presence of moisture, and that reacts with a specific gas in the test gas by changing the properties of the reactant. What is claimed is: 1. A gas detection device for detecting gas, characterized in that the detection chamber includes a moisture retaining material and a heating means for heating the moisture retaining material.