JPH0419552A - Gas detecting element - Google Patents

Abstract

PURPOSE:To prevent malfunction, to obtain an electric signal which can easily be processed, and to stabilize the detection sensitivity by applying a compressive force to a powdery or granular reaction material at all times and make particles securely contact one another. CONSTITUTION:A compressing means 21 is made of an elastic member which energizes moldings 15 and 16 for sealing as shown by arrows A and B to compress the reaction material 14. When a water supply part is heated, the steam partial pressure in a casing is increased and the iron used for the material 14 reacts on, for example, oxygen by the assistance of steam to change into iron oxide, so that the electric resistance between electrodes 17 and 18 increases. In the absence of the oxygen, the reaction into the iron oxide does not advance, so the electric resistance does not increases. Therefore, when the constant compressive force is applied by the means 21 to the powder of mixture (iron powder + NaCl + water) constituting the material 14 at all time, particles are put in an invariably excellent contact state, so malfunction caused by a gap between particles does not occur and the electric signal which can easily be processed is obtained to stabilize the detection sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas detection element that is preferably used, for example, in detecting gas leaks in SF6 gas-filled load switches for power distribution.

[Prior Art] FIGS. 5 to 7 illustrate a conventional SF, a gas-filled electrical appliance, and a gas leak detection device thereof, as disclosed in, for example, Japanese Patent Publication No. 1986-304.

Figure 5 is a schematic diagram of an SF, gas-filled load switch equipped with a gas detection device, in which (1) is the sealed container of the switch, (2
) is a movable contact that opens and closes an electric circuit, (3) is a fixed contact corresponding to this movable contact (2), (4) is a bushing (5) that connects each of the above-mentioned contacts (2), (3)
(6) is a drive shaft that operates the movable contact (2) with a drive lever (7) attached to the outside of the container (1), (8) is a conductor connecting the and an external device (not shown); A locking mechanism (9), which is interposed between the drive lever (7) and the drive shaft (6) and locks the switch, monitors changes in the properties of the gas in the container (1) and detects abnormalities in the gas properties. This is a gas detection device (gas monitoring device) that simultaneously locks the locking mechanism (8) and activates an alarm display device (10) attached to the outside of the container (1).

Next, this gas detection device (9) will be described in detail based on FIG. 6. The detection device (9) has a substantially rectangular appearance, and has a casing (91) in which a large number of holes (91a) are bored and a punch. It consists of a housed switching member.

The switching member further includes a fixed contact (92) and a movable contact (93) that undergoes thermal deformation due to temperature rise. The movable contact (93) contains a reactive substance (93a) that contains Group 1 elements of the periodic table (phosphorus, antimony, etc.) and undergoes an exothermic reaction with oxygen, and a large number of metals coated on both sides of this substance (93a). The metal member (93b) and (93c) having different coefficients of thermal expansion are formed as a thermally responsive element, and the metal member (93b) on the fixed contact (92) side has holes H formed therein.
The coefficient of thermal expansion of metal member 3c) is smaller than that of the other metal member (93b), and each of the metal members (93b) and (93c) is constructed as a bimetal. (11) is the fixed contact (92
) and a movable contact (93). In addition, the fixed contact (92) and the movable contact (93)
) are connected to the locking mechanism (8) through the conductor (94).
and an alarm display element (10) as shown in FIG.

Next, the operation of the gas detection 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 about 0.5 MPa, drops to atmospheric pressure (0, (lOMPa)), and after that, the gas pressure increases and decreases with changes in the outside temperature. However, when the pressure decreases, air flows into the container (1) from the deteriorated area.

In such cases, if oxygen in the air is detected by the gas detection device (9)
The movable contact (9) passes through the hole (91a) in the casing of
3) is contacted with the reactant (93a), and this substance (93a)
) oxidizes Group Ⅰ elements, which are the components of ), and generates heat. Next, the bimetal sandwiching the reactive substance (93a) undergoes thermal deformation, bending the movable contact (93) toward the fixed contact (92),
Contacts the fixed contact and establishes continuity between the two. Thus, at the same time as the locking mechanism (8) operates to stop the operation of the switch, the alarm display device (IO) operates to notify the operator of the abnormality.

[Problem to be Solved by the Invention J] The conventional gas detection element (11) uses a solid reactive substance sandwiched with metals having different coefficients of thermal expansion as described above, so it is easy to manufacture. It is troublesome, does not necessarily have sufficient accuracy and stability, and has the disadvantage that it cannot be constructed using powdered, granular, or liquid reactive substances.

This invention was made to solve the above-mentioned problems, and it is possible to easily construct a detection element using a powdered or granular reactant, or a liquid reactant, and to create a stable and highly sensitive gas detection element. The purpose is to obtain.

"Means for Solving the Problems" The gas detection element according to the first aspect of the present invention includes a housing section,
A powdered or granular reactant is accommodated in the accommodating section and reacts with a specific gas, a compression means provided in the accommodating section compresses the reactant, and a detection means for detecting a change in the reactant. It is composed of

The gas detection element according to the second aspect of the present invention further includes: a housing section, a reactive substance that is housed in the housing section and is formed by blending a liquid substance with a particulate substance that reacts with a specific gas, and a reaction material that is provided in the housing section. The reactor is configured to include a detection means for detecting a change in the reactant.

"Function J The compression means in the first invention constantly applies compression force to the powdered or granular reactant to ensure contact between the particles, thereby stabilizing the detection sensitivity.

The liquid substance in the second invention stabilizes detection sensitivity by ensuring mutual contact between particulate substances.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
FIG. 1(a) and FIG. 1(b) are a front view and a sectional view showing essential parts of a gas detection element according to an embodiment of the first invention,
FIG. 2 is a sectional view showing the gas detection device.

In the figure, (12) is a hollow storage container in which a storage part (12A) is formed inside and openings (12B) (12B) are provided on the negative side and the other side, and (13) (13) is the Opening (12B) A gas permeable polymer film that closes (12B). (14) is a reactant that reacts with oxygen contained in the storage part (12A), and in this example, a mixture of iron powder + NaCl + water is used.

(15) and (16) are molded bodies for sealing at both ends of the storage container (12); (17) and (18) are a pair of electrodes each mounted inside the molded body for sealing; (19) is a conductive wire; (20)
is a detection means composed of the electrodes (17), (18), conductive wires (19), (19), and the like. (21) indicates the sealing molded bodies (15) and (16) by arrow A.

This is a compression means made of an elastic member that compresses the reactant (14) by applying force in the B direction.

Reference numeral (22) in FIG. 2 is a water supply section, which in this embodiment is composed of synthetic zeolite that has absorbed moisture in advance and a heater (both not shown) that heats the synthetic zeolite. (23) is a conducting wire for supplying power to the heater. (24) is the casing (91)
This is a gas-permeable polymer film provided so as to close the opening (91a) provided in the. Note that the other symbols are the same as those in the conventional device, so their explanation will be omitted.

The operation will be explained below. It is assumed that the gas detection device (9) is used as a gas monitoring device, similar to (9) of the SFs gas filled load switch shown in FIG.

Due to deterioration of the load switch, etc., the container (symbol (1) in Figure 5)
If air enters the interior, oxygen will be present in the casing (91), which is in equilibrium with the gas atmosphere on the side of the SF and gas-filled container (1) through the gas-permeable polymer film (24). . When the water supply part (22) is heated, the water vapor partial pressure inside the casing (91) is increased, and the reactant (
The iron used in step 14) reacts with the oxygen with the help of the water vapor and changes into iron oxide, forming the electrodes (17) and (18).
The electrical resistance between increases. On the other hand, if oxygen is not present, the reaction to form iron oxide will not proceed and the electrical resistance will not increase. Therefore, the electrical resistance between the electrodes (17) and (18) makes it possible to detect a specific gas, namely oxygen in the embodiment. Note that the polymer film (24) prevents water vapor from unnecessarily flowing out of the casing (91).

Here, the reactant (14) is constituted (iron powder + NaC1+
Although the water) mixture is a powder, it is constructed so that a constant compressive force is always applied by the elastic member (21), so that the particles are always kept in good contact with each other, and the powder particles are Malfunctions will not occur due to gaps. Therefore, an electrical signal that is easy to process can be obtained, and a highly accurate sensing element can be obtained.

Note that the gap between the powder and granular material is equivalent to the crack in the molded product. In the molded body, a binder is further added to (iron powder + NaCl + water).

After the detection element (11) detects the presence of oxygen and it is determined that SF or gas is leaking, the steps to be taken are the same as in the past.

In the above embodiments, the reaction substance (14) is a powder, but it goes without saying that a granule or a molded product obtained by molding the same can also be used. Further, as the material for the electrode (17) (1 g), it is preferable to use an electrode material such as NaCl or a substance that does not become highly resistive in the presence of water, such as platinum or carbon. Furthermore, it is desirable to use a film that is heat resistant and has excellent oxygen permeability as the gas permeable member (13) or the polymer film (24), and there is no problem as long as it is a thin film for boat fishing. Examples of materials that can be preferably used include polymer films such as polysulfone resin, polycarbonate resin, RL cellulose acetate butyrate, and polymeric resin. Further, as long as the thickness is about 25 μm or less, there is no particular problem in the movement of Ot gas or other gases.

FIGS. 3(a) and 3(b) are a front view and a sectional view of a gas detection element according to an embodiment of the second invention, and FIG. 4 is a gas leak detection device constructed using the above embodiment. In the schematic cross-sectional view, (91a) is the opening provided in the sensing element storage container (91), (25) is the heater, (26) is the outer box for the sensing element, and (13) is the silicone material with excellent oxygen permeability. The liquid-impermeable polymer film (14) consisting of a resin film is a reactive material consisting of a liquid substance consisting of propylene glycol, which dissolves NaCl relatively well and has a low melting point, and a mixture whose main components are NaCl and iron powder. . In addition, for the reactant (14) that reacts with oxygen, after mixing each material, when the whole is allowed to stand still and the solid matter is precipitated, a faint liquid (propylene glycol) forms a liquid film over the entire upper part. It has been adjusted to the extent that A pair of electrodes (17) (1
8) is interposed. Other symbols are the same as in the embodiment of the first invention.

The operation will be explained below.

The atmosphere inside the housing part (12A) is made up of a liquid-impermeable film (12A).
3) Because it is in contact with the external atmosphere through the gas or can easily follow the composition change of the atmosphere to be measured (SF, inside the gas-filled load switch), if the SF or gas leaks and the atmosphere (oxygen) gets mixed in, the reactant will be removed. Iron, the main component of (14), is oxidized,
Increase the resistance between the electrodes (17018). That is,
By knowing the resistance change between the electrodes (17018), it is possible to detect oxygen gas, SF, and gas leakage. Note that the heater (25) shown in FIG.
1) is heated intermittently.

This heating can significantly shorten the detection time. For example, this is effective in determining whether oxygen has already reached an appropriate concentration during heating, but is not always necessary. Further, the response of the equipment after detecting air intrusion is the same as that of conventional equipment.

As described above, according to the above embodiment, the non-volatile liquid substance ensures sufficient contact between the components of the oxygen detecting substance, thereby eliminating factors such as malfunctions caused by racking, which are specific to solid substances. As a result, a highly accurate and stable sensing element can be obtained. Also, even if it is reversed, if it is placed correctly, it will return to its original state. In this case, it is desirable to make the space above the liquid level in FIG. 3(b) as small as possible.

Nao, in the above example, propylene glycol was used as the liquid substance.This compound has a melting point of -32℃ and a boiling point of 21℃.
4.2°C, it is a suitable material because it maintains its liquid state between -20°C and 70'C, which is the operating environment temperature for this type of equipment, and has a low vapor pressure. However, it goes without saying that any stable substance can be used as long as it dissolves the oxidation promoter NaCl to some extent and maintains a liquid state within the operating environment temperature range of the device.

In each of the above embodiments, oxygen gas is detected, but by changing the reactant (14), it is possible to construct a gas detection element that detects other specific gases. Furthermore, although the present invention was used to detect gas leakage from a load switch filled with SF or gas, it is of course possible to use it for other purposes.

[Effects of the Invention] As described above, according to the first aspect of the present invention, compressive force is always applied to the reactive substance layer of the sensing element, so malfunctions can be prevented, and electrical signals that are easy to process can be generated. can be obtained.

Further, according to the second aspect of the invention, there is provided a containing part, a reactant which is housed in the containing part and is formed by blending a liquid substance with a particulate substance that reacts with a specific gas, and a reactant which is provided in the containing part and which is formed by mixing a liquid substance with a particulate substance that reacts with a specific gas. Since the sensor is configured to include a detection means for detecting a change in , there is an effect that a highly accurate and stable gas detection element can be obtained.

[Brief explanation of drawings]

FIG. 1 shows a gas detection element according to an embodiment of the first invention, FIG. 1(a) is a front view, and FIG. 1(b) is a first embodiment.
FIG. 2 is a cross-sectional view taken along line bb in FIG. 3 shows a gas detection element according to an embodiment of the second invention, FIG. 3(a) is a plan view, FIG. 3(b) is a cross-sectional front view, and FIG. 4 is a detection device shown in FIG. A schematic sectional view showing a gas leak detection device using an element, FIG. 5 is a schematic configuration diagram of an SF and waste-filled switch, FIG. 6 is an enlarged sectional view of a conventional gas leak detection element detection section, and FIG. FIG. 2 is a block diagram showing the functions of a conventional dregs leakage detection element. In the figure, (■1) is a gas detection element, (12A is a storage part, (14) is a reactant, (20) is a detection means, (2
1) is a compression means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A storage section, a powdered or granular reactant contained in the storage section that reacts with a specific gas, a compression means provided in the storage section for compressing the reaction material, and a means for detecting changes in the reaction material. A gas detection element characterized by comprising: (2) A storage section, a reactive substance that is accommodated in the storage section and is made by blending a liquid substance with a particulate substance that reacts with a specific gas, and a detection means that is provided in the storage section and detects a change in the reactive substance. A gas detection element characterized by comprising: