JP2008233600A - closure - Google Patents

Abstract

A closure capable of protecting a connection point of a cable from flooding simply and reliably.
A carbon dioxide generating unit 3 in which an acidic substance and a substance that generates carbon dioxide (CO ₂ ) by contact with the acidic substance and water are housed is fixed at the center of the interior of the closure 1. The substance that generates carbon dioxide (CO ₂ ) is preferably carbonate and / or bicarbonate, and the acidic substance is maleic acid, fumaric acid, tartaric acid, hydrogen salt thereof, hydrogen phosphate salt and It is preferably at least one selected from the group consisting of alum.
[Selection] Figure 1

Description

  The present invention relates to a closure that protects a connection point of a cable from flooding.

  Optical cables, electric cables, and the like have various protective measures against external flooding. For example, a method of filling a cable with a filler can be mentioned. Specifically, filling the cable with jelly or the like prevents water from entering the cable even if a pinhole or the like occurs in the cable jacket. Or even if the cable is filled with a swelling material, even if the cable is immersed in water, the swelling material expands with moisture and the airtightness in the cable is increased, so that further water immersion is prevented. . In any of the methods, so-called “water running” in which water moves from the flooded part to the other part through the cable is prevented by improving the airtightness in the cable. The methods listed here are usually called “non-gas maintenance methods”.

On the other hand, the connection point of the cable is housed and protected in an airtight connection point protective case usually called a closure. For example, the cable may be laid in an underground pipeline or in a high place above the ground. In either case, the connection point is accommodated in a closure, so that it can be prevented from being flooded from the outside. It is protected against it.
However, the airtightness of the closure is largely influenced by the skill of the construction work when the cable connection point is housed in the closure. In some cases, the airtightness cannot be sufficiently maintained, and the cable connection point is not external. May not be adequately protected against flooding. The airtightness of the closure can be confirmed by a method using a flash tester. For example, dry air having a pressure of less than 1 atm is enclosed in the closure from a gas valve attached to the closure body, and the closure seam, etc. Check for gas leaks. However, even if there is no gas leakage immediately after construction, the airtightness may deteriorate over time. Therefore, the protection against the flooding of the cable connection point is not sufficient simply by being accommodated in the closure.

Therefore, maintenance measures are taken to more reliably prevent water from entering the closure. Specifically, by sending an inert gas such as dry air into the cable from the central office side and maintaining the pressure in the cable and in the closure higher than atmospheric pressure, a pinhole or the like is generated in the closure. Is a method for preventing water from entering the closure, and is usually called a “gas maintenance method”. In this maintenance method, the pressure in the cable is similarly kept higher than the atmospheric pressure, so that the cable between the connection points is also protected from water immersion (see, for example, Non-Patent Document 1).
In addition, as in the above “non-gas maintenance method”, there is a method of preventing flooding by filling the closure with a filler such as jelly.
Electronic Information Communication Handbook, 7-10 “Communication Line”, IEICE (2000)

However, the maintenance of the closure by the conventional “gas maintenance method” is highly effective in preventing inundation, but has the problem that the equipment is large and the cost load is large. Even in the “gas maintenance method”, it is necessary to identify the closure that has been submerged and repair it, and it is only necessary to temporarily prevent flooding into the closure before repairing. However, for this purpose, the conventional “gas maintenance method” has a large cost load. Furthermore, since most optical cables have a high density, the flow resistance of the gas in the cable when the inert gas is sent from the station side into the optical cable is large. For example, the distance from the closure station is large. Indeed, it becomes difficult to supply an inert gas having a sufficient pressure into the closure. Therefore, there has been a problem in that the closure far from the station building cannot be sufficiently protected from flooding.
On the other hand, the maintenance of the closure by the “non-gas maintenance method” has a problem that it is difficult to perform the cable connection work at the time of construction and is not practical.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the closure which can protect the connection point of a cable from flooding simply and reliably.

In order to solve the problem,
The invention according to claim 1 is a closure characterized in that an acidic substance and a substance that generates carbon dioxide (CO ₂ ) by contact with the acidic substance and water are housed therein.
The invention according to claim 2 is the closure according to claim 1, wherein the acidic substance and the substance that generates carbon dioxide (CO ₂ ) are arranged at the bottom of the closure.
The invention according to claim 3 is characterized in that the acidic substance and the substance that generates carbon dioxide (CO ₂ ) are shielded by a shield made of a water-soluble material. It is a closure.
The invention according to claim 4 is the closure according to any one of claims 1 to 3, wherein the substance that generates carbon dioxide (CO ₂ ) is carbonate and / or bicarbonate. It is.
The invention according to claim 5 is characterized in that the acidic substance is at least one selected from the group consisting of maleic acid, fumaric acid, tartaric acid, hydrogen salts thereof, hydrogen phosphate salts and alum. Or it is a closure of 4.
The invention according to claim 6 is characterized in that the storage amount of the substance that generates carbon dioxide (CO ₂ ) is an amount capable of maintaining the pressure in the closure at least 0.3 atm higher than the atmospheric pressure at room temperature. The closure according to any one of claims 1 to 5.
The invention according to claim 7 is the closure according to any one of claims 1 to 6, further comprising an inundation detection sensor provided therein.
The invention according to claim 8 is the closure according to any one of claims 1 to 7, wherein gas permeation suppression means is provided in an exposed cross section of the cable drawn into the inside.

  According to the present invention, the connection point of the cable can be protected from flooding simply and reliably.

The present invention will be described in detail below.
The closure of the present invention can prevent further flooding even if there is a gap such as a pinhole, resulting in rapid flooding. During this time, the location of the flooding can be identified and repaired. It can be easily and reliably protected from flooding.
For example, the conventional “gas maintenance system” closure is intended to prevent any water from entering the closure, whereas the closure according to the present invention absorbs moisture in the initial stage of water immersion. It is used to prevent further inundation and is completely different from the technical idea in the prior art.

In the closure of the present invention, an acidic substance and a substance that generates carbon dioxide (CO ₂ ) by contact with the acidic substance and water (hereinafter sometimes abbreviated as carbon dioxide generating substance) are housed inside. It is characterized by being. Here, the carbon dioxide generating substance is not particularly limited as long as it generates carbon dioxide by contact with an acidic substance and water, but it is easy to handle but is particularly excellent in the effects of the present invention. Therefore, it is preferably a solid.

  When the carbon dioxide generating substance is a solid, the better the solubility in water, the better. The solid form is not particularly limited and may be a single solid, but in order to improve the solubility in water, it is preferably in the form of granules or fine powder.

  Further, the carbon dioxide generating substance is preferably one that can be stably stored at room temperature in an environment that does not coexist with water. The term “stable” as used herein is not limited to not generating carbon dioxide gas, but means not accompanied by general qualitative changes such as decomposition and alteration.

  Specific examples of the carbon dioxide generating substance include those that generate carbon dioxide by a neutralization reaction with an acidic substance in the presence of water. Preferred examples of such materials include carbonates and bicarbonates.

  Specific examples of the carbonate include sodium carbonate, potassium carbonate, lithium carbonate, magnesium carbonate, calcium carbonate, and barium carbonate. Specific examples of the hydrogen carbonate include sodium hydrogen carbonate and potassium hydrogen carbonate. Among these, sodium hydrogen carbonate is particularly preferable because it is easily available and inexpensive, and is particularly excellent in the effects of the present invention.

  Only one kind of carbon dioxide generating substance may be used, or two or more kinds may be used in combination. When two or more types are used in combination, the combination is not particularly limited as long as the effects of the present invention are not hindered.

The carbon dioxide generating substance is preferably used by being placed or filled in a container installed inside the closure so as not to contact the inner surface of the closure or the cable. The container mentioned here is not particularly limited as long as it can hold a carbon dioxide generating substance and the carbon dioxide generating substance can be easily contacted with water, and the material thereof is not limited to the carbon dioxide generating substance and the acidity described later. There is no particular limitation as long as it does not react with the substance. For example, when carbonate or hydrogen carbonate is used as the carbon dioxide generating substance, various plastics can be used.
Further, when the carbon dioxide generating substance is solid, the carbon dioxide generating substance is packaged with a film or paper having a large number of holes smaller than the particle diameter, and placed on the container. May be. By doing in this way, scattering of the carbon dioxide generating substance in a closure can be prevented reliably.

For example, considering a case where a gap such as a pinhole occurs in the closure and this is the cause of inundation into the closure, if the pressure in the closure is higher than the atmospheric pressure at this time, inundation is prevented. The larger the differential pressure from atmospheric pressure, the more stable the flooding can be prevented.
From such a viewpoint, the storage amount of the carbon dioxide generating substance is preferably an amount capable of maintaining the pressure in the closure at the time of flooding at least 0.3 atm higher than atmospheric pressure at room temperature, and at least 0.4 atm higher. The amount that can be maintained is more preferable, and the amount that can be maintained at least 0.65 atm is particularly preferable.
The increase in pressure in the closure due to the generated carbon dioxide gas varies depending on the internal volume of the closure, etc. even with the same amount of carbon dioxide gas generating substance. In addition, depending on the size of the gap such as pinholes or the state of the exposed cross section of the cable drawn into the closure as described later, some of the generated carbon dioxide gas is lost due to the outflow of the closure. End up. Therefore, in consideration of the shape and internal volume of the closure used, the carbon dioxide generating substance assumes that the carbon dioxide gas does not flow out of the closure, and the pressure inside the closure is less than atmospheric pressure at room temperature. It is most preferable to store an excessive amount more than the amount that can be increased by 65 atm.
For example, when the internal volume of the closure is 10 L, if there is no outflow of carbon dioxide outside the closure, the pressure inside the closure is reduced by the generation of approximately 0.3 moles of carbon dioxide depending on the temperature. It can be at least 0.65 atmospheres higher than atmospheric pressure at room temperature. The required amount of the carbon dioxide generating substance may be calculated with reference to this.
In the present invention, “normal temperature” means a temperature at which the closure is exposed in the installation environment, and specifically, a temperature in the range of about 0 to 40 ° C.

In this invention, an acidic substance is a substance in which the aqueous solution shows acidity, and if it is such, it will not specifically limit.
The acidic substance may be either solid or liquid, but is preferably a solid because it is easy to handle and particularly excellent in the effects of the present invention. As will be described later, the acidic substance is preferably used by being placed or filled in a container installed inside the closure. It is not preferable to contact the inner surface of the closure or the cable or the like by scattering or volatilization during normal times, since these deteriorate. If it is solid, it will not function as an acid unless it comes into contact with water by flooding or the like, so that even if it comes into contact with the inner surface of the closure or a cable or the like in normal times, it does not deteriorate.

  When the acidic substance is a solid, the better the solubility in water, the better. The solid form is not particularly limited and may be a single solid, but in order to improve the solubility in water, it is preferably in the form of granules or fine powder.

  Furthermore, it is preferable that both the carbon dioxide generating substance and the acidic substance are solid. If both are solid, even if they are stored in a mixture in the closure, they can exist stably, whereas the presence of this water during submergence causes the generation of carbon dioxide gas. This is because it proceeds promptly. Further, the degree of freedom of arrangement inside the closure is high, and it is also suitable for storing more carbon dioxide generating substances and acidic substances.

  The acidic substance is preferably one that can be stably stored at room temperature in an environment that does not coexist with water. The term “stable” as used herein refers to not accompanied by general qualitative changes such as decomposition and alteration.

Specific examples of preferred acidic substances in the present invention include polycarboxylic acids such as monocarboxylic acids or dicarboxylic acids that are organic acids; hydrogen salts of the polyvalent carboxylic acids; inorganic salts such as hydrogen phosphates and sulfates. The salt of an acid can be illustrated.
Examples of the organic monocarboxylic acid include lactic acid.
Examples of the organic dicarboxylic acid include maleic acid, fumaric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic acid and the like.
Examples of the organic tricarboxylic acid include citric acid.
The hydrogen salt of organic polyvalent carboxylic acid refers to one in which a part of the carboxylic acid of the organic polyvalent carboxylic acid forms a salt, and specifically, a part of the organic dicarboxylic acid, tricarboxylic acid, etc. The thing in which carboxylic acid forms salts, such as an alkali metal salt, can be illustrated.
Examples of the hydrogen phosphate include monohydrogen phosphate and dihydrogen phosphate.
Examples of the sulfate include alum such as AlK (SO ₄ ) ₂ · 12H ₂ O.
Among these, maleic acid, fumaric acid, tartaric acid, hydrogen salts thereof, hydrogen phosphate and alum are preferable, are easily available and inexpensive, and are particularly excellent in the effects of the present invention. Therefore, fumaric acid, tartaric acid, tartaric acid are preferred. Potassium hydrogen, calcium hydrogen phosphate, baked alum and sodium dihydrogen phosphate are particularly preferred.

  The acidic substance may be used alone or in combination of two or more. When two or more types are used in combination, the combination is not particularly limited as long as the effects of the present invention are not hindered.

The acidic substance is preferably used by being placed or filled in a container installed inside the closure, like the carbon dioxide generating substance. The form is the same as that of the container for carbon dioxide generating substance, and the material is not particularly limited as long as it does not react with the carbon dioxide generating substance and the acidic substance. For example, various plastics can be used. . When the acidic substance is solid, it may be packaged with a film or paper having a large number of holes smaller than the particle diameter, like the carbon dioxide generating substance.
The acidic substance container may be provided integrally with the carbon dioxide generating substance container.

It is preferable that the acidic substance is accommodated in the closure by an amount that can generate at least all of the carbon dioxide gas that can be generated by the carbon dioxide generating substance when immersed. For example, when carbon dioxide is generated by a neutralization reaction, it is preferable to store an acidic substance in an amount sufficient to neutralize all the carbon dioxide generating substances. Therefore, it is preferable to appropriately adjust the storage amount of the acidic substance according to the type and amount of the carbon dioxide generating substance and the kind of acidic substance.
Specifically, in the case where the acidic substance is a monocarboxylic acid compound and the carbon dioxide generating substance is sodium hydrogen carbonate, for example, sodium hydrogen carbonate reacts with an equimolar amount of the monocarboxylic acid compound, and the maximum It is preferable to use at least an equimolar amount of the monocarboxylic acid compound, so that the neutralization reaction can proceed reliably, the monocarboxylic acid is used within a range not impeding the effects of the present invention. More preferably, the compound is used in an equimolar amount or more with respect to the carbon dioxide generating substance. When a dicarboxylic acid compound is used instead of the monocarboxylic acid compound, the dicarboxylic acid compound may be, for example, half the amount of the monocarboxylic acid compound. Further, when an acidic substance other than the carboxylic acid compound is used, it is preferable to appropriately adjust the storage amount in consideration of the strength of the acid.

In the present invention, it is preferable that the acidic substance and the carbon dioxide generating substance are shielded by a shield made of a water-soluble material in the closure. For example, even when both the acidic substance and the carbon dioxide generating substance are solid, as the humidity in the closure increases, the moisture in the air acts as water and comes into contact with the acidic substance and the carbon dioxide generating substance, resulting in a trace amount. Carbon dioxide gas may be generated.
However, if the acidic substance and the carbon dioxide generating substance are kept out of contact with each other by the shield, the shield will not dissolve at the moisture level in the air. Can be effectively suppressed. And since the shield is water-soluble, once it is immersed in the closure, the shield quickly dissolves, the water, the acidic substance and the carbon dioxide generating substance come into contact with each other, and the carbon dioxide is quickly generated. Further, further flooding is prevented quickly by increasing the pressure in the closure.

  As a shielding method in this case, for example, a method of separating an acidic substance and a carbon dioxide generating substance by a shielding wall can be exemplified. Alternatively, like the capsule, the entire acidic substance may be sealed together with a shielding material, and the entire carbon dioxide generating material may be similarly sealed together with a shielding material (when the sealing unit is one each other). Alternatively, a plurality of units in which a predetermined amount of an acidic substance is sealed may be used as one unit, and a plurality of units may be used in which a carbon dioxide gas generating substance is similarly sealed in a predetermined amount. in the case of).

  The material of the shielding material is not particularly limited as long as it is a water-soluble material. Specifically, polysaccharides, starches and the like can be exemplified, but gelatin and hydroxypropylmethylcellulose have sufficient strength in the absence of water. A capsule similar to a capsule used as a so-called “hard capsule” in the pharmaceutical field or the like is also suitable.

  In the present invention, the acidic substance and the carbon dioxide generating substance are preferably arranged at the lower part in the closure when the closure is installed, and more preferably arranged at the bottom part in the closure. This is because the submerged water tends to accumulate at the bottom of the closure and is suitable for promptly generating carbon dioxide gas during submergence. Furthermore, it is because an acidic substance and a carbon dioxide generating substance can be stably held in normal times.

In the present invention, it is preferable that a water immersion detection sensor is further provided inside the closure. The flood detection sensor here may be a conventionally known sensor and is not particularly limited. For example, in the case of a closure used for connecting an optical cable, an optical fiber branched from the cable in the closure is used as a detection optical fiber, a stress applying member is brought into contact with the detection optical fiber, and the stress applying member An optical fiber sensor in which a swelling member that swells with submerged water is disposed on the side opposite to the side on which the detection optical fiber is disposed (see, for example, JP-A-3-197844). According to such an inundation detection sensor, the optical pulse tester (OTDR) detects deformation such as bending or elongation strain of the optical fiber for detection driven by the stress applying member as the swelling member swells. Detects water in the closure.
The number of inundation detection sensors provided inside the closure is not particularly limited, but usually one is sufficient.

Hereinafter, the closure of the present invention will be described in more detail with specific examples.
FIG. 1 is a front view illustrating a closure of the present invention. The optical fiber 20a protrudes from the cross section 200a exposed in the closure 1 of the multi-fiber optical cable 2a. Similarly, from the cross section 200b of the multi-fiber optical cable 2b exposed in the closure 1, the optical fiber 20b protrudes, and the tips of the protruding portions of the optical fibers 20a and 20b are optically connected at an optical connection point 21. The optical fibers 20a and 20b branched out from the optical cables 2a and 2b are optically connected to the detection optical fiber 20c via the optical connection points 22 and 23, and the detection optical fiber 20c is connected to the inundation detection unit 40. The water intrusion detection sensor 4 is configured by being drawn in. The inundation detection sensor 4 is of a type that detects inundation from the deformation of the detection optical fiber 20c by using the optical pulse tester (OTDR), although the details are omitted here. That is, as the swelling member swells, it is driven by the stress applying member, and the detection optical fiber 20c is deformed such as bending or elongation strain. As described above, the optical connection points 21, 22 and 23 are stored in the closure 1 while ensuring waterproofness, and the water intrusion into the closure 1 can be detected by the water immersion detection sensor 4. Reference numeral 3 denotes a carbon dioxide generating unit in which an acidic substance and a carbon dioxide generating substance are stored. The carbon dioxide generating unit 3 is fixed in the center of the bottom inside the closure 1 in the vicinity of the water immersion detection sensor 4.

2A and 2B are diagrams illustrating the overall configuration of the carbon dioxide generation unit 3. FIG. 2A is a perspective view, and FIG. 2B is a front view. Called the embodiment).
In the carbon dioxide generating unit 3, a vessel-type container 32 whose depth is gradually increased from both end portions toward the substantially central portion along the longitudinal direction is formed by the fixing base 30 at the lower portion of both end portions in the longitudinal direction. It is detachably fixed on the bottom surface. The container 32 is divided into two parts by a shielding wall 31 made of a water-soluble material at a substantially central portion where the depth is maximum, and the carbon dioxide generating substance 32a is placed on the first part 3a. The acidic substance 32b is placed on the second portion 3b, and the carbon dioxide generating substance 32a and the acidic substance 32b are exposed and held in the closure 1 so as not to contact each other.

  The shielding wall 31 is fixed to the container 32 by storing the peripheral edge portion in a groove (not shown) provided at a corresponding position on the inner surface of the container 32. The method for fixing the shielding wall 31 to the container 32 is not limited to this, and for example, the peripheral edge of the shielding wall 31 may be bonded and fixed to a predetermined location on the inner surface of the container 32 via a water-soluble adhesive. However, any other method may be used as long as the shielding wall 31 can be stably fixed.

In this way, the carbon dioxide generating substance 32a and the acidic substance 32b do not come into contact with each other in the normal state, but when a gap such as a pinhole is formed in the closure 1, and the water is immersed in the closure 1 from there, the shielded wall is caused by the immersed water. As dissolution of 31 begins, dissolution of carbon dioxide generating substance 32a and acidic substance 32b into water begins, and respective aqueous solutions are prepared. The carbon dioxide gas is generated by mixing the aqueous solution of the carbon dioxide generating substance 32a and the acidic substance 32b by the collapse of the shielding wall 31. Since the container 32 is inclined so that the bottom surface is lowered toward the substantially central portion as described above, the aqueous solution of the carbon dioxide generating substance 32a and the aqueous solution of the acidic substance 32b are both along the inclined surface. The mixture of these aqueous solutions is promoted, and the generation of carbon dioxide gas proceeds promptly.
Carbon dioxide is inert and does not damage the closure and cable.

In the present embodiment, the container 32 can be washed and reused any number of times, and a new shielding wall 31 may be installed at the time of reuse to place the carbon dioxide generating substance 32a and the acidic substance 32b.
Note that the opening of the container 32 may be covered with a lid made of the same material as the shielding wall 31. And the form of the container 32 is not limited to what is illustrated here.

On the other hand, FIG. 3 is a perspective view illustrating the carbon dioxide generating unit 4 provided at the bottom of the closure 1 by a method different from that of the first embodiment. Called the embodiment). The same components as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted. The same applies to the subsequent drawings.
The carbon dioxide generating unit 4 is provided at a position lower than the bottom surface of the closure 1, and a concave portion 40 that is similar to the container 32 is formed at a predetermined position on the bottom surface of the closure 1, and the container 32 can be attached to and detached from the concave portion 40. Is fitted. That is, the container 32 is provided at a position lower than the bottom surface of the closure 1.

  In the present embodiment, since the carbon dioxide generating unit 4 is provided at a position lower than the bottom surface of the closure 1, when the water is immersed in the closure 1, the immersed water easily reaches the container 32, and the first embodiment. The generation of carbon dioxide proceeds more rapidly than that.

  Except for the above points, this embodiment is the same as the first embodiment.

  Instead of detachably fitting the container 32 to the recess 40, for example, a shielding wall 31 is provided at a substantially central portion in the longitudinal direction of the recess 40, and the recess 40 is formed directly on the carbon dioxide generating substance 32a and the acidic substance 32b. However, in this case, the carbon dioxide generating substance 32a and the acidic substance 32b come into contact with the inner surface of the closure, which is not preferable from the viewpoint of maintenance of the closure.

4A and 4B are diagrams illustrating the entire configuration of the carbon dioxide generating unit 5 of still another embodiment. FIG. 4A is a perspective view and FIG. 4B is a front view (what is illustrated here). Hereinafter, this is referred to as a third embodiment).
Unlike the container 32, the container 52 has a bowl-like shape, and the container 52 includes a carbon dioxide generating substance 32a sealed like a capsule with a shield 51 made of the same material as the shielding wall 31. The acidic substance 32b is mixed and exposed and placed in the closure 1.
The carbon dioxide generating unit 5 is provided at a position lower than the bottom surface of the closure 1, and a concave portion 50 that is similar to the container 52 is formed at a predetermined location on the bottom surface of the closure 1. It is detachably fitted. That is, the container 52 is provided at a position lower than the bottom surface of the closure 1.

In the present embodiment, since the carbon dioxide generating unit 5 is provided at a position lower than the bottom surface of the closure 1, when the water is immersed in the closure 1, the immersed water easily reaches the container 52, and the second embodiment. Similarly, the generation of carbon dioxide proceeds more rapidly.
In addition, since the carbon dioxide generating substance 32a and the acidic substance 32b are sealed like a capsule by the shielding material 51, and these sealed ones are mixed, compared to the first and second embodiments, it is more effective at the time of flooding. The degree of mixing of the carbon dioxide generating substance 32a and the acidic substance 32b can be further increased, and the generation of carbon dioxide proceeds more rapidly than in the second embodiment. Further, since the carbon dioxide generating substance 32a and the acidic substance 32b are not exposed in the closure at normal times, for example, even when the humidity in the closure becomes high, moisture in the air may induce the generation of carbon dioxide. In addition, the closure of the present invention can be maintained in high quality over a longer period.
In addition, although the bowl-shaped thing is illustrated here as the container 52, it is not limited to this.

  Except for the above points, this embodiment is the same as the first and second embodiments.

  In the third embodiment, the carbon dioxide generating unit 5 is provided at a position lower than the bottom surface of the closure 1. For example, as in the first embodiment, the carbon dioxide generating unit 5 is interposed via a fixed base. Then, it may be detachably fixed on the bottom surface of the closure 1. However, the third embodiment is preferable from the viewpoint of easy generation of carbon dioxide gas and maintenance of the closure.

  In addition, in 2nd and 3rd embodiment, although the shape has illustrated the thing similar to the container to fit as a recessed part, this invention is not limited to this, A container hold | maintains stably Any shape is possible as long as it is possible.

  Although three embodiments have been specifically described above, the closure of the present invention is not limited to the embodiments shown here as long as it has the features described above.

In the present invention, in order to maintain the state in which the pressure in the closure is higher than the atmospheric pressure for a longer time, as described above, an excessive amount of carbon dioxide generating material may be stored in the closure in advance. For example, you may provide a gas permeation | transmission suppression means in the exposed cross section of the cable drawn in the inside of a closure.
The gas permeation suppression means here is not particularly limited as long as it can suppress the ingress of gas from the cable cross section into the cable. Specifically, a method of applying a gas permeation suppressant such as jelly to the cable cross section (for example, the cable cross sections 200a and 200b in FIG. 1) can be mentioned.

  In the present invention, the connection point of the cable can be protected from flooding by utilizing carbon dioxide gas generated in the closure due to flooding. For example, if the gas permeation suppression means is not provided in the exposed cross section of the cable drawn into the closure, the carbon dioxide gas mainly enters the cable from the cross section of the cable and flows through the cable with time, Furthermore, depending on the case, it flows out of the closure from the flooded part, the amount of carbon dioxide in the closure gradually decreases, and the pressure in the closure eventually becomes about the same as the atmospheric pressure. However, since it takes a long time for the pressure in the closure to be about the same as atmospheric pressure, the pressure in the closure is higher than atmospheric pressure, for example, at least 0.3 atmospheric pressure higher than atmospheric pressure. The closure may be repaired while it is maintained. And if the gas permeation | transmission suppression means is provided in the said cable cross section, the state in which the pressure in a closure is higher than atmospheric pressure can be maintained for a long time. For example, as described above, it is possible to identify a flooded closure using a flood detection sensor provided in the closure.

  The present invention is intended for all cables such as optical cables and metal cables that require protection of connection points by installing a closure.

According to the present invention, it is possible to easily and surely prevent further flooding into the closure without requiring a large-scale facility as in the conventional “gas maintenance method” and within the time required to start repair. Carbon dioxide is an inert gas and does not damage the closure and cable. Therefore, the cable connection point can be protected stably at low cost.
In addition, connection points of cables that are difficult to protect from water flooding by the conventional “gas maintenance method”, such as most optical cables, can be reliably protected.

  The present invention can be used to protect cable connection points such as optical cables.

It is a front view which illustrates the closure of the present invention. It is a figure which illustrates the whole structure of 1st embodiment of the carbon dioxide generation unit in this invention, (a) is a perspective view, (b) is a front view. It is a perspective view which illustrates 2nd embodiment of the carbon dioxide generation unit in the present invention. It is a figure which illustrates the whole structure of 3rd embodiment of the carbon dioxide generation unit in this invention, (a) is a perspective view, (b) is a front view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Closure, 2a, 2b ... Optical cable, 20a, 20b ... Optical fiber, 20c ... Optical fiber for detection, 21, 22, 23 ... Optical connection point, 200a, 200b ... Cable cross section, 3 ... carbon dioxide generation unit, 31 ... shielding wall, 4 ... inundation detection sensor

Claims (8)

A closure characterized by containing therein an acidic substance and a substance that generates carbon dioxide (CO ₂ ) by contact with the acidic substance and water. The closure according to claim 1, wherein the acidic substance and the substance that generates the carbon dioxide gas (CO ₂ ) are disposed at a bottom portion in the closure. The closure according to claim 1 or 2, wherein the acidic substance and the substance that generates carbon dioxide (CO ₂ ) are shielded by a shield made of a water-soluble material. The material that generates carbon dioxide gas (CO ₂₎ is a closure according to claim 1, characterized in that a carbonate and / or bicarbonate.   The closure according to claim 3 or 4, wherein the acidic substance is at least one selected from the group consisting of maleic acid, fumaric acid, tartaric acid, hydrogen salts thereof, hydrogen phosphate salts and alum. 6. The storage amount of the substance that generates carbon dioxide (CO ₂ ) is an amount capable of maintaining the pressure in the closure at least 0.3 atm higher than atmospheric pressure at room temperature. The closure according to claim 1.   Furthermore, the inundation detection sensor is provided in the inside, The closure as described in any one of Claims 1-6 characterized by the above-mentioned.   The closure according to any one of claims 1 to 7, wherein gas permeation suppression means is provided on an exposed cross section of the cable drawn into the inside.

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