JPS63289434A - Detection of gas leakage - Google Patents

Abstract

PURPOSE:To easily detect the leakage of gas at a complicated place and to shorten a detection time, by applying a solution of a resin having film forming capacity to a gas leakage place and forming a balloon like resin film by the pressure of leaked gas. CONSTITUTION:A solution of a resin having film forming capacity is applied to a gas leakage place to volatilize the solvent of said solution and a balloon like resin film is formed by the pressure of leaked gas to detect the leakage of the gas. As the solution of the resin having film forming capacity, an aqueous polyvinyl alcohol solution or an alcohol solution is pref. used. For example, the lower case 1 and upper case of an upper-and-lower split type cylindrical cable splice closure are used to connect communication cables 2 therein and unified by covering the connection part by a tape to detect the gas leakage of the connection part 1a of the upper and lower cases in a structure wherein inert gas such as nitrogen gas is hermetically sealed in the formed cable splice closure.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a gas leak detection method.

[Conventional technology]

Generally, communication cables such as telephone cables are passed through underground piping, and are connected to each other through manholes or the like provided at predetermined intervals.

In general, such connections are made by peeling off the coating at the end of a communication cable to expose the copper wire, etc., connecting it with the copper wire, etc. at the end of another communication cable, and then wrapping the connected part with tape, etc. This is done by rotating it to isolate it from the outside. Then, the above-mentioned connecting part is sealed by placing it in a cylindrical cable splice closure that is divided into two halves, and an inert gas such as nitrogen gas is filled in the cable splice closure, so that the connecting part is kept out of the air. It protects it from being attacked by oxygen.

[Problem that the invention seeks to solve]

When the cable splice closure having the structure described above is used to seal and protect the joints of communication cables, the inert gas sealed within the cable splice closure exerts a great protective effect. Therefore, in the past, soap water, etc., was applied to the joint of the cable splice closure, which is divided into two halves, and when there was a gas leak, the soap water expanded into a balloon shape, which was used to remove the inert gas. We are investigating whether there is a gas leak. However, when checking for gas leaks in this way, soap liquid or the like may flow in complicated areas such as curved parts.

This makes it extremely difficult to detect gas leaks. In addition, it is necessary to remain in place and observe for a while whether the soapy water expands into a balloon shape due to the leaked gas, and such observation takes time. Applying soapy water to each connection part of a long communication cable in this way and observing whether a film has formed while staying there is extremely time consuming and uneconomical. be.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a gas leak detection method that can easily detect gas leaks at complicated locations and can significantly shorten the detection time. .

[Means for solving problems]

In order to achieve the above object, the gas leak detection method of the present invention applies a solution of a resin having film-forming ability to the gas leak location, evaporates the solvent, and forms a balloon-shaped resin film using the gas pressure of the leaked gas. The system is configured to detect gas leaks by detecting gas leaks.

In other words, this method detects gas leaks using a resin solution that has the ability to form a film, and since the resin solution has a relatively high viscosity, it does not act like soapy water when applied to the gas leak location. There is no such thing as flowing down. Therefore, gas leakage can be detected by easily applying it even to complicated parts. In this case, at the gas leak location, the solvent in the resin solution evaporates, and a balloon-shaped resin film is formed by the gas pressure of the leaked gas, and this resin film maintains its state after being formed. Therefore, after applying the above resin solution one after another to a large number of gas leak detection points, the next step is to observe the presence or absence of a balloon-shaped resin film formed by the gas pressure of the leaked gas. Gas leaks at detection points can be detected in a very short time.

As described above, the present invention detects gas leakage using a solution of a resin capable of forming a film.

The resin having the above-mentioned film-forming ability is not particularly limited, and includes polyvinyl alcohol, vinyl acetate resin,
Various resins such as vinyl chloride resin and polyolefin resin can be used alone or in combination, and acetone can also be used when making a solution.

Organic solvents such as alcohol and methyl ethyl ketone can be used as appropriate. Water can also be used as a suitable solvent.

In particular, as the solution of the resin capable of forming a film, it is preferable to use an aqueous solution or an alcohol solution of polyvinyl alcohol. Such an aqueous or alcoholic solution of polyvinyl alcohol shows good results in terms of accuracy and danger to the human body in detecting gas leakage at the joint of the cable splice closure. Particularly preferred is a 10 to 30% by weight (hereinafter abbreviated as "r%") water or alcohol aqueous solution of the polyvinyl alcohol (hereinafter abbreviated as rPVA). Further, a water-alcohol mixed solution of the above PVA may also be used. By detecting gas leaks using such a solution, good detection results can be obtained.

For example, as shown in FIG. 1, a lower case 1 and an upper case (not shown, but having the same shape as the lower case 1) of a cylindrical cable splice closure that is divided into upper and lower halves are used. , the communication cable 2 is connected inside and the connection part is covered with tape or the like (not shown), and the upper and lower cases are integrated as shown in FIG. Joint part 1 of upper and lower cases in a structure sealed with inert gas such as nitrogen gas
It is suitable for detecting gas leaks in a. In FIGS. 1 and 2, numeral 3 is a bolt hole for inserting a connecting bolt 13 for connecting the upper and lower cases, and 4 is a disk-shaped positioning spacer, which is divided into upper and lower halves. 8a is a U-shaped attachment part, and 8 is a fixing part supported by the attachment part 8a and holding and fixing the cable 2 with its own teeth. Reference numeral 7 designates a sealing member for sealing the opening of the cable splice closure, with plate 7a for inner tightening and plate 7 for outer tightening.
b, and a backing material 7c sandwiched between them. Gas leakage at the joint between the lower case 1 and the upper case of the cable splice closure having such a structure can be detected extremely easily and quickly by using the PVA solution. in this case,
When using a 10% aqueous solution of PVA, 1 m! It is possible to detect gas leaks of less than 1/min, and the diameter of the balloon-shaped resin film 14 (see FIG. 3) that is generated is approximately 5IIIn1.

Furthermore, when the PVA concentration is 20%, it is optimal for detection of about 1 ml, 1 minute, and in this case, the diameter of the balloon-shaped resin film produced is about 5 mm. Further, when the PVA concentration is 30%, it is possible to detect a gas leak of 1 mR/min or more, and the diameter of the balloon-shaped resin film is 5 mm or more. The balloon-shaped resin coating 14 thus formed is then solidified as it is. Therefore, later on, this balloon-shaped resin coating 1
The presence or absence of gas leakage can be easily detected by observing the presence or absence of generation of gas. In particular, the PVA concentration is
When the concentration is set to a high concentration of 0% or more, gas leakage of 1 m2/min or less can be prevented due to the effect of the balloon-like resin film formed.

Although the above explanation describes the detection of gas leaks in cable splice closures, this invention can be applied not only to the detection of gas leaks in the cable splice closures mentioned above, but also to the detection of all types of gas leaks. It is.

〔Effect of the invention〕

In the gas leak detection method of the present invention, a solution of a resin having film-forming ability is applied to the gas leak location, a balloon-shaped resin film is formed by the gas pressure of the leaked gas, and the gas leak is detected by the resulting balloon-shaped resin film. Therefore, unlike the conventional gas leak detection method using soapy water, there is no need to stay at the detection location and wait to see whether the soapy liquid swells into a balloon shape. That is, gas leakage can be detected by applying the adhesive to a large number of gas leakage locations at once, and then observing them all at once after a predetermined period of time has elapsed. Therefore, gas leaks at a large number of gas leak detection points can be detected efficiently and in a short time. Furthermore, since gas leakage points are detected using a solution of a resin that has a film-forming ability, it is possible to detect the presence or absence of gas leakage even in gas leakage points with complicated shapes.

Therefore, it becomes possible to easily detect gas leaks in locations where it has been extremely difficult to detect gas leaks in the past.

Next, the present invention will be explained based on examples.

[Examples 1 to 3] A PVA aqueous solution having a concentration as shown in Table 1 below was prepared, and this was applied to detect gas leakage in a cable splice closure having the structure shown in Figs. 1 and 2. . In this case, the amount of leaked gas was set as shown in the same table, and the size and volume of the balloon-shaped resin film (balloon ball) produced at that time was shown in the same table. In other words, according to the example, after applying the gas leak detection solution, even if you do not stay on the spot,
Later on, gas leaks can be detected by checking for the presence or absence of balloons. As a result, it can be seen that the gas leak detection time can be shortened.

(Margins below) Table 1 *: Volume of balloon after 0 minutes elapsed after application of PVA aqueous solution.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a cable splice closure to which the gas leak detection method of the present invention can be applied, with the upper case removed, and Fig. 2 is a perspective view of the cable splice closure with the upper case removed. FIG. 3 is a sectional view taken along line 1--2 in the fixed state, and is an explanatory diagram of the state in which the balloon is formed. l...Lower case 2...Communication cable 14...
・Balloon-shaped resin coating

Claims (2)

[Claims] (1) Gas leakage is detected by applying a solution of a resin having film-forming ability to the gas leakage location, volatilizing the solvent, and forming a balloon-shaped resin film using the gas pressure of the leaked gas. Detection method. (2) The gas leak detection method according to claim 1, wherein the solution of the resin having film-forming ability is an aqueous solution of polyvinyl alcohol.