Patent ID: 12241811

DESCRIPTION OF THE INVENTION

A description will be hereinafter given on a liquid leakage detection line according to an embodiment of the present invention, with reference to the drawings.

A leakage detection line1according to a first embodiment shown inFIG.1andFIG.2includes a first conductor10a, a second conductor10b, and a braid20that directly covers each of the conductors. That is, each of the first conductor10aand the second conductor10bis separately covered by the braid20. The first conductor10aand the second conductor10bare arranged in the liquid leakage detection line1to be configured to be electrically connected to each other through a liquid L to cause change in their conduction state so that the presence of the liquid L is detected. That is, the first conductor10aand the second conductor10bare members that respectively form a first electrode wire11aand a second electrode wire11bforming a pair in the liquid leakage detection line1. The first electrode wire11aincludes, as an essential member, the first conductor10a, and includes, as an optional member, a first braid20covering the first conductor10a. Similarly, the second electrode wire11bincludes, as an essential member, the second conductor10b, and includes, as an optional member, a second braid20covering the second conductor10b. The first electrode wire11aand the second electrode wire11bare supported by a support material30formed into a net shape so as to be disposed in parallel with each other with a clearance D therebetween. Accordingly, the liquid leakage detection line1is configured to cause the liquid L to be transmitted along the support material30and absorbed by the braids20, to thereby electrically connect the first conductor10aand the second conductor10bto each other through the liquid L.

In this embodiment, each of the first conductor10aand the second conductor10bincludes a copper wire101, and a conductive resin layer102formed on an outer side of the copper wire101.

The copper wire101is formed by twisting a plurality of annealed copper element wires. The copper wire101has a cross-sectional area generally set to 0.1 to 1.0 mm2.

The conductive resin layer102is formed of a resin in which a conductive substance such as carbon is dispersed. As a resin for forming the conductive resin layer102, a fluorine-based resin is preferable. Examples of the fluorine-based resin include a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an ethylene-tetrafluoroethylene copolymer (ETFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), and a tetrafluoroethylene resin (PTFE). The conductive resin layer102has a thickness generally set to 0.04 to 0.15 μm.

As shown inFIG.2, the clearance D between the first braid20forming the first electrode wire11aand the second braid20forming the second electrode wire11bis set to generally 2.0 to 5.0 mm, preferably 2.5 to 4.5 mm.

Although it varies depending on the structure of the liquid leakage detection line, the material of the resin yarn to be used, and the like, examples of the liquid L include water; acidic solutions such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid; alkaline aqueous solutions such as ammonia and sodium hydroxide; and organic solvents such as methyl alcohol, ethyl alcohol, and acetone.

The braid20is formed of basalt fibers. The basalt fibers are inorganic fibers formed by extrusion spinning of melted basalt. Thus, the liquid leakage detection line1including the braid20formed of the basalt fibers has excellent flame retardancy, water resistance, and chemical resistance. For example, with respect to flame retardancy, the liquid leakage detection line1can conform to NFPA262 standards. Further, since the basalt fibers have excellent water absorption, the braid20can easily absorb water or a liquid containing water as well as a water-soluble organic solvent, as compared with a braid formed of glass fibers. Thus, the liquid leakage detection line1including such a braid20has high detection accuracy in particular for water.

The braid20is formed by braiding a basalt yarn formed of the basalt fibers twisted together. As compared with glass fibers, the basalt fibers have excellent scratch resistance, and are thus advantageous during braiding with a braiding machine. More specifically, the braiding machine generally includes, for example, a guide ring for guiding a yarn, and the guide ring rubs the yarn during braiding to cause a risk of damaging the fibers forming the yarn. Thus, the basalt fibers having excellent scratch resistance make it relatively easy to form a braid.

The glass yarn needs to be processed with a relatively large amount of a sizing agent to prevent the glass fibers from fraying. When such a glass yarn is used for forming a braid of a liquid leakage detection line, the sizing agent inhibits electrical connection of conductors, thereby reducing the detection accuracy. In contrast, according to the basalt fibers, the basalt yarn with the basalt fibers unlikely to fray can be formed without use of the sizing agent or by being subjected to treatment with a relatively small amount of the sizing agent. Therefore, the liquid leakage detection line1including the braid20formed of the basalt yarn has excellent detection accuracy.

As described above, the basalt yarn can be subjected to treatment with the sizing agent without reducing the detection accuracy of the liquid leakage detection line1.

For the basalt yarn, it is preferable that an S-twisted yarn and a Z-twisted yarn be combined for use to prevent untwisting of portions of the yarns that are to be initially braided for forming the braid20.

The number of strands in a spindle of the braid20is set to generally 1 to 10, preferably 1 to 3, and the number of spindles of the braid20is set to generally 3 to 32, preferably 4 to 24.

The support material30is formed by braiding a plurality of resin yarns304to form a plurality of openings302between the first electrode wire11aand the second electrode wire11b. In this embodiment, the support material30is formed of five resin yarns304that are twilled between the first electrode wire11aand the second electrode wire11bwhile being wound around the first electrode line11aand the second electrode line11bat certain intervals, so that the plurality of openings302are formed between the first electrode wire11aand the second electrode wire11b. With such a configuration, the liquid leakage detection line1allows the plurality of openings302continuously arranged between the first electrode wire11aand the second electrode wire11bto be closed by the liquid L, to thereby enable the first conductor10aand the second conductor10bto be electrically connected to each other.

Each of the resin yarns304preferably has water repellency. This configuration enables the liquid L that closes the plurality of openings302of the support material30to be easily removed with waste cloth or the like. That is, the resin yarn304having water repellency enables each of the conductors to easily return to an electrically unconnected state. In this regard, the resin yarn304is preferably a monofilament. In this case, the diameter of the resin yarn304is generally set to 0.1 to 0.5 mm.

The pitch of the resin yarn304forming the support material30is set to preferably 5 to 20 mm, more preferably 10 to 20 mm.

An opening area of each of the plurality of openings302can be appropriately changed depending on the kind of liquid L and the kind of resin forming the resin yarn304, so as to enable the liquid L to close the opening302. For example, the opening area can be adjusted using, as an indicator, the contact angle of the liquid L with respect to a resin material forming the resin yarn304.

As the resin forming the resin yarn304, preferable is polyphenylene sulfite (PPS), an ethylene-tetrafluoroethylene copolymer (ETFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or the like.

Next, a description will be given on a liquid leakage detection line1according to a second embodiment shown inFIG.3andFIG.4. The same features as those of the first embodiment share the same reference signs, and the descriptions thereof will be omitted.

The liquid leakage detection line1according to this embodiment has both of a first conductor10aand a second conductor10bcovered by a single braid50, and further includes a covering material40that directly covers each of the first conductor10aand the second conductor10b. More specifically, the liquid leakage detection line1includes a first electrode wire11aformed of the first conductor10acovered by the covering material40, and a second electrode wire11bformed of the second conductor10bcovered by the covering material40, and the first electrode wire11aand the second electrode wire11bare covered by the single braid50in a state of being in parallel with and in contact with each other. That is, the first electrode wire11aand the second electrode wire11bare covered together by the single braid50. In this embodiment, the braid50is formed of basalt fibers. In other words, the first conductor10aand the second conductor10beach having the covering material40thereon are indirectly covered by the braid50formed of basalt fiber. Thus, the liquid leakage detection line1is configured to allow the liquid L to be absorbed by the braid50and to pass through the covering material40, to thereby electrically connect the first conductor10aand the second conductor10bto each other through the liquid L.

In the liquid leakage detection line1of this embodiment, the electrode wires in contact with each other are covered by the single braid50to have these electrodes located close to each other, as described above, so that the liquid L can be easily retained around each of the electrodes. For example, the liquid leakage detection line1of this embodiment can be suitably used to directly detect liquid leakage from a vertical pipe and a horizontal pipe provided along a side face and a top or bottom face of a building. More specifically, the liquid leakage detection line1installed on such a pipe enables the liquid L to be retained around each of the conductors without being dropped, and thus suppresses a loss of the liquid L required for electrically connecting the conductors to each other. That is, the liquid leakage detection line1of this embodiment can exhibit excellent detection accuracy even when it is applied to such a pipe as aforementioned that easily causes drops of the liquid L.

The covering material40is formed of a resin yarn404braided to have a plurality of openings402through which each conductor is exposed. The covering material40is thereby configured to allow the liquid L to pass through the plurality of openings402to come into contact with each conductor.

In terms of allowing the liquid L to more reliably pass through the plurality of openings402, the resin yarn404forming the covering material40is preferably a monofilament. In this case, the resin yarn404has a diameter generally set to 0.1 to 0.5 mm.

As the resin forming the resin yarn404, used can be polyphenylene sulfite (PPS), an ethylene-tetrafluoroethylene copolymer (ETFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or the like, and in terms of allowing the liquid L to more reliably pass through the plurality of openings402, polyphenylene sulfite is preferable.

The number of strands in a spindle of the covering material40is preferably set to 1 to 3, and the number of spindles of the covering material40is preferably set to 4 to 24.

The pitch of the resin yarn404forming the covering material40is set to preferably 5 to 20 mm, more preferably 10 to 20 mm.

An opening area of each of the plurality of openings402can be appropriately changed depending on the kind of liquid L and the kind of resin forming the resin yarn404, so as to enable the liquid L to pass through the opening402. For example, the opening area can be adjusted using, as an indicator, the contact angle of the liquid L with respect to a resin material forming the resin yarn404.

The braid50is formed of the basalt yarn forming the braid20in the first embodiment. The number of strands in a spindle of the braid50is preferably set to 1 to 3, and the number of spindles of the braid50is preferably set to 4 to 24.

Next, descriptions will be given on modified examples of the liquid leakage detection line1according to the second embodiment. In the liquid leakage detection line1as a modified example 1 shown inFIG.5, the resistance value of either one (second conductor10b) of the first conductor10aand the second conductor10bis set to be much higher than the resistance value of the other conductor (first conductor10a). That is, the second conductor10bis a resistance wire10b. The resistance value of the resistance wire10bis set to, for example, 10 to 11 Ω/m. As such a resistance wire10b, for example, a nichrome wire can be used. When the first conductor10aand the resistance wire10bare electrically connected to each other through the liquid L, this configuration enables the measurement of voltage depending on the distance from the power supply to the location at which the conductors are connected to each other. This configuration further enables the identification of the location at which the conductors are connected to each other through the liquid L, and consequently facilitates the identification of the location at which liquid leakage occurs in a building or the like.

The resistance wire10bhas a wire diameter generally set to 0.35 to 0.45 mm.

The liquid leakage detection line1of the modified example 1 includes, as a third conductor10c, a return wire10cconfigured to be short-circuited with the conductor10bforming the electrode wire11bat a terminal end portion. In identifying the location at which liquid leakage occurs, an electric current flows through the conductor10b. In this case, when no liquid L is present between the conductor10aand the conductor10b, no electric current flows through the conductor10cas the conductors are insulated by the respective covering materials40. In contrast, when the liquid L is present between the conductor10aand the conductor10b, an electric current flows from the conductor10bto the conductor10a, and flows to the conductor10cthrough the terminal end portion, to thereby enable liquid leakage detection and the identification of the location at which liquid leakage occurs.

The return wire10cis formed of a copper wire103having an insulating resin layer104on an outer side thereof. As a resin for forming the insulating resin layer104, a fluorine-based resin is preferable. Examples of such a fluororesin include a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an ethylene-tetrafluoroethylene copolymer (ETFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), and a tetrafluoroethylene resin (PTFE).

In the liquid leakage detection line1as a modified example 2 shown inFIG.6, only one of the first conductor10aand the second conductor10bis covered by the covering material40. Further, neither the first conductor10anor the second conductor10bhas the conductive resin layer102. This configuration omits a step of covering one of the conductors with the covering material40in the production of the liquid leakage detection line1, and relatively downsizes the liquid leakage detection line1.

As described above, a liquid leakage detection line1according to this embodiment includes: at least two conductors10including a first conductor10aand a second conductor10b, in which the first conductor10aand the second conductor10bare configured to be electrically connected to each other through liquid L, and in which each of the first conductor10aand the second conductor10bis directly covered by a braid20including basalt fibers, or the first conductor10aand the second conductor10bare indirectly covered by a braid50.

The basalt fibers are inorganic fibers formed by extrusion spinning of melted basalt. Thus, the liquid leakage detection line1has the conductors10each covered by the braid20including the basalt fibers or collectively covered by the braid50, and has excellent flame retardancy. Since the basalt fibers are less likely to sting or prick the hands and fingers of workers than glass fibers, the liquid leakage detection line1has good construction workability.

It is preferable that the liquid leakage detection line1further include: a support material30supporting the first conductor10aand the second conductor10b, and that the first conductor10aand the second conductor10bbe supported by the support material30so as to be disposed in parallel with each other with a clearance D therebetween.

Such a configuration in which the first conductor10aand the second conductor10bare supported by the support material30so as to be disposed with the clearance D therebetween suppresses erroneous detection.

The liquid leakage detection line1including the support material30is preferably configured such that the braid20includes a first braid20directly covering the first conductor10a, and a second braid10bdirectly covering the second conductor20, and that the first braid20and the second braid20are supported by the support material30so as to be disposed in parallel with each other with the clearance D therebetween.

Such a configuration in which the first conductor10aand the second conductor10bare directly covered respectively by the first braid20and the second braid20, which are the braids including the basalt fibers, has excellent flame retardancy. Further, the configuration in which the first braid20and the second braid20are supported by the support material30so as to be in parallel with each other with the clearance D therebetween suppresses erroneous detection.

The liquid leakage detection line1is preferably configured such that both the first conductor10aand the second conductor10bare covered by the single braid50, and that at least one of the first conductor10aand the second conductor10bis further covered by a covering material40through which the liquid L can pass.

Such a configuration in which both of the first conductor10aand the second conductor10bare covered by the single braid50and at least one of the first conductor10aand the second conductor10bis covered by the covering material40allows these conductors to be close to each other and thereby easily retain the liquid L therearound. This configuration can thus be applicable to, for example, a vertical pipe and a horizontal pipe provided along a side face or a top or bottom face of a building. That is, the above configuration can exhibit excellent detection accuracy even when it is applied to such a pipe as aforementioned that easily causes drops of the liquid L.

The liquid leakage detection line1including the covering material40is preferably configured such that one of the first conductor10aand the second conductor10bis not covered by the covering material40.

Such a configuration in which one of the first conductor10aor the second conductor10bis not covered by the covering material40reduces the number of steps of producing the liquid leakage detection line1, and relatively downsizes the liquid leakage detection line1.

As described above, the embodiments have been shown as examples, but the liquid leakage detection line according to the present invention is not limited to the configurations of the aforementioned embodiments. The liquid leakage detection line according to the present invention is not limited by the aforementioned operational effects, either. Various modifications can be made to the liquid leakage detection line according to the present invention without departing from the gist of the present invention.

EXAMPLES

Hereinafter, the present invention will be further described by way of Examples.

Example 1

A conductive ETFE was used to form a conductive resin layer on an outer side of a copper wire that is formed by twisting tin plated annealed copper element wires and that has a cross-sectional area of 0.33 mm2. Thus, two conductors were prepared. Using a braiding machine, a braid (number of strands in a spindle×number of spindles: 1×8, pitch: 16.0±2.0 mm) was formed with an S-twisted basalt yarn (BCY11.5-220KV12-S80, manufactured by JCK CO., LTD.) and a Z-twisted basalt yarn (BCY11.5-220KV12-Z80, manufactured by JCK CO., LTD.) to cover each of the conductors, so that two electrode wires were prepared. An ETFE monofilament (830-1-3190, diameter: 0.25 mm, manufactured by Toray Industries, Inc.) as a resin yarn was twilled between the respective electrode wires while being wound around these electrode wires so that the clearance D between the braids respectively forming the two electrode wires was 3.5±1.0 mm, so that a support material (number of strands in a spindle×number of spindles: 1×5, pitch: 10.0±2.0 mm) was formed. The obtained liquid leakage detection line had a width of 6.5±0.5 mm and a thickness of 2.0±0.4 mm.

Example 2

A conductive ETFE was used to form a conductive resin layer on an outer side of a copper wire that is formed by twisting tin plated annealed copper element wires and that has a cross-sectional area of 0.33 mm2. Thus, a first conductor and a second conductor were prepared. Using a braiding machine, a covering material (number of strands in a spindle×number of spindles: 2×8, pitch: 12±3 mm) was formed with a PPS monofilament (diameter: 0.25 mm) to cover each of the conductors, so that the first electrode wire and the second electrode were prepared. With the first electrode wire and the second electrode wire in parallel with each other and in contact with each other, a braid (number of strands in a spindle×number of spindles: 1×12, pitch: 13±5 mm) was formed using a braiding machine and the basalt yarns used for Example 1 to cover all the electrode wires. The obtained liquid leakage detection line had a diameter of 4.0±0.5 mm.

Example 3

A conductive ETFE was used to form a conductive resin layer on a copper wire that is formed by twisting tin plated annealed copper element wires and that has a cross-sectional area of 0.33 mm2. Thus, a first conductor was prepared. A conductive ETFE was used to form a conductive resin layer on a Kanthal D wire (diameter: 0.40 mm), so that a second conductor was prepared. Using a braiding machine and a PPS monofilament (diameter: 0.25 mm), a covering material (number of strands in a spindle×number of spindles: 2×8, pitch: 12±3 mm) was formed to cover the first conductor, and a covering material (number of strands in a spindle×number of spindles: 2×4, pitch: 11±3 mm) was formed to cover the second conductor, so that the first electrode wire and the second electrode were prepared. Further, a return wire (FEP wire, 0.5 sq) as a third conductor (FEP wire, 0.5 sq) was prepared. With the first electrode wire, the second electrode wire, and the return wire in parallel with each other and in contact with each other, a braid (number of strands in a spindle×number of spindles: 1×12, pitch: 13±5 mm) was formed using a braiding machine and the basalt yarns used for Example 1 to cover all of the two electrode wires and the return wire. The obtained liquid leakage detection line had a diameter of 3.5±0.5 mm.

Evaluation Method 1

The following testing equipment was used to observe the detection performance of each of the liquid leakage detection lines. For Example 1, about 100 μS/cm water was dropped onto the liquid leakage detection line at a rate of 0.05 mL/sec to measure a wet width of the liquid leakage detection line and the number of drops of water at the time when the conductors were electrically connected to each other through water. This measurement was performed 10 times to calculate the average values respectively of the wet width and the number of drops. As an evaluation standard, the liquid leakage detection line having the average wet width of 100 mm or less was evaluated as being excellent in detection performance. Examples 2 and 3 were also tested in the same manner as in Example 1. As an evaluation standard of Examples 2 and 3, the liquid leakage detection line was evaluated as being excellent in detection performance when the amount of dropped water was 3.0 mL (corresponding to 60 droplets) or less.

Testing Equipment

Water leakage detector: AD-AS-1AM (detection sensitivity of 50 kΩ, terminal connected at 82 kM), manufactured by TATSUTAMulti-parameter water quality checker (conductivity meter): WA-2017SD manufactured by SATOTECHMicroreactor (drop speed regulator): YSP-201 manufactured by YMCTester: DT4281 manufactured by HIOKIMetal ruler (for measuring wet width): CN9510 manufactured by Shinwa

Evaluation Method 2

Each of the liquid leakage detection lines was cut at a given position to evaluate whether 10 test subjects touching the cut portion with their fingers felt any irritating sensation such as itchiness or pain, based on the following evaluation standard:

(Evaluation Standard)

When 5 or more out of 10 test subjects did not feel itchiness or pain, such a liquid leakage detection line was evaluated as having good construction workability.

The liquid leakage detection line of each of Examples 1 to 3 has the conductors directly or indirectly covered by the braid(s) formed of basalt fibers, and thus has excellent flame retardancy, water resistance, and chemical resistance. As shown in Table 1 andFIGS.7to9, the liquid leakage detection line of each of Examples 1 to 3 is found to satisfy the above evaluation standard and have excellent detection accuracy. Further, the liquid leakage detection line of each of Examples 1 to 3 is found to have good construction workability since 7 out of 10 test subjects did not feel itchiness or pain.

TABLE 1EvaluationWet width (mm)Amount of water (mL)method 1Min.Max.Ave.Min.Max.Ave.Ex. 1154021.45.065.017.1Ex. 2206045.20.301.750.70Ex. 3207040.10.300.900.52

REFERENCE SIGNS LIST

1: Liquid leakage detection line10: Conductor101: Copper wire103: Copper wire102: Conductive resin layer104: Insulating resin layer20: Braid30: Support material302: Opening304: Resin yarn40: Covering material402: Opening404: Resin yarn50: BraidD: Clearance