JP7296570B2 - Traction device and traction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a traction device and method for pulling a line into a cable-laid conduit.

Under a bridge over a river or the like, a pipeline is installed over a long distance of, for example, several hundred meters. The conduit is made of resin such as FRP (Fiber-Reinforced Plastics), and an OF (Oil Filled) cable such as a high-voltage electric wire is laid inside.

In such a pipeline, if the OF cable ignites due to an electric leak or the like, the pipeline itself, which is made of resin, will burn, and the flame will spread to the outside of the pipeline, possibly causing a fire. Therefore, in anticipation of such a situation, it is necessary to take some kind of disaster prevention measures in conduits in which cables are laid.

Patent Document 1 discloses an intra-pipe wire in which a pulling tool with a wire connected thereto is inserted into a pipeline in which a cable is laid and sucked or pumped to move the pulling tool and insert the wire into the pipeline. method is described. This traction device is configured by providing a plurality of single traction devices including a parachute-shaped traction member, a plurality of traction cords provided on the traction member, and a converging portion in which the plurality of traction cords are bundled. It is

In the method of Patent Document 1, when a traction tool is inserted into a pipeline and sucked or pumped by a suction device or an air blower, the traction tool receives an air current flowing in a wide space above the pipeline. According to the document, the wire rod can be inserted into the pipe line by moving the pipe.

Japanese Patent Application Laid-Open No. 2003-244813

The present inventors came up with the idea of drawing a fire-extinguishing tube capable of pressurizing a fire-extinguishing agent into the gap between the conduit and the cable over the entire area of the conduit as a disaster prevention measure. In this way, when the OF cable ignites, the fire extinguishing tube is torn by the heat of the ignited portion, and the fire extinguishing agent is sprayed to the ignited portion to extinguish the fire.

In order to realize this disaster prevention measure, it is conceivable to apply the construction method described in Patent Document 1 and draw a fire-extinguishing tube into the pipeline. However, when the inventors of the present invention verified that the parachute-shaped towing member causes the wind to escape to the side of the parachute, it is not possible to sufficiently receive the wind, making it difficult for the towing device to move sufficiently within the pipeline. Met.

In addition, when air is pumped into a pipeline, air may leak from the joint of the pipeline, or if there is a defect in the pipeline, air may leak from that site (defective part of the pipeline). In such cases, the traction device cannot advance beyond the duct defect.

SUMMARY OF THE INVENTION The object of the present invention is to provide a traction tool and a traction method capable of reliably pulling a fire-extinguishing tube into a cable-laid pipeline.

In order to solve the above problems, a typical structure of the traction tool according to the present invention is a traction tool for pulling a line into a pipeline in which a cable is laid, and is a spindle-shaped tuft in which a large number of fibers are bundled. , a double-structured belt-shaped body that forms a cylinder in the longitudinal direction, and an elongated nozzle having a wire-passing rod attached to both longitudinal ends of the belt-shaped body, and a line is attached to the tuft, The elongated nozzle is characterized by a line threaded through the double structure of the strip, which is paid out with the tuft into the conduit, and the air is pumped through the double structure.

The traction tool having the above configuration includes a spindle-shaped tuft in which a large number of fibers are bundled, and an elongated nozzle. The elongated nozzle is a belt-shaped body with a double structure that forms a cylinder in the longitudinal direction, and wire-connecting rods are attached to both edges in the longitudinal direction of the elongated nozzle. In other words, the elongated nozzle has a structure in which two wire rods are connected by a band. From another point of view, the extension nozzle has a structure in which a hose is folded and both sides of the hose are reinforced with two wire rods. The length of the width of the belt-like body of the double structure is appropriately set according to the inner diameter of the pipeline and the size of the gap between the pipeline and the cable. Therefore, when the elongated nozzle is inserted into the gap between the cable and the conduit in which the cable is laid, the elongated nozzle is placed on the cable. Here, the cross-sectional shape of the conduits and cables is substantially circular. Therefore, in the pipeline in which the cable is laid, the shape of the gap between the cable and the pipeline becomes a crescent shape.

In other words, when the elongated nozzle is placed on the cable, it does not sink into the narrow portion of the crescent-shaped gap. For this reason, the belt-shaped body is made of a woven cloth like a fire hose coated with an elastic resin such as elastomer or rubber, and is flexible but hard to some extent. When the elongated nozzle is extended into the conduit, the elongated nozzle can reliably move through the conduit while remaining on the cable.

For this reason, as in the above configuration, the elongated nozzle and the tuft are paid out together in a state where the line attached to the tuft is passed through the double structure of the strip of the elongated nozzle. You will definitely move on the road. Then, when air is pumped into the double structure of the band, the tufts will pop out of the elongated nozzle from the position reached in the conduit and beyond. Furthermore, since the tufts have a fusiform shape formed by bundling a large number of fibers, they can ride the wind well and move reliably in the pipeline.

For example, when air is pumped into a pipeline, air may leak from the joint of the pipeline, or if there is a defect in the pipeline, air may leak from that site (defective part of the pipeline). In such cases, the tuft cannot advance past the duct defect. Therefore, in the towing tool having the above configuration, the air can be pumped into the double structure after the extension nozzle is drawn out so as to reach beyond the joint portion of the pipeline and the missing portion of the pipeline. In this way, the spindle-shaped tufts fly out of the elongated nozzle from the position reached by the elongated nozzle, that is, the position ahead of the joint and the missing part of the pipeline, and are not affected by air leakage and can be easily carried by the wind. It can move inside the pipeline reliably.

In addition, since a line such as a messenger rope (string) is attached to the tuft, the line can be reliably pulled into the duct by pulling the tuft out of the duct. Here, as an example, when the conduit is an FRP pipe and the cable is an OF cable such as an electric wire, the operator pulls the line into the conduit, then ties a fire-extinguishing tube to the line and recovers the line. This allows the fire-extinguishing tube to be drawn into the pipeline. In this way, in a situation where the OF cable catches fire due to an electric leak or the like, the fire extinguishing tube is torn by the heat in the pipeline, and the fire extinguishing agent is sprayed to the ignited part, so that the fire can be extinguished.

In order to solve the above problems, a representative configuration of the pulling method according to the present invention includes a spindle-shaped tuft in which a large number of fibers are bundled, a double-structured belt-shaped body that is a cylinder in the longitudinal direction, and a belt-shaped body. A pulling method for pulling line into a cable-laid conduit using a pulling tool comprising an elongated nozzle with wire-through rods mounted on opposite longitudinal edges, the pulling method comprising: A long line is attached to the tuft, the line is passed through the double structure of the strip of the elongated nozzle, the elongated nozzle is paid out from one end of the duct into the duct together with the tuft, and the elongated nozzle is higher than the missing part of the duct. When it reaches the end, air is pumped into the double structure to move the tuft to the other end of the pipeline while maintaining the tension of the line, and the tuft is recovered.

The components corresponding to the technical concept of the traction device described above and their descriptions are also applicable to the method. That is, in a state in which a line is attached to a spindle-shaped tuft, an elongated nozzle is fed out from one end of the duct into the duct together with the tuft. Air is pumped into the double structure. In this way, the spindle-shaped tufts fly out of the elongated nozzle from the position reached by the elongated nozzle, i.e., the position ahead of the defective portion of the pipeline, and can be easily carried by the wind without being affected by air leakage from the defective portion. can reliably move through the pipeline.

Furthermore, when the tufts move through the duct, the tension of the line is maintained so that the tufts do not loosen, thereby adjusting the movement speed of the tufts. For example, if the moving speed of the tuft is too high, the tuft will rush into a narrow portion of the crescent-shaped gap between the duct and the cable and cannot move. However, by adjusting the movement speed of the tufts, the tufts are attracted to the wide part of the crescent shaped gap (ie, the part where the wind velocity is high and the pressure is low), and the tufts can be reliably moved through the duct.

The line can then be drawn into the duct by retrieving the tuft that reaches the other end of the duct. After drawing the line into the pipeline, the worker can tie the fire-extinguishing tube to the line and recover the line, thereby drawing the fire-extinguishing tube into the pipeline.

ADVANTAGE OF THE INVENTION According to this invention, the traction tool and the traction method which can pull a fire-extinguishing tube into the pipeline with which the cable was laid reliably can be provided.

FIG. 4 is a diagram showing a pipeline to which a traction device is applied in an embodiment of the present invention; It is a figure explaining the leading conductor of the traction tool in embodiment of this invention. It is a figure explaining the extension nozzle of the traction tool in embodiment of this invention. It is a figure which shows the state of the traction tool which moves in a pipeline. It is a figure which shows the state of a traction tool following Fig.4 (a). FIG. 6 is a diagram showing the state of the leading conductor of the traction tool moving in the pipeline of FIG. 5;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are given the same reference numerals to omit redundant description, and elements that are not directly related to the present invention are omitted from the drawings. do.

FIG. 1 is a diagram showing a pipeline to which a traction tool is applied according to an embodiment of the present invention. FIG. 1(a) is a diagram showing a pipeline 102 installed under a bridge 100. FIG. FIG. 1(b) is a cross-sectional view of the pipeline 102 of FIG. 1(a) taken along the line AA. As shown in FIG. 1(b), a plurality of pipelines 102 are installed under the bridge 100, but one pipeline 102 is representatively shown in FIG. 1(a).

Under the bridge 100 shown in FIG. 1A, a pipeline 102 is installed over a long distance of, for example, several hundred meters. The pipeline 102 is made of resin such as FRP, and a high-voltage electric wire (OF cable 104) and the like are laid inside. Such pipelines may be installed not only under the bridge 100 but also underground. In such a conduit 102, if the OF cable 104 catches fire due to an electric leak or the like, the conduit 102 itself, which is made of resin, will burn, the flame will spread to the outside of the conduit 102, and finally a fire will occur. can be.

Therefore, in this embodiment, a disaster prevention measure is adopted in which a fire extinguishing tube 110 indicated by a dashed line in FIG. Although details will be described later, the traction tool 200 includes leading conductors 106 and 108 shown in FIG. 2 and an elongated nozzle 201 shown in FIG. Here, the inside of the conduit 102 is the gap 112 between the conduit 102 and the OF cable 104 shown in FIG. Therefore, it has a crescent shape.

A fire suppression tube 110 is drawn into the conduit 102 located between the manholes 114,116. Both ends of the fire-fighting tube 110 are also connected to fire-fighting pumps 118 , 120 located within the manholes 114 , 116 . Fire extinguisher is supplied under pressure from fire pumps 118 and 120 to fire tube 110 .

In this way, in a situation where the OF cable 104 catches fire, the fire extinguishing agent is sprayed to the ignition site by breaking the fire extinguishing tube 110 due to the heat of the ignition site, so that the fire can be extinguished.

FIG. 2 is a diagram illustrating leading conductors 106 and 108 of traction tool 200 in accordance with an embodiment of the present invention. The leading conductors 106 , 108 are used to pull the fire extinguishing tube 110 into the conduit 102 in which the OF cable 104 is laid, ie, the gap 112 .

The leading conductor 106 shown in FIG. 2( a ) has a plurality of (here, three) tufts 122 . The tuft 122 is formed into a spindle shape by bundling a large number of fibers, and further surrounds a rigid shaft 124 with the bundle of fibers. As an example of the fiber bundle, a PE cord (3 twisted, 8 mm diameter, bulk density: 0.2 g/cm ³ ) with a length of 1000 mm is prepared, untwisted, and then folded in two to form a plurality of strands. The combined product is regarded as one bundle. Therefore, the total length of the fiber bundle is about 500 mm. Also, the shaft 124, which is more rigid than the bundle of fibers, is a 3 mm diameter vinyl chloride rod here, but is not limited to this.

The fibers of the tuft 122 are swelled by untwisting the PE cord, so that the tuft 122 easily forms a spindle shape, and by surrounding the rigid shaft 124 with a bundle of fibers, the spindle shape can be reliably maintained.

A line (string 130 ) is attached to the rear end 126 of the tuft 122 via a connecting portion 128 . The string 130 may be made of a material such as polyethylene that is light and has a small coefficient of friction between the pipeline 102 and the OF cable 104 . As the string 130, for example, a rope for mooring a boat or the like may be used.

The leading conductor 108 shown in FIG. 2B is a modification of the leading conductor 106 shown in FIG. The leading end portion 132 has a flat shape as shown in FIG. 2(c), and here, the leading ends 134 (see FIG. 2(b)) of the three tufts 122 are fixed in a row. The leading end portion 132 can be configured by, for example, sandwiching the leading end of the tuft 122 between two resin films.

FIG. 3 is a diagram illustrating the extension nozzle 201 of the traction tool 200 according to the embodiment of the present invention. Elongated nozzle 201 is used with leading conductors 106 , 108 when drawing fire tube 110 into gap 112 of conduit 102 .

The elongated nozzle 201 comprises a band 202 and two wire rods 204 , 206 . The belt-shaped body 202 is made of a flexible material, such as a fire hose, but somewhat rigid. The material of the band-shaped body 202 is not limited to this, and the material of the band-shaped body 202 may be a woven cloth such as a fire hose coated with an elastic resin such as elastomer or rubber. Wire-passing rods 204 , 206 are made of FRP, for example, and are attached to both longitudinal edges 208 , 210 of strip 202 .

Both edges 208 and 210 of the band-shaped body 202 are connected by a body portion 212 so as to be airtight. The main body part 212 has a double structure 213 that forms a tube in the longitudinal direction as shown. Thus, the elongated nozzle 201 is a belt-like body 202 with a double structure 213 that forms a cylinder in the longitudinal direction. In other words, the elongated nozzle 201 has a structure in which two wire rods 204 and 206 are connected by the strip 202 . From another point of view, the extension nozzle 201 has a structure in which a hose is folded and both sides of the hose are reinforced with two wire rods 204 and 206 .

Further, in the band-shaped body 202 , both edges 208 and 210 are folded back in the width direction so as to wrap the wire-connecting rods 204 and 206 as shown, and the tips 214 and 216 are fused to the body portion 212 . Since the wire rods 204, 206 are attached to both edges 208, 210 of the strip 202 in this way, they are not twisted even when they are drawn out into the gap 112 of the pipeline 102 (see FIG. 4).

The tuft 122 of the leading conductor 106 shown in FIG. 2 has a fusiform shape inflated by bundling a large number of fibers. However, if there is a defective portion 218 (see FIG. 4A) in the pipeline 102, even if air is pumped into the pipeline 102, the air will leak from the defective portion 218, and the leading conductor 106 will be removed from the pipeline 102. It is not possible to go beyond the cutout 218 . Note that the missing portion 218 may be a joint portion of the pipeline 102 or the like.

Therefore, in the present embodiment, a configuration is adopted in which the leading conductor 106 can reliably move inside the conduit 102 even when air leaks from the missing portion 218 of the conduit 102 . The band-shaped body 202 has a total length L longer than the distance from one end 220 of the conduit 102 shown in FIG. 112 is appropriately set.

FIG. 4 is a diagram showing the state of the traction tool 200 moving inside the pipeline 102. As shown in FIG. FIG. 4(a) is a diagram showing the inside of the pipeline 102, and is a schematic diagram showing a state in which the pipeline 102 is viewed from above. FIG. 4(b) is a BB cross-sectional view of the pipeline 102 of FIG. 4(a).

The traction tool 200 is in a state in which a cord 130 attached to the leading conductor 106 is passed through the double structure 213 of the belt-like body 202 of the extension nozzle 201 as shown in FIG. 4(b). In addition, not only the string 130 but also the leading conductor 106 itself is pushed into the double structure 213 of the belt-like body 202 . Here, the total length of the string 130 is set longer than the total length of the pipeline 102 .

Furthermore, in the traction tool 200 shown in FIG. 4( a ), with the leading conductor 106 pushed near the tip 222 of the elongated nozzle 201 , the elongated nozzle 210 and the leading conductor 106 are placed together in the gap 112 in the conduit 102 . is being brought out. Elongated nozzle 210 and lead 106 are paid out by a payer 224 attached to one end 220 of conduit 102 .

The payout device 224 has a support base 226 and a ball roller 228 supported by the support base 226 . The ball rollers 228 have a structure like a pair of tires, are driven by a motor (not shown), and sandwich the elongated nozzle 201 into which the leading conductor 106 is pushed from above and below, thereby filling the gap 112 in the conduit 102 . , the extension nozzle 201 and the leading conductor 106 are paid out together. A traction device 200 having a leading conductor 106 and an elongated nozzle 201 is wound up and stored in a drum (not shown), and is pulled by a feeding device 224 from one end 220 to the other end of the pipeline 102 as indicated by an arrow C in the figure. 230 in gap 112 .

Here, since the gap 112 between the conduit 102 and the cable 104 has a crescent shape, the gap 112 has a wide portion 232 and narrow portions positioned on both sides of the wide portion 232 in the width direction as shown in FIG. and portions 234,236.

The elongated nozzle 201 has a structure in which wire-connecting rods 204 and 206 are attached to both longitudinal edges 208 and 210 of a belt-like body 202, and the two wire-connecting rods 204 and 206 are connected by the belt-like body 202 as described above. It has become.

Therefore, when the elongated nozzle 201 is pushed into the gap 112 between the pipe line 102 and the OF cable 104, it is placed on the cable 104 as shown in FIG. 4(b). In addition, since the belt-shaped body 202 is a rigid material to some extent, the dimension in the width direction does not easily change. As a result, the elongated nozzle 201 does not slip off the wide portion 232 of the gap 112 while riding on the cable 104 . Further, in the elongated nozzle 201, the inner diameter of the conduit 102 and the size of the gap 112 are adjusted so that the edges 208, 210 of the strip 202 do not enter the narrow portions 234, 236 of the gap 112 while riding on the cable 104. The length W (see FIG. 3) of the width of the strip 202 is set according to .

That is, when the elongated nozzle 201 is placed on the cable 104, it does not sink into the narrow portions 234, 236 of the crescent-shaped gap 112 and bite into it. Therefore, when the band-shaped body 202 is made of a somewhat hard material and the elongated nozzle 201 is fed into the pipeline 102 by the feeding device 224, the elongated nozzle 201 stays on the cable 104 and moves into the pipeline. 102 can reliably move within the gap 112 .

For this reason, like the traction tool 200, the extension nozzle 201 and the leading conductor 106 are drawn out together in a state in which the string 130 attached to the leading conductor 106 is passed through the double structure 213 of the belt-shaped body 202 of the extending nozzle 201. This ensures that the elongated nozzle 201 moves inside the conduit 102 together with the leading conductor 106 .

Further, in the traction tool 200, the extension nozzle 201 is extended so as to reach beyond the missing portion 218 of the pipeline 102 as shown in FIG. 4(a). That is, the tip 222 of the elongated nozzle 210 passes through the missing portion 218 of the pipeline 102 and reaches a position closer to the other end 230 of the pipeline 102 than the missing portion 218 .

FIG. 5 is a diagram showing the state of the traction tool 200 subsequent to FIG. 4(a). Subsequently, in the pulling tool 200, air is pressure-fed into the double structure 213 of the band-shaped body 202 of the elongated nozzle 201 by the air pressure-feeding device 238 shown in FIG. Air pumping device 238 is located near one end 220 of conduit 102 . The air pumping device 238 is a device connected to the double structure 213 of the strip 202, and drives a compressor (not shown) to push air (see arrow D) into the double structure 213 of the strip 202. to pump.

When air is pumped into the double structure 213 of the band 202, the leading conductor 106 reaches the position reached by the tip 222 of the elongated nozzle 201 in the conduit 102, i. Extends nozzle 201 from. Furthermore, since the tuft 122 of the leading conductor 106 has a fusiform shape inflated by bundling a large number of fibers, it rides well on the wind blown out from the double structure 213 (see arrow E) to reduce the influence of air leakage. It is possible to reliably move inside the pipeline 102 without being affected (see FIG. 6).

FIG. 6 is a diagram showing the state of the leading conductor 106 of the traction tool 200 moving in the conduit 102 of FIG. FIG. 6(a) is a diagram showing the inside of the pipeline 102, showing the state of the pipeline 102 viewed from the side. FIG. 6(b) is a cross-sectional view of the pipeline 102 of FIG. 6(a) taken along line FF.

The leading conductor 106 has a fusiform tuft 122 that is bulged by bundling a large number of fibers. Therefore, the leading conductor 106 protrudes from the elongated nozzle 210 into the gap 112 between the conduit 102 and the OF cable 104, and the wind blown out from the double structure 213 shown in FIG. 6(a) (see arrow E). When it receives the wind, it can reliably move inside the pipeline 102 by receiving the wind well.

Further, since the leading conductor 106 has a plurality of spindle-shaped tufts 122 (three in this case), it can close the crescent-shaped gap 112 and receive wind pressure well as shown in FIG. 6(b).

Here, when the leading conductor 106 moves within the gap 112, the operator moves the leading conductor 106 while maintaining tension so that the string 130 does not loosen. By moving the leading conductor 106 while maintaining the tension of the cord 130 in this manner, the moving speed can be adjusted.

As an example, if the moving speed of the leading conductor 106 is too high, the tuft 122 may rush into the narrow portions 234 and 236 of the crescent-shaped gap 112 and become unable to move. By adjusting the speed of movement of the leading conductor 106, the tufts 122 are drawn to the wide portion 232 of the crescent-shaped gap 112 (ie, the portion where the wind speed is high and the pressure is low). As a result, the leading conductor 106 can reliably move within the gap 112 . That is, it is more appropriate to express that the leading conductor 106 moves along with the air current rather than moving under the wind pressure.

Furthermore, the tuft 122 is formed not only by bundling fibers but also by surrounding a rigid shaft 124 (see FIG. 6(b)) with a bundle of fibers, so that the spindle shape can be reliably maintained. Therefore, when the tuft 122 is exposed to the wind in the gap 112, the tuft 122 can reliably move in the gap 112 while maintaining its spindle shape without being bent and caught in the narrow portions 234, 236 of the gap 112, for example.

Since the total length of the string 130 attached to the leading conductor 106 is longer than the total length of the pipeline 102, the leading conductor 106 moves within the gap 112 and moves toward the other end of the pipeline 102 facing the manhole 120 in FIG. 230 (see FIG. 5). Therefore, the operator can reliably pull the cord 130 into the conduit 102 by recovering the leading conductor 106 to which the cord 130 is attached and pulling out the traction tool 200 from one end 220 of the conduit 102 .

After pulling the string 130 into the pipeline 102, the operator can tie the fire-extinguishing tube 110 to the string 130 and recover the string 130, thereby pulling the fire-extinguishing tube 110 into the pipeline 102. .

When the leading conductor 108 (see FIGS. 2(b) and 2(c)) with a head portion 132 instead of the leading conductor 106 moves through the gap 112 in the conduit 102 shown in FIG. , the tips 134 of the three tufts 122 are bundled together by the head portion 132, so that the tufts 122 can be prevented from being caught in the gap 112 more reliably.

As described above, by using the tow tool 200 in the present embodiment, the string 130 and furthermore the fire-extinguishing tube 110 can be reliably drawn into the pipeline 102 in which the OF cable 104 is laid, thereby preventing the above-mentioned fire prevention. countermeasures can be implemented.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood.

INDUSTRIAL APPLICABILITY The present invention can be used as a pulling tool and pulling method for pulling a line into a cable-laid pipeline.

DESCRIPTION OF SYMBOLS 100... Bridge, 102... Pipeline, 104... OF cable, 106, 108... Leader, 110... Fire-extinguishing tube, 112... Gap, 114, 116... Manhole, 118, 120... Fire-extinguishing pump, 122... Chamber, 124... Shaft , 126... Rear end of tuft 128... Tie part 130... String 132... Head part 134... Tip of tuft 200... Traction tool 201... Elongation nozzle 202... Belt-like body 204, 206... Wire threading rod , 208, 210...Both edges of the belt-like body 212...Body portion 213...Double structure 214, 216...Tips of both edges 218...Deficient portion of pipeline 220...One end of pipeline 222...Extended nozzle 224... Feeding device 226... Support base 228... Ball roller 230... Other end of pipeline 232... Wide gap part 234, 236... Narrow gap part 238... Air pumping device

Claims (2)

A towing device for drawing a fire-extinguishing tube into a cable-laid conduit,
A leader having a spindle-shaped tuft in which a large number of fibers are bundled;
Equipped with a double-structured belt-shaped body that is cylindrical in the longitudinal direction, and an elongated nozzle having a wire-connecting rod attached to both longitudinal ends of the belt-shaped body,
A line is attached to the leading conductor ,
said elongated nozzle passes said line through a doublet of said strip and is paid out with said lead into said conduit to pump air through said doublet ;
the line is drawn into the conduit by the movement of the leading conductor receiving the air;
A tow tool , wherein the fire-extinguishing tube is tied to the line and drawn into the pipeline by retrieving the line . A leader having a spindle-shaped tuft in which a large number of fibers are bundled;
A conduit in which a cable is laid by using a traction tool comprising a double-structured belt-shaped body that is cylindrical in the longitudinal direction and an elongated nozzle having a wire-connecting rod attached to both longitudinal ends of the belt-shaped body A towing method for drawing a fire extinguishing tube into a
attaching a line longer than the total length of the conduit to the leading conductor ;
passing the line through the duplex structure of the strip of the elongated nozzle;
The elongated nozzle is extended from one end of the conduit into the conduit together with the lead conductor , and when the elongated nozzle reaches beyond the missing part of the conduit, air is pumped into the double structure,
While maintaining tension on the line, move the leading conductor to the other end of the conduit, retrieve the leading conductor , draw the line into the conduit, and tie a fire tube to the line. and pulling said fire extinguishing tube into said conduit by retrieving said line .

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