| 摘要 |
PROBLEM TO BE SOLVED: To obviate the occurrence of a deformation phenomenon even under a negative pressure state which is nearly vacuum by covering an internal insert tube with a helical pipe, covering its outside surface with a net-like pipe, covering the net-like pipe with an outer cover tube and packing a packing member into a space held by the internal insert tube and the outer cover tube. SOLUTION: The outside surface of the internal insert tube 11 of the flexible pipe 10 is covered with the helical pipe 12, the outside surface of the helical pipe 12 is covered with the net-like pipe 13 and the outside surface of the net- like pipe 13 is covered with the outer cover tube 14. The outer cover tube 14 is formed to a tubular form by, for example, extrusion molding of a polyurethane based resin and is welded to the net-like pipe 13 by the heat at the time of the extrusion molding. The internal insert tube 11 and the outer cover tube 14 are joined both to an operator side mouthpiece on a base end side. The internal insert tube 11 and the outer cover tube 14 are directly joined at the front end. The flexible packing member 16 like, for example, an elastomer, is packed into the space 15 between the internal insert tube 11 and the outer cover tube 14 to eliminate an air layer from the inside of the space 15.
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