| 摘要 |
PURPOSE:To rapidly and efficiently lay an optical fiber in the pipe by forming a space which has the total sectional area larger than the space sectional area of an inner pipe and continues in a longitudinal direction between the inner pipe and an outer pipe. CONSTITUTION:The double pipes are constituted of the inner pipe 2 and the outer pipe 3 disposed around this pipe apart therefrom to form such space 4 which has the total sectional area larger than the space sectional area of the inner pipe 2 and continues in the longitudinal direction between the inner pipe 2 and the outer pipe 3, and the inner and outer pipes are partically connected with spacers to each other. A negative pressure state is maintained at all times in the internal space 1 if the air force fed into the internal space 1 is sucked in the outer space 4. The optical fiber is rapidly and efficiently inserted and laid in the internal space 1 in this way. |
