LENGTH MEASUREMENT METHOD FOR EXISTING PIPE

摘要

PROBLEM TO BE SOLVED: To provide a measurement method for existing pipe capable of preventing the supply rate of resin liquid based on length measurement result from becoming inexact, when branches exist on the way to take out part positioning from an end to the other end of the main pipe and exact measurement cannot be done because of erroneous recognition of reflected sound. SOLUTION: A length measurement method for existing pipe provided with branch pipes 23A and 23B branched from a main pipe path 22 is processed by that an acoustic length meter 13 is arranged on one end of the main pipe 22 and the sound emitted from the acoustic length meter 13 is reflected on the other end to detect the reached time of the reflected sound, and an acoustic absorber 25 is positioned corresponding to 1/4 wave length of the sound from the opening in the pipe paths 23A and 23B of the main supply pipe 22 to make the pipe paths 23A and 23B other than the objective length measurement correspond to no-reflection state.