PURPOSE: To provide a measuring method in which the inside diameter of a buried pipe such as a gas pipe or the like can be measured easily and surely.
CONSTITUTION: A transmitter 12 and a receiver 15 are inserted respectively into both sides of a pipe 2 to be measured. Radio waves at a prescribed frequency band are transmitted continuously from the transmitter 12, and they are received by the receiver 15. The receiver 15 investigates the strength of the received radio waves, and it finds a frequency at a point at which the strength is fluctuated largely. Then, the frequency at the point is substituted in the relational expression of the frequency to the inside diameter of the pipe: (inside diameter) = (light velocity)/(1.706 × frequency), and the smallest inside diamter of the pipe in a part to be inspected is computed.
FURUSAWA HAJIME
HOSOHARA YASUHARU
KOBORI TAKASHI
