| 摘要 |
PROBLEM TO BE SOLVED: To improve sensitivity in detecting a gas layer in a liquid in a pipe by providing a sound absorbing material layer on the outer periphery of a pipe which receives the reflected echoes of ultrasonic waves emitted along the diameter of the pipe from the outside of the pipe and emitting ultrasonic waves from the outside of the sound absorbing material layer. SOLUTION: The sound absorbing material layer 1 is provided on the outer periphery of a pipe 2, which is an object to be measured. Next, a probe 3 constituting the device for detecting a gas layer in a pipe is brought into contact with the outer surface of the sound absorbing material layer 1 from the outside of the sound absorbing material layer 1, and ultrasonic waves are emitted toward the piping 2. As a result, direct echoes 4 and indirect echoes 5 from the probe 3 are made incident along the diameter of the pipe 2. The direct echoes 4 are transmitted through a liquid in the pipe 2 and are reflected by the outer periphery 2a or inner periphery 2b of the pipe 2, and the indirect echoes 5 are propagated through the wall thickness part (between the outer periphery 2a and the inner periphery 2b) of the pipe 2 in circumferential directions. As the sound absorbing material layer 1 is provided on the outer periphery of the pipe 2, the echo intensity of the indirect echoes 5 is lower in comparison with the case that the sound absorbing material layer 1 is not provided, and the amount of attenuation of ultrasonic waves become large as the number of repeated reflections is increased. |
