| 摘要 |
PURPOSE:To perform checking of air leakage uniformly and quickly, by comparing background noises and an object sound generated by minute bubbles, which are collected by an underwater microphone, and issuing air leakage warning when the result indicates a specified significant difference or more. CONSTITUTION:An underwater microphone 5 is immersed in a liquid tank 2. At first background noises are collected. Then, a wheel 3 is immersed. The object sounds, which are generated by minute bubbles that are blown out of the pin hole part of the wheel 3 and minute bubbles that collide with the underwater microphone 5, are collected. Then, the sound pressure level differences between the background noises and the object sounds are compared in a comparator 23. When the result is a specified significant difference or more, air leakage warning 24 is issued. |
