| 摘要 |
PURPOSE:To prevent an explosive atmosphere from being generated and gas components from being changed and to miniaturize an apparatus by supplying and discharging a gas of the same kind as a low temperature liquefied gas to and from a ballast tank, respectively. CONSTITUTION:A submerging body 2 for carrying a flaw detecting and inspecting instrument is provided with a propulsion machine 3 for movement and a ballast tank 4 having a gas exhaust valve 7, a liquid discharge valve 8 and a gas supply valve 9. A liquefied gas of the same kind as the one accommodated in a tank to be inspected is filled in the ballast bank 4. A gas of the same kind as the liquefied gas can be supplied from a gas supply member 10 like a pipe or the like. When the submerging body 2 is to be moved downward, buoyancy is reduced by opening the gas supply valve 9 to discharge the gas 6. When the submerging body 2 is to be moved upward, buoyancy is increased by opening the gas supply valve 9 to supply the gas from the gas supply member 10.
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