PURPOSE: To provide the subject equipment capable of making the inside of a storage tank with an atmosphere enriched in the content of nitrogen by introducing a volume of air deoxygenated through a gas-separation membrane unit into storage tank, where the volume is equal to that enriched in the content of oxygen by the gas-separation membrane nitrogen.
CONSTITUTION: Oxygen in the air is initially removed by driving a vacuum pump 14 and a fan 16 and supplying the air in a tank 11 accommodating stored materials through a duct 15 to a gas-separation membrane unit 13. The resultant nitrogen-enriched air from which oxygen is removed is then supplied through a supply passage 17 to the tank 11 and the above-removed oxygen-enriched air is exhausted. The same volume of the air as that of the exhausted oxygen- enriched air is sucked through an air-intake inlet 21 to duct 15 by a function of the fan 16. The sucked air is mixed with the nitrogen-enriched air from the tank 11 and subsequently introduced through the gas-separation membrane unit 13 into the tank 11.
KOBAYASHI TAKAKI
SAWADA TASUKE
