Cryogenic storage tanks are typically used for storing and transporting cryogenic liquids such as liquid oxygen and liquid nitrogen, requiring low pressure and low temperature to be maintained inside. During use, air and impurity gases need to be removed from the tank to ensure a high vacuum level.
The vacuum extraction process requires the use of special vacuum pumps, generally either centrifugal pumps or dry sliding vane pumps. Centrifugal pumps can provide a large volume of gas removal, while dry sliding vane pumps are more suitable for handling high-purity gases.
Before using the vacuum pump, all tank hatches and vents should be opened to allow for better gas removal. The pump is then connected to the tank's vent port, and the other end is connected to a vacuum gauge to monitor the internal vacuum level.
When the vacuum pump begins to extract air, the tank and pump must be maintained in a specific operating state. Typically, the vacuum pump should run for 60-90 minutes to remove most of the gas and impurities, while maintaining appropriate temperature and pressure.
