The structure of cryogenic storage tank is different from ordinary pressure vessel, its structure adopts unique vacuum jacketed structure, that is, according to different design requirements in the closed metal liner and the outer shell using different insulation methods (vacuum powder material insulation, fiber material insulation, multi-layer insulation, etc.), so that the sandwich layer to achieve a certain degree of vacuum. This type of low-temperature storage tanks in the structure and use of the special characteristics of the decision of this type of products are technology-intensive products. Its manufacturing and production process involves low-temperature materials, low-temperature welding, low-temperature adsorption and other low-temperature technology and pressure vessel technology, vacuum technology, leak detection technology and other comprehensive technology, therefore, the corresponding inspection and testing technology requirements and ordinary pressure vessels there are certain differences.
　Due to its structure as a fully enclosed vacuum sandwich vessel, the medium is a low-temperature liquid, the liner can not be directly tested, to increase the difficulty of the inspection work. At the same time, the corresponding test specifications, procedures are not clear, the actual operation of the test is not strong, but also to the periodic inspection work has brought some difficulty. In order to ensure the reliability of the test, the need for a systematic analysis of the factors affecting the safety of the operation of cryogenic storage tanks, to understand the internal laws of cryogenic storage tanks, so as to determine the important links and key factors of the test content, methods.
　For liquid nitrogen tanks, when filling liquid nitrogen, evaporation will take forty-eight hours to restore the normal state, the time required to restore the normal state of a good liquid nitrogen tank can be reduced to twelve hours, evaporation loss can be eliminated by 50%. We understand the characteristics of liquid nitrogen and the brief structure of the liquid nitrogen tank, it is accurate to use it, but also to give full play to its performance. The main points of use are outlined below.
　First, there should be a person responsible for the management, use and maintenance. Liquid nitrogen tank storage room to the atmosphere, such as the storage of multiple liquid nitrogen tanks in a closed room, the evaporated nitrogen will remain in the room, resulting in a lack of oxygen, it is likely to produce asphyxiation. Manipulation of liquid nitrogen tanks should be gently put to stop collision with other objects, due to the liquid nitrogen tank by the exhaust and become a high vacuum, the surface and the tank by the atmospheric pressure is proportionally large, dr a 10 and dr a 30, for example, the pressure on the outer tank, about 40 kg to 90 kg, although it is made to bear three times the strength of self-weight, manipulation should be very careful, do not lose or collision.
　Second, the first time to fill the liquid nitrogen, or liquid nitrogen tank in a dry state, the first check to see if there are dents outside the tank or produce other extraordinary circumstances. If there are no foreign objects inside the tank, and if the base is solid. If these conditions are good, the tank can be filled with liquid nitrogen and should be held in a well ventilated place, usually outdoors. If held indoors, the doors and windows must be opened to link the good ventilation state. The filling of liquid nitrogen is a kind of pressurized injection method, which is to open the liquid valve from the large liquid nitrogen container and connect the flexible hose, and directly fill the liquid nitrogen tank with liquid nitrogen. The other is to directly use the funnel pouring method, which should be extra careful to make the end of the funnel slightly away from the neck tube, so that the liquid nitrogen evaporated gas can be smoothly from the gap between the funnel and the container, otherwise the liquid will overflow from the funnel, which will not only increase the loss of liquid nitrogen, but also produce frostbite accident. The rate of filling liquid nitrogen should be sluggish, first inject a small amount, and then stop for a few minutes, so that it cools and then gradually inject enough to the specified capacity.