It is known that the liquid nitrogen tank is not a special equipment, but a container for liquid nitrogen, and liquid nitrogen cannot be carried on the plane.
In addition, from the definition of special equipment, only those with relatively high risk, such as boilers, pressure vessels, and hoisting machinery, belong to special equipment. Conventional liquid nitrogen tanks are only liquid nitrogen biological containers, which do not involve any use pressure, so they are not.
We know that the conventional liquid nitrogen tank has an outlet gas, so the gasified nitrogen can be discharged to ensure zero pressure in the container;
However, the dry shipper liquid nitrogen container needs to use nitrogen to preserve biological samples. It is not just a container for storing liquid nitrogen. It has a metal mesh screen + adsorbent inside to absorb the liquid nitrogen in the tank and then emit it through evaporation. Nitrogen is used to ensure low temperature and preserve samples. This is the only way to board airplanes and high-speed trains without worrying about passing the security check.
Therefore, there is always nitrogen in the dry-type liquid nitrogen container, and the presence of nitrogen means that there is pressure. Does it belong to special equipment?
Of course not!
The dry shipper liquid nitrogen container is one of the branches of the liquid nitrogen tank. Except for the additional filter and adsorption, the other structures are the same. Some conventional liquid nitrogen tanks have specially designed neck plugs to retain the air outlet. It also has a nitrogen storage inside. But the nitrogen is flowing, it does not accumulate in the tank all the time, and then forms a high pressure, causing dangerous events.
Therefore, dry shipper liquid nitrogen containers are not special equipment!