Liquid nitrogen tank storage is divided into two kinds of vapor phase and liquid phase, the root of which is deep cryogenic liquid nitrogen.
However, there are differences in sample preservation temperatures between Vapor phase liquid nitrogen storage and liquid phase due to the different ways in which liquid nitrogen operates!
One is a stepped temperature and the other is a constant temperature submerged in liquid nitrogen! Stepped temperature refers to Vapor phase liquid nitrogen storage!
Almost all liquid nitrogen containers that use vapor phase liquid nitrogen storage, such as the KGSQ BioBank series, have separate partitions for liquid nitrogen and samples, meaning that the liquid nitrogen is stored separately and the samples have separate storage areas. They are mostly located with the liquid nitrogen at the bottom of the entire biological sample library and the samples stored next to the liquid nitrogen, with trays between them.
The advantage of this design is that samples can be frozen using nitrogen after evaporation of liquid nitrogen without touching the liquid nitrogen, avoiding the problem of liquid nitrogen flowing into the freezing tube or the freezing tube floating on the liquid nitrogen surface, or even cross-contamination.
This design also makes the internal temperature of the Vapor phase liquid nitrogen storage container step, that is, the temperature gradually increases from the bottom up, the closer to the liquid nitrogen storage area, the lower the temperature, because it is close to the liquid nitrogen “body”, but also to enjoy the evaporated liquid nitrogen first.
The higher the temperature, the further away from the liquid nitrogen area, the higher the temperature, which is why the temperature is always higher near the mouth of the tank.
Vapor phase liquid nitrogen storage gives more options for sample preservation, allowing the selection of temperature zones based on sample preference, as well as the ability to perform experiments on the temperature sensitivity of some biological samples.
In addition, explain a little more, Vapor phase liquid nitrogen storage temperature is called step temperature, because the temperature in the horizontal area is uniform, but the temperature difference between the top and bottom of about 10 ℃!