Liquid nitrogen is volatile, but it is extremely “gifted” for frozen items. For this reason, people have developed cryo tanks, storage tank shapes, and vacuum structures, which retain liquid nitrogen at deep and low temperatures for refrigeration and freezing items.
Many users have questions: How cold is this cryo tank to ensure that the liquid nitrogen does not volatilize? After all, the temperature of liquid nitrogen is already very low.
In fact, the cryo tank itself is at room temperature, and it becomes a low-temperature tank after filling with liquid nitrogen. The position where liquid nitrogen is present is -196 °C.
The reason why the volatilization of liquid nitrogen can be reduced is not because the cryo tank temperature is lower, but its design principle.
According to the Dewar vacuum jacket, after several generations of improvement, it has become the current liquid nitrogen tank. The inner and outer bladders are evacuated, and the middle is filled with insulating and adsorbent materials to enhance the thermal insulation performance of the storage tank and ensure the low temperature of liquid nitrogen.
Of course, only the vacuum inner and outer tank is not enough to support the cryo tank’s low temperature.
In order to reduce the volatilization of liquid nitrogen, the cryo tank neck tube is designed to be very thin, and only the lifting cylinder or basket containing the sample passes through. Usually, there is a neck plug to seal, leaving only a slight pressure relief gap. Besides the neck plug, a lock is also added. cover to ensure sample safety.
So, it’s not how cold the cryo tank is, but because its structure is designed to retain the temperature of the liquid nitrogen.