Is the Dewar tank of liquid nitrogen sealed?

2024-05-20 09:52:42

Almost everything is sealed for the purpose of thermal insulation. This is true for thermos cups, and it is also true when people keep warm from the cold;

As a result, in our inertial thinking, if we want to maintain the temperature of a certain object, we need to seal it;

This is how many users think of using Dewar tanks for liquid nitrogen, thinking that it is the sealing that allows them to store liquid nitrogen for a long time!

Is that so?

Is the Dewar tank for liquid nitrogen sealed?


For safety reasons, all Dewar tanks for liquid nitrogen have exhaust gaps!

The reason is that if it is sealed, there is a high probability of explosion or damage to the container!

Liquid nitrogen has a low boiling point of -196.56°C. Its characteristics determine that its volatilization is inevitable. Although the liquid itself is colorless, odorless and non-toxic, and has the ability to quickly freeze all non-metallic items, the volume of nitrogen after volatilization expands nearly a hundred times, effectively Due to the airtight design in the space, nitrogen has been accumulating and cannot be effectively discharged, which is the source of pressure.

In the same way, the Dewar tank for liquid nitrogen has a storage capacity of 1-175 liters of liquid nitrogen and a small amount of naturally vaporized nitrogen. If it cannot be discharged in the container, it is a potential danger. This kind of volatilization is unavoidable. The vacuum + insulation layer design of the liquid nitrogen tank can only reduce part of the heat exposure of the liquid nitrogen. The way the product is opened and used determines that it cannot avoid a small amount of heat entering.

When heat enters, liquid nitrogen will vaporize. As a manufacturer, you must consider the dispersion of gas, which cannot accumulate all the time in the Dewar tank for liquid nitrogen. Therefore, the positions of the neck plug and the tank mouth are changed to reduce the diameter. Leave a gap at the mouth of the jar. The nitrogen gas that rises due to gasification expansion is naturally discharged from here, ensuring the balance and stability in the liquid nitrogen Dewar tank.

Therefore, the Dewar tank for liquid nitrogen is not sealed!

Is the Dewar tank of liquid nitrogen sealed