The use of liquid nitrogen Dewar is inseparable from liquid nitrogen filling, and filling of liquid nitrogen often encounters some physical phenomena caused by alternating cold and heat.
Users who commonly use liquid nitrogen Dewar know and know how to distinguish whether there is a quality problem in the container. Users who have new needs and have just used liquid nitrogen containers are easy to misjudge and attribute some non-quality problems to the lack of insulation of the container, or the real quality. Think of the problem as a physical phenomenon, like frosting on a lid plug!
It may be a quality problem, or it may only be a physical phenomenon, which needs to be judged according to the specific situation!
If it is just filled with liquid nitrogen, a small amount of frost forms on the neck plug of the liquid nitrogen tank, which is a normal phenomenon.
Because the temperature of the injected liquid nitrogen is -196°C, in addition to quickly freezing organisms, it can also quickly freeze the water that comes into contact with it. When the liquid nitrogen Dewar is filled with liquid nitrogen, the opening is wide open, and the low temperature of liquid nitrogen will condense the moisture in the surrounding air, forming a small amount of frost, so it is a normal phenomenon.
However, if the filling of liquid nitrogen has been completed, and after staying for several hours, the frost on the liquid nitrogen Dewar cover not only does not disappear, but also becomes thicker and thicker, and even the surface of the liquid nitrogen tank begins to frost, indicating the vacuum degree of the container. is problematic. At this time, don’t rush to put in samples, but immediately contact the brand manufacturer to provide a solution.
Although frosting is an alternating phenomenon of cold and heat, it will gradually fade after the low temperature source disappears; continuous frosting can only indicate that the low temperature source-liquid nitrogen is always there. Therefore, if you find that the liquid nitrogen Dewar cover is frosted, first determine the filling time of liquid nitrogen, and then observe. The persistent frost is probably caused by a vacuum problem.