If you forget to cover the neck plug during use,there will be three situations,the third situation is dangerous.
1. Liquid nitrogen volatilizes in large quantities
Liquid nitrogen is a low-temperature liquid that is easily volatile at -196°C.It will evaporate more quickly when exposed to heat. The liquid nitrogen tank is designed to better isolate heat,so that liquid nitrogen can be stored for a long time.The neck plug is made of polyurethane foam, which is not easy to break and has good thermal insulation properties and can isolate most of the heat.
If you forget to cover the neck plug,hot air will enter through the mouth of the tank and accelerate the evaporation of liquid nitrogen.If there are samples stored in the tank,the safety of the samples will be affected and the samples may become inactive.
Therefore,when we find that we have forgotten to cover the neck plug,we must first measure the height of the liquid nitrogen in the tank,refill it,and then cover the neck plug.