The neck tube is one of the most critical components of a liquid nitrogen tank, serving both structural and functional roles. It connects the tank’s inner vessel, which stores the liquid nitrogen, to the outer shell, which maintains the vacuum insulation. Though small in size, the neck tube plays a decisive role in the tank’s insulation efficiency and overall performance.

First, the neck tube acts as the only rigid connection between the inner and outer chambers. Since the space between them is a high vacuum for insulation, direct contact must be minimized to prevent heat transfer. The neck tube therefore supports the inner vessel’s weight while maintaining a sealed and stable structure.

Second, it is a thermal barrier. Made from low thermal conductivity materials such as stainless steel or aluminum alloy, the neck tube limits heat conduction from the external environment into the liquid nitrogen. The shorter and narrower the neck tube, the smaller the area for heat transfer—hence, the better the insulation and the slower the nitrogen evaporation rate.

Finally, the neck tube serves as the operating channel for daily use. It allows users to fill liquid nitrogen, insert canisters, or measure liquid levels. The neck plug placed inside also helps reduce nitrogen loss and protect against external contamination.

In short, the neck tube ensures the tank’s mechanical stability, insulation performance, and operational convenience. Its design and material quality directly determine how long the tank can maintain cryogenic conditions and how efficiently it performs over time.