Causes of Rust in Biological Liquid Nitrogen Tanks

Biological liquid nitrogen tanks are primarily used to store biological samples. They are typically made from aluminum alloy or stainless steel, materials known for their excellent resistance to rust and corrosion. However, under certain conditions, rusting may still occur. Below are the main reasons that can lead to rust in biological liquid nitrogen tanks:

1. Chemical Corrosion

Highly corrosive chemicals such as acidic substances (e.g., strong acids, acidic cleaning agents) can damage the protective surface layer of the tank, resulting in rust. Therefore, in daily use, it is essential to avoid contact between the tank and corrosive materials like concentrated hydrochloric acid, sulfuric acid, or strong alkalis.

2. Environmental Conditions

In specific environments with high humidity, high salinity, or exposure to corrosive gases, the surface of the liquid nitrogen tank may corrode more rapidly.

3. Physical Damage

Scratches, abrasions, or dents on the tank surface can compromise its protective coating, making those areas more susceptible to corrosion. Care should be taken during handling and storage to avoid any physical damage to the tank.

4. Improper Maintenance

When the tank is left unused, residual substances such as melted cryogenic samples can remain after the evaporation of liquid nitrogen, potentially corroding the inner liner. Therefore, after the liquid nitrogen is depleted, the tank should be thoroughly cleaned and dried.

Additionally, if the vacuum seal of the tank is damaged (e.g., the vacuum exhaust port is compromised), the insulation performance will degrade. This can lead to frost formation on the upper part of the tank, increased liquid nitrogen loss, and accelerated corrosion. It is important to inspect the vacuum exhaust port for damage before use.

Preventive Measures to Avoid Rust and Extend Tank Life:

• Avoid contact between the tank and corrosive chemicals, especially strong acids and alkalis.

• Keep the storage environment dry and well-ventilated, and avoid areas with high humidity, salinity, or corrosive gases.

• Handle and store the tank carefully to prevent physical damage.

• Thoroughly clean and dry the tank during idle periods to remove any residues that may cause internal corrosion.

• Regularly inspect the vacuum level and appearance of the tank, and address any issues promptly.

Conclusion

In summary, rust in biological liquid nitrogen tanks can be caused by chemical corrosion, environmental factors, physical damage, and improper maintenance. By taking appropriate preventive measures and conducting regular maintenance, the service life of the tank can be extended, and the risk of rusting significantly reduced.