The inner canister, often called the rack or carrier, is a key structural component inside a liquid nitrogen tank. Although it is not part of the insulation system, its design directly affects sample safety, ease of operation, and long-term storage reliability. A well-designed canister ensures efficient use of space while minimizing risks during daily handling.

One of the primary design considerations is material selection. Most canisters are made from lightweight aluminum alloy or stainless steel. Aluminum alloy is preferred in many applications because it is light, corrosion-resistant, and easy to handle, reducing operator fatigue during frequent lifting. The material must maintain mechanical strength at cryogenic temperatures and should not become brittle at –196°C.

Another critical aspect is the bottom structure, commonly classified as open-bottom (perforated) or closed-bottom designs. Open-bottom canisters allow liquid nitrogen to flow freely, ensuring rapid cooling and uniform temperature distribution for stored samples. They are ideal for long-term static storage. Closed-bottom designs, on the other hand, reduce direct exposure to liquid nitrogen and help limit sample disturbance during lifting, making them suitable for short-term access and frequent retrieval.

The dimensions and compatibility of the canister must match the tank’s neck diameter and internal height. Proper clearance ensures smooth insertion and removal without scraping the neck, which could damage the insulation structure over time. Standardized dimensions also help users organize vials, straws, or sample boxes efficiently.

Ergonomics and safety are also important. Many canisters feature reinforced handles, anti-slip grips, or balanced lifting points to prevent accidental dropping. Smooth edges and rounded corners reduce the risk of damage to both the tank interior and stored containers.

In summary, the design of a liquid nitrogen tank canister focuses on material performance at ultra-low temperatures, optimized bottom structure, precise dimensional matching, and safe handling. Thoughtful canister design not only protects valuable samples but also improves operational efficiency and extends the service life of the tank.