Why Dewars Are Widely Used in the Gas Industry

Dewar flasks—also known as cryogenic liquid cylinders, portable cryogenic tanks, or mobile low-temperature liquid containers—are commonly referred to as liquid nitrogen tanks when storing LN₂. In Chinese industry standards, they are known as welded vacuum-insulated cylinders.

Today, Dewars are increasingly popular in the global industrial gas sector for several compelling reasons:

1. Greatly Enhances and Ensures Gas Purity

Portable cryogenic tanks are made of stainless steel with vacuum insulation, ensuring a clean, contamination-free environment for gas storage. Unlike traditional gas cylinders, these tanks avoid impurities such as moisture, air, and rust during the filling process, effectively maintaining high gas quality.

2. High Storage Capacity

A typical XL-45 Dewar with a 169L effective volume can store:

• 1L of liquid oxygen → 0.74799 m³ gaseous O₂

• 1L of liquid nitrogen → 0.64633 m³ gaseous N₂

• 1L of liquid argon → 0.78091 m³ gaseous Ar

This equates to 19–25 traditional 40L high-pressure gas cylinders, depending on the gas type. The use of Dewars significantly reduces logistics and storage costs. Moreover, they occupy less floor space and eliminate frequent cylinder changes, improving workflow and safety in workshops.

3. Improved Gas Management

Due to their large storage capacity, portable cryogenic tanks support centralized gas supply, promoting streamlined and scientific management within user facilities.

4. Pressure Closely Matches Application Needs

Dewars operate at a low working pressure—typically below 1.6 MPa (e.g., XL-45 model)—compared to 15 MPa in traditional high-pressure cylinders. This 9x pressure reduction greatly enhances safety during production, transport, and storage.

5. Simple Operation and Easy Maintenance

These cryogenic tanks are user-friendly and require minimal maintenance, making them suitable for a wide range of industrial and laboratory environments.

6. Enhanced Safety

High-pressure gas cylinder explosions are a recurring safety hazard in the industry, often due to:

• Difficulty distinguishing old oxygen, argon, nitrogen, or CO₂ cylinders

• Reusing expired or damaged cylinders

• Over-pressurization during gas use

In contrast, cryogenic liquids like LOX, LIN, LAR, and LCO₂ stored in Dewars:

• Operate at lower pressures

• Are easily labeled and identified

• Allow simpler and safer gas management

This significantly reduces the risk of explosions and improves overall workplace safety.