How is Nitrogen Stored?

Nitrogen is stored as a compressed gas in high-pressure cylinders or as a liquid in cryogenic tanks at −196°C (−320.8°F). Cryogenic tanks are particularly useful for large-scale storage, while cylinders are often used for smaller quantities of nitrogen gas.

This guide covers all you need to know about the main nitrogen storage solutions. We’ll cover both the popular and lesser-known methods, after which you’ll learn about the key safety considerations to keep in mind when storing nitrogen.

How Is Liquid Nitrogen Stored?

Below, we cover the small-scale and large-scale storage options for liquid nitrogen.

Small-Scale Storage Options

Dewars are the go-to storage solution for smaller amounts of liquid nitrogen. These specialized containers come in various sizes (typically ranging from 1 to 400 liters), which makes them ideal for laboratories and medical facilities.

Dewars feature a distinctive design with a cylindrical body and tapered neck. This specific shape isn’t meant for aesthetics – it’s engineered to minimize heat intrusion and reduce evaporation rates.

The construction of dewars involves several layers of insulation – vacuum insulation is typically combined with materials like aluminum foil and glass paper to maintain a temperature of -196°C.

If you’ve ever used a thermos to keep your coffee hot, you’ve used a similar technology – dewars are essentially super-powered versions of the vacuum flask invented by Sir James Dewar in 1892.

Large-Scale Storage Options

For storage of large volumes of liquid nitrogen, cryogenic storage tanks are the industry standard. These tanks are designed to hold thousands of liters of liquid nitrogen and are commonly found in:

• Industrial plants
• Food processing facilities
• Research institutions that require continuous supply

Cryogenic tanks are constructed from high-grade stainless steel and feature double-walled insulation with a vacuum layer in between. Many tanks also incorporate multi-layer insulation (MLI) using reflective materials like aluminum foil to further reduce thermal conductivity.

To ensure safe and efficient operation, large-scale tanks are equipped with pressure relief valves, level sensors, and venting systems that manage internal pressure and prevent over-pressurization.

Nitrogen Gas Storage Methods

Nitrogen in gas form requires different storage methods than its liquid counterpart. You should use high-pressure cylinders for storing nitrogen gas.

These cylinders are manufactured from high-strength materials (typically carbon steel or aluminum) and are designed to withstand pressures up to several thousand PSI. They come in various sizes (usually from 20 to 300 cubic feet) to accommodate different volume requirements.

High-pressure cylinders also feature specialized valves and regulators that control the flow of gas and ensure safe operation.

Advanced Storage Technologies – Nitrogen Vapor Freezers

If you’re looking for high-end nitrogen storage solutions, you can opt for a specialized option like a nitrogen vapor freezer. These systems store samples in nitrogen vapor instead of liquid, offering precise temperature control in the range of -150°C to -190°C..

Nitrogen vapor freezers typically feature advanced monitoring capabilities and backup systems to ensure consistent temperatures. They’re particularly useful for research facilities and biobanks where precise temperature control is crucial.

Vapor phase storage offers many benefits over liquid storage. 

Most importantly, it reduces the risk of cross-contamination and provides easier access to stored materials.

In vapor phase storage, samples are suspended above the liquid nitrogen in the nitrogen vapor, which maintains cryogenic temperatures (typically -150°C to -190°C) while avoiding direct contact with the liquid. This approach is preferred for samples like DNA, RNA, cell cultures, and blood components where liquid immersion might compromise sample integrity.

Storage Safety Considerations

Proper safety protocols and measures are essential when storing nitrogen in any form. The most important ones include:

• Pressure relief mechanisms – all storage containers must be equipped with pressure relief mechanisms to prevent dangerous pressure buildup.
• Adequate training – personnel handling nitrogen storage systems must be properly trained in safety procedures and emergency protocols. This includes understanding the risks of oxygen displacement and the proper use of personal protective equipment.
• Effective ventilation – storage areas require adequate ventilation to prevent oxygen depletion – which can be life-threatening – if there is a nitrogen leak.
• Install oxygen monitors – in the event of a nitrogen leak, an oxygen monitor provides an early warning of oxygen depletion.
• Ongoing monitoring – regular monitoring of storage systems is crucial and includes checking pressure levels, inspecting for damage or wear, and ensuring proper ventilation in storage areas.

Further Reading: Is Nitrogen Inert?

Effectively Store Your Nitrogen

Now that you know how to store nitrogen gas and liquid nitrogen, you can choose the right method for your specific use case(s). From compact dewars used in labs to massive cryogenic tanks for industrial applications, each solution offers unique advantages depending on the purpose and scale.

In any case, prioritizing safety protocols – such as pressure relief systems, staff training, and adequate ventilation – will help prevent accidents and ensure smooth, uninterrupted operations.