Liquid Nitrogen Dewar Sizes: Choosing the Right Size for Your Application

The right liquid nitrogen (LN₂) dewar size comes down to two things: how much LN₂ your operation actually goes through, and how much room you have for the container. Most lab and medical dewars run from about 4 liters up to 50 liters, and choosing within that range is mostly a matter of matching capacity and refill frequency to your needs.

Before you size anything, though, confirm you need a dewar at all. The word gets used interchangeably with “liquid cylinder,” and the two containers do very different jobs.

Dewar vs. Liquid Cylinder: What’s the Difference?

A dewar and a liquid cylinder are two different containers, and sorting them out before you shop saves you from buying the wrong thing. People swap the terms freely, but they aren’t the same vessel.

A dewar is a smaller, portable container with no wheels, roughly the size of a small pony keg. It’s built to store and transport modest volumes of liquid nitrogen, and you dispense from it by pouring, dipping, or fitting a pressurized transfer device.

A liquid cylinder is the larger, upright vessel that rolls on a caster base. It holds far more, commonly 160, 180, or 230 liters, and it supplies both liquid nitrogen and gaseous nitrogen through a built-in pressure-building system.

If you need nitrogen gas on tap, that’s a cylinder. If you need to store liquid and pour it into other equipment, that’s a dewar.

When Are Dewars the Practical Choice Over a Bulk Tank?

Dewars make sense when a permanent bulk tank isn’t on the table, which is the reality for a lot of operations. Many startups, laboratories, and research groups run out of office buildings or leased space.

Space constraints and building codes frequently rule out a permanent bulk liquid nitrogen installation.

That’s where dewars earn their spot. They give you a dependable LN₂ supply without the footprint or infrastructure a bulk system demands. For a lab going through a few liters a week, a bulk tank would be overkill anyway.

What Sizes Do Liquid Nitrogen Dewars Come In?

Lab and medical dewars typically range from about 4 liters up to 50 liters, with several steps in between. The MVE Lab Series is a good reference point, since it’s a common choice in labs and medical facilities and spans that whole range in seven models.

Static evaporation rate is the amount of liquid nitrogen a full dewar loses per day just sitting there. Liquid nitrogen sits at -196°C (-320°F), so it’s always boiling off slowly, and a well-insulated dewar simply slows that loss down.

Bigger dewars evaporate more per day and weigh more once they’re filled with nitrogen, though the increase isn’t perfectly linear from one model to the next. Neck opening and usable height grow across the range too, which affects what you can lower into the container.

How Do You Match Dewar Size to Your Application?

Match the size to how much LN₂ you use, how much you need to move the container, and what you need to fit inside it.

• Consumption and refill frequency: a small 4 to 10 liter dewar suits low-volume work like keeping a modest set of samples cold or topping off a small piece of equipment, while a 30 to 50 liter unit stretches the time between fills for heavier daily use. Lower-evaporation models hold their nitrogen longer, so you refill less often and disrupt your workflow less.
• Portability and weight: a full Lab 4 weighs around 13 pounds and is easy to move with your hands, but a full Lab 50 runs about 120 pounds and is meant to stay put or roll on a cart. Consider who’s moving it and how far.
• Neck opening and access: wider necks accept larger racks, canisters, and dippers, so if you’re storing sample inventory rather than just holding liquid, the opening size can matter as much as the capacity.

For many small labs, a mid-range dewar covers sample storage and routine dispensing without forcing a refill every few days. Push toward the larger end only when your usage genuinely justifies the extra weight and cost.

What About Larger Biological Storage Needs?

Larger inventories of biological material are usually kept in big cryogenic storage freezers that the facility owns outright, with the gas supplier simply delivering liquid nitrogen to keep them filled. This is the standard model if you outgrow what a portable dewar can hold.

These freezers store large quantities of samples: animal semen, embryos, germplasm, and other genetic material.

Smaller dewars like the Lab Series can play a supporting role here, used to top off the bigger storage tanks between deliveries. On the sample-storage side, MVE’s SC (Small Capacity) and XC (Extra Capacity) series are purpose-built to hold straws, goblets, and vials, organized in canisters in a portable, low-loss package.

Where Can You Get the Right Dewar for Your Space?

WestAir supplies liquid nitrogen dewars through MVE Bio and can source the full range of MVE dewar sizes, so you can match the container to both your storage volume and your available space.

The MVE Lab Series handles LN₂ storage and dispensing across that 4 to 50 liter range. The SC and XC series cover sample storage for straws and vials. Different sizes, same goal: the right amount of liquid nitrogen in a footprint that fits your facility.

If you’re not sure where your usage lands, reach out to us at WestAir and we will point you to the model that fits.

Tyler O'Brien

Tyler is a results-driven marketing professional specializing in the industrial gases and equipment industry, bringing his 10 years of technical expertise and digital marketing acumen to the complex industrial gas B2B environment.