How to store liquid nitrogen and how long it keeps
Liquid nitrogen cannot be stored — only slowed down. Loss rates by vessel type, why a sealed container is dangerous, and what a room with liquid nitrogen needs.
Liquid nitrogen boils at −196 °C, and in any room heat reaches it from every side. So the question «how long does it keep» really means «how slowly does it evaporate in this vessel». The answer depends on insulation, size and how often the vessel is opened.
What liquid nitrogen is stored in
| Vessel | Volume | Boil-off | Used for |
|---|---|---|---|
| Dewar flask | 5–50 l | 0.1–0.5 l per day | laboratories, biological samples, small one-off jobs |
| Low-pressure cryogenic cylinder | 180–230 l | 1.5–2.5% per day | workshops and labs with daily draw-off |
| Stationary tank | 10–50 m³ | 0.1–0.3% per day | continuous industrial consumption |
Larger vessels lose a smaller percentage because the surface heat comes through grows more slowly than the volume. Hence the practical rule: storing nitrogen «in reserve» in small containers does not pay, and neither does keeping a large volume on site without regular draw-off, because the losses run every day.
How many days nitrogen will last
For a Dewar flask the manufacturer states a static holding time: a well-insulated 35 l flask holds nitrogen for months if left closed. Daily draw-off and opening the lid shorten that many times over. A 200 l cryogenic cylinder at 2% per day loses about 28 l in a week without any use.
Three rules that cannot be broken
- Never seal liquid nitrogen. One litre of liquid makes about 0.7 m³ of gas; a closed container without a relief valve ruptures. Dewar lids are loose for exactly this reason.
- The room must be ventilated. Nitrogen is not toxic but displaces oxygen. In a small room a spilled cryogenic cylinder lowers oxygen to a dangerous level with no smell at all. Such rooms get an oxygen sensor with an alarm.
- Only suitable containers and protection. Ordinary plastic, rubber and carbon steel turn brittle at −196 °C. Work in cryogenic gloves and a face shield, and never carry nitrogen inside a car.
When to move to a tank
If cryogenic cylinders are swapped several times a week and losses and logistics become a visible cost, the next step is a stationary liquid nitrogen tank with an ambient vaporizer. For a daily draw-off of a few dozen litres, cryogenic cylinders are usually enough. Unit and price comparisons per litre, kilogram and cubic metre are in Price of CO₂, nitrogen and argon.
Read nextLiquid nitrogen or dry ice: which one to use for coolingFrequently asked questions
Can liquid nitrogen be kept in a thermos?
A household thermos is not designed for −196 °C: the glass flask can crack and the screw cap turns it into a pressure vessel. For short-term handling only a laboratory Dewar flask with a loose, vented lid is suitable.
Why does a cryogenic cylinder lose nitrogen even when nobody uses it?
Heat leaks through the insulation, supports and valves all the time. The liquid evaporates, pressure rises to the relief valve setting and the gas is vented. A healthy cylinder loses 1.5–2.5% a day; noticeably more usually means the vacuum insulation has degraded.
You may also need
Cryogenic cylinders for liquid nitrogen (LIN, N₂)
Cryogenic cylinder for liquid nitrogen
Model: CC-N2
Portable vacuum-insulated cylinder for storing liquid nitrogen (LIN, N₂) with gas or liquid withdrawal. Volume, working pressure and configuration are selected for your process.
Price on request
On request
Cryogenic tanks for liquid nitrogen (LIN, N₂) 10–50 m³
Cryogenic tank for liquid nitrogen 30 m³
Model: CT-N2-30
Stationary vacuum-insulated cryogenic tank for storing liquid nitrogen (LIN, N₂), geometric volume 30 m³. Supplied with valves, pressure control, vaporizers and a pressure-reducing unit; turnkey installation available.
Price on request
Made to order
