Liquid nitrogen (LN₂) is one of the most widely used cryogenic fluids in modern industry due to its extremely low temperature, inert behavior, and high expansion ratio. It plays a critical role in manufacturing, food processing, medical preservation, electronics cooling, and laboratory research.
Understanding liquid nitrogen density, weight, and physical properties is essential for safe storage design, transportation planning, and industrial process optimization.
This guide explains the key characteristics of cryogenic nitrogen and how it is supplied and stored in real industrial applications.
What is Liquid Nitrogen?
Liquid nitrogen vaporizes at -196°C (321°F). It can be produced by lowering its atmospheric temperature and condensing it into an inert, non-toxic, and transparent state. Due to its low-freezing temperature characteristics, this non-toxic liquid is appropriate for various applications, such as freezing food items, preserving biological specimens, and generating inert atmospheres in manufacturing environments.
Physical Properties:
- Boiling Point: -196°C (-321°F)
- Melting Point: -210°C (-346°F)
- Density: Approximately 807 kg/m³ in liquid form at -196°C; 1.250 kg/m³ as a gas at 20°C
- Color: Clear, colorless
- Odor: Odorless
- Expansion Ratio: 1:680 when transitioning from liquid to gas
Density and Weight of Liquid Nitrogen
1. Density of Liquid Nitrogen:
- At its boiling point (-196°C), the density of liquid nitrogen is approximately 807 kg/m³. This is lower than the density of water, which means liquid nitrogen is less dense and occupies more volume per unit weight.
- Density in Different Units: Liquid nitrogen density is often expressed as 0.807 g/cm³ or 50.5 lb/ft³.
Liquid Nitrogen Density vs. Pressure
Explore how the density of liquid nitrogen might vary with pressure.
| Pressure (bar) | Pressure (atm) | Temperature (°C) | Density (kg/m³) | Comments |
| 1 | 0.987 | -196 | 807 | Standard atmospheric pressure (boiling point) |
| 1.5 | 1.48 | -190 | ~810 | Increased pressure slightly raises the density |
| 2 | 1.97 | -185 | ~815 | Pressure raised to slow the evaporation rate |
| 3 | 2.96 | -180 | ~820 | Higher pressure maintains liquid state |
| 4 | 3.94 | -175 | ~825 | Increased compression effect |
| 5 | 4.93 | -170 | ~830 | Elevated pressure for specific cryogenic needs |
Description of Columns:
Pressure (bar): Indicates the pressure exerted on the liquid nitrogen in bar units.
Pressure (atm): Conversion of pressure from bar to atmospheric pressure (1 bar ≈ 0.987 atm).
Temperature (°C): Approximate temperatures corresponding to different pressures, showing slight changes as pressure increases.
Density (kg/m³): Estimated density values can vary slightly due to pressure-induced changes.
Comments: Explanations or notes on how pressure influences the density of liquid nitrogen.
2. Density of Nitrogen Gas:
- When liquid nitrogen evaporates, it becomes nitrogen gas. At room temperature (20°C), the density of nitrogen gas is about 1.250 kg/m³, making it slightly lighter than air (the density of air is 1.293 kg/m³).
- At standard temperature and pressure (STP), nitrogen gas density is 1.250 kg/m³, whereas, at very low temperatures (-196°C), the density increases to about 4.56 kg/m³, causing the cold gas to sink below warmer air.
3. Weight of Liquid Nitrogen:
- One litre of liquid nitrogen weighs about 0.807 kg. For industrial applications, a gallon of liquid nitrogen weighs approximately 6.73 pounds (3.05 kg).
Temperature and State Transitions of Nitrogen
1. Temperature of Liquid Nitrogen:
- Liquid nitrogen has a boiling point of -196°C (-321°F), which means it remains liquid only at extremely low temperatures. This makes it significantly colder than most substances, even in cryogenic terms.
2. Melting and Freezing Points of Nitrogen:
- The melting point of nitrogen is -210°C (-346°F), at which it transitions from a solid to a liquid. Below this temperature, nitrogen exists as a solid.
3. Expansion Ratios:
- Liquid nitrogen expands dramatically when converted to gas. At room temperature, the expansion ratio from liquid nitrogen to nitrogen gas is about 1:680, meaning one litre of liquid nitrogen produces 680 litres of nitrogen gas.
Properties of Liquid Nitrogen
- Inert Nature: Being chemically inert, liquid nitrogen doesn’t react with most substances, making it ideal for creating safe, non-reactive environments.
- Non-Toxic and Odourless: It is safe for applications in food and pharmaceuticals but requires proper safety measures due to its extreme cold.
- Heavier than Air: In cold gaseous form, nitrogen gas is denser than air, posing safety hazards in enclosed spaces.
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Applications of Liquid Nitrogen
Because of its density and cryogenic temperature, liquid nitrogen is widely used across various industries.
- Food Preservation: Used for flash-freezing foods, which preserves quality and texture better than conventional freezing methods.
- Medical Use: Commonly used to preserve biological samples, including blood, tissues, and vaccines, and for cryotherapy treatments.
- Industrial Cooling: Used in cooling systems, it helps manage the heat in various manufacturing processes, including metalworking and electronics.
- Inert Atmospheres: Liquid nitrogen creates oxygen-free environments for packaging food, reducing spoilage and extending shelf life.
Liquid Nitrogen Storage & Supply Models
DSW provides liquid nitrogen packaging and supply solutions from laboratory dewars to large industrial bulk storage systems. Supply selection depends on consumption volume, pressure requirements, and delivery logistics.
Microbulk System
Compact tank with integrated vaporiser for small to medium users.
Use: Labs, hospitals, food processing
Cylinder & Dewar Supply
Flexible liquid nitrogen cylinders for low or intermittent demand.
Use: Backup, small users, remote sites
Bulk Tank System
High-capacity cryogenic tank with vaporisation and pressure control.
Use: Manufacturing, laser cutting, chemicals
ISO Tank / Trailer Supply
Mobile bulk transport and on-site liquid nitrogen delivery.
Use: Distribution, temporary supply
Why Liquid Nitrogen Density Matters in Storage
Liquid nitrogen density directly affects cryogenic storage system design, transportation planning, and safety calculations. Engineers must understand density to correctly size tanks and calculate safe operating limits.
Density directly affects:
- Tank sizing
- Transport weight calculations
- Evaporation loss calculations
- Filling ratios
Example Calculation
If a cryogenic tank holds:
10,000 liters of LN₂
Weight calculation:
10,000 × 0.807 kg = 8,070 kg
This calculation helps engineers design safe foundations, select proper transport equipment, and ensure structural safety.
Liquid Nitrogen vs Nitrogen Gas Density
Liquid nitrogen expands rapidly when it vaporizes. Understanding the density difference between liquid and gas phases explains why proper ventilation is critical. Density values also vary slightly depending on temperature and pressure conditions.
| State | Temperature | Pressure | Density |
|---|---|---|---|
| Liquid nitrogen | −196 °C | 1 bar | ~807 kg/m³ |
| Liquid nitrogen | −185 °C | 3 bar | ~820 kg/m³ |
| Liquid nitrogen | −170 °C | 5 bar | ~830 kg/m³ |
| Nitrogen gas | 20 °C | 1 bar | ~1.25 kg/m³ |
Engineering Insight:
Because liquid nitrogen expands about 680 times when vaporized, even small liquid volumes can produce large gas volumes. This is why cryogenic storage areas must always have proper ventilation systems. Temperature changes mainly affect density, while pressure has a secondary influence.
Infrastructure for Liquid Nitrogen Handling
Handling liquid nitrogen requires specialised cryogenic infrastructure to maintain low temperatures and prevent gas formation. Vacuum insulation is commonly used, employing double-walled pipes with a vacuum between them to minimise heat transfer.
Safety Considerations
- Oxygen Depletion: Liquid nitrogen gas can displace oxygen in the air, creating suffocation risks in confined spaces. Monitoring oxygen levels is critical.
- Pressure Build-Up: As it expands, liquid nitrogen can cause pressure build-up in containers, posing explosion risks if not properly vented.
- Frostbite Hazard: The extreme cold can cause severe frostbite on contact with skin, so handling requires appropriate protective gear.
TECHNICAL FAQs
About Liquid Nitrogen and LN2 Supply
The density of liquid nitrogen is about 807 kg per cubic meter at its boiling point of −196 °C under atmospheric pressure.
No. Water has a density of about 1000 kg per cubic meter, which makes it denser than liquid nitrogen. Liquid nitrogen has a density of about 807 kg per cubic meter.
One liter of liquid nitrogen weighs about 0.807 kilograms under normal atmospheric conditions.
Liquid nitrogen density is important for calculating storage capacity, transport weight, cryogenic tank design, and safety margins in industrial applications.
Expert conclusion
Liquid nitrogen’s low temperature, non-toxicity, and inert properties make it a valuable tool across industries. However, understanding its density, weight, and expansion properties is crucial for safe and effective use. Whether used for preserving food or medical samples, liquid nitrogen’s versatility continues to make it a critical component in everyday and specialised applications.
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