Liquid nitrogen is an extremely cold liquid with a temperature of -321°F (-196°C). It is made by cooling down regular nitrogen gas to extremely cold temperatures. Liquid nitrogen has a number of industrial and medical uses due to its cold temperature. However, liquid nitrogen can be dangerous if mishandled or consumed. Consuming liquid nitrogen can cause severe internal tissue damage due to its ultra-cold temperature.
What is liquid nitrogen?
Liquid nitrogen is nitrogen in a liquid state at an extremely low temperature. Nitrogen makes up about 78% of the air we breathe. Under normal conditions, nitrogen is a colorless, odorless, and inert gas. However, by cooling air down to -320°F (-195.8°C), nitrogen gas condenses into a liquid form. At atmospheric pressure, nitrogen liquefies at -320.44°F (-195.8°C). This is the boiling point of liquid nitrogen.
Liquid nitrogen looks like water but it is far colder. Its extremely cold temperature makes it useful for freezing and preserving biological samples, freezing foods, and various industrial applications. Liquid nitrogen has a density of 0.807 g/mL at its boiling point, which is less dense than water (1 g/mL).
Properties of liquid nitrogen
Some key properties of liquid nitrogen include:
- Temperature: -320°F (-195.8°C), boiling point
- Density: 0.807 g/mL
- Color: Colorless
- Texture: Liquid
- Phase: Liquid
Liquid nitrogen vaporizes into a gas at standard atmospheric pressure and temperatures higher than -320°F (-195.8°C). It is cryogenic liquid, meaning it exists as a liquid only at extremely cold temperatures.
How is liquid nitrogen made?
Liquid nitrogen is made by first liquefying air and then distilling the liquid air to separate the nitrogen. The basic process involves:
- Filtering: Air is filtered to remove impurities like dust and water vapor.
- Compression: The filtered air is compressed to high pressures using compressors.
- Cooling: The compressed air is cooled using heat exchangers until it liquefies.
- Distillation: The liquid air mixture is distilled to isolate pure liquid nitrogen.
- Storage: Liquid nitrogen is stored in special cryogenic storage tanks.
The liquid air mixture starts to condense around -200°F (-129°C). Further cooling and distilling separates the oxygen and nitrogen based on their boiling points. Nitrogen has a lower boiling point of -320°F (-196°C) compared to oxygen’s boiling point of -297°F (-183°C). This allows nitrogen to be purified as it vaporizes first during the distillation process.
Industrial production
Industrially, large liquid nitrogen plants can produce thousands of liters of liquid nitrogen per day. Compressors and heat exchangers are used to compress and cool air to condense it into liquid. The liquid air is further processed using fractionating columns to isolate the pure nitrogen. Liquid nitrogen is stored and transported in special vacuum-insulated containers called Dewars.
Small-scale production
Small quantities of liquid nitrogen can also be produced in physics laboratories using liquid nitrogen Dewar flasks. These special vacuum flasks use liquid nitrogen as the coolant instead of water. Passing compressed air through a coil immersed in the liquid nitrogen condenses the air into liquid. The liquid nitrogen keeps replenishing as the newly formed liquid air evaporates.
Uses of liquid nitrogen
The ultra-cold temperature of liquid nitrogen makes it invaluable for many uses:
Freezing and cryopreservation
Biological samples like cells, tissues, organs, and other materials are preserved through freezing with liquid nitrogen. This prevents damage from chemical reactivity and decay at higher temperatures. Liquid nitrogen’s low temperature of -320°F (-195°C) provides rapid freezing and reduced cellular damage during cryopreservation.
It is commonly used to store and preserve eggs, sperm, embryos, and other reproductive cells and tissues in fertility clinics. Many medical facilities also use liquid nitrogen to store blood products, vaccines, and other delicate biological materials.
Food freezing
The food industry uses liquid nitrogen for quickly freezing foods like ice cream, baked goods, meats, and other foods. Foods frozen with liquid nitrogen freeze much faster with smaller ice crystals. This minimizes damage to cell structures and results in better texture after thawing.
Some foods like ice cream are directly immersed in liquid nitrogen to flash freeze them. The ultra-cold temperature gives ice cream a smoother consistency by preventing large ice crystals from forming.
Cooling and refrigeration
Since liquid nitrogen evaporates at -320°F (-196°C), it can absorb large amounts of heat without increasing in temperature. This makes it ideal as a coolant for various applications:
- Computer hardware cooling in servers and overclocked processors
- Cooling of sensors and film in spacecraft components
- Cooling suits for race car crews to withstand heat exposure
- Keeping electrical cables and motors cold in power plants
The evaporating liquid nitrogen gas also displaces air, creating an inert environment. This is useful for cooling oxygen-sensitive devices and materials.
Manufacturing processes
Liquid nitrogen’s properties make it useful in several manufacturing and assembly processes:
- Shrink fitting: Shrinking metal parts using liquid nitrogen to assemble machinery and tools
- Foam/plastic freezing: Cooling and solidifying foams or plastics after production
- Cell rupturing: Rupturing cells to extract contents like flavors, fragrances, pigments
- Cryogenic grinding: Making small particles of materials like rubber, plastic, spices
The ultra-cold temperature embrittles materials, making them easier to fragment into small particles for grinding applications.
Other uses
Some other uses and applications of liquid nitrogen include:
- Producing nitrogen gas and liquid oxygen
- Transportation coolant for sensitive biological materials
- Chemical analysis of samples using liquid nitrogen solvents
- Inflating party balloons with cold nitrogen gas
- Special effects like creating smoke and fogs for movies
Liquid nitrogen has a wide range of uses across science, medicine, industry, and entertainment due to its unique ultra-cold physical properties. Proper handling precautions are necessary to prevent potential hazards from the extreme temperatures.
Dangers of liquid nitrogen
Despite its many uses, liquid nitrogen can be hazardous if mishandled. Some key dangers include:
Extreme cold
Liquid nitrogen has a temperature of -320°F (-195°C), which can cause frostbite and tissue damage upon contact with skin. Prolonged exposure can lead to severe blistering and loss of sensation. Spilled liquid nitrogen can quickly condense oxygen from the air, creating an asphyxiation hazard.
Rapid expansion
Liquid nitrogen expands by a factor of 700 when going from liquid to gas phase. The rapid expansion can cause explosions or pressure bursts in tightly sealed containers. Tissue damage can occur if liquid nitrogen is rapidly injected in body cavities.
Asphyxiation
Liquid nitrogen evaporates into large volumes of nitrogen gas, which can displace oxygen in the air in enclosed spaces. This can cause asphyxiation due to lack of oxygen for breathing.
Frostbite and tissue damage
Contact with skin or eyes can cause severe frostbite burn injuries and permanent eye damage. Ingestion of liquid nitrogen can severely damage tissues and organs due to freezing.
Embrittlement
Materials like rubber and plastic become brittle and prone to shattering when cooled with liquid nitrogen. This can send debris flying dangerously.
Is liquid nitrogen safe to drink?
No, drinking liquid nitrogen is extremely dangerous and hazardous to health. Liquid nitrogen has a boiling point of -320°F (-195°C), which is hundreds of degrees below the normal body temperature of 98.6°F (37°C).
Drinking even a small quantity of liquid nitrogen can severely damage internal organs due to the thermal shock of ultra-cold temperatures. Tissues like the esophagus and stomach can get severely injured by frostbite burns and rupturing. The expansion of evaporating liquid nitrogen can also damage tissues by freezing and explosive pressure.
There have been several cases of people getting injured or even dying from drinking liquid nitrogen. It is used safely when handled properly, but ingesting it is always dangerous.
Effects of ingesting liquid nitrogen
Drinking liquid nitrogen can have the following adverse effects:
- Immediate frostbite and burning of the mouth, throat, and esophagus
- Tissue damage and rupturing of the stomach due to rapid freezing
- Vapor expansion can tear tissues due to internal pressure
- Asphyxiation from displacing air and evaporating into large volumes of nitrogen gas
- Death due to rupturing of tissues and internal bleeding
The mouth, throat, and stomach lining are especially vulnerable to thermal shock from liquid nitrogen ingestion. The extremely cold temperature can immediately damage and kill tissues. Stomach perforation, aspiration of liquid nitrogen into the lungs, and asphyxiation are also major risks.
Medical treatment like endoscopies and surgery may be required for ingestion injuries. Long term complications like scarring, strictures, and intestinal obstruction can also occur after tissue damage from liquid nitrogen. But immediate medical care is vital for survival and preventing serious complications.
What does liquid nitrogen taste like?
Liquid nitrogen does not have any distinct taste. However, it will immediately boil and vaporize inside the mouth into nitrogen gas. This can create a brief fizzy or popping sensation. The ultra-cold temperature also damages taste receptors, so any taste is only momentary before numbness.
The main sensations are extreme cold, frostbite pain, choking from nitrogen gas release, and damage to the tongue and mouth tissues. The mouth may appear burned or blistered afterwards.
Overall, the sensation of ingesting liquid nitrogen is an immediate freezing pain followed by tissue damage, bloating from gas release, and loss of sensation. The risks and complications of ingestion heavily outweigh any brief tastes or sensory effects.
Is it safe to eat food frozen with liquid nitrogen?
Eating foods frozen or prepared using small amounts of liquid nitrogen is generally safe. Examples include liquid nitrogen frozen ice cream, cocktails, and frozen desserts prepared in front of customers.
The liquid nitrogen fully evaporates into nitrogen gas during preparation, leaving only frozen food behind. This uses specially trained chefs under controlled conditions.
However, safety precautions are still necessary:
- Ensure proper ventilation so nitrogen gas dissipates and doesn’t displace air
- Avoid direct contact with bare skin to prevent cold burns
- Do not ingest untreated liquid nitrogen left over in drinks
- Wait for food to stop steaming or bubbling to allow nitrogen to evaporate
Foods that may accidentally contain traces of liquid nitrogen are unsafe to eat. There have been incidents of gastrointestinal tearing from eating undercooked frozen foods still containing pockets of residual liquid nitrogen.
So fully cooking or thawing such foods is vital to prevent accidental ingestion risks. Foods directly prepared with liquid nitrogen using proper safety protocols and handled correctly after preparation should be safe to consume.
Medical uses of liquid nitrogen
Liquid nitrogen has some medical and therapeutic uses under professional medical supervision:
Cryosurgery
Liquid nitrogen can be used to destroy abnormal skin tissues by freezing lesions with a cotton swab or spray device. This cryosurgery is often used for removing warts, moles, and premalignant growths. It is also used to treat some cancers like prostate cancer by freezing malignant tissues at very cold temperatures.
Cryotherapy
Controlled application of liquid nitrogen vapors or liquid droplets on the skin surface stimulates localized cold shock proteins and causes vasoconstriction. This cryotherapy treatment is used to improve skin pores, reduce inflammation, and rejuvenate the skin.
Tissue preservation
Liquid nitrogen’s ultra-cold temperature allows long-term preservation of biological tissues and cells. This has applications in banking cells, reproductive tissues, and organs for future medical use in transplantation or infertility treatment.
Thermography
Liquid nitrogen can be dripped on the skin to lower temperature. Infrared thermography of the skin as it rewarms can help assess blood vessel health. This liquid nitrogen stress test is sometimes used to evaluate risks for cardiovascular disease.
Anesthesia
The extreme cold of liquid nitrogen can have local anesthetic effects by numbing nerve transmission. Topical liquid nitrogen anesthesia is sometimes used for minor procedures on the skin or foot calluses. However, safer alternatives like lidocaine are more commonly used.
The risks involved means direct application of liquid nitrogen requires clinical experience and appropriate precautions. When handled properly under medical supervision, liquid nitrogen can serve as a versatile cryogenic tool for some therapeutic uses.
Liquid nitrogen ingestion cases
There have been a number of incidents where people consumed liquid nitrogen and suffered severe medical consequences:
British teenager – 2012
An 18-year-old woman drank a cocktail containing liquid nitrogen at a bar in Lancashire, England. She was rushed to the hospital but died due to stomach perforation and organ failure caused by the tissue-freezing liquid nitrogen. The bar was fined for serving unsafe drinks.
Man in San Francisco bar – 2016
A man had to undergo gastrectomy surgery to remove his stomach after drinking a cocktail with liquid nitrogen at a bar. The liquid nitrogen severely damaged his stomach tissues, causing internal bleeding and life-threatening medical complications.
YouTube liquid nitrogen challenge – 2018
An internet challenge dared people to drink liquid nitrogen on video. A 48-year-old woman in the United Kingdom had to have her stomach removed after attempting this challenge caused severe internal necrosis and organ damage.
| Case | Date | Effects |
|---|---|---|
| British teenager | 2012 | Stomach perforation, organ failure |
| Man in San Francisco | 2016 | Stomach removal surgery |
| YouTube challenge | 2018 | Stomach removal, organ damage |
These cases illustrate the real risks of internal tissue damage, asphyxiation, and even death from drinking liquid nitrogen. Even small amounts can be life threatening without immediate proper medical treatment.
Is liquid nitrogen illegal?
Liquid nitrogen itself is legal to purchase and handle in most parts of the world. However, there are some regulations governing its sale and use:
- May require proof of business purpose for bulk quantities
- Restricted for sale only to licensed individuals or businesses
- Storage and transportation regulated for safety
- LABELLING: Containers must be properly labeled as liquid nitrogen
- MINIMUM AGE: Legal age limits for purchase (e.g. 18 years)
Using liquid nitrogen dangerously or recklessly can breach laws. Serving liquid nitrogen cocktails responsibly requires proper training and protocols. Inducing someone to ingest liquid nitrogen may constitute assault or manslaughter in some cases.
Unauthorized access and theft of liquid nitrogen from industrial or laboratory supplies can also breach regulations. Overall, liquid nitrogen is typically legal with proper handling precautions and not serving it directly for consumption. Check local laws for any specific regulations.
Conclusion
Liquid nitrogen is an extremely cold cryogenic liquid with many industrial and medical uses. However, ingesting liquid nitrogen is always dangerous and potentially fatal. The ultra-cold temperature can immediately damage body tissues, causing severe injuries like perforated stomach. Several cases of people being harmed or killed underscore the risks of consuming liquid nitrogen. While useful when handled carefully, human consumption of liquid nitrogen should always be avoided.
