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Jai Ganesh

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Liquid Nitrogen

Liquid Nitrogen

Gist

In medicine, it is used in cryosurgery, subjecting abnormal tissues like tumors or warts to extreme cold for removal. Liquid nitrogen is also essential for the cryopreservation of cell samples, tissues, and organs, both for research and transplantation.

Summary

Liquid nitrogen (LN2) is nitrogen in a liquid state at low temperature. Liquid nitrogen has a boiling point of about −196 °C (−321 °F; 77 K). It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose viscosity is about one-tenth that of acetone (i.e. roughly one-thirtieth that of water at room temperature). Liquid nitrogen is widely used as a coolant.

Physical properties

The diatomic character of the N2 molecule is retained after liquefaction. The weak van der Waals interaction between the N2 molecules results in little interatomic attraction. This is the cause of nitrogen's unusually low boiling point.

The temperature of liquid nitrogen can readily be reduced to its freezing point −210 °C (−346 °F; 63 K) by placing it in a vacuum chamber pumped by a vacuum pump. Liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in an insulating layer of nitrogen gas bubbles. This effect, known as the Leidenfrost effect, occurs when any liquid comes in contact with a surface which is significantly hotter than its boiling point. Faster cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen rather than liquid nitrogen alone.

Handling

As a cryogenic fluid that rapidly freezes living tissue, its handling and storage require thermal insulation. It can be stored and transported in vacuum flasks, the temperature being held constant at 77 K by slow boiling of the liquid. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks. The development of pressurised super-insulated vacuum vessels has enabled liquid nitrogen to be stored and transported over longer time periods with losses reduced to 2 percent per day or less.

Details

Liquid nitrogen is simply nitrogen that has gone from its natural gaseous state to a liquid state. Nitrogen is an element that is abundant in the Earth’s atmosphere, making up almost eight parts of all the planet’s air. It is colorless and odorless. It is represented by the symbol N in chemistry.

What is the dew point of nitrogen?

Nitrogen becomes liquid when its temperature goes below -195.8°C. That is why it’s not common to find it in that state without artificial intervention. On hitting room temperature, nitrogen evaporates at a rapid boil.

How is liquid nitrogen made?

There are several methods. Generally, industrial production of pure liquid nitrogen is achieved by distilling it from liquid air. Air is composed of oxygen (21%), nitrogen (78%), and a small percentage of other gases. To get the air to a liquid state, it undergoes a liquefaction process by means of strong compression by pistons that inject the air, and then it is cooled to very low temperatures. Some 700 liters of air in the gaseous state condense into just 1 liter of liquid air.

Nitrogen and other liquid gases are stored in Dewar containers, which are pressurized vessels that provide high thermal insulation.

What are the industrial uses of liquid nitrogen?

In construction and maintenance of public works, liquid nitrogen is used to temporarily freeze a section of pipe and thus prevent its contents from spilling out when opening it to carry out some work. It can also be injected into an area where a crack has been covered with sealing material, producing a plug of frozen matter to buy time and let the repair be fixed.

It is also used for manufacturing electronic components and as a shielding gas in welding processes.

In laboratories for various fields, it is used to remove solvents or water in a gaseous state using by cold traps.

In medicine, it is used in cryosurgery, subjecting abnormal tissues like tumors or warts to extreme cold for removal. Liquid nitrogen is also essential for the cryopreservation of cell samples, tissues, and organs, both for research and transplantation.

Liquid nitrogen is used to conserve and store semen, both animal and human. This technology is crucial for sperm banks that are used in artificial insemination.

In the food industry, it is used in deep-freezing processes for vegetables and animal products, which enables preservation and transportation. It is also commonly used for making ice cream and math.

What precautions should be taken for handling liquid nitrogen?

Liquid nitrogen is not a toxic material, which is why it is widely used in the food and medical industry; however, its characteristics require certain precautions in handling.

At such low temperatures, liquid nitrogen can quickly cause cold burns or even frostbite on the limbs. The use of insulating clothing is recommended, as well as gloves and safety glasses. Whenever working with liquid nitrogen, proper ventilation or self-contained breathing apparatuses should be used.

Nitrogen is colorless and odorless. A liquid nitrogen leak can evaporate and accumulate in an imperceptible cloud of gas that will displace the air in an enclosure, creating a suffocation hazard for humans and other living beings. Periodic reviews of the containers’ pressure and the other systems associated with their use is recommended.

Additional Information:

Top 5 Facts to Know About Liquid Nitrogen

As an essential component of life on Earth, nitrogen is found in all living systems. Nitrogen can be found in organic materials, foods, and more. Named after the Greek word nitron, for “native soda,” and genes for “forming,” nitrogen is the fifth most abundant element in the universe. Nitrogen also happens to be the largest-volume inorganic chemical sold in the world, capable of supporting a multitude of applications from food freezing to metal treating and beyond. With its wide availability and flexible applications, liquid nitrogen has become one of the most popular cryogenic liquids around. Here are the top five things to know about this cool (pun intended) liquid gas:

1. It won’t kill you (mostly).

Odorless, colorless, and non-toxic liquid nitrogen is generally safe for use. But while it’s non-irritating, that doesn’t mean you can just use it without any precautions. Adding large quantities of nitrogen to the air reduces the amount of oxygen, which creates an asphyxiation risk. Excessive inhalation of nitrogen can also cause dizziness, nausea, vomiting, loss of consciousness, and eventually death. So be sure to always use liquid nitrogen in a well-ventilated area.

2. It’s in the air we breathe.

Nitrogen is 75% of the air we breathe. The remainder of the air in Earth’s atmosphere is made up of approximately 21% oxygen and small amounts of other gases, such as carbon dioxide, neon and hydrogen. And although it’s a major component of air, nitrogen is not capable of supporting life on its own.

3. It’s COLD.

Liquid nitrogen is a cryogenic liquid, meaning it boils at 77 K (−195.8° C or −320.4° F). This means liquid nitrogen is cold enough to cause severe frostbite almost immediately if it comes into contact with skin. And while its super-low temperature might seem dangerous, it also makes it ideal for applications such as refrigeration. Liquid nitrogen is often used to store sperm, eggs, and other cells used in medical research or fertility clinics. However, to avoid damage and injuries, always wear proper safety gear when handling liquid nitrogen.

4. Special storage is required.

Because of its extremely cold temperature, liquid nitrogen must be stored in special insulated containers. Liquid nitrogen is often stored, shipped, and handled in containers called dewars. Dewars are portable, double-walled containers that are open-necked, free-venting, and vented to prevent pressure buildup. Depending on the design of the Dewar flask, liquid nitrogen can be stored for hours or for up to a few weeks. However, liquid nitrogen should only be stored in well-ventilated areas to avoid overpressurization.

5. You can eat it!

The culinary use of liquid nitrogen was first mentioned in an 1890 recipe book titled Fancy Ices by Agnes Marshall (looks like she was onto something!). Since then, liquid nitrogen has been brought into the present day by restaurants in the preparation of ice cream, fun math, and innovative food. Liquid nitrogen allows normally long cooking processes to be created within moments of the speed at which it cools food. In ice cream, the rapidity of chilling leads to the formation of smaller ice crystals, which provides the dessert with a smoother texture. In the preparation of math, liquid nitrogen can be used to quickly chill glasses or freeze ingredients. Liquid nitrogen can also be added to drinks to create a smoky effect. If you’re interested in a liquid nitrogen math, the Barton G in Los Angeles serves up drinks with a nitrogen twist.

With its applications ranging from specialty ice cream shops and math to medical practices and beyond, liquid nitrogen looks like it’s here to stay. But with such a cold substance comes specific requirements for safe storage, handling, and usage. At CalOx, we specialize in liquid nitrogen, from regular deliveries to storage, delivery, and handling equipment, along with training and maintenance.

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