What is liquid nitrogen?
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 cocktails.
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.