Liquid Nitrogen is nitrogen that is cold enough to exist in liquid form. It is used for many cooling and cryogenic applications. Here are some liquid nitrogen facts and information about handling liquid nitrogen safely.
Liquid Nitrogen Facts :-
Liquid nitrogen is the liquefied form of the element nitrogen that is commercially produced by fractional distillation of liquid air. Sometimes liquid nitrogen is denoted as LN2, LN, or LIN. Liquid nitrogen has the UN number 1977. At normal pressure, liquid nitrogen boils at 77 K (−195.8°C or −320.4°F). The liquid to gas expansion ratio of nitrogen is 1:694, which means liquid nitrogen boils to fill a volume with nitrogen gas very quickly.Nitrogen is non-toxic, odorless, and colorless. It is relatively inert. It is not flammable. Nitrogen gas is slightly lighter than air once it reaches room temperature. It is slightly soluble in water. Full line of products and services to streamline your medical gas-supply operation and reduce the stress of gas-supply management.
Liquid Nitrogen Safety :-
Liquid nitrogen is cold enough to cause severe frostbite upon contact with living tissue. Wear proper safety gear when handling liquid nitrogen to prevent contact or inhalation of extremely cold vapor. Make sure exposed skin surfaces are covered and preferably insulated.
TBecause it boils so rapidly, the phase transition from liquid to gas can generate a lot of pressure very quickly. Do not enclose liquid nitrogen in a sealed container, as this may result in bursting or an explosion.
Adding a lot of nitrogen to the air reduces the relative amount of oxygen. This can result in an asphyxiation risk. Cold nitrogen gas is heavier than air, so the risk is greatest near the ground. Use liquid nitrogen in a well-ventilated area.
Liquid nitrogen containers may accumulate oxygen which is condensed from the air. As the nitrogen evaporates, there is a risk of violent oxidation of organic matter.
Specification :-
- Nitrogen 99.999%
- Oxygen <5vpm
- Moisture <2vpm
- Argon is included in the nitrogen
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Features :-
- Refrigerated liquefied gas
- Boiling point -196°C
- Gas/vapour heavier than air
- Odourless, colourless and non toxic
- Chemically inert at ambient temperatures
Liquid Nitrogen Uses :-
- Freezing and transport of food products
- Cryopreservation of biological samples
- Coolant for superconductors, vacuum pumps, and other materials and equipment
- Cryotherapy to remove skin abnormalities
- Shielding materials from oxygen exposure
- Cooling materials for easier machining or fracturing
Application :
In its liquid form nitrogen is used as a cryogen for many applications where very low temperatures or rapid temperature reduction is required. The inert property of gaseous nitrogen enables it to be used for applications where a substance needs to be protected from oxidation or combustion by atmospheric air, or from contamination by moisture.
- Artificial Insemination : Nitrogen is often used for the storage of semen samples for artificial insemination of cattle.
- Blanketing and inerting : Nitrogen is used to maintain a dry inert atmosphere over chemicals during storage, reaction or processing.
- Controlled atmospheres : The atmosphere and ambient temperature surrounding naturally respiring products such as fruit is actively controlled to provide optimum conditions for long-term storage.
- Electronics : Used in the inerting of printed circuit board reflow and wave ovens, to prevent oxidation and facilitate the use of weaker fluxes which decompose more easily without leaving a residue.
- Food freezing / chilling : Liquid nitrogen freezes food quickly, producing a higher-quality product compared to to conventional refrigeration.
- Food inerting : Used in brewing, soft drinks and wine-making industries to exclude air from the product and de-aerate water.
- Food packaging : Used in modified atmosphere packaging, liquid nitrogen can increase the shelf-life without the need for vacuum-packing, artificial preservatives or freezing.
- Freeze-drying : In the freeze-drying process, materials dissolved in water or organic solvents are frozen into particles or droplets. A vacuum is applied to the freezing chamber along with a controlled amount of heat sufficient to drive off moisture by sublimation.
- Glass : Nitrogen and hydrogen are used in the float glass process for manufacturing flat glass. In this process perfectly flat glass with a very high quality is achieved by floating liquid glass on a bath of molten tin.
- Heat treatment : Pure nitrogen is used to protect some of the most reactive metals during heat treatment. These metals readily form a protective oxide surface layer from the small amount of oxygen in the nitrogen and need no further protection.
- Lasers : Nitrogen is used as an assist gas for laser cutting of stainless steel, aluminium and non-metallic materials.
- Metals : Nitrogen is used in iron and steelworks applications for degassing and metal-stirring, purging, cooling, slag splashing, gas knives and as a carrier gas for injecting de-sulphurising compounds. It is also used for aluminium-extrusion inerting.
- Pipe-freezing : Repairs can be made to a pipe containing a liquid by using liquid nitrogen to freeze a plug of liquid on each side of the section of pipe to be opened.
- Purging : Applications include inerting reactors and storage tanks, purging vessels and pipelines of flammable or toxic gases and vapours, and the sparging and pressure transfer of liquids.
- Shrink-fitting : Liquid nitrogen is used to shrink components so they are small enough to be inserted into another component.
- Sample storage : Liquid Nitrogen can be used to store medical or research samples such as blood, plasma and semen – safely.