The applications of nitrogen compounds are naturally extremely widely varied due to the huge size of this class: hence, only applications of pure nitrogen itself will be considered here. Two-thirds of nitrogen produced by industry is sold as the gas and the remaining one-third as the liquid. The gas is mostly used as an inert atmosphere whenever the oxygen in the air would pose a fire, explosion, or oxidising hazard. Some examples include:
Nitrogen gas is also used to provide an unreactive atmosphere. It is used in this way to preserve foods. As a modified atmosphere, pure or mixed with carbon dioxide, to nitrogenate and preserve the freshness of packaged or bulk foods (by delaying rancidity and other forms of oxidative damage like changing colours). Pure nitrogen as food additive is labelled in the European Union with the E number E941.
Light bulbs industry
Bulbs should not be filled with air since hot tungsten wire will combust in presence of oxygen. You can’t maintain vacuum either or external atmospheric pressure will break the glass. So, they must be filled with non-reactive gas like nitrogen. We can use inert gases like argon or helium instead of Nitrogen, but they are more expensive & rarer than nitrogen.
Fire suppression systems
Fire suppression is achieved by reducing the oxygen concentration where the fire will extinguish, while remaining at a level acceptable for human exposure for a short period of time.
Stainless steel manufacturing
There are various instances when nitrogen can be added to steel during steelmaking such as melting, the ladle processing and the casting operations. Nitrogen effect on hardness, formability, strain ageing and impact properties.
Tire filling systems
Nitrogen is used to inflate race car and aircraft tires, reducing the problems caused by moisture and oxygen in natural air. Nitrogen is less likely to migrate through tire rubber than oxygen, which means that your tire pressures will remain more stable over the long term. That means more consistent inflation pressures during a use as the tires heat up.
Aircraft fuel systems
In some aircraft fuel systems nitrogen is used to reduce fire hazard.
Chemical analysis and chemical industry
Nitrogen is commonly used during sample preparation in chemical analysis. It is used to concentrate and reduce the volume of liquid samples. Nitrogen is also important to the chemical industry. It is used in production of fertilisers, nitric acid, nylon, dyes