Liquid nitrogen is a liquid with a low temperature of -196 ° C and is obtained from nitrogen gas which accounts for more than 70% of the air content. Inert, colorless, non-toxic, volatile, and widely used. Liquid nitrogen is volatile at low temperatures, so it is generally stored in a special container - liquid nitrogen tank.
According to the classification of liquid nitrogen purity, it is often divided into food grade liquid nitrogen and industrial grade liquid nitrogen. The purity of food grade liquid nitrogen is higher, because it takes into account the safety of human consumption, the purity reaches 5 9 or 99.999%. Industrial grade liquid nitrogen purity is not as high as food grade liquid nitrogen purity, and different industries have different requirements for liquid nitrogen purity.
Food grade liquid nitrogen applications such as liquid nitrogen ice cream, liquid nitrogen biscuits, medical liquid nitrogen freezing, anesthesia also require high purity liquid nitrogen. Other industries such as chemicals, electronics, and metallurgy have different requirements for liquid nitrogen purity.