Other effects of nitrogen Due to the chemical inertness of nitrogen, commonly used as a protective gas, such as: fruits, food, light bulb filling gas. In order to prevent some objects from being oxidized by oxygen when exposed to the air, filling the granaries with nitrogen can make the grain not moldy, not germinating, and long-term preservation. Liquid nitrogen can also be used as a deep refrigerant. As a cryogenic agent in the hospital to remove spots, bags, beans and other operations are often used, that is, spots, bags, beans and so on frozen off, but prone to scars, is not recommended. High purity nitrogen is used as a carrier gas for instruments such as chromatographs. Used as a bright annealing protective gas for copper pipes. Together with high-purity helium and high-purity carbon dioxide, they are used as laser gas for laser cutting machines. Nitrogen is also used as a protective gas for food preservation. In the chemical industry, nitrogen is mainly used as a protective gas, replacement gas, washing gas, and safety gas. Used for aluminum products, aluminum profile processing, aluminum thin rolling and other protective gas. Used as a protective gas for reflow welding and wave soldering to improve welding quality. Used as a protective gas in float glass production to prevent oxidation of tin tanks.