At atmospheric pressure, the temperature of liquid nitrogen is-196℃; 1 m3 liquid nitrogen can be expanded into 696 m3 2 1℃ pure gaseous nitrogen. Liquid nitrogen is a colorless and odorless liquid, and it is a cryogenic gas under high pressure. Liquid nitrogen (often written as LN2) is a liquid form formed by nitrogen at low temperature. The boiling point of nitrogen is-196℃. Under normal atmospheric pressure, if the temperature is lower than this, liquid nitrogen will be formed. If pressurized, liquid nitrogen can be obtained at a higher temperature.
In industry, liquid nitrogen is fractionated from air. After air is purified, it is liquefied in a pressurized cooling environment, and separated by using the difference of boiling points of each component in the air. There is no problem for human skin to contact liquid nitrogen directly, and it will be frostbitten for more than 2 seconds, which is irreversible.
Chinese name: Liquid nitrogen English name: liquid nitrogen chemical formula: N2 molecular weight: 28.0 1 CAS registration number: 7727-37-9 melting point: -209.8℃ boiling point:-196.56℃ water solubility: slightly soluble in water density: 0.81. 2 1 transport code of dangerous goods: 22006 stability: stable decomposition products: physical and chemical characteristics of nitrogen, transport information, storage protection, danger, poisoning treatment, first-aid measures, fire-fighting measures, first-aid treatment, use, industrial use, biological and medical use, regulatory information, and chemistry with physical and chemical properties. : 7727-37-9 molecular formula: N2 molecular weight: 28.0 1 main component: content: high purity nitrogen ≥ 99.999%; Industrial level ≥ 99.5%; Grade Ⅱ ≥98.5%. Appearance and properties: liquid, colorless and tasteless. Melting point (℃):-209.8 boiling point (℃):- 196.56 relative density (water = 1): 0.808 (- 196℃) latent heat of evaporation: 5.56kJ/ Mol relative vapor density (air =/kloc) Other physical and chemical properties: stability: stable prohibited substances: conditions for avoiding contact without data: polymerization hazards of prohibited substances: non-polymerized decomposition products: nitrogen transport information: dangerous goods number: 22006 UNNo. : 1977 packing category: Z0 1 note: the storage tank must be inspected regularly and kept in a trouble-free state. People and goods are not allowed to ride together in the means of transport and should be stored in a closed space. Precautions for storage protection operation: closed operation. Closed operation to provide good natural ventilation. Operators must be specially trained and strictly abide by the operating procedures. Operators are advised to wear winter clothes and gloves. Prevent the gas in the workplace from leaking into the air. When handling, handle with care to prevent damage to cylinders and accessories. Equipped with leakage emergency treatment equipment. Precautions for storage: Store in a cool and ventilated warehouse. The reservoir temperature should not exceed 30℃. The storage area should be equipped with emergency treatment equipment for leakage. Engineering control: closed operation and good natural ventilation. Respiratory system protection: generally no special protection is needed. However, when the oxygen concentration in the air in the workplace is lower than 18%, air respirator, oxygen respirator or long tube mask must be worn. Eye protection: Wear a safety mask. Physical protection: wear winter clothes. Hand protection: wear cold gloves. Other protection: avoid high concentration inhalation. Prevent frostbite. Dangerous route of invasion: inhalation health hazard: skin contact with liquid nitrogen can cause frostbite. If there is too much nitrogen produced by vaporization under normal pressure, the partial pressure of oxygen in the air will decrease, and in extreme cases, it will cause hypoxia and suffocation. Danger of explosion: this product will not burn or explode. First aid measures for poisoning treatment Skin contact: If frostbite occurs, seek medical attention. Inhalation: leave the scene quickly and go to a place with fresh air. Keep the respiratory tract unobstructed. If you have difficulty breathing, give oxygen. If breathing stops, give artificial respiration immediately. See a doctor. Hazard characteristics of fire-fighting measures: In case of high heat, the pressure inside the container increases, which is in danger of rupture and explosion. Harmful combustion products: This product is nonflammable. Fire extinguishing method: This product is nonflammable. Use atomized water to keep the container cool in the fire. Spraying atomized water can accelerate the evaporation of liquid nitrogen, but the water gun should not be sprayed on liquid nitrogen. Emergency treatment emergency treatment: quickly evacuate the people in the leaked and polluted area to the upwind place, isolate them and strictly restrict access. It is suggested that emergency personnel wear self-contained positive pressure respirator and winter clothes. Don't touch the leak directly. Cut off the leakage source as much as possible. Use an exhaust fan to send the leaked gas to the open space. Leaked containers should be properly treated, repaired and inspected before use. When the inhaled nitrogen concentration is not too high, the patient initially feels chest tightness, shortness of breath and weakness; Then there are fidgety, extremely excited, running around, shouting, being in a trance, and unsteady gait. This situation is called "nitrogen poisoning" and can enter a lethargic or coma state. Inhalation of high concentrations can lead to rapid coma and death due to respiratory and cardiac arrest. 1. Evacuate the personnel in the leaked contaminated area to the upwind place quickly, and set up an isolation zone to strictly restrict access. 2. Notify the fire department and relevant units. 3. Emergency personnel should wear self-contained positive pressure breathing apparatus, winter clothes and gloves. 4. Avoid leaking liquid into the basement or other closed places where people work. If it is unavoidable, notify the relevant departments immediately. 5. Don't touch the leak directly. 6. Cut off the leakage source as much as possible. 7. Misty water mist can be used to accelerate the evaporation of liquid, but water gun can't be used to shoot liquid. 8. Prevent gas from accumulating in the depression, and send the leaked gas to the open place with an exhaust fan. 9. It is forbidden to stay in low-lying or downwind places. Uses Industrial uses In industrial production, liquid nitrogen obtained by fractionation of compressed liquid air can be used as a deep refrigerant. Because of its chemical inertness, it can be directly contacted with biological tissues and immediately frozen without destroying its biological activity, so it can be used for: (1) quickly freezing and transporting food or making ice products; (2) To carry out low-temperature physics research; (3) Demonstrate the low temperature state in science education. Soft objects at room temperature will be as fragile as glass if immersed in liquid nitrogen; (4) Provide the temperature required for high-temperature superconductors to show superconductivity, such as YBCO. (5) It can be used as a refrigerant to quickly freeze biological tissues and prevent them from being destroyed. (6) Used in industrial nitrogen fertilizer production. (7) Used for chemical detection, such as BET specific surface area test. Biological and medical uses (1) are used to kill red imported fire ants. (2) During the operation, rapid freezing is helpful to stop bleeding and remove the epidermis that needs to be removed. Inserting a needle of-170 degree into cancer tissue to freeze cancer cells (3) storing living tissues, biological samples and eggs; (4) It can be used as a refrigerant to quickly freeze biological tissues and prevent them from being destroyed. Cryotherapy Liquid nitrogen cryotherapy is a new technology in the field of modern therapeutics. Cryotherapy with liquid nitrogen is a comprehensive effect of cryobiology. Normal cells will be irreversibly damaged when they are extremely frozen. It is through extreme freezing that the cells in the enchantment are quickly killed and the enchantment returns to normal. Generally used to treat boils, corns and dermatoses. Cryosurgery is also used to treat breast cancer. In 20 12, Israeli medical company Iccure developed a new technology for treating breast cancer by cryotherapy, which uses liquid nitrogen to freeze and kill breast cancer cells, and the company is conducting clinical trials on it. If the trial is successful, breast cancer patients will be able to "remove" their tumors without surgery. Regulatory information Regulatory information Regulations on Safety Management of Hazardous Chemicals (promulgated by the State Council on February 1987), Detailed Rules for the Implementation of Regulations on Safety Management of Hazardous Chemicals (Hua Laofa [1992] No.677) and Regulations on Safe Use of Chemicals in Workplaces ([1996] No.423). Classification and Labeling of Commonly Used Hazardous Chemicals (GB 13690-92) classifies this substance as Class 2.2 nonflammable gas.