Helium medical gas role

Helium He1.Alias-English name Helium. 2.Usage Used for ultra-low temperature research, gas analysis, welding, leak detection, chemical vapor deposition, crystal growth, plasma dry engraving, special mixtures, etc., used as a standard gas, balancing gas, medical gas, balloons, electronic tubes, diving suits, etc., inflatable. 3. 3. Method ① Separated from natural gas. ② separated from the air. ⑧ extracted from some radioactive minerals. 4. Physical and chemical properties molecular weight: 4.0026 melting point (2555kPa): -272.1 ℃ Boiling point (101.325kPa): -268.94 ℃ Liquid Density (4.20K, 100.312kPa): 125.2kg/m3 Gas Density (0 ℃, 101.325kPa): -0.1785 kg/m3 Relative density (gas), 0 ℃, 101.325kPa, 0 ℃, 101.325kPa. Relative density (gas, 0℃, 101.325kPa): 0.138 Specific volume (21.1℃, 101.325kPa): 6.0304 m3/kg Gas-liquid volume ratio (15℃, 100kPa): 748 L/L Critical temperature: -268.0℃ Critical pressure: 229 kPa Critical density: 69.3 kg/m3 Compressibility coefficient: Temperature ℃ Compression coefficient 100kPa 1000kPa 1 0000kPa 15 50 1.0005 1.0004 1.0049 1.0043 1.0487 1.0429 Heat of melting (1.2K, 2555kPa): 0.0836kJ/kg Heat of vaporization (-268.926℃, 101.325kPa): 20.42 kJ/kg Specific heat capacity ( Gas, 25°C, 101.325kPa): Cp=5238.3 J/(kg-K) Cv=3213.7J/(kg-K) Specific Heat Ratio (Gas, 25°C, 101.325kPa): Cp/Cv=1.63 Vapor Pressure (0.5K): 0.0000022kPa (2.0K): 3.17kPa (5.0K): 197.1 kPa Viscosity (0°C, 101.325kPa): 0.01864 mPa-S (liquid, 3.0K): 0.0033 mPa-S Surface tension (4.2K): 0.096 mN/m Thermal conductivity (0°C, 101.325kPa): 0.1426 W/(m-K) (liquid, 2.4K): 0.01883 W /(m-K) Refractive index (gas, 0°C, 101.325kPa): 1.000035 Helium is a colorless, odorless, tasteless and non-toxic noble gas at room temperature and pressure. It does not burn. Slightly soluble in water and organic solvents. Solubility in water at a pressure of 101.325 kPa is 0.00901 ml/g (0°C), 0.00834 ml/g (30°C), 0.00887 ml/g (60°C). Solubility in some organic solvents at 20°C, 101.325 kPa is 31.3 ml/1 in methanol, 28.1 ml/1 in ethanol, 30.9 ml/1 in acetone, 30.9 ml/1 in benzene, 30.1 ml/1 in ethanol, 30.9 ml/1 in acetone, and 30.9 ml/1 in benzene. 30.9ml/1 in methanol, 28.1ml/1 in ethanol, 30.9ml/1 in acetone, 18.0ml/l in benzene. helium is the second lightest gas after hydrogen, it is easy to diffuse and penetrate, and is chemically stable, therefore, it is often used as a leak detection gas. 5.Toxicity-safety protection Helium itself is non-toxic, but in high concentrations have the effect of asphyxiation. For symptoms of asphyxiation, see argon. Helium is expelled in its original form when inhaled. Helium has the same solubility in body fluids and blood as it does in water, but it is much less soluble than nitrogen. Therefore, it is less anesthetic than nitrogen. Liquid helium containers are mainly made of stainless steel. The helium-containing exhaust gas can be discharged directly into the atmosphere.