Helium, He
Molecular weight g/mol: 4.003
Purity: 99.9999%
CAS: 7440-59-7 EC: 231-168-5 UN: 1046 (Compressed); 1963 (Refrigerated liquid)
Typical Filling Pressure: 15 °C: 200 bar(a) 70 °F: 2,640 psi(g)
Characteristics: Colourless and odourless gas. Non-reactive. Asphyxiant in high concentrations.
Liquid State | |
Density at b.p. 1 atm kg/l: | 0.1240 |
Density 20 °C kg/l: | |
Vapor pressure 20 °C bar: | |
Specific heat kJ/kg*K: | |
Rel.Spec.wgt, air=1 (15 °C.1 bar): | 0.14 |
Density 15 °C 1 atm kg/m3: | 0.17 |
Gaseous state | |
Specific heat (15 °C) kJ/kg* K: | 5.193 |
Thermal conductivity µW/cm• K: | |
Solubility in water at P=1 bar l/kg: | |
Boiling point (1 atm) | |
Temp. °C: | -268.9 |
Heat of vaporization kJ/kg | 20.8 |
Critical point | |
Temp. °C: | -268.0 |
Pressure bar: | 2.28 |
Density kg/l: | 0.0699 |
Flammability in air | |
Lower limit % volume: | n.a. |
Upper limit % volume: | n.a. |