Tracer gas Helium

  • Occurs in nature only atomically, builds no molecules. Chemically inertly due to its (only) completely occupied valence electron shell.
  • After hydrogen the secondly most frequent element in the universe.
  • Natural gas contains on the average 0,4% He and is thereby the economically most important source for the helium production.
  • By all gases Helium is the most difficult to liquefy and cannot be converted in solid state at normal pressure. At 30 bar: Freezing point -271.4 °C; Boiling point at normal pressure is -269 °C.
  • Density (20 °C): 0.1664 gram/liter
  • Mol mass: 4.003 u (small, light molecule, which passes easily small leakages)
  • moderate price for industrial applications

Some applications:

  • Inert gas for welding light metals and alloys
  • filling gas for balloons
  • additive to the breathing air when deep diving against the diver´s palsy
  • Medical technology; in case of breathing problems
  • Ion beams from Helium nucleus to mediate eye or cerebral tumors