Assertion: helium | /r/ObjectUse | used as an inert-gas atmosphere
Facets:
value: for welding metals such as aluminum
type: PURPOSE
value: in rocket propulsion
type: TEMPORAL
Source sentences:
text: Helium is used as an inert-gas atmosphere for welding metals such as aluminum; in rocket propulsion (to pressurize fuel tanks, especially those for liquid hydrogen, because only helium is still a gas at liquid-hydrogen temperature); in meteorology (as a lifting gas for instrument-carrying balloons); in cryogenics (as a coolant because liquid helium is the coldest substance); and in high-pressure breathing operations (mixed with oxygen, as in scuba diving and caisson work, especially because of its low solubility in the bloodstream).