Helium is a unique molecule that is used for much more than inflating balloons at the county fair. After hydrogen, helium is the lightest element and has the smallest molecular cross-section of any gas. Helium is one of the rare gases in our earth’s atmosphere in which it is present in a concentration of only 5 ppm.
It is completely inert to chemical reaction and radiation. Its thermal conductivity surpasses that of any other inert gas and is three times greater than neon, its nearest inert competitor. Helium’s boiling point of -452.1oF (-268.9oC) gives it refrigeration capabilities beyond those of any other substance. Helium provides a high rate of permeability and ease of detection with only slight solubility in the bloodstream. It is nonflammable and is only slightly soluble in water. It is usually shipped at high pressures at or above 2400 psig at 70oF (16 550 kPa at 21.1oC) in cylinders and in bulk units. It is also shipped as a cryogenic liquid.
Safety, Storage & Handling:
Gaseous helium is commonly stored in high pressure cylinders, hydril tubes, or tube trailers. Liquid helium is commonly stored at the consumer site in cryogenic liquid cylinders, portable customer stations, and specially designed insulated tanks. To minimize helium transfer losses, the shipping container for liquid helium is normally used for storage.
Users of liquid helium must also take special precautions in addition to those necessary for the safe handling of such inert liquefied gases as nitrogen and argon. The extremely low temperature of liquid helium makes these special precautions imperative; it can solidify all other gases and …more