Liquid Helium

Liquid helium is inert, colorless, odorless, non-corrosive, extremely cold, and nonflammable. Helium will not react with other elements or compounds under ordinary conditions. Since helium is non-corrosive, special materials of construction are not required. However, materials must be suitable for use at the extremely low temperatures of liquid helium
Being odorless, colorless, tasteless, and nonirritating, helium has no warning properties. Humans possess no senses that can detect the presence of helium. Although helium is nontoxic and inert, it can act as a simple asphyxiant by displacing the oxygen in air to levels below that required to support life. Inhalation of helium in excessive amounts can cause dizziness, nausea, vomiting, loss of consciousness and death. Death may result from errors in judgment, confusion, or loss of consciousness that prevents self-rescue. At low oxygen concentrations, unconsciousness and death may occur in seconds and without warning. Personnel, including rescue workers, should not enter areas where the oxygen concentration is below 19.5%, unless provided with a self-contained breathing apparatus or air-line respirator
Physical Properties