Cryogenic Liquids:

Most cryogenic liquids are odorless, colorless, and tasteless while vaporized to a gas.  As liquids, many have no color (except liquid oxygen that is light blue).  Therefore, while the cold liquid and vapor are exposed to the atmosphere a warning appears.   Since the boil-off gases condense moisture in the air that a fog forms which extends over an area larger than the vaporizing gas? Several cryogenic liquids are inert gases, and might inert an enclosed space.  Inert gases would not support life.

The liquid and its boil-off vapor both could rapidly freeze human tissue and could cause many common materials such as plastic, carbon steel, and rubber to become brittle or fracture under stress. Liquids in holdings and piping at temperatures at or below the boiling point of liquified air (-318ºF) could cause the surrounding air to condense to a liquid.

Very cold liquified gases (hydrogen, helium, and neon) could even solidify air or other gases to that they are straightly exposed.  In many cases, plugs of ice or foreign material will develop within cryogenic container vents and openings and cause the vessel to rupture.  Contact the supplier immediately if a plug forms.  Do not attempt to erase the plug; move the vessel to a remote location.

All cryogenic liquids process huge volumes of gas while they vaporize.  For instance, 1 volume of saturated liquid nitrogen at 1 atmosphere vaporizes to 696.5 volumes of nitrogen gas at room temperature at 1 atmosphere.

While vaporized within a sealed container, cryogenic liquids generate enormous pressures.  It has the potential to generate a pressure of more than 14,500 psig if 1 volume of liquid helium at 1 atmosphere is warmed to room temperature and vaporized in a totally enclosed container. Since of this high pressure, cryogenic containers are commonly protected along with two pressure-relief devices, a pressure-relief valve and a frangible (simply broken) disk.

Several safety precautions which must be taken along with compressed gases also apply to liquified gases. Therefore, a few additional precautions are essential since of the special properties exhibited through fluids at cryogenic temperatures.