What is cryogenic gas

Cryogenic gas plants have today emerged in the current market scenario as the most efficient and cost effective technology of producing and distributing pure gases like oxygen and nitrogen. The technology is perfect for large sized gas plants. The best feature of these gas plants is that they can produce liquid products.

Cryogenic gases are liquefied gases at standard temperature and pressure. They are kept in their liquid state at very low temperatures. The word "cryogenics" in English means "the production of icy cold". Cryogenics in physics means the study of the production of extremely low temperatures (below -150 °C, -238 °F or 123 K). Thus cryogenic gas is a gas which has been supercooled such that it is a liquid or solid at a standard temperature.

Cryogenic materials include the liquids argon, nitrogen, oxygen and helium, and solid carbon dioxide (dry ice). Carbon dioxide and nitrous oxide, which usually have slightly higher boiling points are also included in the category of cryogenic gas. One of the most commonly used element in cryogenics is Liquid nitrogen. Liquid helium is also used. Infact liquid helium allows for the lowest attainable temperature to be reached. It is to be noted that all types of cryogenic liquids are gases at normal temperatures and pressures. These gases are then cooled below room temperature and this should be done before an increase in pressure can liquefy them. Under different conditions of temperature and pressure, different cryogens become liquids.

However all cryogen liquids have two common properties:

• They are very cold.
• A little quantity of liquid can expand into very large volumes of gas.

Cryogenic gases are very popular and they are used as fuels, oxidizers and refrigerants. These gases are to be stored properly to get their maximum usage. In poorly insulated containers, it is very likely that some cryogenic gases actually condense the surrounding air, forming a liquid air mixture. That is the reason they should be held in special containers like Dewar flasks, which are generally about 1.8 m (6 feet tall) and 91.5 cm (3 feet) in diameter. For commercial applications they are stored in giant tanks. In museums, cryogenic gas is stored in smaller vacuum flasks fitted in a protective casing. There are cryogenic transfer pumps used on LNG piers. These pumps are used to transfer Liquefied Natural Gas from LNG Carriers to LNG storage tanks.

Cryogenic gas also has some hazards associated with it like as they may be flammable, as in Hydrogen, LPG or they may be oxidizers, as in Fluorine, Oxygen and hence they must be carefully used.

A quick recap Cryogenic gas is a gas formed at very low temperature (below 150°C). Commonly used cryogenic materials is liquid nitrogen and liquid helium. The gas is produced through a process of compression and cooling. Used widely as a fuel and also refrigerant. Everyone who works with cryogenic gas must know their hazards. Everyone should know how to work safely with them.