Explanation:

Cryogenic liquids

• Cryogenic liquids are liquefied gases that are kept in their liquid state at very low temperatures.
• The word "cryogenic" means "producing, or related to, low temperatures," and all cryogenic liquids are extremely cold.
• Cryogenic liquids have boiling points below -150°C (- 238°F)
• All cryogenic liquids are gases at normal temperatures and pressures.
• These gases must be cooled below room temperature before an increase in pressure can liquefy them.
• Different cryogens become liquids under different conditions of temperature and pressure, but all have two properties in common: they are extremely cold, and small amounts of liquid can expand into very large volumes of gas.

Each cryogenic liquid has its own specific properties but most cryogenic liquids can be placed into one of three groups:

• Inert Gases: Inert gases do not react chemically to any great extent. They do not burn or support combustion. Examples of this group are nitrogen, helium, neon, argon and krypton.
• Flammable Gases: Some cryogenic liquids produce a gas that can burn in air. The most common examples are hydrogen, methane and liquefied natural gas.
• Oxygen: Many materials considered as non-combustible can burn in the presence of liquid oxygen. Organic materials can react explosively with liquid oxygen. The hazards and handling precautions of liquid oxygen must therefore be considered separately from other cryogenic liquids.