Cryogenic liquids are liquified gases that are kept in their liquid state at very low temperatures. All cryogenic liquids are extremely cold. It has boiling points below -150° C. 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: these are extremely cold, and small amounts of liquid can expand into very large volumes of gas.