From Hazardous Chemicals Handbook, Second Edition


Cryogenics, or low-temperature technology, is the science of producing and maintaining very low temperatures usually below 120 K, as distinct from traditional refrigeration which covers the temperature range 120 to 273.1 K. At or below 120 K, the permanent gases including argon, helium, hydrogen, methane, oxygen and nitrogen can be liquefied at ambient pressure as exemplified by Table 8.1. Any object may be cooled to low temperatures by placing it in thermal contact with a suitable liquefied gas held at constant pressure. Applications can be found in food processing, rocket propulsion, microbiology, electronics, medicine, metal working and general laboratory operations. Cryogenic technology has also been used to produce low-cost, high-purity gases through fractional condensation and distillation. Cryogens are used to enhance the speed of computers and in magnetic resonance imaging to cool high conductivity magnets for non-intrusive body diagnostics. Low-temperature infrared detectors are used in astronomical telescopes.

Table 8.1: Properties of common cryogens


Boiling point ( C)

Volume of gas produced on evaporation of 1 litre of liquid (litres)


































Carbon dioxide



Every gas has a critical temperature above which it cannot be liquefied by application of pressure alone (Chapter 4). As a result, gases used, e.g., as an inert medium to reduce oxygen content of atmospheres containing flammable gas or vapour (Chapter 6)...

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Products & Services
Cryogenic Equipment
Cryogenic equipment produces or is used in the production of very low temperature materials or processes.
Welding Gases and Thermal Process Gases
Welding gases and thermal process gases are specialized gases for welding, cutting or other thermal processing applications.
Chemical Process and Petrochemical Gases

Chemical process and petrochemical gases are materials used in the production of compounds or products. They are used in processes such as inerting, blanketing, purging, sparging, and stripping. These gases are used in many applications including treatment and sterilization, medicine, energy solutions, and manufacturing.

Electronic and Semiconductor Gases
Electronic and semiconductor gases are specialized for microelectronic manufacturing or semiconductor processing applications such as thin film deposition (CVD, PVD), etching, RTP, packaging or soldering.

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