This section provides safety information and precautions regarding cryogenic fluids and defines the hazards associated with their use.
Definitions
A cryogenic liquid is defined as a liquid with a normal boiling point below –150 °C.
Cryogenic liquids escape from their storage containers via evaporation as a part of their normal operation. Properties of cryogenic liquids are shown in Table 9.1. A 160 L tank loses a gas amount equivalent to 2 L of liquid per day, depending on the type of Dewar material used. To minimize the heat loss, cryogenic liquid containers are usually in vacuum-jacketed design. Excessive venting and/or a partial ice accumulation on vessel walls are a sign of an integrity problem in the vessel or in process line. A leaking container should not be used and be transported to a well-ventilated area.
| Table 9.1: Properties of cryogenic liquids | |||||
|---|---|---|---|---|---|
| Gas | Boiling Point Centigrade | Boiling Point Kelvin | Volume Expansion to Gas | ||
| Helium-3 | -269.9 | 3.2 | 757 to 1 | ||
| Helium-4 | -268.9 | 4.2 | 757 to 1 | ||
| Hydrogen | -252.7 | 20.4 | 851 to 1 | ||
| Deuterium | -249.5 | 23.6 | ... | ||
| Tritium | -248.0 | 25.1 | ... | ||
| Neon | -245.9 | 27.2 | 1438 to 1 | ||
| Nitrogen | -195.8 | 77.3 | 696 to 1 | ||
| Carbon monoxide | -192.0 | 81.1 | ... | ||
| Fluorine | -187.0 | 86.0 | 888 to 1 | ||
| Argon | -185.7 | 87.4 | 847 to 1 | ||
| Oxygen | -183.0 | 90.1 | 860 to 1 | ||
| Methane | -161.4 | 111.7 | 578 to 1 | ||
| Krypton | -151.8 | 121.3 | 700 to 1 | ||
| Tetrafluoromethane | -128 | 145 | . . . | ||
| Ozone | -111.9 | 161.3 | . . . | ||
| Xenon | -109.1 | 164.0 | 573 to 1 | ||
| Ethylene | -103.8 | 169.3 | . . . | ||
| Boron trifluoride | -100.3 | 172.7 | . . . | ||
| Nitrous oxide | -89.5 | 183.6 | 666 to 1 | ||
| Ethane | -88.3 | 184.8 | ... | ||
| Hydrogen chloride | -85.0 | 188.0 | ... | ||
| Acetylene | -84.0 | 189.1 | ... | ||
| Fluoroform | -84.0 | 189.1 | ... | ||
| 1,1-Difluoroethylene | -83.0 | 190.0 | ... | ||
| Chlorotrifluoromethane | -81.4 | 191.6 | . . . | ||
| Carbon dioxide | -78 5(b) | 194.6 | 553 to 1 | ||
Adopted from Canadian Centre for Occupational Health and Safety, OSH Answers Fact Sheets.
References and sources for information from the relevant websites and documentation of different universities, NGOs and government agencies used in the preparation of this website are provided at references.