The importance of safety in any scientific endeavor is never in question. However, when cryogenic temperatures are involved, safety is especially important. In addition to observing the normal precautions, one must also take into account the variations of physical properties that occur at low temperatures. At these tempera tures, some properties not only exhibit large differences from their normal values but also can vary widely over a small temperature range. Before any cryogenic project is started, a thorough knowledge of the possible hazards is necessary. Only in this way can the safest operation be attained. Over the hundred-year history of cryogenic research, this has been shown to be the case. Keeping this requirement in mind is an essential ingredient in the quest for accident-free work. The past four or five decades have seen a great expansion of cryogenic technology. Cryogenic liquids, such as oxygen, nitrogen, hydrogen, and helium, have become commonly used in a number of different applications and are easily available in any part of the United States and, indeed, almost anywhere in the world. Not only are these liquids available, they have become less expensive and also available in ever larger quantities. As quantities increase, so also do the conse quences of mishaps. The future seems to hold promise of ever larger and more widespread use of the common cryogens. Thus, the importance of safety also increases as time progresses.

Cryogenics, a term commonly used to refer to very low temperatures, had its beginning in the latter half of the last century when man learned, for the first time, how to cool objects to a temperature lower than had ever existed na tu rally on the face of the earth. The air we breathe was first liquefied in 1883 by a Polish scientist named Olszewski. Ten years later he and a British scientist, Sir James Dewar, liquefied hydrogen. Helium, the last of the so-caBed permanent gases, was finally liquefied by the Dutch physicist Kamerlingh Onnes in 1908. Thus, by the beginning of the twentieth century the door had been opened to astrange new world of experimentation in which aB substances, except liquid helium, are solids and where the absolute temperature is only a few microdegrees away. However, the point on the temperature scale at which refrigeration in the ordinary sense of the term ends and cryogenics begins has ne ver been weB defined. Most workers in the field have chosen to restrict cryogenics to a tem perature range below -150°C (123 K). This is a reasonable dividing line since the normal boiling points of the more permanent gases, such as helium, hydrogen, neon, nitrogen, oxygen, and air, lie below this temperature, while the more common refrigerants have boiling points that are above this temperature. Cryogenic engineering is concerned with the design and development of low-temperature systems and components.

Cryogenics Safety Manual: A Guide to Good Practice, Third Edition promotes the safe application and development of low temperature engineering. The book also details the hazards involved in the operation, handling, and development of cryogenic devices. The text is divided into five chapters. Chapter 1 describes the health precautions and legislations involved in the field. Chapter 2 tackles the specific hazards and safety measures in handling and maintaining air separation plants. Chapter 3 discusses the precautions to be observed in the different procedures concerning natural gas, ethylene, and methane. Chapter 4 covers the proper safety measures and maintenance of plants and equipment designed to handle liquid and gas states of hydrogen at low temperatures, and Chapter 5 talks about the special precautions in handling helium, neon, krypton, and xenon. Chemists, physicists, engineers, and safety personnel involved in the field of cryogenics would benefit from this helpful guide.

This book describes the current state of the art in cryogenic safety best practice, helping the reader to work with cryogenic systems and materials safely. It brings together information from previous texts, industrial and laboratory safety polices, and recent research papers. Case studies, example problems, and an extensive list of references are included to add to the utility of the text. It describes the unique safety hazards posed by cryogenics in all its guises, including issues associated with the extreme cold of cryogenics, the flammability of some cryogenic fluids, the displacement of oxygen by inert gases boiling off from cryogenic fluids, and the high pressures that can be formed during the volume expansion that occurs when a cryogenic fluid becomes a room temperature gas. A further chapter considers the challenges arising from the behavior of materials at cryogenic temperatures. Many materials are inappropriate for use in cryogenics and can fail, resulting in hazardous conditions. Despite these hazards, work at cryogenic temperatures can be performed safely. The book also discusses broader safety issues such as hazard analysis, establishment of a safe work culture and lessons learned from cryogenic safety in accelerator labs. This book is designed to be useful to everyone affected by cryogenic hazards regardless of their expertise in cryogenics.