Selecting a Valve for Cold Service
Since the first quarter of the 19th century, countless scientists and natural philosophers have taken on the study of "cold." Commercializing on the mastery of these discoveries, life on this planet has never been the same. For example, in the early 1800s, a temperature of–110 degC [–166 degF] was not proven to exists. The vocabulary, never mind the means to attain it, did not exist. Through many years of experimentation and the rough road of trying to commercialize on scientific breakthroughs in the marketplace, we enjoy the advancements to human life and the comfort it brings.
It has been generally accepted, at least commercially, that the cryogenic temperature range starts at–150 degC (–238 degF). Certain gases are considered "cryogenic" because it takes more than just an increase in pressure to compress a volume of gas—as stipulated by Robert Boyle. Little did he know at the time (1665) that the relationship between volume and pressure would become much later the cutting edge for cold research.