A cryogenic dewar is both one of the main breakthrough inventions for the development of cryogenics in the 19th century and a crucial element today for storing certain common gases. We analyse what a dewar tank exactly is and what precautions must be taken in order to ensure its safety.
A cryogenic dewar, dewar tank or dewar container is a vessel designed to store cryogenics (whose boiling points are lower than most substances). In order to do so, the dewar flasks present a vacuum space between the outside walls and the liquid stored inside, that acts as an insulator.
Thus, a cryogenic dewar can be simple (double walls and a space between them, such as household thermos for hot and cold drinks) or present other more complex elements like valves or gauges, built for other uses (such as a liquid nitrogen dewar or LN2 dewar).
Today, a cryogenic dewar is used to store, transport or provide on-demand cryogenic gases.
The technology for using and producing cold has seen a tremendous surge in the latter half of the 20th century, and the invention of cryogenic dewar was one of the most important achievements to develop cryogenics.
Dewar flasks in fact are named after James Dewar, a Fullerian Professor of Chemistry at the Royal Institution, in London in 1877. In the midst of his research on cryogenics, he sought to understand heat transfer processes to achieve thermal insulation. He also wanted to comprehend the properties of fluids in order to produce cryogenic temperatures.
After a research that took him 15 years, he was able to invent what still constitutes the basis of the cryogenic dewar today: the silvered, double walled vacuum vessel, where he introduced powders such as silica, charcoal or lamp black, in order to act as vacuum space powders.
Thanks to this invention, he was able to develop a storage system for liquid hydrogen that was able to keep the liquified gas cold enough.
The cryogenic dewars are characterized by their great adaptability. There are many different form on the market and each one has special specifications for the type of gas it stores. Some of the most common are:
There are a number of safety hazards related to cryogens and their storage.
As you could see, cryogenic dewars require frequent and exhaustive maintenance to comply with usage and safety regulations. In Cryospain we have a unit specialized in dewars maintenance that is operating since 2005 and we have repaired over 2000 units. If you have any questions, please contact us and our expert team will be happy to assist you.
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