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A self-pressurising dewar (silver) being filled with liquid nitrogen from a larger storage tank (white). A cryogenic storage dewar (or simply dewar) is a specialised type of vacuum flask used for storing cryogens (such as liquid nitrogen or liquid helium), whose boiling points are much lower than room temperature.
A vacuum flask (also known as a Dewar flask, Dewar bottle or thermos) is an insulating storage vessel that slows the speed at which its contents change in temperature. It greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings by trying to be as adiabatic as possible.
A non refrigerated air-transportable dewar for 750 liters of liquid hydrogen was developed by H.L. Johnston in ca. 1952. [2] The heat flow to the liquid hydrogen shell was 4 watts, boil-off about 7.5 liters per day, or 1% of the rated capacity. They were equipped with valves, instruments, and a vacuum pump.
Volumetric flask is used for preparing liquids with volumes of high precision. It is a flask with an approximately pear-shaped body and a long neck with a circumferential fill line. Dewar flask is a double-walled flask having a near-vacuum between the two walls. These come in a variety of shapes and sizes; some are large and tube-like, others ...
Cold trap immersed in cold medium in Dewar flask. Some workers prefer the opposite arrangement, where vapors flow down the wall of the trap, and are sucked up the inner tube; this reduces blockage.
This page was last edited on 1 October 2012, at 18:29 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
Dewar may refer to: Clan Dewar; Dewar (caste), a fishing caste from India; Vacuum flask (also known as a Dewar flask), a vacuum-insulated container used to maintain internal temperature for extended periods, named for British chemist James Dewar. Cryogenic storage dewar, a specialized vacuum flask for extremely cold fluids
In the last case the bottle is constructed with an inner and outer shell separated by a vacuum (dewar flask) so that the low temperature can be maintained by evaporative cooling. [ citation needed ] Case I