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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.
Büchner flask A Büchner funnel is attached to the flask via a black elastomer adapter. The hose barb is connected via vacuum hose to a vacuum source such as an aspirator. The flask should be clamped before use or the hose will likely cause it to tip. Cross section of a Büchner Flask. Note the hose barb pointing right for attaching a vacuum ...
The vacuum flask was so efficient at keeping heat out, it was found possible to preserve the liquids for comparatively long periods, making an examination of their optical properties possible. Dewar did not profit from the widespread adoption of his vacuum flask – he lost a court case against Thermos concerning the patent for his invention ...
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. It is named after inventor James Dewar, who developed it for his own work. They are commonly used in low-temperature physics and chemistry.
Diagram of the vacuum filtration apparatus. By flowing through the aspirator, water will suck out the air contained in the vacuum flask and the Büchner flask.There is therefore a difference in pressure between the exterior and the interior of the flasks : the contents of the Büchner funnel are sucked towards the vacuum flask.
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 ...