vacuum flask

views updated May 17 2018

vacuum flask Container for keeping things (usually liquids) hot or cold. A vacuum flask consists of double, silvered glass walls, separated by a near vacuum. This vessel is held in an insulated metal or plastic case. The vacuum reduces heat transfer by conduction of convection between the contents and the surroundings. The silvering on the glass minimizes heat transfer by radiation. James Dewar invented the vacuum flask in 1892.