Thermally insulated chamber

Abstract

Novel construction is disclosed for a thermally insulated chamber for batch treatment of materials therein at low temperature wherein frequent opening and closing of the outer door of the chamber is practiced. The chamber walls as well as the insulated outer door of the chamber are constructed of rigid but relatively light metallic frames which remain at near ambient temperature. These frames are covered by sheet metal linings on their outer faces and by a plurality of abutting sheet metal inner liners spaced from the outer liners, the space therebetween being filled with insulating material. Buckling and warping of the walls and door as a result of shrinkage is avoided by limiting the maximum linear dimension of each inner liner, by provision of flexible expansion joints in the inner surface and flexible support members which attach the linings to the basic framework, so arranged that paths of only low thermal conductance occur. The designed chambers are especially useful for removal of coatings on material at cryogenic temperature by contacting the chilled material with a high velocity stream of impact medium. An inner door is provided to close the doorway when the outer door is opened.