Patent GB-942370-A (GB)
Title: Improvements in heat insulation in double walled containers
IPC: F17C13/00
Filed: 1962-06-12
Abstract: 942,370. Heat-insulated pipes. UNION CARBIDE CORPORATION. June 12, 1962 [June 21, 1961], No. 22449/62. Heading F2P. [Also in Division F4] A container, e.g. a tank or pipeline, for the storage of low temperature liquefied gases such as oxygen or hydrogen, quick frozen biological specimens or living tissues, for example, or a container in the form of a rocket motor, comprises an inner vessel separated from an outer casing by an evacuated insulation space which is provided with a multilayer insulation of low-heat-conductive fibrous material 11 and heatradiation-impervious material 10, a low heat-conductive compressible material 12 being positioned between and in contact with adjacent layers of insulation, the area of contact being a minor part of that of the adjacent layers. The material 11 may be glass fibre sheet material and may comprise permanently precompacted layers composed of fibres having diameters less than 15 microns. The material 12 may be in the form of glass fibre strips, as shown in Fig. 4, or in the form of sheets having a multiplicity of holes therein, Fig. 6 (not shown). The material 10 may be a metal or a metal-coated material such as aluminium coated plastic film; it may be in the form of metallic foil having a thickness of between 0.2 mm. and 0.002 mm. and when of aluminium the thickness is preferably between 0.05 mm. and 0.002 mm. Alternatively, the material 10 may be made of tin, silver, gold, copper or cadmium. It should have an emissivity of between 0.005 and 0.2, preferably between 0.015 and 0.06. The multi-layer insulation preferably includes between 4 and 200 layers per inch of aluminium foil and glass fibre material. The material 12 may be made of uncompacted, resilient and fluffy material in sheet form and preferably is compressible so that its density after installation is equal to at least twice its density before installation; it may be made of glass filaments having diameters between 0.2 and 5 microns, preferably between 0.5 and 3.8 microns. Alternatively, the material 12 may be made of woven fibrous materials such as glass cloth. Binders may be used in the fibrous material 11, e.g. colloidal silica, cellulose and water glass. As described with reference to Fig. 4 the material 10 is 0.25 mil. thick annealed aluminium foil, the material 11 is 2 mil. thick unwoven glass fibre sheets and the material 12 is in the form of strips of the same glass fibre material; each strip 12 may consist of a plurality of ribbons of the material. Apparatus for assembling the insulation on a container 13, Fig. 5, comprises a spindle 14 upon which the container is mounted and which is driven by a motor 18 through a speed controller 17 and a belt 16, a roll 19 for the material 10 which is fitted with a friction brake 21, a roll 22 for the material 11 and rolls 23 for the material 12. The material 12 covers between 2% and 10% of the area of the adjacent layers of insulation. It may be bonded to or incorporated in the material 11 and may be applied only after every third layer. Heat-radiation-impervious strips of material may be provided adjacent the strips of material 12, Fig. 7 (not shown). The inner vessel of the container may be only partially covered with the insulation.