| 摘要 |
921,273. Obtaining high vacua. UNION CARBIDE CORPORATION. Aug. 11, 1960 [Aug. 31, 1959], No. 27789/60. Class 8(1). A double walled heat insulating system such as a double walled flask for holding liquefied gases such as O 2 N 2 , H 2 A or He for heat insulating deep frozen solids comprises as a hydrogen selective getter PaO exposed to the vacuum space between the double walls and a non hydrogen selective getter also exposed to the vacuum space between the double walls. The getter is palladium oxide in conjunction with non selective getters specially treated, e.g. metallic Ba powder shielded with palladium foil. The H 2 selective getter located adjacent a warm part of the vessel wall is used in combination with the absorbent material for H 2 O vapour 0 2 , N 2 A, CO, CO 2 CH 4 located adjacent a cold part of the vessel wall e.g. silica gel, charcoal or a natural or synthetic zeolitic molecular sieve e.g. faujazite, chabazite, erionite (natural) or sodium X zeolite or calcium zeolite A (synthetic), activated by dehydration to absorb any water released by the non hydrogen selective getter, a further absorbent such as zeolitic molecular sieves having a pore size of 4 or 5 angstrom units or P 2 O 5 is used, disposed in the connecting channel. In the Figure, the facing surfaces of the inner and outer metal walls 12, 14 may be polished or provided with opacified powder, insulating material or composite heat insulation such as low heat conductive material and heat radiation barriers. The low heat conductive material may be fibre strip, glass wool or fibre glass, preferably the latter, and may also support the heat radiation barriers. The heat radiation barriers may comprise metal, metal oxide or metal coated material such as A1 coated plastic film, or heat reflective and/or absorptive material. The heat reflective material may be thin metal foils e.g. Al foil strip, Sn, Ag. Au, Cu, Cd. The strips of the heat radiation barrie rs and of the low heat conductive material maybe spirally wrapped around the inner wall 12 or they may be concentric layers. The hea tradiation barriers are provided with small holes to allow evacuation. The evacuation pip 20 is crimped and soldered or welded. Sealed glass capsule 21 with vacuum or argon filling and containing the hydrogen selective getter in powdered form is placed in chamber 23. Channel 23a has a water selective adsorbent, e.g. silica gel. After 20 has been sealed chamber 23 is deformed with a pair of pliers or a screw clamp to crush the capsule. Alternatively a thin film of metalcontaining getter is applied to an inert foil as a plating or coating and is wound in a loose coil and sealed in the capsule or a selective hydrogen getter vapour is deposited on silica powder. The adsorbent is placed in blister 27 which has a filter or screen. The container is of carbon steel, stainless steel or Al. Specification 853,585 and U.S.A. Specifications 2,882,243, 2,900,800 and 2,967,152 are referred to. |
