Receptacles – Compartmented container – Compartments accessible from different planes
Patent
1996-06-07
1999-06-15
Moy, Joseph M.
Receptacles
Compartmented container
Compartments accessible from different planes
2065244, 206484, 53406, B65D 8572
Patent
active
059113367
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum stabilizer and a method for the manufacture thereof.
Such stabilizer can be advantageously exploited for maintaining a satisfactory vacuum degree inside a thermally insulating jacket under vacuum, where also insulating materials of different type may optionally be present.
A vacuum jacket of this kind allows to eliminate or considerably reduce the heat exchange between the environment and an inner chamber, or piping, lying at a temperature different from room temperature, generally lower.
A few typical examples of these end-uses are the Dewar vessels, employed for the storage of cryogenic fluids, as well as the pipings for the transport of same fluids or the insulating panels of refrigerators and freezers; a very and interesting recent case is represented by the tankers containing liquid methane or the liquefied petroleum gases (LPG).
It is known, in the current practice, that a good thermal insulation may be realized by means of a vacuum jacket, which may optionally contain insulating materials like glass wool, colloidal silica, perlite or organic polymers, in the form of foams (for instance open cell rigid polyurethanes or expanded phenolic resins) or in the form of a multilayer, particularly a polyolefinic multilayer mode from polypropylene, polyethylene, olefinic copolymers and so on).
It is known too that the vacuum realized in such a jacket, during its preparation, tends to degrade with the time, because of the degassing of the walls of the jacket, because of a gas infiltration (e.g. CO, CO.sub.2, O.sub.2, H.sub.2, H.sub.2 O, N.sub.2 and so on), because of the possible leaks of the walls or finally, in the case of a wall made from a plastic material, because of a permeation of gases through the walls, particularly the atmospheric gases.
Such a drawback is overcome, in the practice, by introducing one or more materials allowing to fix said gases and the vacuum is normally maintained by resorting to gas sorbing materials, located in the jacket.
These gas sorbing materials can operate according to the physical sorption principle, like for instance in the case of the zeolites and of other molecular sieves, of active carbon and so on; a drawback of these physical sorption agents, however, resides in a reversible sorption of the gases, as a function of temperature, and therefore they are not completely suitable for the purposes of the thermal insulation. Better results, to this purpose, are reached by employing materials which can irreversibly adsorb and fix the gases, according to a chemical reaction, like for instance the drying agents, in the case of water vapor, or the so-called getter materials, in the case of gases like CO, CO.sub.2, O.sub.2, N.sub.2 and so on or, again, water vapor.
In the following, when not better specified, the drying agents and the getter materials will be generally indicated as chemical sorption agents or simply "sorption agents"; this chemical technique is well known from the state of the art, for instance from the international publication WO 93/25,843 in the name of the Application and published on Dec. 23, 1993, after the priority date of the present application.
The document, cited as a reference with respect to the physico-chemical aspects of the sorption of gases and vapours, describes the combined use of a drying agent, selected from barium oxide, strontium oxide, phosphorus oxide and mixtures thereof, and of a non-evaporable getter material essentially consisting of an alloy containing barium and lithium, in particular an alloy having the raw formula BaLi.sub.4 ; according to said document, it is optionally possible to introduce into the jacket also the oxide of a noble metal, preferably palladium, allowing to convert the last traces of hydrogen into water, which is then chemically fixed by the drying agent. As to the purpose, the use of silver and/or ruthenium oxide give rise to equally satisfactory results as the ones coming from the use of Pd oxide.
Said PCT document was teaching too to introduce
REFERENCES:
patent: 3114468 (1963-12-01), Francis et al.
patent: 4668551 (1987-05-01), Kawasaki et al.
patent: 5018328 (1991-05-01), Cur et al.
patent: 5091233 (1992-02-01), Kirby et al.
patent: 5191980 (1993-03-01), Boffito et al.
Belloni Fortunato
Ferrario Bruno
Manini Paolo
Porta Paolo Della
Moy Joseph M.
SAES Getters S.p.A.
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