Abstract: The regionally coated noble metal element used in glass production has an uncoated region for contacting a glass melt and an H2-impervious layer or an H2-impervious and O2-impervious layer on a side opposite from the uncoated region, which has a layer thickness ?1 mm, is heat-resistant, and is either liquid or solid. This layer is made from at least one glass or glass mixture, an at least partly crystallized glass or a ceramic material. The coated noble metal element can be a Danner channel, a Vello draw head, an A-draw head, a Vello needle, a drawdown needle, a discharge ring or a Danner blowpipe. A process for coating a noble metal element to produce the regionally coated noble metal element is also described.

Abstract: The coated noble metal element used in glass manufacture, such as a noble metal pipe, has an uncoated side that contacts a glass melt and an H2-impervious layer or an H2-impervious and O2-impervious layer, which is provided on a side opposite from the uncoated side. The H2-impervious layer or H2-impervious and O2-impervious layer is heat-resistant and is liquid or solid. In one process for providing the layer on the noble metal element an empty space between the noble metal element and a ceramic insulating jacket is filled with a coating material, and then the coating material is melted so that it wets a surface of the noble metal element. The coating material can include glass cullet, crushed glass or glass powder or is a mixture of crushed glass and ground ceramic material.

Abstract: The regionally coated noble metal element used in glass production has an uncoated region for contacting a glass melt and an H2-impervious layer or an H2-impervious and O2-impervious layer on a side opposite from the uncoated region, which has a layer thickness?1 mm, is heat-resistant, liquid or solid. This layer is made from at least one glass or glass mixture, an at least partly crystallized glass or a ceramic material. The coated noble metal element can be a Danner channel, a Vello draw head, an A-draw head, a Vello needle, a drawdown needle, a discharge ring or a Danner blowpipe. A process for coating a noble metal element to produce the regionally coated noble metal element is also described.

Abstract: The coated noble metal element used in glass manufacture, such as a noble metal pipe, has an uncoated side that contacts a glass melt and an H2-impervious layer or an H2-impervious and O2-impervious layer, which is provided on a side opposite from the uncoated side. The H2-impervious layer or H2-impervious and O2-impervious layer is heat-resistant and is liquid or solid. In one process for providing the layer on the noble metal element an empty space between the noble metal element and a ceramic insulating jacket is filled with a coating material, and then the coating material is melted so that it wets a surface of the noble metal element. The coating material can include glass cullet, crushed glass or glass powder or is a mixture of crushed glass and ground ceramic material.

Abstract: The regionally coated noble metal element for use in glass production has an uncoated region for contacting a glass melt and a side opposite from the uncoated region is provided with an H2-impervious layer or an H2-impervious and O2-impervious layer. The H2-impervious layer or H2-impervious and O2-impervious layer has a thickness greater than or equal to 1 mm, is heat-resistant, liquid, or solid. This layer is made from at least one partly or completely crystallized glass or a glass mixture or a ceramic material. Processes for coating the noble metal element are also described.

Abstract: The apparatus for reduced-pressure refining of a glass melt includes a refining bank formed so that a reduced pressure is generated by a glass flow in it. The refining bank has a component, which is made from a refractory metal or refractory alloy acting as glass-contact material. The refractory metal or alloy contains molybdenum, tungsten, tantalum, and/or hafnium. The device of the present invention includes a protective gas reservoir for a protective gas and an automatically operating valve connecting the reservoir with the refining bank so that an inner side of the component that would otherwise be exposed when a pressure rise or a falling glass melt column occurs is protected from oxidation by the protective gas. A process for using the device during refining of the glass melt is also part of the invention.

Abstract: The invention relates to a method and a device for refining a glass melt, using negative-pressure apparatus. According to the invention, the glass melt is fed to a refining bench by means of an uptake pipe and is discharged from the refining bench by means of a downpipe, a negative pressure being created over the flow of glass in the refining bench. The invention is characterised in that the uptake pipe and/or the downpipe and/or the refining bench has/have at least one component consisting of at least one refractory metal and/or of a refractory metal alloy as the glass contact material.

Abstract: The invention relates to a coated metal element used for producing glass, said element having a coating on the opposite side to the glass melt that is impermeable to H2, or to H2 and O2. The invention also relates to a method for coating metal elements used for producing a glass melt and glass, according to which an insulating casing is applied to the side of the metal element to be coated, in such a way that a cavity is formed between the surface to be coated and the insulating casing, the cavity is filled with the coating material and said material is melted at a sufficiently high temperature.

Abstract: The invention relates to a device for purifying molten glass;