Abstract: A vacuum degassing apparatus for molten glass includes a vacuum housing which is evacuated to be depressurized therein; a vacuum degassing vessel which is provided in the vacuum housing to vacuum-degas molten glass as the molten glass flows therein; an uprising pipe which connects to the vacuum degassing vessel, and sucks and draws up undegassed molten glass to introduce the undegassed molten glass into the vacuum degassing vessel; and a downfalling pipe which connects to the vacuum degassing vessel and draws down the degassed molten glass from the vacuum degassing vessel to discharge the degassed molten glass. The cross sectional area of the path at the upper end portion of the uprising pipe is larger than the cross sectional area of the path at the lower end portion of the uprising pipe.

Abstract: A vacuum degassing apparatus for molten glass includes a vacuum housing which is evacuated to be depressurized therein; a vacuum degassing vessel which is provided in the vacuum housing to vacuum-degas molten glass as the molten glass flows therein; an uprising pipe which connects to the vacuum degassing vessel, and sucks and draws up undegassed molten glass to introduce the undegassed molten glass into the vacuum degassing vessel; and a downfalling pipe which connects to the vacuum degassing vessel and draws down the degassed molten glass from the vacuum degassing vessel to discharge the degassed molten glass. The cross sectional area of the path at the upper end portion of the uprising pipe is larger than the cross sectional area of the path at the lower end portion of the uprising pipe.

Abstract: A process for producing a glass for cathode ray tubes, having a Sb2O3 content of from 0 to 0.19% as represented by mass percentage and containing H2O, which process comprises a step of melting a raw material in an atmosphere under a pressure of P0 to obtain a molten glass, and a step of vacuum degassing the molten glass in an atmosphere under a pressure PA which is lower than P0, wherein the pressure P of the molten glass is made to be at most (6.1 W+0.06) atm in the vacuum degassing step, wherein W is the content of said H2O as represented by mass percentage.

Abstract: A vacuum degassing apparatus for molten glass includes a vacuum housing; a vacuum degassing vessel provided in the vacuum housing; an uprising pipe which connects to the vacuum degassing vessel; and a downfalling pipe which connects to the vacuum degassing vessel. The vacuum housing has an accommodating portion to accommodate the uprising pipe and an accommodating portion to accommodate the downfalling pipe, at least one of which is divided horizontally into a plurality of sections to form a plurality of divided rooms juxtaposed in the vertical direction, and the respective divided rooms are provided with a pressure controller to control the pressures of the respective divided rooms independently.

Abstract: To provide a novel glass composition having the property of browning substantially improved, while securing an adequate X-ray absorption property and while suppressing devitrification of a panel glass to a practically problem-free level, in preparation for higher voltage and larger current for projection type cathode ray tubes. A panel glass for cathode ray tube, having a glass composition containing substantially no PbO, and more than 10 mass % and at most 15 mass % of ZnO, wherein (MgO (mass %)+ZnO (mass %))/(SrO (mass %)+BaO(mass %)+CaO (mass %))>0.55, and wherein when the sum of Na2O (mol %), K2O (mol %) and Li2O (mol %), as represented by mol percentage, is represented by R2O, 0.15?Na2O (mol %)/R2O?0.25, and 0.45?K2O (mol %)/R2O?0.55, and the linear absorption coefficient of X-ray having a wavelength of 0.06 nm is at least 36.0 cm?1.

Abstract: A vacuum degassing apparatus for molten glass, comprising: a vacuum housing which is evacuated to be depressurized therein; a vacuum degassing vessel which is provided in the vacuum housing to vacuum-degas molten glass as the molten glass flows therein; an uprising pipe which connects to the vacuum degassing vessel, and sucks and draws up undegassed molten glass to introduce the undegassed molten glass into the vacuum degassing vessel; and a downfalling pipe which connects to the vacuum degassing vessel and draws down the degassed molten glass from the vacuum degassing vessel to discharge the degassed molten glass; wherein the cross sectional area of the path at the upper end portion of said uprising pipe is larger than the cross sectional area of the path at the lower end portion of said uprising pipe.

Abstract: A vacuum degassing apparatus for molten glass, comprising:

Abstract: A vacuum degassing apparatus for molten glass, comprising:

Abstract: A process for producing a glass for cathode ray tubes, having a Sb2O3 content of from 0 to 0.19% as represented by mass percentage and containing H2O, which process comprises a step of melting a raw material in an atmosphere under a pressure of P0 to obtain a molten glass, and a step of vacuum degassing the molten glass in an atmosphere under a pressure PA which is lower than P0, wherein the pressure P of the molten glass is made to be at most (6.1 W+0.06) atm in the vacuum degassing step, wherein W is the content of said H2O as represented by mass percentage.