Abstract: The double-walled noble metal duct (1) for conducting a glass melt has an outer noble metal pipe (1b) and an inner noble metal pipe (1a) extending within the outer pipe, so that an inner space (21) is formed within the inner pipe and an intermediate space (23) is formed between the inner pipe (1a) and the outer pipe (1b). The intermediate space is completely filled with glass melt when the double-walled noble metal duct conducts the glass melt, when the outer pipe (1b) has an exhaust vent (4). The outer pipe (1b) also has a bottom outlet (7) communicating with the intermediate space for removal of oxygen bubbles formed on the outer wall. The noble metal duct can be used in glass conditioning and in the manufacture of glass articles that are devoid of polyvalent ions.

Abstract: The sleeve-type glass melt agitator has a rotatable cylindrical sleeve provided with outwardly protruding vane elements and through-going openings in its outer cylindrical surface to stir the glass melt when the sleeve is rotated. The sleeve type agitator is arranged vertically in a glass melt feed channel in a glass melt feed system for making glass tubes or pipes according to the Vello or down-drawn process. During formation of glass tubes or pipes from the glass melt the sleeve-type agitator is rotated as the glass melt flows downward to prevent formation of schlieren in the glass melt, which causes glass material losses.

Abstract: The present invention relates to a method of treating a component which is intended for a facility for producing or preparing glass melts and has surfaces which are made of noble metal and come into contact with glass melts during operation.

Abstract: The invention relates to a method for cutting glass tubes, characterised by the following steps: a glass strand is drawn; a heating device is driven synchronously with the glass strand and is directed towards the region of a desired separation point; the glass strand is drawn in the region of the desired separation point; a separation device is driven synchronously with the glass strand; the separation device is actuated in such a way that it severs the glass strand at the desired separation point.

Abstract: The invention relates to a device for producing a glass rod. The device comprises a Danner blowpipe (1); a nozzle for applying stream of glass to the surface of the Danner blowpipe (1) at one end of said blowpipe (supply end) at a relatively high temperature in order to form a glass film, which is removed at the other end (discharge end) in the form of a bulb at low speed. According to the invention, the device is characterised as follows: the Danner blowpipe (1) is constructed as follows: the peripheral wall consists of an external metal jacket (2) and a ceramic body (3) surrounded by said jacket; a respective clamping plate (6.1, 6.2) is provided at the supply end and at the discharge end; the discharge-end clamping plate (6.2) is connected in a fixed manner to the shaft (6); the supply-end clamping plate (6.

Abstract: The invention relates to a process for the production of internally-hardened glass tubes, in which in a tube-drawing process for the production of glass tubes that is known in the art, a coated drawing tool, for example in the process according to Danner a coated mandrel or in the process according to Vello or in A-drawing process a coated needle, is used, whose coating releases coating material upon contact with the inside surface of the tube that is produced and accumulates on the inside glass surface. The chemical resistance is increased by this internal hardening. The invention also relates to devices for implementing this process and uses of the tubes that are produced according to these processes.

Abstract: The double-walled noble metal duct (1) for conducting a glass melt has an outer noble metal pipe (1b) and an inner noble metal pipe (1a) extending within the outer pipe, so that an inner space (21) is formed within the inner pipe and an intermediate space (23) is formed between the inner pipe (1a) and the outer pipe (1b). The intermediate space is completely filled with glass melt when the double-walled noble metal duct conducts the glass melt when the outer pipe (1b) has an exhaust vent (4). The outer pipe (1b) also has a bottom outlet (7) communicating with the intermediate space for removal of oxygen bubbles formed on the outer wall. The noble metal duct can be used in glass conditioning and in the manufacture of glass articles that have polyvalent ion vacancies.

Abstract: The sleeve-type glass melt agitator has a rotatable cylindrical sleeve provided with openings or small loops in its outer surface. The sleeve type agitator is arranged vertically in a glass melt feed channel in a glass melt feed system for making glass tubes or pipes according to the Vello or down-drawn process. During formation of glass tubes or pipes from the glass melt the sleeve-type agitator is rotated as the glass melt flows downward to prevent formation of schlieren in the glass melt, which causes glass material losses.

Abstract: A power distribution system includes circuits each having an electronic circuit breaker as a protection for short-circuits and/or overloads, and a clocked power supply unit. The clocked power supply unit is connected to the circuits and feeds power to the circuits. The electronic circuit breaker has a power stage and an adjustable current limiting device connected to the power stage. The adjustable current limiting device, in the event of an overload, when a first adjustable current threshold is exceeded, turns off the power stage after a first adjustable disconnection time has expired, and in the event of a short circuit, after a second adjustable current threshold has been exceeded, turns off the power stage after a second disconnection time has expired.

Abstract: A power distribution system includes circuits each having an electronic circuit breaker as a protection for short-circuits and/or overloads, and a clocked power supply unit. The clocked power supply unit is connected to the circuits and feeds power to the circuits. The electronic circuit breaker has a power stage and an adjustable current limiting device connected to the power stage. The adjustable current limiting device, in the event of an overload, when a first adjustable current threshold is exceeded, turns off the power stage after a first adjustable disconnection time has expired, and in the event of a short circuit, after a second adjustable current threshold has been exceeded, turns off the power stage after a second disconnection time has expired.

Abstract: Production of lower alkyl esters of higher fatty acids from an oil phase and lower alcohols by catalytic transesterification at reaction temperatures of up to 100.degree. C.