Glass is used as a transparent and chemically inert envelope for lamps and lamp fittings of all types, and for a wide range of power ratings from miniature lamps to television studio lamps of up to 10 kW. Because it is a superb electrical insulator at normal temperature it is used for glass-to-metal seals in lamps, and has been widely used in this manner for receiving and transmitting valves of all types. It continues to be used in CRTs and semiconductor devices. In these applications the versatility of glass as an hermetic sealant to itself or other glasses, metals and ceramics makes possible the efficient performance of electric al or electronic devices under onerous conditions, with up to 25 years lifetime. In its purest and most transparent form glass continues to be exploited in optical-fibre technology for telecommunications and for a wide range of sensors for control equipment.

Inspec keywords: hermetic seals; insulators; glass; glass-metal seals; lamps; refractories; cathode-ray tubes

Other keywords: hermetic sealant; power ratings; transparent; semiconductor devices; lamp fittings; refractories; CRT; insulator; glass-to-metal seals; television studio lamps; miniature lamps

Subjects: Light sources