lysrør

Lyströr (fluorescent tubes) are gas-discharge lighting devices used for general illumination. They consist of a sealed glass tube filled with a small amount of mercury vapor and an inert gas, with a phosphor coating on the inner surface. When energized, an electrical discharge excites the mercury atoms to emit ultraviolet light, which in turn excites the phosphor to produce visible light.

Construction and sizes vary, but the most common form factors are linear tubes such as T8 (about 26 mm in diameter) and T12 (about 38 mm). Typical lengths include 0.6 m, 1.2 m and 1.5 m, though other lengths exist. Some tubes are single-ended, others double-ended, with different electrical connections. Operation requires a ballast to regulate current; older installations used magnetic ballasts and starters, while modern systems use electronic ballasts that improve efficiency, ensure quicker startup, and support dimming in some cases.

Performance standards for lysrør have historically emphasized energy efficiency and light quality. They deliver higher luminous efficacy than many incandescent lamps, with typical ranges around 60–100 lumens per watt depending on design and ballast. Color temperature usually spans from warm to cool white (roughly 2700–6500 Kelvin), and color rendering index (CRI) is commonly in the 80–90 range, suitable for office and commercial environments.

Safety and environmental considerations include the presence of mercury, requiring careful handling and recycling at end of life. Tubes are fragile and can break; spill or breakage protocols and proper disposal through recycling streams are recommended. In recent years, lysrör have been increasingly replaced or retrofitted with LED alternatives due to advances in efficiency and lifetime, though they remain common in older buildings and various industrial settings.