Low Pressure Mercury Fluorescent Tubes
ANSWER
Tubular fluorescent lamps light come from phosphors. Triphospors coat the inside of the lamp and convert energy from a low pressure gas discharge into visible light.
The colour temperature and colour rendering are determined by the phosphor mix coated on the inside of the tube.
They come in three types, T12, T8 and T5.
Argon Filled T12 (38mm dia) tubes have been discontinued.
Krypton-filled triphosphor T8 (26mm) dia tubes are used in switchstart, quick start and high frequency luminaries. T8 lamps have a higher efficacy, longer life, improved lumen maintainance and better colour rendering. Triphosphor (or multi-phosphor) tubes offer a wide range of colour temperatures from very warm (2700k), warm (3000k) and intermediate (3500k) through to cold white (4000k), daylight (5000-5500k) and northlight (6000-6500k).
T5 flourescent lamps have a circumference of 16mm or 5/8" of an inch in diameter. Differences in length and socket pin determine wattage, they are generally shorter with higher outputs. They come in the same colours as T8 lamps.
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