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Osram Last Generation BC Capped Fluorescent |
In 1936 GEC demonstrated the viability of mains voltage hot cathode tubes, and discovered that substituting part of the zinc for beryllium in the phosphor could change its colour from greenish to orange, and by combining this with a blue phosphor it was possible to create improved white light. This breakthrough was shared with GE of USA, who, thanks to its greater resources, beat GEC to market by a few months. GEC put its first lamp on sale in 1938, a crude 3-foot 30W tube that was much less refined than GE's products. Owing to the imminence of war it was quickly re-designed around available materials - such as the ballast of the 80W mercury lamp and bayonet caps of incandescent lamps. This resulted in the unusual British design of a 5ft bayonet-capped tube, which remained the workhorse of British lighting until 1964.
In 1942 GEC made another important breakthrough with the discovery of calcium halophosphates. These delivered ~30% more light, from a single phosphor rather than a blend, were consideraby cheaper, and non-toxic. GEC placed its first halophosphate lamps on the market in 1946, and by 1948 they were copied by all manufacturers worldwide. The 1950s then saw the start of the 'lumen war', being driven mainly by GE and Sylvania in USA, and Nichia of Japan, which more than doubled halophosphate efficacy by 1980. This lamp represents the final incarnation of BC-capped fluorescent tubes, whose production was finally discontinued in 1990.
| Manufacturer: | Osram Ltd | |
| Lamp Power: | 80 Watts | |
| Lamp Current: | 0.87 Amps | |
| Lamp Voltage: | 99 Volts | |
| Cap Type: | B22d/27x35 | Brass + Vitrite |
| Bulb Type: | T-38 | T-12 in eighths/inch |
| Bulb Finish: | White | 3Ca3(PO4)2.Ca(F,Cl)2:Sb,Mn |
| Electrodes: | Triple Coil + Shield | Triple Carbonate emitter |
| Discharge Length: | ||
| Atmosphere: | Hg | Ar | |
| Luminous Flux: | 5,750 lm (@ 100h) | 5,200 lm (@ 2000h) |
| Luminous Efficacy: | 71.9 lm/W (@ 100h) | 65.0 lm/W (@ 2000h) |
| Colour Temperature & CRI: | CCT: 3450K | CRI: ~Ra 80 |
| Chromaticity Co-ordinates: | CCx: 0.407 | CCy: 0.397 |
| Rated Lifetime: | 10,000 hours | to 70% survival & 80% flux |
| Warm-up & Re-strike Time: | 1 minute to 95% flux | Instant |
| Burning Position: | Universal | |
| Nominal Length: | 1524 mm | 60 inches |
| Factory: | St. Helens | Merseyside, England |
| Date of Manufacture: | January 1990 | Date Code: XA |
| Original Value: | GB £5.25 (1980) | |
