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F15T8 with Zinc Beryllium Silicate Phopshor |
This lamp is representative of the first model. It is made in T8 glass only because that size was available from Lumiline lamps. The 18" length was chosen because when driven at 0.25 amperes, for which the first electrodes were developed, the resulting power of 15W delivered the most efficient lamp whose voltage was low enough to operate with a simple choke ballast from 110-120V mains voltages. The first lamps had instant-start electrodes and single contact Lumiline caps, but this presented difficulties in manufacture. Before the commercial introduction, the design was changed to preheated cathodes with the familiar bi-pin caps, and due to an increase in electrode efficiency, lamp current was raised to 0.30A so as to maintain the power of 15W.
The next lamp was made with T12 glass but same power and length to offer lower surface brightness, and it was noted that it had a lower voltage. While maintaining a choke ballast, that permitted the length to be increased and yielded a third lamp, the more powerful rating of 24" 20W. A lamp for high mains voltages then followed, achieved by doubling the length of the 15W T8 lamp to arrive at the 36" long 30W T8 model. It was these four models that were launched simultaneously as the starting range. All employ a mixture of pale yellow fluorescing zinc beryllium silicate and blue fluorescing magnesium tungstate to achieve white light.
| Manufacturer: | Westinghouse | |
| Lamp Power: | 15 Watts | |
| Lamp Current: | 0.300 Amps | |
| Lamp Voltage: | 56 Volts | |
| Cap Type: | G13 medium bi-pin | Steel |
| Bulb Type: | T-26 | T-8 in eighths/inch |
| Bulb Finish: | White | (ZnBe)2SiO4:Mn and MgWO4 |
| Electrodes: | Coiled-Coil + Anode Plates | (Ba,Sr,Ca)CO3 emitter |
| Discharge Length: | 394 mm | 15.5 inches |
| Atmosphere: | Hg | Ar | |
| Luminous Flux: | 585 lm (@ 100h) | |
| Luminous Efficacy: | 39.0 lm/W (@ 100h) | |
| Maximum Brightness: | 7000 lux | 2040 foot-lamberts |
| Colour Temperature & CRI: | CCT: 3500K | CRI: Ra 72 |
| Chromaticity Co-ordinates: | CCx: 0.405 | CCy: 0.391 |
| Rated Lifetime: | 2500 hours | |
| Warm-up & Re-strike Time: | 2 minutes | Instant |
| Burning Position: | Universal | |
| Nominal Length: | 457 mm | 18 inches |
| Factory: | Fairmont, VA | U.S.A. |
| Date of Manufacture: | 1944 1st Quarter | |
| Original Value: | US $0.57 (1942-46) | |
