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Philips SOX-Plus Extended Life Lamp |
The fundamental difference between SOX and SOX-Plus at the time was an improved electrode assembly. A significant proportion of early failures could be traced to electrolysis of the pinch seal, and cracking of the glass-to-metal seals. This region had been a weak point in all previous lamps, since there is no sodium-resistant glass coating at the point where the lead wires enter the discharge tube - it is only present over the outer sides of the glass-sleeved lead wires, and not at the extremities where the wires emerge. Consequently a small tube of magnesium oxide was embedded into the glass here in an attempt to keep sodium away from the seals - but it was only partially successful.
The improved design on SOX-Plus was originally introduced for SOX-E lamps, and consists of a single piece sodium-resistant glass sleeve over a lead wire of iron-nickel-cobalt alloy. Since the glass sleeve is completely resistant to sodium, no ceramic bead is necessary and the occurrence of seal leaks is dramatically reduced. No other change was made to the lamp other than to equip it with a new red coloured cap.
Today at Philips, the SOX-Plus lamp has almost entirely superseded the original SOX design which has been made obsolete. In due course it is expected that SOX-Plus in turn will be superseded by the newer SOX-PSG types.
| Manufacturer: | Philips Lighting Ltd. | |
| Lamp Power: | 35 Watts | |
| Lamp Current: | 0.60 Amps | |
| Lamp Voltage: | 70 Volts | |
| Cap Type: | BY22d | Red Alkyde Insulator |
| Bulb Finish: | Indium Tin Oxide Film | Soda-lime glass |
| Bulb Type: | Inner: TU-14 x 32 | Outer: T-50 |
| Overall Length: | 311 mm | 12¼ inches |
| Light Centre Length: | 183 mm | 7¼ inches |
| Arc Length: | ||
| Electrodes: | CCC-4 Black Tungsten | BCT emitter |
| Atmosphere: | Na | 99% Ne, 1% Ar | Outer: Hard Vacuum |
| Luminous Flux: | 4,550 lm | (@ 100 hrs) |
| Luminous Efficacy: | 130.0 lm/W | (@ 100 hrs) |
| Colour Temperature & CRI: | CCT: 1700K | CRI: Ra-44 |
| Chromaticity Co-ordinates: | CCx: 0.574 | CCy: 0.425 |
| Burning Position: | Verical Base Up ± 95° | |
| Rated Lifetime: | 12,000 hours | to 70% survival |
| Warm-up & Re-strike Time: | 11½ minutes | Instantaneous |
| Factory: | Hamilton | Scotland |
| Date of Manufacture: | January 1996 | Date Code 6A |
| Original & Present Value: | £36.03 (1995) | £46.40 (2005) |
