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Philips SOX-Plus Extended Life Lamp |
Traditional SOX lamps suffer a weakness at the glass-to-metal seals. These are normally made to unborated dumet wire sleeved in 2-ply soda-lime glass having an external borate layer. Since the borate does not extend over the end of the glass bead to the encapsulated leadwire, that weak spot is protected by embedding a small tube of magnesia into the glass to keep away sodium, but it is only partly successful. Cracking of the seals due to sodium attack affects a small percentage of lamps. Gas leakage between the core and sheath of dumet is another rare failure mechanism. In 1986 Philips introduced the so-called 'SR' Sodium-Resistant electrode assembly, which was initially applied only for its Belgian-made SOX-E range. It replaced the dumet seal with a single piece leadwire of 'Vacovit' iron-nickel-chromium alloy, sleeved with a single layer of pure borate glass. No ceramic bead is necessary. Elimination of premature seal failures leads to a small improvement in life.
Even though the SOX-Plus life claims showed a significant improvement, the actual gain was minimal as traditional lamps had been out-performing their life claim for several years. Rather than updating those claims to reflect reality, Philips cunningly developed the parallel range of SOX-Plus lamps, identifiable by their red caps, and increased profits by selling these new 'long life' lamps at higher prices.
| Manufacturer: | Philips Lighting Ltd. | |
| Lamp Power: | 35 Watts | |
| Lamp Current: | 0.60 Amps | |
| Lamp Voltage: | 70 Volts | |
| Cap Type: | BY22d | Red Alkyde Insulator |
| Bulb Type: | T-50 | T-16 in eighths/inch |
| Bulb Finish: | Indium-tin oxide film | Soda-lime glass |
| Electrodes: | CCC-4 Beehive | Black W + BCT emitter |
| Arc Length: | ||
| Atmosphere: | Na | 99% Ne, 1% Ar | Outer: Hard Vacuum |
| Luminous Flux: | 4,550lm (@ 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 |
| Rated Lifetime: | 12,000h (85% survival) | 20,000h (50% survival) |
| Warm-up & Re-strike time: | 11½ minutes | Instantaneous |
| Burning Position: | Vertical Cap Up ± 110° | |
| Overall Length: | 310 mm | 12¼ inches |
| Light Centre Length: | 183 mm | 7¼ inches |
| Factory: | Hamilton | Scotland |
| Date of Manufacture: | January 1996 | Date Code 6A |
| Original / Present Value: | GB £36.03 (1995) | GB £61.86 (2014) |
