RLOD#18 (2020.05.24) 1985 Philips ML-C 160W

During the 1980s Philips produced an interesting variant of its ML self-ballasted mercury fluorescent lamps, the 160 W ML-C shown here, with C standing for Comfort. In this lamp the standard yttrium vanadate phosphate borate phosphor was substituted by the vanadate and YAG phosphor blend used in the company’s HPL-C lamps. The enhanced red-orange fluorescence output combined with an optical absorption in the blue increases the red output fraction by 4 points to around 20 %, which reduces the color temperature by ~15 % to 3050 K, resulting in a pleasing warm-white light. Moreover, the flux output is increased by 8 % to 3350 lm, which surpasses that of 200 W GLS lamps by 12 %, resulting in a 40 % higher lumen efficacy (20.9 vs 15.0 lm/W). Finally, the light color rendering index is raised by 5–10 points to 70 Ra8, the highest CRI of all mercury lamps. All these characteristics, combined with a mean service life of 6 kh (six times that of GLS lamps) and a significantly reduced glare, made the ML-C an ideal choice for the low-cost upgrade of quality incandescent lighting installations in applications requiring warm-white light and visual comfort, such as in city beautification. Interestingly, the lamp is also provided with an E40 end cap so as to fit the large sockets that were used in older incandescent downlighters and streetlight luminaires. Philips never listed the ML-C 160W in its brochures and catalogs, so this must have been a special order from a customer that had very specific requirements not met by standard lamps.