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Philips Biosol MLU 500W Sun-Tanning |
The arc tube is of an early hand-made quartz style having shrink-seals to molybdenum foils, and includes an auxiliary ignition electrode. The tungsten ballast filament is loaded less than in an ordinary mercury-blended lamp, because it was intended to allow this to be run directly on the mains as a pure infrared radiation source. It can also be brought into series with the arc to deliver UV+IR treatment, thanks to the 4-pin cap (of which only 3 pins are connected). Or with an external ballast, the mercury arc can be operated without the infrared component. The bulb is blown in a special soft glass whose transmission curve extends deep into the UV-C, which is now known to be acutely carcinogenic. A complex glass stem assembly having a Y-shaped press seal supports both radiation sources, its exhaust tube being fused into the side of the stem like old Jaeger-style incandescent lamps.
By 1951 this high power lamp had been joined by the smaller and simpler Biosol MLU 250W with fixed series filament and arc. That was considerably more popular on account of its much lower cost. By 1955 that had been replaced by the Ultraphil MLU 300W, following the obsolescence of the Biosol series due to the dangers of their short wavelength radiation. This MLU 500W rating was still listed as an ultraviolet radiation source for industrial applications late as 1966, but is believed to have been discontinued very soon afterwards.
| Manufacturer: | Philips Lighting | Type 29960/20 |
| Lamp Power: | 500 Watts | 200W arc, 300W filament |
| Lamp Current: | 2.25 Amps | |
| Lamp Voltage: | 220-230 Volts | |
| Cap Type: | Jumbo P4 | Philite insulator |
| Bulb Type: | R-190 | R-60 (in eighths/inch) |
| Bulb Finish: | Inside Frosted | UV softglass |
| Electrodes: | Backwound Tungsten | BCT emitter |
| Electrode gap: | 60mm | Quartz ID: 18.5mm |
| Atmosphere: | Ar | Hg (2.5 bar) | Outer: Argon-Nitrogen |
| Luminous Flux: | 8000 lm | (25 UV Finsens) |
| Luminous Efficacy: | 16.0 lm/W | |
| Colour Temperature & CRI: | CCT: 5100K | CRI: Ra25 |
| Chromaticity Co-ordinates: | CCx: 0.345 | CCy: 0.385 |
| Irradiance @ 50cm: | UV-A: 17.0W/m² -- UV-B: 10.0W/m² -- UV-C: 0.23W/m² | |
| Beam Distribution | 120° | to half peak intensity |
| Rated Lifetime: | 1,000 hours | |
| Warm-up & Re-strike Time: | 3 minutes | 5 minutes |
| Burning Position: | Universal | |
| Overall Length: | 255 mm | 10 inches |
| Factory: | Eindhoven | The Netherlands |
| Date of Manufacture: | 1953 May | Date Code: K8 |
| Original Value: | Hƒℓ 198 (1952) | DM 135/- (1966) |
