Osram 'Ultra-Vitalux' Mercury-Blended

After the introduction of the earliest incandescent lamps for therapeutic and sun-tanning applications, such as the Osram 'Vitalux' lamps, developments took a different direction on each side of the Atlantic. America was first to introduce the use of a mercury discharge to raise the proportion of UV radiation, and its S-1 and S-2 lamps were characterised by a medium pressure mercury arc in parallel with a tungsten filament. Those were copied by German Osram's 'Solarca' lamp, until 1937 when Osram introduced its superior 'Vitalux-U', later re-named 'Ultra-Vitalux' as featured here.

It comprises a high pressure mercury arc tube in series with a tungsten filament, the latter forming the electrical ballast for the arc. The high pressure arc very considerably elevated the percentage of erythemal radiation to about 5x greater than sunlight, creating the first of the modern suntan lamps.

The outer bulbs of all ultraviolet lamps are fabricated in a special glass free of iron oxide, to allow the transmission of UV radiation. Soft glasses tend to discolour and lose their UV transmission over time due to the process of solarisation. The Osram Ultra-Vitalux is unusual in that its glass has a slight violet colouration, due it being doped with about 0.2% of nickel oxide. The colour has no particular purpose, but was found the slow the rate of degradation and enable the production of a lamp having improved UV maintenance during life. In 1941 GE copied the Osram approach of a high pressure self-ballasted lamp with the introduction of its 'RS Sunlamp', featuring a novel reflector bulb to facilitate its use and with a further improved hard glass bulb. In 1942 Osram copied the GE concept of an integrated reflector and applied that to its violet-glass Reflector Ultra-Vitalux.
Manufacturer: Osram Kommanditgesellschaft
Lamp Power: 300 Watts
Lamp Current: 1.30 Amps
Lamp Voltage: 220 Volts
Cap: E27s/50x55 Ni plated brass
Bulb Finish: Inside Frosted Nickel-doped pink glass
Bulb Type: A-110 A-35 (in eighths/inch)
Overall Length:
Light Centre Length:
Electrodes: Open coil with protrusion Thoria emissive pellet
Atmosphere: Inner: Hg,Ar Outer: Nitrogen
Luminous Flux: 1700 lumens
Luminous Efficacy: 5.7 lm/W
Colour Temperature & CRI: CCT: 3250K CRI: Ra78
Chromaticity Co-ordinates: CCx: 0.415 CCy: 0.390
Ultraviolet Flux: UV-A: 9.2% --- UV-B: 5.7% --- UV-C: 0.3%
Burning Position: Universal
Rated Life:
Warm Up / Re-strike Time:
Factory: Berlin Rotherstraße Germany
Date of Manufacture: April 1941 Date Code: f11
Original Value:
References: 1) Die Entwicklung neuer künstliche Lichtquellen, A.Ruttenauer, Technisch-wissenschaftliche Abhandlungen aus dem Osram-Konzern, Band 2 1931 pp.77-82
2) Der Osram Ultra-Vitalux Strahler, K.Larché, Technisch-wissenschaftliche Abhandlungen der Osram-Gesellschaft, Band 5 1953 pp.43-48
3) US Patent 2,212,879 - Electric Discharge Lamp - H.Kalsing, H.Krefft, F.Rössler - Osram KG - Filed 1938-Aug-16.
4) Photmetric and Mean Horizontal Spectroradiometric measurements