Osram Medium Pressure Mercury HgH 2000

Early mercury lamps made by German Osram were split into two principal families. The HgH types employed an arc tube of hard glass, while the HgQ types made use of a quartz arc tube. These two categories are directly comparable with the British MA and MB types respectively.

It was furthermore customary in many parts of continental Europe to name lamps according to their output in dekalumens (1 dekalumen = 10 lumens). Thus this HgH 2000 lamp is a 20,000 lumen device, drawing some 450 watts. It was joined by the smaller HgH 1000 (265W) and the smaller HgQ 300 (75W) and HgQ 500 (120W) types.

The arc tube here is fabricated from aluminosilicate glass that has been blown into a mould, to form the desired shape. The end sections around the electrodes are of reduced diameter, the purpose being to increase the temperature here slightly, and attain a faster run-up time than usual. Heat reflectors of platinum paint are applied behind the electrodes to provide extra thermal insulation. The electrodes take the form of open tungsten coils containing an emissive pellet - most likely of thorium oxide.

The end seals are of typical Osram style, found also in many of the spectral lamps having hard glass discharge tubes. Two molybdenum rods are first sealed into a graded sealing glass, and it is remarkable to note that the seal is made almost without oxide on the wire (the colour remains silvery). This assembly is then fused into the end of the arc tube. Unusually for a medium pressure mercury lamp, this model has two auxiliary ignition electrodes, whereas one is usually sufficient in competitor lamps.
Manufacturer: Osram GmbH
Lamp Power: 450 Watts
Lamp Current: 3.7 Amps
Lamp Voltage: 125 Volts
Cap Type: E40s/45 Brass + Porcelain
Bulb Type: T-50 T-16 in eighths/inch
Bulb Finish: Clear Borosilicate hard glass
Electrodes: C-6 Open Coil Thoria pellet emitter
Arc Length:
Atmosphere: Inner: Hg | Ar (1 atm) Outer: Nitrogen
Luminous Flux: 19,000 lm @ 100 hrs
Luminous Efficacy: 42.2 lm/W @ 100 hrs
Colour Temperature & CRI: CCT: 5400K CRI: Ra 6
Chromaticity Co-ordinates: CCx: 0.337 CCy: 0.421
Lifetime: 5000 hours
Warm-up & Re-strike Time: 5 minutes 5 minutes
Burning Position: Vertical ± 45°
Overall Length: 315 mm 12⅜ inches
Light Centre Length: 192 mm 7½ inches
Factory: Berlin Werk-S Germany
Date of Manufacture: February 1957 Date Code: kfX
Original Value: DM 50/- (1958)
References: 1) Osram Catalogue, Germany 1958, p.62
2) Osram Brochure Liste-Q Quecksilberdampf-Hochdrucklampen, Germany, 1955 October.