Mercury Ultra Violet Lab-Arc H85A3/UV
The lamp illustrated here has been constructed principally for laboratory applications as a source of the ultra-violet mercury spectrum. It is essentially modelled on the earlier H-3 mercury lamp created for general lighting applications, but instead employs an outer envelope made from UV-transmitting hard glass.

It is intriguing that despite its relatively recent date of construction, the arc tube was still being fabricated according to a design conceived in the 1930's! This is typical of many American lamps, where the same design may be employed for several decades after it had been made obsolete in main stream lamps. Each product was treated as an individual entity, and its design would not be changed until there was a very good reason to do so - cost apparently not being a significant factor!

Thus the arc tube in this lamp is hand made throughout, consisting of a a quartz tube sealed at each end to tungsten rods via two graded sealing glasses. A pair of diaphragms are formed just ahead of the electrodes, these serving principally to keep the arc in the centre of the tube and prevent flicker when used in projection apparatus. Another advantage is that material sputtered from the electrodes is substantially contained within these end chambers, helping to reduce blackening of the central arc tube portion. The end chambers are externally coated by hand with platinum paint to keep the temperature high in these regions. The arc tube is supported in pressed nickel cups and a short length of nickel wire is looped around the arc tube to assist in ignition. This is necessary since in these early design arc tubes, no auxiliary starting electrodes were employed.
Manufacturer: General Electric Company, U.S.A.
Lamp Power: 85 Watts
Lamp Current: Amps
Lamp Voltage: Volts
Cap: E26s/25 (Medium) Brass
Bulb Finish: Clear UV-transmitting borosilicate
Bulb Type: T-32 T-10 in eighths/inch
Overall Length: 143 mm 5 5/8 inches
Light Centre Length: 76 mm 3 inches
Electrodes: Backwound tungsten Thoriated shank
Atmosphere: Inner: Hg | Ar Outer: Nitrogen
Luminous Flux: 3,050 lm @ 100 hours
Luminous Efficacy: 36 lm/W @ 100 hours
Colour Temperature & CRI: CCT: 6000K CRI: Ra 16
Chromaticity Co-ordinates: CCx: 0.315 CCy: 0.380
Burning Position: Universal
Rated Life: 500 hours (to 50% survival)
Warm Up / Re-strike Time:
Factory: Cuyahoga, NELA Park Cleveland OH, U.S.A.
Date of Manufacture: Circa 1970
Original / Present Value: $23.90  (1971)
 
References: 1) GE Lamp Catalogue, USA, 1975, p.49