Sylvania Lumalux LU200 HPS
The high pressure sodium lamp illustrated here is typical of the style manufactured by GTE Sylvania in USA. The ET shape bulged tubular envelope is found almost exclusively on these products. The arc tube is uniquely centred by a metal rod which is located inside one end of the niobium arc tube feedthrough, and at the other end is located in a small glass tube extending above the stem press.

The optical alignment in Sylvania lamps is second to none. The arc gap between the electrodes in this early lamp is set by the level at which three niobium tie-wires are welded to the niobium seal tube, see second thumbnail photo. The 200W rating, for use on an S66 ballast, is unique to the American market and was introduced primarily as a replacement for 400W mercury lamps, since it produces very nearly the same luminous flux.

The arc tube is of the monolithic type in which the end seals are formed between two adjacent pieces of ceramic of an identical composition, penetrated by the niobium sealing tube. Sylvania lamps make use of an internal amalgam reservoir in which the sodium amalgam is entirely contained within the arc tube, and this has a number of advantages.

In lamps having an external amalgam reservoir, the seal temperature must necessarily be very high in order to raise the amalgam reservoir to its operating temperature. However if the amalgam is located inside the arc tube, the seal temperature can be lower. This reduces the rate of degenerative reactions with the frit sealing glass which otherwise lead to sodium loss and a rapid lamp voltage rise during life.
Manufacturer: GTE Sylvania
Lamp Power: 200 Watts
Lamp Current: 2.4 Amps 3.6A Starting current
Lamp Voltage: 100 Volts 2-4kV Ignition voltage
Cap Type: E39s/41 Brass + vitrite
Bulb Finish: Clear Lead borosilicate glass
Bulb Type: ET-57 ET-18 in eighths/inch
Overall Length: 248 mm 9¾ inches
Light Centre Length: 146 mm 5¾ inches
Arc Length: 63.6mm 2½ inches
Electrodes: Backwound Tungsten Barium Calcium Tungstate
Atmosphere: Na,Hg | Xe Outer: Hard Vacuum
Luminous Flux: 22,000 lm @ 100 hrs 19,800 lm @ 12,000 hrs
Luminous Efficacy: 110.0 lm/W @ 100 hrs 99.0 lm/W @ 12,000 hrs
Colour Temperature & CRI: CCT: 2100K CRI: Ra 22
Chromaticity Co-ordinates: CCx: 0.523 CCy: 0.415
Burning Position: Universal
Rated Lifetime: 24,000 hours to 50% survival
Warm-up & Re-strike Time: 3-4 minutes 1 minute
Factory: Manchester, NH U.S.A.
Date of Manufacture: July 1982 Date Code SR019
Original & Present Value: Unknown
References: 1) Osram Sylvania Sodium Lamp Engineering Bulletin, August 1998.
2) Osram Sylvania Sodium Lamp Specification Guide, October 2003.