Multi-Vapor II High Performance Metal Halide
The traditional light source found in the vast majority of American metal halide lighting installations is a simple sodium-scandium lamp. Essentially they are based on the ordinary mercury vapour arc tube, but with the addition of sodium and scandium iodides to the arc to impart the usual advantages of metal halide doses. The end chambers of the arc tube are roughly pinched into a conical shape to raise the temperature here and more consistently control the vapour pressure of the halides from lamp to lamp, and the third auxiliary starting electrode is also employed so the lamps can be used with ordinary mercury vapour ballasts.

However, the bulky arc tubes take a long time to warm up, 10-15 minutes to cool before the lamp can be re-ignited in the event of a power failure, and the lamp-to-lamp variation in arc tube shape leads to colour differences. The poor thermal control at the arc tube ends also limits performance.

Many problems can be overcome by employing a more compact, better shaped arc tube as is standard practice with European metal halide products to deliver higher luminous flux through improved thermal control. But here there is no room for the third auxiliary starting electrode in the end seals, and a higher ignition voltage is required than traditional American circuits can provide. The GE Multi-Vapor II lamp shown here was the first American lamp to offer a high-performance arc tube for use in existing circuits. Within the plastic portion above the cap is a form of high voltage electronic ignitor, and a third lead in the stem of the outer bulb carries the pulse from this to an external probe beside the arc tube. Thus this high performing lamp could be successfully retrofitted into old fashioned lighting systems.
Manufacturer: General Electric Co. of U.S.A.
Lamp Power: 175 Watts
Lamp Current: 1.4 Amps
Lamp Voltage: 135 Volts
Cap Type: E40s/45 Ni plated brass + vitrite
Bulb Type: ED-75 ED-231/2 (in eighths/inch)
Bulb Finish: Eu:YVO4 phosphor Lead Borosilicate glass
Electrodes: Coil with balled tip Thoriated tungsten
Arc Length: 21.0 mm 0.827 inch
Atmosphere: (Na-Sc-Th)Ix, Hg,Cd | Ar Outer: Vacuum
Luminous Flux: 15,750 lm @ 100h 12,150 lm @ 4000h
Luminous Efficacy: 90.0 lm/W @ 100h
Colour Temperature & CRI: 3100K Ra 70
Chromaticity Co-ordinates: CCx: 0.437 CCy: 0.392
Rated Lifetime: 10,000 hours to 50% survival
Warm-up & Re-strike Time: 2 minutes 10 minutes
Burning Position: Vertical base up ± 15°
Overall Length: 197 mm 73/4 inches
Light Centre Length: 127 mm 5 inches
Factory: Ravenna, Ohio, U.S.A.
Date of Manufacture: November 1989
Original Value: GB £77.18 (1991)
 
References: 1) GE Lamp Catalogue, USA, 1989, p.70
2) GE Lamp Specification Bulletin 6374-132MV (April 1990)
3) GE-Tungsram UK Price List, 1991
4) GE Lamp Training - Metal Halide Lamps - October 1990