Osram Metal Halide Powerstar HQI-T 400W/DH

This lamp is representative of Osram's third generation of rare earth metal halide lamp, and was introduced in the late 1970s. Many aspects of its construction are similar to the second generation design, although this particular lamp is optimised for horizontal burning whereas the 2nd generation lamp featured on this website is the equivalent model for vertical burning. The main difference between the two is in the filling of the arc tube - the horizontal model being dosed with slightly less mercury and modified halide chemistry to account for the more significant upward bow of the arc, whose increased length would otherwise cause a rise in lamp voltage and power dissipatation, with a consequent negative impact on lifetime and colour.

The main technical step forward with this 3rd generation lamp is the inclusion, for the first time, of a hydrogen getter in the outer envelope. Metal halide arc tubes are particularly sensitive to trace impurities of hydrogen - it causes an increase in the re-ignition voltage of the discharge on each half-cycle of the mains, and rising concentrations can eventually lead to lamp failure. The 2nd generation lamp required a glass bulb made of a glass having a particularly low hydroxyl ion concentration, however that requirement could be relaxed following the introduction of the hydrogen getter. The getter takes the form of two small strips of steel near the pinch-seals of the arc tube, the surfaces being coated with a zirconium-aluminium alloy which has a high affinity for hydrogen. The new getters replaced the earlier barium film, but it was later learned that although they were effective in eliminating hydrogen, they were less effective for other gases. The fourth generation lamp saw their use combined with the re-introduction of the barium getters.
Manufacturer: Osram GmbH
Lamp Power: 360 Watts
Lamp Current: 3.5 Amps
Lamp Voltage: 120 Volts
Cap Type: E40s/45 Ni plated brass + porcelain
Bulb Type: T-46 T-14½ in eighths/inch
Bulb Finish: Clear Borosilicate
Electrodes: Backwound Tungsten No emitter
Arc Length: 48 mm 1 7/8 inch
Atmosphere: DyI3,TlI,CsI | Ar:Kr85 Outer: Hard Vacuum
Luminous Flux: 25,000 lm @ 100 hours
Luminous Efficacy: 69 lm/W @ 100 hours
Colour Temperature & CRI: CCT: 5900K CRI: Ra 85
Chromaticity Co-ordinates: CCx: 0.330 CCy: 0.365
Rated Lifetime: 6,000 hours to 70% flux
Warm-up & Re-strike Time: 2 mins to 80% flux 10-15 minutes
Burning Position: Horizontal ± 45°
Overall Length: 285 mm 111/4 inches
Light Centre Length: 175 mm 67/8 inches
Factory: Spandau, Berlin Germany
Date of Manufacture: October 1982 Date Code: qU3
Original / Present Value: Unknown
References: 1) Osram Power Stars Technical Manual, August 1984.
2) Osram Outdoor and Indoor Lighting Catalogue, Germany, 1984.