Iwasaki Two Kilowatt Clear Mercury Discharge
The 2kW mercury lamp has never been a particularly popular light source, with its market being restricted almost exclusively to Japan and certain European countries where mercury lighting still remains. The vast size of the lamp and the luminaire it requires invariably meant that the same lighting levels could be achieved at lower cost by employing two 1kW lamps instead. The principal application is in high bay industrial floodlighting of very large high-roofed production areas, exterior floodlighting in shipyards etc. Today the 2kW lamp is manufactured solely by Japan's Iwasaki Electric Company in only very small quantities for replacement purposes.

Technologically the lamp is simply a scaled-up version of smaller mercury products, there is no particular challenge to making a lamp of this size. Perhaps the only important addition is a ceramic heat deflector disk welded in place in the neck of the outer bulb; this is required simply to keep the cap and lampholder temperature down as low as possible. The arc tube is fabricated from high purity quartz of 32mm diameter, and at the cap end there is a third auxiliary electrode for ignition. The main electrodes are impregnated with a double carbonate mixture + thoria to provide good electron emission.

Supporting such a bulky arc tube in a safe fashion requires a full metal frame support made of heavy gauge nickel-manganese wire, a slightly springy material which helps to absorb some shocks. Steel strips locate the frame accurately within the outer bulb, the BT shape being essential here to allow a large contact area at the crown. The base is mechanically clamped to the glass for extra strength.
Manufacturer: Iwasaki Electric Co., Ltd
Lamp Power: 2000 Watts
Lamp Current: 8.00 Amps
Lamp Voltage: 270 Volts
Cap Type: E40s/82x80 Ni plated brass + ceramic
Bulb Finish: Clear Borosilicate hard glass
Bulb Type: BT-200 BT-63 in eighths/inch
Overall Length: 495 mm 19½ inches
Light Centre Length: 310 mm 12¼ inches
Arc Length:
Electrodes: Backwound tungsten Double carbonate emitter
Atmosphere: Inner: Hg | Ar (2 atm) Outer: Nitrogen
Luminous Flux: 120,000 lm @ 100 hrs
Luminous Efficacy: 60.0 lm/W @ 100 hrs
Colour Temperature & CRI: CCT: 5700K CRI: Ra 15
Chromaticity Co-ordinates: CCx: 0.320 CCy: 0.379
Burning Position: Universal Horiz. lumens 5% less
Rated Lifetime: 10,000 hours Rated to 70% survival
Warm-up & Re-strike Time: 12 minutes 20 minutes
Factory: Saitama, Tokyo Japan
Date of Manufacture: October 1997 Date Code: 7K15
Original & Present Value: Unknown
References: 1) EYE Lamp Catalogue 1998.