GE Infrared Drying Bi-Post Lamp 500T40/3

Incandescent lamps have long been used as a convenient source of heat. Even in the 1890s manufacturers offered high power carbon lamps for domestic radiators. However it it was not until the late 1930s that filament lamps suddenly gained popularity for industrial heating, following the pioneering work of Ford with standard incandescent lamps to accelerate paint drying in its automobile production.

GE was quick to recognise this new application, and during WW2 introduced the first industrial infrared lamp. It was rated 250W in a G-30 bulb, with an under-run tungsten filament to maximise the proportion of infrared energy and shift its radiation to more useful longer wavelengths. More powerful 375W and 500W versions soon followed, as well as a smaller 125W rating to provide a slower ramp-up in temperature for conveyor-belt applications.

The growth of the automotive industry fuelled a desire for more powerful lamps to reduce paint drying times, and the lengths of paint curing tunnels. However, a common problem of the lower wattage lamps was degradation of the capping cement at the high ambient tempeatures of the ovens, which typically contained many hundreds of lamps. During the 1940s GE therefore introduced its 500W and 1000W designs with the Bi-Post base illustrated here. The filament has a unique triangular shape - this proving more efficient when used in conjunction with an external reflector to deliver beams of both high irradiance and high uniformity. The original lamps had a 3.5" LCL, but this was later shortened to 3.0625" to provide higher beam intensity from the same reflectors. This 500W rating was discontinued in 1953-54, but the 1000W remained listed until 1973-74.
Manufacturer: General Electric U.S.A.
Lamp Power: 500 Watts
Lamp Voltage: 115 Volts
Lamp Current: 4.35 Amperes
Cap Type: G22 Medium Bipost Glass
Bulb Type: T-125 T-40 in eighths/inch
Bulb Finish: Clear Borosilicate glass
Filament Type: Triangular Single Coil
Atmosphere: Nitrogen Red P getter
Luminous Flux: 3,375 lumens
Luminous Efficacy: 6.75 lm/W
Colour Temperature: CCT: 2450K
Colour Rendering: Ra 100
Chromaticity Co-ordinates: CCx: 0.480 CCy: 0.411
Lifetime: 5000 hours min.
Burning Position: Universal
Overall Length: 184 mm 71/4 inches
Light Centre Length: 77.8 mm 31/16 inches
Factory: Mattoon, IL U.S.A.
Date of Manufacture: 1950 December Date Code: H36
Original Value: US $5.50 (1948)
References: 1) GE Large Lamp Catalogue, 1948, USA, p.28.
2) GE Large Lamp Catalogue, 1953, USA, p.58.