Quartz Infrared 500T3/CL
Illustrated here is one of the first quartz infrared lamps, invented by Bill Hodge and Alton Foote of GE in the 1950s. Earlier lamps were based on standard incandescent designs in G-30 spherical or R-40 reflector bulbs, which delivered circular beams not well suited to consistent irradiance along conveyor-type applications. Their large dimensions also limited power densities to about 1000W/sq.ft. Experiments were made to develop linear lamps to produce rectangular beams, but still higher power densities were desired.

Trials were made to seal a filament into a narrow quartz tube, but these blackened far too quickly due to the reduced internal surface on which vaporised tungsten was deposited. This was overcome following the discovery that the water cycle which transports tungsten from the filament to the bulb wall could be halted by eliminating hyrdogen impurities with a tantalum getter. This was provided in the form of small tantalum discs, which perform the dual role of supporting the filament axially along the quartz tube. The quartz IR lamp was introduced in the mid 1950s, and immediately achieved power densitities up to 5000W/sq.ft

The first lamps had tubes of low cost sand-fused silica with a translucent diffuse finish. This lamp is a later model having a clear tube of fused natural quartz, a very expensive material that raised lamp cost by about 60% but achieved a notable increase in radiation intensity thanks to the sharper imaging of the filament in external reflectors. At the time these lamps were introduced, there was no established cap type for linear quartz products. They therefore make use of 6" flexible nickel-braided wires, the connection to the lamp being protected and stengthened by a small shield of folded nickel sheet welded over each of the ends.
Manufacturer: General Electric Co. USA
Lamp Power: 500 Watts
Lamp Voltage: 115-125 Volts
Lamp Current: 4.177 Amperes
Cap Type: Nickel caps & wires 6" length
Bulb Type: T-10.5 T-3 in eighths/inch
Bulb Finish: Clear Quartz
Filament Type: C-8 Coiled Axial
Atmosphere: Argon 600mBar Tantalum getter
Luminous Flux: 4000 lumens
Luminous Efficacy: 8.0 lm/W
Luminous Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: 2500K Ra 100
Chromaticity Co-ordinates: CCx: 0.478 CCy: 0.414
Lifetime: >5000 hours
Burning Position: Horizontal
Overall Length: 224mm 813/16 inches
Lighted Length: 127mm 5 inches
Factory: Bellevue, OH U.S.A.
Date of Manufacture: 1963 September Date Code: 93
Original Value: US $12.00 (1969)
References: 1) GE Large Lamp Catalogue 1960 USA, p.37
2) GE Large Lamp Catalogue 1969 USA, p.40
3) Revolution in Lamps, R.Kane & H.Sell, publ. The Fairmont Press, 2001, pp. 65-74
4) US Patent 2,864,025 - Infrared Ray Generating Device - Foote A.G. & Hodge W.F (General Electric), Filed 24 August 1953.