Philips Infrared Linear Reflector IRG 13342F/01

During the later 1950s there was a drive towards increased power densities from infrared lamps, primarily from the automotive industry which demanded shorter paint drying times. There was also a desire for better uniformity of irradiation. This lamp was one of the more novel departures from established practices to meet those requirements. Philips took the innovative step of shifting from single ended GLS and blown reflector lamps to this linear design. The reduced dimensions allowed closer packing of lamps for higher radiation levels, while the linear construction achieved greater uniformity.

The filament is a coiled-coil that is not self-supporting, and is wound around a tube of quartz which supports it when used horizontally. However, the lamp cannot be burned vertically as the coils quickly sag towards the lower end. Power is supplied from a stem at one end of the tubular bulb - one of the leadwires passing through the quartz tube and being connected to the far end. The filament is limited to a rather low temperature to avoid reaction of the tungsten with its silica support - burning at only 1725K. This restricts its power density quite significantly.

The filament is mounted off-centre in a side-aluminised borosilicate glass tube, such that it delivers a beam angle of about 60 degrees. Interestingly, there are two aluminised spots on the clear side of the bulb - these presumaby serving to facilitate correct orientation of the filament with respect to the reflector before sealing. These lamps appear not to have been a commercial success - the 1955 catalogue noting that they would be withdrawn and replaced by the newer construction of linear quartz infrared lamps.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 500 Watts
Lamp Voltage: 230-250 Volts
Lamp Current: 2.08 Amperes
Cap Type: B22d-3 25X35 Brass & Vitrite
Bulb Type: T-38 T-12 in eighths/inch
Bulb Finish: Internal Aluminised Borosilicate glass
Filament Type: CC-8 Coiled-Coil Axial
Atmosphere: Vacuum Red P & Barium getters
Luminous Flux: 195 lumens
Luminous Efficacy: 1.75 lm/W
Colour Temperature & CRI: 1725K Ra 95
Peak Wavelength: 1350 nm
Chromaticity Co-ordinates: CCx: 0.551 CCy: 0.397
Lifetime: Min. 5000 hours
Burning Position: Horizontal
Overall Length: mm inches
Lighted Length: mm inches
Factory: Eindhoven The Netherlands
Date of Manufacture: 1959 January
Original Value: Unknown
References: 1) Philips International Lamp Catalogue, 1955, p. A62.