Philips Infraphil Blown Reflector 13373F/479
Philips introduced its first IR therapeutic lamps in 1946 under the 'Infraphil' brand, optimised for human irradiation. Whereas most IR lamps have low temperature filaments below 2500K and lives exceeding 5000 hours, the Infraphil operates at ~2900K with life ~300 hours. The short life of this consumer lamp not stimulated sales, but has a scientific basis in that the radiation peak is shifted to 1000nm and is able to penetrate much deeper into human tissue.

For IR therapy it is desirable to maximise the penetration of heat deep into the muscle, but this is limited by the onset of pain when skin temperatures exceed 44°C. This is why the Infraphil lamp was never made in powers exceeding 150W. However thanks to the wavelength shift, Philips was first with a biologically-optimised lamp whose heat was delivered below skin level - allowing an increase in power density without risk of pain, and much more effective treatment.

The first Infraphil was the model 7525 of 1946 with a deep parabolic reflector to produce a much more concentrated beam than other IR lamps. The flat grid filament ensures better beam uniformity than ordinary filament constructions. Within a few years it was replaced by the 7526 ruby stained version, and around 1950 was re-named 13373F/479 as on this lamp. The ruby coating is not only to reduce glare, but has a very important function in blocking wavelengths below 600nm which are absorbed by haemoglobin in the blood, allowing IR levels to be increased without risk of haemolysis. The lamp is equipped with a 3-pin bayonet cap to allow use only in the dedicated Philips Infraphil luminaires. Around 1965 this type was superseded by a lower cost lamp having the more standardised R-125 bulb with flatter front face.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 150 Watts
Lamp Voltage: 210 Volts
Lamp Current: 0.71 Amperes
Cap Type: B22d-3/25x26 Brass + vitrite
Bulb Type: R-125 R-40 in eighths/inch
Bulb Finish: Ruby stained Borosilicate glass
Filament Type: C-11 Horizontal Grid
Atmosphere: 85:15 Argon-Nitrogen Red P & ZrAl getters
Luminous Flux: 15 lumens
Luminous Efficacy: 0.1 lm/W
Luminous Intensity: N/A
Beam Distribution: Approx 10° to 50% peak intensity
Colour Temperature & CRI: CCT: 2900K (Filament) Ra 50
Chromaticity Co-ordinates: CCx: 0.650 CCy: 0.330
Lifetime: 300 hours
Burning Position: Universal
Overall Length: 180 mm 71/32 inches
Light Centre Length:
Factory: Emmasingel, Eindhoven Netherlands
Date of Manufacture: 1961 March
Original Value:
References: 1) Philips Catalogue, 1959 Australia, p.F7.
2) Philips Catalogue, 1962 UK, p.A24.
3) Philips Catalogue, 1964 UK, p.A29.
4) Philips Catalogue, 1964 Australia, p.F6.
5) Infraphil.info - The History of Philips Infraphil 1945-2014
6) Philips Research - 100 Years of Key Innovations
7) Philips Lighting Correspondence Course - No.13 IR Radiators & Applications p.17-19, 21-22 (1988).
8) Lamps for Personal Care, Philips Brochure, p.12-15 (1987)
9) Photoelectric measurement.