Philips HPLR 125W with E40 Cap

This lamp is representative of one of the last Philips mercury reflector lamps made with the company's Magnesium Fluoro-Arsenate phosphor before changing to the more efficient Yttrium Phosphate-Vanadate chemistry during latter part of the 1960s.

Unusually for such a low wattage rating, it employs an E40 cap, which was only produced upon special request. The original 125W mercury fluorescent lamps of the 1930s employed E40 caps and it was not until the 1950s with the development of Magnesium Fluoro-Germanate phosphors, which permitted a significant reduction in bulb size, that the smaller E27 cap became standard for the 125W rating. Mercury lamps were not manufactured in reflector bulbs prior to that time, so it is surprising that such a late model as this should have been offered with the large E40 cap. Possibly the reflector bulb was offered as an upgrade for older E40 luminaires originally made for non-reflector lamps.

The bulb is blown in borosilicate glass, and is acid-etched on its internal surface. This homogenises the light colour throughout the beam, since the arc tube radiates the classic blueish-green light while the phosphor coating around it adds the red component. The bulb is double-coated, first with a partially translucent layer of white titanium dioxide powder which acts as a diffuse reflective coating, and then overcoated with the vanadate fluorescent powder. The coating thicknesses are adjusted so as to allows a small amount of light to escape through the coating, but the vast majority is reflected downwards. Due to the uncoated bulb crown, the red ratio is slightly lower than non-reflector types having the same phosphor coating.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 125 Watts
Lamp Current: 1.15 Amps
Lamp Voltage: 125 Volts
Cap Type: E40s/45 Ni plated brass + vitrite
Bulb Type: R-125 R-40 in eighths/inch
Bulb Finish: 6MgO.As2O5:Mn2++ TiO2 Pearl Borosilicate glass
Electrodes: Backwound Tungsten
Arc Length: 23mm inches
Atmosphere: Inner: Hg|Ar Outer: Nitrogen
Luminous Flux: 5,500 lm (@ 100hrs)
Luminous Efficacy: 44 lm/W (@ 100hrs)
Beam Distribution: 120° to 50% peak intensity
Colour Temperature & CRI: CCT: 4000K CRI: Ra 50
Chromaticity Co-ordinates: CCx: 0.380 CCy: 0.380
Rated Lifetime: 24,000 hrs to 50% survival
Warm-up & Re-strike time: 4 minutes 10 minutes
Burning Position: Universal
Overall Length: 199 mm 7 13/16 inches
Factory: Eindhoven Netherlands
Date of Manufacture: December 1969 Date Code 9M
Original / Present Value: Unknown
References: 1) Philips Lichtcatalogus "Gasontladingslampen" c. 1975.
2) Philips Training Manual MTO Turnhoutlampen, Hogedruk-Kwiklampen, Van der Stap & Goethals, 1986.