Philips HPR 125W Mercury Actinic Reflector

The Philips HPR lamp was developed in the late 1940s for reprographic applications. The high actinic content of the beam makes it ideal in copy board equipment, for black and white photographic reproduction. It also found applications in silk screen printing, and provided a powerful source of blacklight radiation when used with a Woods' glass filter.

At the heart of the lamp is standard high pressure mercury arc tube. This is sealed into a reflector-shaped bulb having an internally aluminised coating, and made from a special glass that is mildly transmissive to UV radiation down to about 300nm. The reflector features longitudinal ridges to broaden the otherwise very narrow beam from the mercury arc, and the deeply curved front bowl bears numerous tiny pyramidoidal indents to thoroghly homogenise the light distribution. It is interesting to note that this complex-shaped glass reflector has been blown into a three-piece mould, with a fourth section for the front lens area - it would not of course be possible to remove the solidified glass bulb shell from an ordinary 2-part split mould.

The result is a high intensity beam of about 30° to half-peak. In the intended application, a number of lamps would be inclined at 35° to the copy board surface, that orientation resulting in impressively uniform irradiation. The neck of the lamp is sprayed black to avoid backward glare.

The HPR 125W proved extremely popular and was widely specified for many decades. It began to decline only in the 1980s when it was gradually replaced by higher power linear and metal halide sources. It was finally discontinue around 1990, following the closure of the Philips Eindhoven Strijp-S glass works that produced the special glass bulbs.

Manufacturer:	Philips Lighting
Lamp Power:	125 Watts
Lamp Current:	1.15 Amps
Lamp Voltage:	125 Volts
Cap Type:	E27/30	Nickel plated brass
Bulb Type:	ER-108	ER-34 in eighths/inch
Bulb Finish:	Aluminised & black neck	Hard Glass
Electrodes:	Backwound tungsten	Double carbonate emitter
Atmosphere:	Inner : Argon	Outer : Nitrogen
Luminous Flux:	2900 lumens
Luminous Efficacy:	23.2 lumens per Watt
Peak Intensity:	N/A
Beam Angle:	30 degrees	Batwing distribution
Colour Temperature & CRI:	CCT: 6000K	CRI: Ra16
Chromaticity Co-ordinates:	CCx: 0.315	CCy: 0.380
Rated Lifetime:	2000 hours	to 20% UV maintenance
Burning Position:	Univesal
Overall Length:	222 mm	8³/₄ inches
Light Centre Length:	N/A
Factory:	Turnhout	Belgium
Date of Manufacture:	1984 August	Date Code: D4
Original Value:	GB £29.84 (1988)


References:	1) Philips Lamp Catalogue 1984 NL p.223.
	2) Philips Lamp Catalogue 1985 UK pp.429-430.
	3) Philips Lamp Catalogue 1952 UK p.38.
	4) Philips Lamp Catalogue 1955 International p.B17.
	5) Philips UK Price List, 1988.