Westinghouse Beauty-Lite Mercury H33GL-400/R

The Westinghouse 'Beauty-Lite' lamp, launched in 1972, was developed to improve the colour rendering of skin tones. It became a popular low cost alternative to the then new metal halide lamps, but as the price of those systems fell it diminished in popularity and was de-listed by the mid 1980s.

The main phosphor is europium activated yttrium phosphate vanadate, identifiable by its characteristic peaks around 605-630nm. It is augmented by a second phosphor of europium activated strontium chlorapatite emitting in the broad blue region of the spectrum and peaking around 440nm.

Westinghouse identified that a primary reason for the poor rendition of skin tones by mercury lamps was due to the strength of the mercury yellow line. This was countered by adding the blue emitting phosphor, which increased colour temperature. A greater weight of the usual red-emitting vanadate could then be added to bring the colour temperature back towards the usual level of a deluxe white mercury lamp, and the combination of this plus the reduced yellow radiation greatly improved skin tone rendering.

Due to the high quantum efficacy of both phosphors, luminous flux is not negatively compromised by this change. The red ratio is 12.5%, marginally higher than the 11% that is a typical for /DX lamps, and colour temperature is also reduced slightly to 3850K. The averaged Ra8 colour rendering index is substantially unchanged, but the R14 test colour, representing skin tone rendition, is improved. However there is a dramatic drop in the CCy co-ordinate. This puts its colour point well below the blackbody locus and imparts a slight rose-coloured hue to the light.
´╗┐Manufacturer: Westinghouse Electric Company
Lamp Power: 400 Watts
Lamp Current: 3.2 Amps
Lamp Voltage: 140 Volts
Cap Type: E39/41 Brass + vitrite
Bulb Type: BT-117 BT-37 in eighths/inch
Bulb Finish: Sr5(PO4)3Cl:Eu2+& YVO4:Eu3+ Leaded borosilicate
Electrodes: Backwound Tungsten Trimetallic oxide emitter
Arc Length:
Atmosphere: Ar|Hg Outer: Nitrogen
Luminous Flux: 20,000 lm
Luminous Efficacy: 50.0 lm/W
Colour Temperature & CRI: CCT:3850K CRI: Ra43
Chromaticity Co-ordinates: CCx:0.385 CCy: 0.373
Lifetime: 24,000 hours to 50% survival
Warm-up & Re-strike Time: 5 minutes 5 minutes
Burning Position: Universal
Nominal Length: 292 mm 11.5 inches
Light Centre Length: 178 mm 7 inches
Factory: Bath NY U.S.A.
Date of Manufacture: May 1982 Date Code: 52
Original Value:
References: 1) Spectral measurement of lamp
2) US Patent 3,670,194, Color-Corrected High Pressure Mercury Vapor Lamp, W.A.Thornton & M.C.Unglert (Westinghouse), Filed 1971-Jan.