Osram Vialox NAV-R 310/360W

Considering the popularity of reflector-type High Pressure Mercury lamps, it was perhaps a logical development to extend similar principles to the High Pressure Sodium lamp. The first such lamps were introduced by Osram-GEC in 1976, however the design never became especially popular.

One reason lies in the fact that mercury lamps require a phosphor coated outer envelope to provide colour correction and an increase in luminous efficacy, whereas sodium lamps do not. Due to the large surface area of coated mercury lamps the possibilities for optical control are limited, and this requires luminaires to have large and expensive reflectors. Additionally, dust is likely to collect on the upper surface of the ellipsoidal bulbs, reducing lumen maintenance during life. Reflector mercury lamps offer a cost saving with the luminaire by eliminating reflectors, while solving the problems of lumen depreciation due to dust accumulation. High Pressure Sodium lamps with clear outer bulbs can however be used in lower cost compact optical systems, and the tubular bulb does not accumulate dust so significantly. Therefore in new lighting installations, a reflector sodium lamp offers little advantage.

Osram-GEC initially offered its reflector sodium lamps in 250W and 400W ratings, but more success was achieved with the introduction of this 310/360W rating. It is equipped with an internal ignitor and is intended as a retrofit for mercury reflector lamps. On a 400W mercury ballast it burns at 360W and delivers 8% energy saving and 83% more light. Further savings of 21% can be achieved by selecting a tapping 10V lower on the ballast, while still delivering 58% more light. Due to continued low sales, this class of lamp was made obsolete at the time of Osram's closure of its Shaw factory in 1999.
Manufacturer: Osram UK Ltd.
Lamp Power: 310/360 Watts
Lamp Current: 3.4 Amps @ 310W 3.7 Amps @ 360W
Lamp Voltage: 110 Volts @ 310W 120 Volts @ 360W
Cap Type: E40s/45 Ni plated brass + vitrite
Bulb Type: RD-166 RD-52 in eighths/inch
Bulb Finish: TiO2 Reflector Borosilicate glass
Electrodes: Backwound Tungsten BCT emitter
Atmosphere: Inner: Na,Hg|Xe Outer: Hard Vacuum
Luminous Flux: 31,500 lm (@ 310W, 100h) 37,000 lm (@ 360W, 100h)
Luminous Efficacy: 102 lm/W (@ 310W, 100h) 103 lm/W (@ 360W, 100h)
Luminous Intensity: 8800 cd (@ 310W, 100h) 9800 cd (@ 360W, 100h)
Beam Distribution: 110° to 50% peak intensity
Colour Temperature & CRI: CCT: 2100K CRI: Ra 23
Chromaticity Co-ordinates: CCx: 0.526 CCy: 0.418
Rated Lifetime: 10,000 hours to 90% flux & survival
Warm-up & Re-strike time: Ignition 40s + Run-up 6min Restrike 15-20 minutes
Burning Position: Universal
Overall Length: 260 mm 101/4 inches
Factory: Shaw, Oldham England
Date of Manufacture: June 1998 Date Code o868
Original / Present Value: GB £96.98 (1994) GB £168.30 (2013)
References: 1) Osram UK Lighting Catalogue 1993/94
2) Osram UK Price List November 1994
3) Osram-GEC Lighting Catalogue 1985/86
4) Osram-GEC Solarcolour Plug-In Brochure, 1972
5) Osram-GEC Solarcolour Brochure, 1981
6) Osram-GEC Solarcolour Brochure, c.1988