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SON High Pressure Sodium
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Updated
26-VII-2006 |
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The High Pressure Sodium lamp is the invention of General Electric USA, although Osram-GEC, and Mazda and Philips were also key players in the race to be first to create this lamp. The fundamental principal behind the lamp is that the narrow, monochromatic sodium resonance lines can be considerably broadened if the sodium vapour pressure is increased. However, higher wall temperatures are required to achieve this and the advanced glasses which can just about withstand sodium attack in the low pressure lamp become blackened in a matter of minutes at higher temperature.
The key to the success of the high pressure sodium lamp is an arc tube fabricated of translucent ceramic, since there is no known glass which withstands the corrosion of sodium at high temperature. Aluminium oxide (alumina) is the chosen ceramic since, when combined with minute traces of dopants to control the grain structure, it can be made translucent by a process which is suited to mass production.
Once the ceramic tube is made, the problem of sealing an electrical conductor through it must then be faced. It is standard practice to use special sealing glasses, but these still represent a weak point in the lamp design. Other designs are liable to cracking or may leak over time. The lamps on this page highlight many of the different sealing techniques which have been tried, while also representing a broad selection of the different lamp styles that have been made available over the years. |
| | Early Lamp Designs |
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Atlas |
250W |
| SON-T Stellox - the first commercial British lamp |
| 1970 |
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GE |
400W |
| LU400/BD Early Lucalox American lamp |
| 1971 |
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GEC |
120W |
| SON-I with internal snap-switch ignitor |
| 1976 |
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GE |
50W |
| Early low wattage lamp with niobium wire seals |
| 1980 |
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Thorn |
70W |
| Early low wattage lamp with large bore arc tube |
| 1983 |
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Westinghouse |
150W |
| Canadian-made lamp with niobium cup seals |
| 1974 |
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| | Modern Lamp Designs |
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Philips |
250W |
| Standard High Pressure Sodium lamp |
| 1980 |
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Sylvania |
200W |
| Lumalux LU200 of typical U.S. Sylvania design |
| 1982 |
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Norleco |
250W |
| SON-T 250W of design for USA market |
| 1980 |
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Tungsram |
250W |
| TC 250W with double niobium wire seals |
| 1985 |
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Thorn |
70W |
| SON XL-T with cermet end seals |
| c. 1990 |
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Thorn |
400W |
| SON XL-T with sintered moly antenna on tube |
| 1991 |
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Sylvania |
400W |
| Twin arc tube lamp for instant restrike |
| 1989 |
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GE |
70W |
| SON-I with internal electronic ignitor circuit |
| 1990 |
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Iwasaki |
150W |
| Ignitron lamp with internal FEC ignitor |
| 1997 |
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Iwasaki |
150W |
| Sunlux Ultra Ace with Unsaturated Vapour |
| 2000 |
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Sylvania |
100W |
| SHP-MF Mercury-Free high pressure sodium |
| 1996 |
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Thorn |
70W |
| SON-R Reflector style high pressure sodium |
| 1982 |
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Reflux |
250W |
| Reflux lamp with special side reflector |
| 2003 |
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GEC |
250W |
| SON-L SolarStream Gas-filed Linear style |
| 1996 |
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Thorn |
400W |
| SON-TD Double ended quartz design |
| 1987 |
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Osram |
400W |
| NAV-TS Vialox Standard Gas-filled Linear style |
| 1989 |
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Osram |
150W |
| SON-TS Super double ended design |
| 2000 |
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| | High Colour Rendering / 'White' Light |
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Matsushita |
50W |
| K-HICA-Light White SON with elliptical arc tube |
| c. 1985 |
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Iwasaki |
50W |
| NHT50 SDX White SON High Colour Rendering |
| c. 1985 |
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Philips |
50W |
| SDW-T White SON with high CRI |
| 1991 |
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Philips |
150W |
| SON-T Deco for City Beatification projects |
| 1995 |
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Philips |
100W |
| SDW-TG Reduced size Mini WhiteSON |
| 2002 |
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| | Experimental Designs |
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Westinghouse |
400W |
| Corstar sapphire arc tube experimental lamp |
| 1977 |
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Thorn |
70W |
| Corstar sapphire arc tube experimental lamp |
| c. 1983 |
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Thorn |
400W |
| SON-Deluxe with infra-red reflecting sleeve |
| c. 1983 |
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Thorn |
40W |
| SON-E Experimental low wattage lamp |
| c. 1984 |
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Tesla |
70W |
| SHC with Monolithic 2-Piece PCA design |
| 1987 |
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Osram |
70W |
| SON-Plus with side arm to measure vacuum |
| 1991 |
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