108CAM
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Diehard MV, HPS, SOX & Preheat Fluorescent Fanatic
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| This is something that I've always wondered. What is the purpose of the silver colour that coats the inside of HPS & SOX lamp bases? I've noticed that only sodium based lamps have it and have always wondered what it's meant to do.
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Fluro starter pings combined with a 50hz ballast hum and blinking tubes is music to my ears.
Rest in Peace Electronic Lamp Manufacturers of Australia
1925-2002
Bring back the AJF Zodiacs!
Total incidents since joining LG: 18
Lamps accidently broken or smashed: 15
Ballast explosions/burnouts: 3
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Medved
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| The outer bulb has vacuum in it, so in order to have really a complete vacuum there (so no glow discharge or so could start there), a "getter" is used to absorb the remaining gasses. Usually that is in the form of a mix of metals, initially sprayed out from their holder (a ring of U-shape reservoir, fast heated by induction) and then deposited onto larger surface, so it has sufficient surface area to do the absorbing...
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No more selfballasted c***
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Rommie
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| Medved is correct, the getter is mostly comprised of barium.
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Econolite03
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Matthew E.
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| What happens if the coating turns white? Is the lamp useless?
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”The Shape of Quality… in Lighting” - Philips Lighting, 1985
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dor123
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Other loves are printers/scanners/copiers, A/Cs
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| The getter turns white if oxygen leaked into the lamp, so the lamp is useless then.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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108CAM
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Diehard MV, HPS, SOX & Preheat Fluorescent Fanatic
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| Thanks for the info! This is something that I had been curious about ever since I got my first HPS lamp.
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Fluro starter pings combined with a 50hz ballast hum and blinking tubes is music to my ears.
Rest in Peace Electronic Lamp Manufacturers of Australia
1925-2002
Bring back the AJF Zodiacs!
Total incidents since joining LG: 18
Lamps accidently broken or smashed: 15
Ballast explosions/burnouts: 3
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joseph_125
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Interestingly Philips marketed a line of SOX lamps that used solid state zirconium-cobalt getter pellet instead of the traditional barium getter. They're quite rare and I think were only ever marketed in Europe. They look really unique though as the lamps are completely clear. http://www.lamptech.co.uk/Spec%20Sheets/D%20SLP%20Philips%20SOXPSG35.htm |
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Rommie
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| Yes, the PSG range. They were only made in 35W and 55W (26W/36W for SOX- E) as the position of the pellet meant that the getter was not as effective on longer lamps.
Quite rare, as you say, especially with the different coloured caps, after a while they changed to normal coloured ones, presumably as a cost-cutting exercise.
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Lampwizard
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| As far as I know some getters for certain lamp types (forgot which ones; quartz lamps?) also function as a hydrogen getter to prevent it from diffusing from the outer bulb through the glass of the discharge vessel. Apparently, the ingress of H2 increases the lamp re-ignition voltage up to the point when the lamps fails to re-ignite, thus rendering the lamp useless...
However, this kind of getter is placed inside a metal ring and does not come in the form of a silver-like layer.
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Philips colour 27: best fluorescent tube colour.
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