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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Energy saving lamps
I wonder if any of you knowledgeable folks out there know why compact
fluorescent lamps take time to get up to full brilliance?, in my kitchen I have a conventional 5" linear fluorescent and it is at full brilliance as soon as you switch it on. Trevor Smith |
#2
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Energy saving lamps
Trevor Smith wrote:
I wonder if any of you knowledgeable folks out there know why compact fluorescent lamps take time to get up to full brilliance?, in my kitchen I have a conventional 5" linear fluorescent and it is at full brilliance as soon as you switch it on. Basically, the operating temperature of the linear tube - I assume you mean 5' - is much closer to room temperature. With CF, they run at 100C or so. In order to get the optimum pressure of mercury when running, the 'off' pressure is rather lower. It's also a compromise between electrode life and turn-on speed. If it takes 1-2 s to start, then it allows the electrodes to warm up before the tube is started. This causes less wear of the electrodes and blackening at the ends than 'instant on'. (this is completely seperate from the tubes taking time to warm up once on) |
#3
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Energy saving lamps
Ian Stirling wrote: Trevor Smith wrote: I wonder if any of you knowledgeable folks out there know why compact fluorescent lamps take time to get up to full brilliance?, in my kitchen I have a conventional 5" linear fluorescent and it is at full brilliance as soon as you switch it on. Basically, the operating temperature of the linear tube - I assume you mean 5' - is much closer to room temperature. With CF, they run at 100C or so. In order to get the optimum pressure of mercury when running, the 'off' pressure is rather lower. It's also a compromise between electrode life and turn-on speed. If it takes 1-2 s to start, then it allows the electrodes to warm up before the tube is started. This causes less wear of the electrodes and blackening at the ends than 'instant on'. (this is completely seperate from the tubes taking time to warm up once on) Sorry I meant 5', when you say they run at 100C I take it you don't mean the operating temperature as I have just touched the tube of a 15 watt CF and it is warm but definitely not 100C Trevor Smith |
#4
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Energy saving lamps
In article . com,
"Trevor Smith" writes: Ian Stirling wrote: Trevor Smith wrote: I wonder if any of you knowledgeable folks out there know why compact fluorescent lamps take time to get up to full brilliance?, in my kitchen I have a conventional 5" linear fluorescent and it is at full brilliance as soon as you switch it on. Actually, it's not. Initial output is nearer the final brightness than is the case with compact fluorescents, but long linear tubes still have a run-up time, and it's actually much longer than a compact fluorescent (20 minutes is quite typical). Basically, the operating temperature of the linear tube - I assume you mean 5' - is much closer to room temperature. With CF, they run at 100C or so. In order to get the optimum pressure of mercury when running, the 'off' pressure is rather lower. Conversely, long linear tubes are designed to run at 40C in a ambient of 25C. (Actually, that's T12 tubes -- I don't have the figure for T8 tubes, but it's probably not a lot higher.) Another factor is that most compact fluorescent tubes use a mercury amalgam pellet to control the mercury vapour pressure over the range of operating temperatures the tube might find itself in. It takes time for this pellet to warm up and for the mercury to diffuse out of it. This is not necessary in T12 and most T8 tubes, although all the new T5HE and T5HO linear tubes use it. Sorry I meant 5', when you say they run at 100C I take it you don't mean the operating temperature as I have just touched the tube of a 15 watt CF and it is warm but definitely not 100C It will depend on the enclosure, but they are designed to run with the tube up to 100C. -- Andrew Gabriel |
#5
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Energy saving lamps
The message
from Ian Stirling contains these words: It's also a compromise between electrode life and turn-on speed. If it takes 1-2 s to start, then it allows the electrodes to warm up before the tube is started. Doesn't it also increase the output per unit area? A more important consideration in CFLs than in linear units. -- Skipweasel Pay no attention to that man behind the curtain. |
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