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9w UVC PL-S Abuse

9w UVC PL-S Abuse

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Installed this back on 17/07/2016... was removed on 07/04/20 after the hozelock Easyclear 6000 pump decided to go dead short to earth and take out my RCD.
Normally I change these every year but as you can see I have been neglecting my duties!
It's gone quite brown and the end of the lamp is almost like a mirror when you hold it up to inspect it.
One of the cathodes is broken but I know for a fact this was working a few months ago but it probably wasn't doing much at this stage!

These lamps suffer from solarization of the glass. The intense 253.7 and 185.1nm UVC radiation is usually absorbed by the phosphor in normal lamps but in clear lamps there is none and the glass decomposes. The cheapo lamps made from quartz are more susceptible to this whereas the more expensive UV lamps of Philips and Osram ect use a very thin coating (5nm) of Alon C inside the glass which provides a great increase of lamp life and allows it to maintain 50% of initial UVC output for up to 8000 hours. Cheap lamps typically drop below 50% within 1000h.

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Album name:FrontSideBus / Compact fluorescent
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Date added:Apr 21, 2020
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Date Time:2020:04:11 12:03:57
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dor123
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Apr 22, 2020 at 12:37 AM Author: dor123
The phosphor of regular fluorescent lamp, absorbs only tiny amount of UVC. The majority of the UV is blocked by the glass.
Quartz aren't prone to solarization as seen in quartz arctube of MV and MH lamps. Perhaps the UVC transparent glass used in this lamp is prone to this.

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 European date format (dd.mm.yyyy).

I lives in Israel, which is a 230-240V, 50hz country.

rjluna2
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Robert


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Apr 22, 2020 at 08:18 AM Author: rjluna2
That's interesting how these germicide lamps ages

Pretty, please no more Chinese failure.

James
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Apr 22, 2020 at 02:20 PM Author: James
Quartz is in fact exceptionally prone to solarization by short wavelength UVC, and the phenomenon is even worse at low temperatures. In a high pressure mercury or metal halide lamp the wavelengths are longer, and the temperature is also much higher, so the quartz is not attacked.

Also, the phosphor of a regular fluorescent lamp absorbs virtually all of the UVC. The phosphor is specifically engineered to have the maximum possible absorption of 253.7nm mercury radiation, such that this can be converted via the fluorescence process to longer wavelengths. If the phosphor did not absorb the UVC, then there would be very little light generation from a fluorescent lamp - since over 60% of the electrical power input is radiated in the UVC wavelengths! You are right of course that the glass also absorbs the UVC in a regular lamp - but in a phosphor-coated tube that function is not required since the UVC has already been filtered out by the phosphor.
Bottled lightning
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Apr 22, 2020 at 10:03 PM Author: Bottled lightning
The clear areas around the electrodes are interesting, l wonder how long the plastic base on the new one will last.
James
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Apr 22, 2020 at 11:12 PM Author: James
That is a very good observation about the clear areas, I never considered that before! Completely the opposite of most normal lamps. Perhaps it is because the electrodes operate much hotter, and then the quartz is warm enough to limit the effects of solarization.
Medved
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Apr 23, 2020 at 01:30 AM Author: Medved

The phosphor of regular fluorescent lamp, absorbs only tiny amount of UVC. The majority of the UV is blocked by the glass.


That would mean extremely inefficient lamp design.
But the glass UV absorbtion is important for safety reason: Even when the phosphor absorbs 90+% of the UV (I would guess the optimum would be somewhere there), the remaining few percents would be still way too much for the lamp to be safe for general use. For safety the absorbtion must be in the 99.99+% ballpark, so orders of magnitude greater than the phosphor alone. On the other hand loosing the few percent of UV means not much energy loss compare to the visible absorbtion of the phosphor layer if it were to absorb the extra few percents.

No more selfballasted c***

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Aug 05, 2020 at 04:24 AM Author: Jovan
Burned lamp looks quite cheap.Exhaust place is welded like on starters.
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