CFLs and their Hg Content

[Paul M. Eldridge]

There seems to be a genuine concern over the mercury contained within
CFLs and the potential health and environmental risks this represents.
Looking at reader feedback to various media coverage you see this come
up time and time again, and you get the impression some folks view
CFLs much like toxic nuclear waste.

So with that in mind, I wanted to get a better sense of how the major
lamp manufactures compare, but this hasn't been as easy as I had
expected.

As a starting point, the EPA tells us a typical CFL contains 4
milligrams of Hg.

Source:
http://www.nema.org/lamprecycle/epafactsheet-cfl.pdf

According to GE's website, the average is 5 milligrams (close enough).

Source:
http://www.gelighting.com/na/home_lighting/ask_us/faq_compact.htm

The data for Osram Sylvania suggests mercury content can vary
considerably (i.e., from less than 1.8 mg to just under 15 mg) but,
for the most part, it falls within the range of 3 mg to 5 mg.

Source:
http://www.sylvania.com/content/display.scfx?id=003690938

Lastly, we have Philips and in the case of their "Extreme Low Mercury"
line, these numbers are reported to all fall below 2 mg.

Source:
http://www.lighting.philips.com/gl_...main=global&parent=4390&id=gl_en_news&lang=en

But here's where things get a bit murky for me. I had initially
thought the "Extreme Low Mercury" line might be the same thing as
Alto, but that's not the case. For example, the 25-watt Marathon
Universal, which proudly wears the Alto badge, contains 2.64 mg of Hg.

So are these "Extreme Low Mercury" lamps available only in Europe and
is this designation something different from Alto? Or is it a case
that the numbers for Alto will eventually drop over time?

Philips has kindly listed the mercury content of specific Alto and
non-Alto CFLs, but not all (e.g., their popular "Twister" line). It
would be helpful if manufacturers were a little more forthcoming with
this information, so that we, as consumers and specifiers, could make
better-informed choices.

Cheers,
Paul

 

[Victor Roberts]

From a quick visual inspection, in one of the OSRAM DULUXSTAR 21W/827 lamps
which are used in my mother's kitchen, I can discern a tiny ball of Mercury
which has condensed at the bottom of the tube.

The ball has roughly a diameter of 1mm by inspection. Assuming that's that
most of the Mercury in the tube and assuming the little ball is roughly
spherical (which because of surface tension on such a tiny amount is not a
very unreasonable assumption), plugging r = 1/20 cm into the formula for the
volume of a sphere, V = 4/3 * Pi * r^3, and then multiplying that with the
density of Mercury d = 13.5 g/cm^3, I get:

0.007 g = 7 mg, which seems to be close to the values reported on your
references above, albeit on the high end.

Are you sure the ball is not a mercury amalgam?

--
Vic Roberts
http://www.RobertsResearchInc.com
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[Don Klipstein]

[snip]

Are you sure the ball is not a mercury amalgam?

No, I guess I'm not. Are there any fluorescents or CFLs which contain mercury
amalgams?

Yes, there surely are. I have some where this little ball is solid, and
bounces around with a rattling sound if I shake the lamp vigorously.

And if so, shouldn't I expect to see spectral lines of the
particular amalgam component in addition to the mercury lines themselves? On
the DULUX I see only mercury lines and fluorescence bands and lines from
terbium and europeum ions.

Only if the amalgam component other than mercury leads to a vapor
component with concentration no less than maybe 3 orders of magnitude
below that of the concentration of the mercury vapor.
I doubt the amalgam has an alkali metal since alkali metals react with
the usual grades of glass enough to cause problems in lamps. Even sodium,
potassium and lithium can't produce enough vapor to show up much in a
spectrum at even 80 degrees C or so. I give similar to worse prospects
for thallium, indium, gallium, aluminum, cadmium, zinc, barium, strontium,
and calcium. I say no better for tin, lead and magnesium since these fare
worse for visible and near-UV. Cadmium may achieve only 2 orders of
magnitude weaker in vapor concentration than mercury at a given
temperature, but it is noted as a toxic material. I also doubt use of
less-common rubidium and cesium and radioactive francium and radium -
along with probably all metals in the first column of the periodic table
probably having some ability to react with most glass in a bad way within
lamps even at hardly above room temperature. Almost any other metal
produces even less vapor than any of the above at fluorescent lamp bulb
inner surface temperatures.

- Don Klipstein ([email protected])

 

[Victor Roberts]

[snip]

Are you sure the ball is not a mercury amalgam?

No, I guess I'm not. Are there any fluorescents or CFLs which contain mercury
amalgams?

Yes, Many if not most CFLs use mercury amalgams. You can
usually tell by looking at the shape of the bulb. Lamps
without amalgams use cold chambers, typically small bumps in
the glass at the ends of the tubes that are outside the path
of the discharge. Without either a cold chamber or an
amalgam the mercury pressure would be too high since the
tubing is so small.

And if so, shouldn't I expect to see spectral lines of the
particular amalgam component in addition to the mercury lines themselves? On
the DULUX I see only mercury lines and fluorescence bands and lines from
terbium and europeum ions.

No. The goal is to change only the mercury pressure, not
the spectrum. Anything that competes with Hg for energy
from the electron cloud will decrease efficacy . Typical
amalgam materials are led, tin, or bismuth.

--
Vic Roberts
http://www.RobertsResearchInc.com
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